Feasibility of Diverting and Detaining Flood Water and Urban Storm Runoff, and the Enhancement of Natural Recharge

Feasibility of Diverting and Detaining Flood and Urban Storm Runoff and the Enhancement of Ground Water Recharge in the Tucson Area, Pima County, Arizona (Phase I Draft)

Authors Water Resources Research Center

Publisher Water Resources Research Center, University of Arizona (Tucson, AZ)

Download date 09/10/2021 23:23:52

Link to Item http://hdl.handle.net/10150/314310 Phase I Draft FEASIBILITY OF DIVERTING AND DETAINING FLOOD WATER AND URBAN STORM RUNOFF, AND THE ENHANCEMENT OF NATURAL RECHARGE.

Water Resources Research Center College of Earth Sciences University of Arizona FEASIBILITY OF DIVERTING AND DETAINING

FLOOD AND URBAN STORM RUNOFF

AND THE ENHANCEMENT OF GROUND WATER

RECHARGE IN THE TUCSON AREA

PIMA COUNTY ARIZONA

DRAFT

THE WATER RESOURCES RESEARCH CENTER

COLLEGE OF EARTH SCIENCES

UNIVERSITY OF ARIZONA

TUCSON, ARIZONA 85721

MAY 1980 ACKNOWLEDGEMENTS

Prepared for

United States Army Corps of Engineers Los Angeles District Tucson Urban Study Regional Flood Control Element

The University of Arizona College of Earth Sciences Water Resources Research Center in cooperation with College of Agriculture

Investigators:

Professor Sol D. Resnick, Director, WRRC Dr. K. James DeCook, Hydrologist, WRRC Dr. L. G. Wilson, Hydrologist, WRRC in cooperation with:

Mr. J. E. Posedly, Department of Soils, Water and Engineering, College of Agriculture

Project Coordinator:

Jonathon C. Goldman

Contributors: Editors:

John E. Stufflebean K. James DeCook Dale A. Altshul Sol D. Resnick John B. Price Jonathon C. Goldman Jonathon C. Goldman Sol D. Resnick

Staff: Graphics:

L. Donald R. Brokaw J. Newhouse A. Troutner S. Schuster N. Svacha

i ABSTRACT

ii TABLE OF CONTENTS

PHASE I FEASIBILITY OF DIVERTING AND DETAINING FLOOD WATER AND URBAN STORM RUNOFF, AND THE ENHANCEMENT OF NATURAL RECHARGE

Page

ACKNOWLEDGEMENTS

ABSTRACT

CONTENTS iii

LIST OF TABLES vi LIST OF FIGURES viii

INTRODUCTION 1

PURPOSE AND SCOPE 1 HOW TO USE THIS REPORT 1 LOCATION AND DESCRIPTION OF STUDY AREA 2

DIVERSION AND DETENTION 4

PRECIPITATION 5 RAINFALL - RUNOFF RELATIONSHIPS 38 RUNOFF 77 METHODS OF DIVERSION AND DETENTION 113 CHANNEL HYDRAULICS 115 CHANNEL MODIFICATIONS 116

Historic 116 Present and Planned 117

EVAPORATION AND TRANSPIRATION 124 QUALITY (DIVERSION AND DETENTION) 127 QUALITY (GROUND WATER RECHARGE) 137

RECHARGE ENHANCEMENT 141

INTRODUCTION 141 METHODS 142

Spreading - Basins /Pits 142

iii Page

Factors that Affect Basins and Pits 143 Design and Operation of Basins and Pits 146 Examples of Basins and Pits 151

Wells /Shafts 153

Factors that Affect Wells and Shafts 158 Design and Operation of Wells and Shafts 164

Augmenting Streambed Infiltration 168

Factors that Affect Streambed Infiltration 168 Design and Operation of Streambed Infiltration Enhancement 170

TECHNICAL INFORMATION REQUIREMENTS /COLLECTION TECHNIQUES 170

Infiltration 170 Percolation 173 Storage 175 Recovery 177

DATA AVAILABLE 178

Infiltration 178 Recharge 187 Hydrogeologic Conditions 191 Subsidence 205

SOURCES AND USE 207

CENTRAL ARIZONA PROJECT 208

History 208 The Plan at Present 209 Quality of Delivered CAP Waters 214 Delivery Sites 214 Summary 215

BENEFICIAL USE 215

Legal Definition 215 Uses 220 Reduction of Flood Damage 220 Flood Damage Reduction by Diversion, Detention and Recharge of Storm Runoff 221 Municipal and Domestic Uses 223

iv Page

Mining and Industrial Uses 232 Agriculture 239

Summary 247

Recreational Use 242

Summary 247

Other Benefits 248 Exchanges 248

LAND USE INVENTORY AND PROJECTIONS 250

NATURAL DRAINAGE SYSTEM LAND USE 251 LAND USE PROJECTIONS 253

REFERENCES CITED 254

BIBLIOGRAPHY 268

APPENDICES 275

APPENDIX A - 276 APPENDIX B 299 APPENDIX C 303 APPENDIX D 347 APPENDIX E 358 APPENDIX Z 389 APPENDIX K 400 APPENDIX X 403 APPENDIX Y 405

v TABLES

Number Title Source

LA Normals, Means & Extremes National Weather Service 2A Duration array - return periods Reich, 1978 3A Coefficients - Atterbury Fogel, 1969 4A Hydrologic effects - Urbanization Savini & Kammerer, 1961 5A Description, Curve numbers, Coefficients - Kao et al., 1973 Urban Watersheds 6A Mean rainfall - runoff Modified SCS Boyer & DeCook, 1975 7A Events - Tucson Area Arai et al., 1977 8A Storms and Runoff High school WS Diskin & Resnick, 1976

9A Storms and Runoff Arcadia WS Diskin & Resnick, 1976 10A Statistical parameters High school WS Diskin & Resnick, 1976 11A Statistical parameters Arcadia JJS 12A Relationships between Variables High School WS 13A Relationships between Variables Arcadia WS 14A Rainfall - Runoff data Tucson Arroyo WS Foerster, 1972 15A Rainfall - Runoff data Atterbury WS 16A Distrubution of annual Streamflow Condes de la Torre, 1970

17A Monthly flood peaks above base IV II II II 18A Variablility of peak discharge II II II II 19A Flood Volumes it II II

20A Historic peak flows U.S. Army Corps of Engineers, 1975

21A Peak flows - IR & SPF " 1973

22A Average Velocities of flow II 1975 & 1973 23A Rates of Rise and Duration n y n n 1975 & 1973 24A 5 Highest peak flows by year - High School Diskin & Resnick, 1976 WS 25A 5 Highest peak flows by year - Arcadia WS 26A Peak flows by frequency - High School and - Arcadia Watersheds 27A Urban Runoff Pima Ass'n. of Governments, 1977 28A Annual Runoff - Urban & Semi -Urban

vi TABLES (cont.)

Number Title Source

100 Range and Mean of Chemical Constituents Laney, 1972 110 Water and Suspended Sediment discharges Laney, 1972

RECHARGE ENHANCEMENT

1B Tucson Basin Inflow, outflow, Infiltration. Burkham, 1970

2B Tucson Basin Water Budget

3B Hydrogeologic Characteristics Fogg, 1978

10 CAP Water Allocation, Delivery Schedule - Bureau of Reclamation, 1979 and Priorities

20 Consumptive uses and demand Quality - (Summary) Quantity

- v. 30 Treated Water Quality Standards & Goals Bóz`et,1974

40 Ground Water Quality - Upper Santa Cruz Pima Association of Governments, Groundwater Basin 1979

50 Industrial Water Consumptive Use Projections 1978

60 Industrial Water Quality Demands Federal Water Pollution Control Admin., 1968

70 Projected and Total Irrigation Consumption Pima Association of Governments, 1978 80 Herbicide Levels for Irrigation Waters Federal Water Pollution Control Admin., 1968

90 Effluent Quality Gudelines for Various Uses RGA Consulting Engineers, 1979 100 Summary of generalized Land use in Eastern City of Tucson et al., 1975 Pima County

vii FIGURES

Number Title Source

Fig. 100 Location of Study Area WRRC

I, lA Precip. and Temperature Summaries National Weather Service

2A Precipitation monthly (WRRC, 1979)

3A Total Precipitation 1976 Wood, NWS

4A Total Precipitation 1977 Wood, NWS

5A Total Precipitation 1978 Wood, NWS

u 6A Total Precipitation 1979 Wood, NWS

" 7A Precipitation vs. Altitude Condes de la Torre, 1970

8A Atterbury, Experimental Watershed Boyer & DeCook, 1975

9A Walnut Gulch Experimental Watershed (Renard & Kepple.)

" 10A Isohyetal map Storm of Aug. 20, 1956, Woolhiser & Atterbury Schwalen, 1960

" 11A Frequency of magnitude of storm centers Woolhiser & Schwalen, 1960

12A Storm Center, Area -Depth Relations Woolhiser & Schwalen, 1960

" 13A Isohyetal map Storm of July 16, 1975 Boyer & DeCook Atterbury 1975

" 14A Depth of Rainfall - Recurrence Fogel & Duckstein, 1969

" 15A Occurrences - Depth Osborn et al., 1972

" 16A 2 yr. - 6 hr. Precipitation Zeller, 1977

" 17A 2 yr. - 24 hr. precipitation Zeller, 1977

viii FIGURES

Number Title Source

Figure 100 Location of Study Area WRRC

" IA Precipitation & Temperature Summaries National Weather Service ft 2A Precipitation monthly (WRRC, 1979) 3A Total Precipitation, 1976 Wood, NWS

4A Total Precipitation 1977 Wood, NWS 5A Total Precipitation 1978 Wood, NWS 6A Total Precipitation, 1979 Wood, NWS If 7A Precipitation vs. Altitude Condes de la Torre, 1970 It 8A Atterbury Experimental Watershed Boyer & DeCook, 1975

" 9A Walnut Gulch Experimental Watershed Renard & Kepple) l0A Isohyetal map; storm of 8/20/56, Atterbury Woolhiser & Schwalen, 1960 11A Frequency of magnitude of Storm Centers Woolhiser & Schwalen, 1960

" 12A Storm Center, Area -Depth Relations Woolhiser & Schwalen, 1960

" 13A Isohyetal map; storm of 7/16/75, Atterbury Boyer & DeCook, 1975 tt 14A Depth of Rainfall - Recurrence Fogel & Duckstein, 1969

it 15A Occurrences - Depth Osborn et al., 1972

it 16A 2 yr. - 6 hr. precipitation Zeller, 1977

17A 2 yr. - 24 hr. "

18A 5 yr. - 6 hr. it "

If tt 19A 5 yr. - 24 hr. "

20A 10 yr. - 6 hr. " 21A 10 yr. - 24 hr. It

22A 25 yr. - 6 hr. t,

23A 25 yr. - 6 hr. t,

If 24A 50 yr. - 6 hr. " 25A 50 yr. - 6 hr. If

It 26A 100 yr. - 6 hr. " 27A 100 yr. - 24 hr. 28A Area - Depth Curves N WS, 1961 29A Point -Area Conversions; 30- minute Osborn, Lane & Meyers, 1979 30A Point -Area Conversions ;60 -minute

31A Point -Area Conversions; 2 -hr. "

ix FIGURES - Cont'd

Number Title Source

Figure 32A Point -Area Conversion; 6 -hr. Osborn, Lane & Meyers, 1979

tt tt " 33A Fraction of Watershed Area 34A Intensity - Duration of Flow Reich, 1978 It 35A Peak discharge - Recurrence)Walnut Gulch Osborn & Laursen, 1973

It " 36A Peak discharge vs. Drainage Area It 37A Urban Hydrology - Experimental Watersheds Kao et al., 1973 38A Rainfall - Runoff small watersheds tt tt 39A Urbanization effect on curve number t tt 40A Volume - peak relationships tt tt 41A Model -max series; rainfall - runoff Fogel et al., 1974 42A Impervious area - depth of runoff 43A Hydrograph - High School Watershed Arai et al., 1977-

It It " 44A Hydrograph - Railroad Watershed

tt It " 45A Hydrograph - Arcadia Watershed

It tt " 46A Hydrograph - T -3 Watershed 47A Tucson Arroyo - Arroyo Chico Watershed 48A Channel losses; Santa Cruz River Condes de la Torre, 1970 49A Distribution of daily flows Sabino Creek It It

" 50A Frequency of no flow 11 1,

51A Mean annual flood - drainage area it tt 52A Regional frequency curves - Santa Cruz It

" 53A Hydrograph - WS #4; Walnut Gulch Renard and Keppel, 1966

It 54A Hydrographs - Walnut Gulch t 55A Hydrographs - Aug. 12, 1975 Diskin & Lane, 1976

It " 56A Hydrographs - Sept. 13, 1975

il It " 57A Optimal unit hydrographs 58A Flow arrival rates Baran et al., 1971 59A Distribution of flow arrivals

" 60A Watershed Boundaries Tucson Area Pima Assoc. of Governments, 1977

tt 110 Historic and pre -historic diversions WRRC Tucson

120 Evaporation Cooley, 1970

x FIGURE -- Cont'd

Number Title Source

Figure 1B Porosity, Specific Retention & Specific Bianchi & Muckel, 1970 Yield

2B Recharge Basins Schematic U.S. Army Corps of Engineers, 1979

3B Graph for determining dimensions of Brown et al., 1978 spreading & settling basins

4B Intake Rate - Month Bianchi & Muckel, 1970

5B 23rd Avenue flow path Wilson, 1979

6B WRRC Intake rate

7B WRRC Water content - depth 8B Pit Intake Wilson & Rasmussen, 1976

I1 9B Recharge Well- Schematic U.S. Army Corps of Engineers, 1979

VI 10B Recharge well - cross section lt 11B Graph for design of injection wells Brown et al., 1978

° 12B Mixing ratios Percious, 1969 13B "Maxwell" cross section U.S. Army Corps of Engineers, 1979 It 14B Suspended Sediment - Infiltration Matlock, 1965 15B In- Channel Basins U.S. Army Corps of Engineers, 1979 16B Serpentine Basins 1 17B Infiltration volume - Tucson Burkham, 1970 18B Inflow- Infiltration

19B

20B 21B Discharge - Drainage Area 22B Discharge /Infiltration - Frequency 23B Discharge - Infiltration Matlock, 1965 l/ 24B Basin Cross- section Fogg, 1978 p 25B Change in water level Arizona Water Commission, 1973

11 26B Change in water level - pumpage It 27B Depth to water Fogg, 1978 28B Water level contours 29B Regional transmissibility Anderson, 1972 30B Fence diagram - WRRC Wilson, 1971b

xi FIGURE- - Cont'd

Number Title Source

Figure 200 Proposed Routes - TucsonCAP Aqueduct Bureau of Reclamation, 1979

tl It " 201 It 202 If

203 If

11 204 Hydrograph - Davis Leopold & Maddock, Jr., 1954 It 205 Agricultural Districts Pima Associations of Govern- ments, 1978 206 Crop Salt Tolerance Federal Water Pollution Control Administration, 1968 207 Subsidence Cross- Sections WRRC, 1980

End of Phase I

xii INTRODUCTION

PURPOSE AND SCOPE

This report has been prepared under contract to the United States Army Corps of Engineers, Los Angeles District as an integral portion of the Regional Flood Control Element of the Tucson Urban Study. It is the purpose of this Report to provide baseline information necessary for evaluation of the potential for diverting and detaining flood waters and urban storm runoff for domestic, industrial, agricultural, recreational or other beneficial uses and /or improving and augmenting natural mechanisms of ground -water recharge in the Tucson area and identifying specific sites for such activities.

Because the questions regarding the feasibility of diverting and detaining flood waters and urban storm runoff and the enhancement of natural recharge are quite broad, the Corps of Engineers has identified three Phases of the study of this topic. The first Phase is a reconnaissance investigation. This reconnaissance summarizes known information pertinent to the identification and evaluation of potential sites for diversion, detention and enhancement of natural recharge and is limited to three sources of water -- runoff from small urban, suburban and desert watersheds, flood waters in major streams and washes, and water delivered by the Central Arizona Project. Sources of water not included in this investigation are agricultural and mining tail - waters, waters of Brawley Wash and its tributaries in the Avra -Altar Valley, and ground water imported from other ground -water basins. These sources are dealt with in other portions of the Tucson Urban Study. The second and third Phases of this research are the identification of diversion, detention and recharge enhancement sites, and the development of detailed plans of study for demonstration projects, respectively. The scope of this Report is limited to Phases I and II. Should the first two Phases fail to identify possible sites for diversion, detention or recharge enhancement, the development of site -specific plans, Phase III, would not be practical.

HOW TO USE THIS REPORT

The first section of this Report, the Introduction, contains a description of the purpose and the scope of the Report, this discussion on the use of this Report, and a broad, physiographic description of the Tucson Area.

The second section provides a state -of- the -art review of diversion and detention followed by a similar discussion of recharge enhancement. This section may serve as a textbook on the hydrologic theory governing the practices of diversion, detention and recharge enhancement.

1 This is followed by the third section which includes general information on local water sources and uses, and local land uses.

This Report should be used as a source of information from which to base plans and decisions regarding the use of flood waters and urban storm runoff and /or the water delivered by the Central Arizona Project to recharge ground -water in the Tucson Area. Previous research may be examined from the Selected Bibliography included at the end of the Report.

LOCATION AND DESCRIPTION OF STUDY AREA

The Tucson Area occupies the easternmost valley within Pima County in southern Arizona. The Basin, as it occurs within Pima County, occupies approximately 1,000 square miles and slopes to the northwest from a high at the Pima -Santa Cruz County line of about 3,500 feet elevation to approximately 2,000 feet at the northwestern edge. The mountains bounding the Basin range from 3,000 to 6,000 feet in elevation on the west and from 6,000 to 9,400 feet on the east. The terms "Tucson Basin" and "Tucson Area" may be taken as similar descriptions except that basin refers to the lower -lying valley floor which is underlain by water -bearing strata. The Tucson Basin is generally considered that part of the Upper Santa Cruz River Basin as it occurs within Pima County. A location map is available as Figure 100.

2 LOCATION OF STUDY AREA

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3 DIVERSION AND DETENTION

4 DIVERSION AND DETENTION

PRECIPITATION

The National Weather Records Center in Asheville, North Carolina is the national storehouse for climatological data. Local sources for information on precipitation include the National Weather Service Office and the University of Arizona. Arizona Climate 1931 -1972, by Sellers and Hill (1974) contains summaries of weather data from 333 stations in Arizona, 17 of which are within the areal scope of this report. These summaries include the mean and extreme values of temperature and precipitation for the period of record, a brief description of the climate at the station, and average monthly temperatures and total monthly precipitation for each month of record. These summaries are presented in Appendix A. Values for temperature and precipitation summaries for the National Weather Service Office at Tuscon International Airport, updated to 1978, are presented in Table 1A. The average annual temperature and precipitation for the period of record are graphed in Figure lA. The smoothed curve of average annual temperature suggests a cyclic trend and the smoothed curve of average annual precipitation also shows some cyclic character. The normal annual precipitation is 11.05 inches.The normal and extreme values for maximum and minimum temperatures are also graphed in Figure 1A. The average, minimum, and maximum monthly precipitation values are graphed in Figure 2A. More than 55 percent of the average annual precipitation (11.05 inches) occurs in July- August -September, and 28 percent occurs in December through March.

Using the data from a network of volunteer- operated rain gages, Wood (1979) developed isohyetal maps for annual precipitation distribution in the Tucson area (Figures 3A through 6A). While it is difficult to make generalizations about the rainfall distribution from only four years of data, there is a clear relationship between altitude and precipitation. Condes de la Torre (1970) demonstrated, using local data, the increase of average annual and peak maximum monthly precipitation with altitude (Figure 7A).

Three types of storms produce precipitation in Southern Arizona. Winter storm events are the result of large -scale cyclonic storms embedded in the prevailing westerlies. These storms, which generally occur between December and March, originate over the Pacific Ocean and move eastward across the continent.Their usual course brings them inland at Washington or Oregon, southeastward along the lee (eastern) side of the Rockies, and then eastward through the central Great Plains region; only under rather unusual circumstances, which develop perhaps once in six winters, do these storms divert southward, so that they enter the continent as far south as San Francisco and can subsequently affect Southern Arizona.These storms, owing to

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6 t WSO, TUCSON, ARIZONAAVERAGE ANNUAL PRECIPITATION .11ro.~.1rw.c.. 5 YEAR SMOOTHING ÉRAGE' MPERAJÚR AL AL' U. S. DEPARTMENT OF COMMERCEA ATL OCEANIC AND ATMOSPHERIC ADMINISTRATION UIVi h- .1-tiEs NATIONAL. WEATHER SERVICE 1900 11.06"PRECNO MIN.MAX.RECORDS: PRECIP:TEMP.PRECIP:TEMP: 16°xIII °F, -DEC. JUNE 1974 1970 5.1624.17 INCHES, INCHES, 1924 1905 1008090

11 12 13 EXTRE MIN PrecipitationI. in Inches 14 UPDATED THROUGH 1978 G maximum monthly_.

F-- average monthly

--minimum monthly

I I I (

J F M A M J J A S 0 N D J upnmi) 13/77 I;ZRVICE OF:7TCE, - 1976 - TUCSON AND VICINITY 1/10/77 .______., 05 - ":..`1C1 e .--:-...... TOTAL PRECIPITATION IseARAIA 4. ... . ht - -,..---rpt-,.Arydrtr-r-e $01taillir2716, I !.. % 1,4,7%. - I ..., ... 1 ... i'. ' 's _ -... -4, --;,------7. k. 4 :." .... ,.7-- - ' 33 0;5 .. ..""-/ , ..,. ,, .....,. ,.. ',. .: , ..1 , ""% ..t.:L....-...:;-.7. . 1'1 / ----..."--":.7 . , ..,, ".... %, I. 16114N ---'4% ' "J.N... ' , , ,.... - . a'L,, 4- 4, '*-) ..,...... --.---4- (..,7":..' , ,...... ""'' `+*, --;...... 7.,, - ,...... _ ". \ N. . - ,,,-.4c ,,...-... . \,.1.-1-t. , --e-, ,.. -....i...... L. , I ,...... ,I,-4 - .....t..: ,....,-.7 ' -".\ -.54;..(1,--4.:.--.. ', ---,,Lc-:.4.. 7;../..'..-"ti '....' , -"""...)S-" ' ;"- uErin v./ *toot .4.1 °so k. 95 t i : --, .-...... : iir '4,, .1. ,,-.0 - i.""N,._l' ' 'i,/-4- I,. --... -.' ...T.3.--- -,-,_,/ -:.*'. '- - - .1 et / / vot I/44. 11.54 -:. -..i.., ,, , . >!,,t, 4., 1/"'- o" . - I - IN ) /14411 41 11.4.14W1.1%610 Or. .s:$ . 10.44 4 yile 'Oat, tV{Ao% -/'.7.;%';')Vj 9,, 7 L111,fo (3.5 REMARKS OF 4444 11.6\,I 0 MAP Dv CITY-COUNTY P ING DEPARTMENT TjeSOn /0 II" *4Dick New Wood, WSO, Tlicson, rainfall 'gages for Arizona 1977 L>ant,a.'(35 Soilth) . LodEe 23.CO" al I -.Tr/ ir7 '7( 13.30 - 12 S g: v c / #` 44. ' ~ ..`ciTw'Niÿ .. l . MM ;; ór, ---., 12.12 .:. y 11. 7â vJ ------t,1 000000 rrT PEAK 18.10 ».. M w». in .4.400/1 Obi 1... 1 I% »w« . . M 1. o + 114, lt. --4:1 ... 10.54 (GRN VLY)11.88 rit: Hopkins 28.24 I.. MT.1.. 1 M. 1 dQRIDNQßaS OF MAP IT CITYCOUNTY PIANNIN EPANTYENT/Zt12.9s/ (WS ti /, lettst 1 0°5 16.96ri. 3entio: E XMPtETtP TOTAL PRECIPITATION - TUCSON AREA..- 1977 WEATHEROFFICIALRICHARDTvcsoa AR.A.ONAINA.S' CHARGEWOOD =CE OFFICE TUCSON,INITANAT''NALWEATHER SERVICE AIRPORT ¿ZONA 85706 OFFICE TOTAL PRECIPITATION - TUCSON AREA =- 1978 WEATHERTUCSON,INTERNATIONAL SERVICE ARIZONA AIRPORT OFFICE 85706 20.61 Oracle 32.94 M. . San Manuel Pine ...... 11..Yn...... w....r.+...... r....1 f.. . W 0 .1 6" \ : rA ¡r T 0. I; i.o( . , IA., I= t!,1 624:}1 1 1 . Z 13.38 3 t . . . 1.- L J.f __ i/\ . ,. S ; _-.....a... 14ï'4 i r'.`. `_ FI ; r ^,.,,, /' 1` , r..- '.. ..° :^, / , 1-I ` i -./+. \ < /`"L..rs/ .'! 16.69 '' tr ^ .. Ku 1 .,¡ 19.3 t,\ r/ 1. `r..y 4.30 ¡ . i f ! -,l \ %,l., ~ '1:"9 i1 J. _/-..i` -1 ` ` % /, .84 u\ ' .. / 1t;L .o H lonoo A /17.93' t r/ . //\.':;. 19 07 ; . J. , ' Kitt43.72...- Peak_17.8 I8' _1j 406.011 OUhrlPl.t-1 ED lb' Green ; rJaMl..co .... Valley . Ib" Santa Rita Lodge 50.77 If" 5mi W .50 Tuc 1 zit" Benson RICHARD4ArCOf F A I TIC1 I AA. l W1WOOD CHARGE rf er_71.n/V2 4/..rrlpe 21.82 Mt,. Hopkins Z4 _KA O 23.18 TOTAL PRECIPITATION - 1979 - TUCSON AREA . Red Rock 11.47 1 4r u..e..r. 4 . . ;.M.4 ..-...... w.r Nat G t,. ...4(4 4..4( D' : ^OCir4 4 " ' C Catal.inàF ` -.. F. :. +: s . (,..a, - N ....., . L 14.15 ,4 0 20o1Q/ . UPPER SANTA CRUZ RIVER BASIN, ARIZONA A7 computed as follows (Schwalen, 1942, p. 468 --469) : Average ratio of stream/tow to rainfall Gaging station (percent) Sonoita Creek near Patagonia (period of record, 1931 -41) 2.5 Santa Cruz River near Nogales (period of record, 1931 -41) 3. 0 Santa Cruz River at Tucson (period of record, 1923 -41) .6 Rillíto Creek near Tucson (period of record, 1923-41) 1.0

Average annual

Peak maximum monthly

6 2000 3000 4000 5000 ALTITUDE. IN FEET ABOVE MEAN SEA LEVEL FIGURE 2.- Variation of the average annul and peak maximum monthly precipitation with altitude.

13 the fast -moving air currents in which they are embedded, usually produce no more than two days of almost continuous widespread precipitation, but, once the southerly flow pattern is established, it tends to persist, resulting in a series of storms at approximately one - week intervals. Precipitation from these storms is usually of light to moderate intensity, but the accumulation over several storms can be considerable. Rainfall of heavier intensity can occur on those very rare occasions when a low pressure system stagnates and inten- sifies along the California coast for several days before moving inland (Sellers and Hill, 1974).

Storms of the second type, which are the less frequent type of summer storms, are associated with deep surges of tropical air from the Gulf of Mexico and the Pacific Ocean. These storms generally weaken as they move northward into Arizona, but when conditions are right, an event that occurs perhaps once every four or five years, they can contribute large amounts of precipitation over a wide area. Most of the record summer storms have resulted fran these tropical storms that occur most frequently in late August and September (Sellers and Hill, 1974).

Most of the summer precipitation in Southern Arizona is derived from the third type of storm, which results fr an moist tropical air from the Gulf of Mexico flowing over strongly heated mountain terrain. This precipitation is of a showery nature, beginning abruptly, continuing intermittently for a brief period, generally less than half an hour, then slowly tapering off. Even though these summer showers are of short duration and cover a small area, they are often very intense. These showers are usually accompanied by thunder and lightning, and are most frequent and intense in the mountainous areas.The strong influence of thermal heating results in diurnal variation in the occurrence of precipitation. In Tucson, there is a sharp increase in rainfall occurrence between 1:00 P.M. and 4:00 P.M. and it tapers off between 10:00 P.M. and 11:00 P.M. (Sellers and Hill, 1974).

The nature of the summer thundershowers has been studied at the Atterbury Experimental Watershed (Figure 8A).

"Atterbury Experimental Watershed is located about 10 miles southeast of downtown Tucson, Arizona in a mostly rural area. The watershed is representative of the valley floors in the Southern Arizona portion of the Basin and Range Province. The watershed area is about 18.2 square miles containing several small subwatersheds. Land slopes are less than five percent and the drain - ageway channels have relatively low gradients. The entire watershed drains from southeast to northwest, having a length of about eleven miles and an

14 2. GOLF LINKS ROAD NOTE: Sue - WATERSHED RI W -IBX, W -2, ANO w -3 LIE + TANK -1Lakei de OUTSIDE CITY OF TUCSON (Kinneson Lake) IN UNOEVELOPED RURAL AREA. f R -3ES CAL ANTE RO R-36 N

W-18 Lf( R-37 IRVINGTO --{ 1R-7 T. 14 S 4-c- R. t tR6 L- T15S. \ w( i \ N \ \W V \ (: E \ i¡` wa+i 1 R-U rrC JiR-e + I ®\ R-38 R 9 ®0 R 301t t. \z

41 > \R-131 .. \ R-14a \ 0 \ \477, \1R-16 I /

40 R- I 7

TANK WATER RESOURCES RESEARCH 2 CENTER ( R-2Ú R-21 ATTERBURY EXPERIMENTAL WATERSHED tJV R- 35r UNIVERSITYOF ARIZONA 1975 ¡ + FXPI ANATION WAIN WATERSHED BOUNDARY . \.. \\.. -..\ TANK SUB -WATERSHED BOUNDARY R-33 -_.1 RECORDING RAIN GAGE ¡ 26\. R-27i

. 16 5. ' NON- RECORDING RAIN GAGE t , I fz a FLUME OR WEIR 7 R-28

$UB WATERSHE2 ABEA-50-MI, W -IA 4.97 - R-29 W-19 2.24 W -1 BX 5.90 W- 2 4.60

W -3 . 0.47 SCALE 2 TOTAL WATERSHED AREA 18.18 0_-_-._.-,-....,__ __ 2 4 K M.

Figure1. Atterbury Experimental Watershed Near Tucson.

Additional recorders measure flow through the concrete channel at Irvington Road and the flume on sub - watershed W -1A. Collection of information on runoff and .rater levels started in 1956.``

STORM CHARACTERISTICS

Summer rainfallin Southern Arizona occurs most commonly when moisture is brought into the region from the Gulf of Mexico or the Gulf of California. The source of the moisture for the storm of July 16, 1975 was the remnants of a dying tropical storm that moved westward from the Gulf of Mexico. Shortly after noon the characteristic heavy cumulonimbus clouds began forming near the eastern ed ^e of Tucson's /alley floor close to the Rincon Mountains. Rainfall started about 1:30 PM and was heaviest during the first 50 -60 minutes, then decreased to alight drizzle. Precipitation ceased entirely in all areas within 90 minutes. Wind gusts up to 77 mph were ooserved at avis- :Monthan Air Force 3ase control tower, five miles west of the main storm center.

Precipitation occurred over the entire watershed, recorded amounts ranging from 0.44 to 3.64 inches. Most rainfall occurred over suowatershed W -1(collectively, '4-14 plus -13 plus 13X), where t'no gages recorded more than three inches. Figure 2is an isohyetal map of the storm showing the wide range of

15 approximate maximum width of three miles. Main drain - ageways eventually terminate by flowing into Lakeside Lake, the northern boundary.

Soils range from sands and gravels on the rounded, gently sloping ridges to loams or clays on some bottomlands of the lesser drainageways.A cemented zone of lime (caliche) 6 to 24 inches below the surface is present in some areas of the watershed. Infiltration from precipitation generally does not extend to more than a few inches of soil depth.

Vegetation is primarily creosote bush, mesquite, palo verde and annual grasses. Cactus species include cholla, prickly pear and some sparse sahuaro. Recently, the portion closest to Tucson has become urbanized with the construction of homes, schools and shopping centers. The only subwatershed significantly affected so far is W -lA. However, new growth is encroaching on the lower portion of W -1B also.

Major instruments located on the watershed are rain - gages and water level recorders. The Water Resources Research Center maintains 38 raingages at approximately one -mile intervals over the entire area of the watershed. Ten of these are automatic recording gages while the remainder are divided between the standard 8 -inch and plastic non -recording types. Recording gages have 10 or 15 minute chart intervals for intensity determinations and two have been modified to provide an expanded depth scale. Rain- fall data have been collected since 1955.

Water level recorders are installed at the small ponds separating the upper subwatersheds, at Lake- side Lake and on the Stella Road bridge over the main drainageway just upstream from the lake. Additional recorders measure flow through the concrete channel at Irvington Road and the flume on subwatershed W -lA. Collection of information on runoff and water levels started in 1956." (Boyer and DeCook, 1975).

Thunderstorms have also been studied at the Walnut Gulch Experi- mental Watershed (Figure 9A).

"Walnut Gulch is a westward draining ephemeral tributary of the San Pedro River, entering at Fairbank,

16 }-v

1 ^

17 Arizona. Its 58 square mile drainage area above the lower gaging station is considered representative of the mixed grass -brush rangelands of southern Arizona and southwestern New Mexico. Elevations range from 4,200 feet at the water outlet to 6,000 feet at the upper end in the foothills of the Dragoon Mountains. Approximately 70% of the annual precipitation of 14 inches occurs during July, August, and September in the form of intense, small -diameter, convective thunderstorms that cause essentially all of the runoff. Runoff generated by one of these small thunderstorms usually traverses dry channels before reaching the watershed outlet. Most channel reaches carry water 1% of the time or less. On the average, five to ten flow events occur annually at most of the gaging station. Flow from the first several showers of the season is generally completely absorbed in the channel system. Unconsolidated sand and gravel deposits, varying in depth from 6 feet to 15 feet, overlie tight conglomerate bedrock in much of the channel system." (Kepple and Renard, 1962).

The three stages of thunderstorm development are the cumulus stage, characterized by updrafts throughout the cell; the mature stage, characterized by both updrafts and downdrafts in the lower half of the cell; and the dissipating stage, characterized by downdrafts prevailing throughout the cell. These storms usually cover an area less than 25 square miles and show a definite maximum, or storm center. An isohyetal map of a storm that occurred on August 20, 1956 over Atter- bury Watershed is shown in Figure 10A. The isohyets (lines of equal rainfall) are nearly elliptical with the steepest rainfall gradients along the major axis (Woolhiser and Schwalen, 1960).

From a study of many storms over Atterbury Watershed, Woolhiser and Schwalen (1960) estimated the median value of the storm center depth at 1.1 inches, and found that only 10 percent of all storms had a depth greater than 2.1 inches.The frequency of magnitude of storm centers is graphed in Figure 11A. They fit a regression line between logarithms of the difference between maximum depth at the storm center and the isohyetal depth, and the area enclosed by the isohyet (Figure 12A). The regression equation was:

log Y = 1.57 log X + 1.08 where Y = isohyetal area (square miles) X = storm center depth minus isohyetal depth (inches).

18 o

SCALE:l,I= MILE o

FIGURE2. ISOHYETQ LMAP STORM OF AUG. 20,I956 10.0 9.0 8.0 7.0 60' 5.0

4.0 1

3.0

2.0

1.5

1D 0.9 a 0.8 0.7 0.6 0.5

0.4

0.3

02 99.999.199.599 99 95 90 90 7060 504030 20 10 5 2 I 05 02 09 005 001 PER CENT EQUAL TO OR GREATER THAN GIVEN DEPTH FIGURE.,4'.- FREQUENCY OF MAGNITUDE OF STORM CENTERS

lo 9 - 1_ MINIM 8 (1) 7 , Ui f J 6 5 Iffl W 4 - 111 } ., / , O/ A. Y. V; / x / / r=0.94 1.0 } / U) - 0.9 MUM IN =%1 )-0.8 CO 0.7 , Q0.6 ,, L.L.J0.5 0 Q4 h O`- - U N v Z 0.3 f FIGURE5 Iaz / Cr STORMCENTER AREA-DEPTHREATIONS

i I I.

1 I 1 } o .' / . ` 0.01 OD5 0.1 0.5 1.0 2 3 X - DEPTH ATSTORM CENTER MINUS DEPTH OF ISOHYET (INCHES) 20 The authors concluded that the storm center depths were log -normally distributed and that no particular part of the watershed consistently receives higher rainfall than another part.

The characteristics of a storm that occurred over the Atterbury Watershed on July 16, 1975 were described by Boyer and DeCook (1975). The rainfall started at 1:30 P.M. and was the heaviest for the first 50 -60 minutes. The precipitation ceased within 90 minutes.The isohyetal map is shown in Figure 13A. An area greater than six square miles was enclosed by the 2.5 inch contour, and the maximum point amount was 3.64 inches. The maximum intensities were 3.60 inches for one hour and 1.52 inches for ten minutes (9.12 inches per hour). The estimated point- maximum return period for this storm was 75 -100 years.

Fogel and Duckstein (1969) studied the spatial distribution, storm center characteristics, and point rainfall frequency of nearly 200 convective storms using data from the Atterbury Watershed network of gages. The isohyets were found to be elliptically shaped with the major axis about one and one half times the length of the minor axis. Fogel and Duckstein used an exponential model to represent the spatial distribution according to the relation:

r2b R = R e -7f 0 Where R = depth of rainfall along an isohyet r = distance of isohyet from the storm center R0 = storm center depth b = dispersion parameter

Using Atterbury data, together with some data from extreme events on Walnut Gulch and the Alamogordo Creek watershed in New Mexico, the equation of best fit for the dispersion parameter was:

b =0.27e-0.67R0

The model resulting from these two equations results in a circular pattern that reasonably approximates the observed elliptical pattern. The departure of the isohyets from circularity is due to storm movement. Radar studies have shown that a thunderstorm moves very little during its lifetime, thereby supporting the circular model.

Only one storm center occurred in 81 percent of the events, while 2 centers were located in 14 percent and 3 centers were located in 5 percent of the storms. The storm center locations were randomly distributed and their magnitudes were estimated by the Gumbel type 1 extremal distribution (ibid.).

21 3. ISOHYETAL RAINFALL AVERAGES WATERSHED AREA MEAN

W -1 13.1 2.00 W -2 W -3 5.1 0.91 TOTAL 18.2 t.68

W -IMAX. a MEAN INTENSITIES MAX 10* 1.52. 1(10 0.99" MAXfiO =3.60" k60.2 38"

W-1

I.SS+ WATER RESOURCES RESEARCH CENTER UNIVERSITY OF ARIZONA ATTERBURY EXPERIMENTAL WATERSHED TUCSON, ARIZONA STORM OF JULY 16, 1975 EXPLANATION

MAIN WATERSHED BOUNDARY SU8- WATERSHED BOUNDARY m RECOROING RAIN GAGE NON. RECORDING RAIN GAGE RAINFALL AMOUNTS IN INCHES ISOHYETAL CONTOUR INTERVAL c 0.50"

SCALE 0 t 2- MILES

0 1 2 3 KM

Figure 2. isohyetal Map for Storm of July 16, 1975. Lxv

heavy rainfall. Mean precipitation for the storm in W -1 and subwatershedstJ -2 plus:i -3 .;,as determined by planimetering the isonyetal map to find the area enclosed by each contour interval. The means for W -1 and for .. -2 plus W -3 were 2.00 inches and 0.91 inches, respectively. The ,man for the entire 13.2 square mile watershed was 1.68 inches.

Four recording raingayes are located on subwatershed W-1 Charts for these oages were e;amir,ed to provide intensity measurements. The maximum 10 minute intensity was 1.52 inches, witha meanof 0.99 in 10 minutes for the four cages. Similarly, the maximum and average intensities for the four gages in 60 minutes were found to be 3.50 inches and 2.33 inches, respectively. This information is summarized en Figure 2.

A large area was encompassed by the two inch isohyetal contour ;Figure 2). Within the watershed boundary the area was almost six square 'miles, with a ,Wean rainfall,...cunt higher than 2.5 inches for the storm. Additional locations outside the watershed to the east were enclosed by this sa ^e contour; however, the raingage network was not sufficiently extensive to completely define the area w ovin the

22 The frequencies of point rainfall depths per event were well described by a geometric distribution with the conditional probability (p) of having rain equal to 0.48, while the probability of at least one storm center occurring over a given area a specified number of times during a season was evaluated using a Poisson distribution with the mean number of events per year (X) equal to 5.33. Assuming that these two probability distributions are independent and uncorrelated, Fogel and Duckstein derived maximal and minimal distributions of point rainfall depths. When compared to frequencies determined from long -term (70 -year) historical records from the University of Arizona U.S. Weather Bureau Station, the maximal distribution exhibited a similar mean (1.27 inches), a greater variance (0.86 versus 0.54 inches), and a lower recurrence interval for the higher rainfall depths (Figure 14A). The rainfall model was sensitive to p, especially at higher rainfall amounts, and mildly sensitive to X.

The average annual rainfall over the entire Walnut Gulch watershed varies from 7 to 14 inches per year, with a mean (1955 to 1965) of 11.2 inches. The annual rainfall at a particular point on the watershed varied from 5 to 21 inches over a 10 -year period. This reflects the influence of the summer thunderstorm rainfall that con- tributes all but about two inches of the annual precipitation (Hickok, 1965) .

Records from the 95- raingage network on the Walnut Gulch Water- shed have been used to develop a stochastic model of thunderstorm rainfall. The first part of the model determines whether a storm will occur, and if so, the time of occurrence. The second part generates runoff- producing rainfall through addition of individual synthetic storm cells. Osborn, et al.(1972) discussed the uncertainties involved in modeling runoff- producing rainfall, specifically the number of cells, spatial distribution of the cells, and the cell center depth, using probability distributions. They listed 17 assumptions and simplifications incorporated in the rainfall model that are possible causes for uncertainty in the output (see Appendix B). They also tested the validity of the model and found that the rainfall model does generate storm depths and volumes comparable to runoff- producing rainfall from 12 years of record (ibid.)(Figure 15A).

The depths of maximum rainfall for durations from 30 minutes to 24 hours and return periods from 1 to 100 years are given on many separate maps in a U.S. Weather Bureau publication (1961).

Zeller (1977) described a procedure for determining the rainfall depths for storm durations up to 24 hours and return periods up to 100 years. His procedure involved using precipitation maps of Pima County from the National Weather Service (Figures 16A through 27A), an averaging procedure designed to minimize map- reading error, extrapolation procedures to obtain values for lower duration storms, and an

23 5 4 3 mod ,o LL ..."" theoretical type 1 o .0" extremal distributionto historical record fitted owa.I- I o 1.5 2 3 4 5 6RECURRENCE 8 10 INTERVAL20 30 40 50 (yrs.) 100 200 12 YEARS, SYNTHETICWALNUT GULCH DATA DATA

O Figure 1y{. Accumulativesynthetic occurrences and.5 12 years based of Walnut on maximum Gulch data. storm depths comparing 12 years of I.0 MAXIMUM STORM DEPTH (INCHES) 1.5 2-0 2.5 3.0 35 40 32 iI tTN 31V2 SOURCE: NATIONAL WEATHER SERVICE 31 I/2 10 ------1 PIMA COUNTY, ARIZONAo 10 }------1 20 30 F---4 MILES 40 N i 2-YEAR--10- ISOPLUVIALS 6-HOURPRECIPITATION PRECIPITATION OF IN2-YEAR TENTHS 6-HOUR OF AN INCH . t I 4 (. .E 11.., 171(1721) 3 14 = t6 16

N 16 ,,, . SOURCE : NATIONAL. WEATHER SERVICE PIMA COUNTY, ARIZONAM N 2 -YEAR 24 -HOUR PRECIPITATION 0 IO 0 IO 20 30 40 MILES ---30-NPRECIPITATION ISOPLUVIALS OFIN TENTHS2 -YEAR 24OF -HOUR AN INCH Ì rf' (7fß ' 19 U-112._ .AJO t4ON19 _.s 1 /1 2` I9 i 1 / 2 2 RIGHT 31 1/2 SOURCE : NATIONAL WEATHER SERVICE 24 24 PIMA COUNTY, ARIZONA N V 10 o 10 20 30 40 MILES 5 -YEARPRECIPITATION -30--m6 -HOUR ISOPLUVIALS IN PRECIPITATION TENTHS OF AN INCH OF 5 -YEAR 6 -HOUR 23 24 3 251 311/2 .% t IGHTSON 3 1 I/ m SOURCE : NATIONAL WEATHER SERVICE 2 28 26 10 PIMA COUNTY, ARIZONA0 10 20 30 40 N 5 -YEAR 24 -HOUR PRECIPITATION MILES --20- ISOPLUVIALS OF 5 -YEAR 24- HOUR. I PRECIPITATION IN TENTHS OF AN INCH <<: , (t F 31 1/2ow SOURCE: NATIONAL WEATHER SERVICE 28 28 10 PIMA COUNTY, ARIZONA0 1 0 20 30 40 MILES (V --20-'10 -YEARISOPLUVIALSPRECIPITATION 6 -HOUR OF 10 PRECIPITATION -YEARIN TENTHS 6 -HOUR OF AN INCH ! 1 i f, 2? M .AJO 26 r. 32 2 lq - r,, I 32 ,, /r1_ 1 ' 1 1- ---1 1 ., i I \ f I I [IA/10 UiVARI PK.\ w \ I 1 31I /Z G r I 3 !. 7 ! t4 `'' ' N ~`,...1 WR HTSON 3 I I/Z ., ~\ 3 il 1 SOURCE: NATIONAL WEATHER SERVICE -.r 34 34 32 PIMA COUNTY, ARIZONA 10 N 10-YEAR 24-HOUR PRECIPITATION ` Io o 20 30 40 MILES ----20- ISOPLUVIALS OF 10-YEAR 24-HOUR 1 PRECIPITATION IN TENTHS OF AN INCH I :2I4 3 N 3 30 / 31 1/2 R I GHTSOMN 311/2 ` SOURCE : NATIONAL WEATHER ` SERV ICE IO PIMA COUNTY, ARIZONAIO "-- 25-YEAR 6-HOUR PRECIPITATION [ 0 I I 20 I 30 I 40 . 0 I MILES PRECIPITATION IN ISOPLUVIALS OF 25-YEAR 6-HOUR TENT HS OF AN INCH I t.v 3 N_ 36- .. 38. 34 MON ../ 40 .-\ j ,F@N 3 tEt: I 1 \ \,_ .0"l3z,,1 3' A /QUI / / VARI PK. 40 r y 34% I r-ato- .. / R IpHTSON I ,36I 3 1/2 SOURCE: NATIONAL WEATHER SERVICE 40 42 4?yp / PIMA COUNTY, ARIZONA "= óat 10 0 10 20 i 30 40 y MILES 25-YEAR--30- 24-HOURPRECIPITATION PRECIPITATION IN TENTHS OF AN INCH ISOPLUVIALS OF 25-YEAR 24-HOUR 3 34 32 311/2 SOURCE : NATIONAL WEATHER SERVICE /3) PIMA COUNTY, ARIZONA 34 00 10 0 10 20 30 40 50 -YEAR 6 -HOUR PRECIPITATION MILES I PRECIPITATION IN TENTHS OF AN INCH ISOPLUVIALS OF 50 -YEAR 6 -HOUR M

3 1/ 42 SOURCE : NATIONAL WEATHER SERVICE 46 4 PIMA COUNTY, ARIZONA N IO E 0 10 E 20 1 30 I 40 50-YEAR 24-HOUR PRECIPITATION i i MILES ---30^ISOPLUVIALSPRECIPITATION OF 50-YEAR IN 24-HOUR TENTHS OF AN INCH t cj z Ì u's 31_ ILS. 22I

31 1/2 1 1/2 to SOURCE : NATIONAL WEATHER SERVICE 40 36 10 PIMA COUNTY, ARIZONAO 10 20 30 40 MILES (V 100_PRECIPITATION_IN -YEAR 6 -HOUR-30--' ISOPLUVIALS TENTHS PRECIPITATION OF ANOF INCH100 -YEAR 6 -HOUR 4 48. T LEVMON (i 11/2 IGHTSOAL 31 I(2 SOURCE : NATIONAL WEATHER SERV ICE 4846 1 PIMA COUNTY, ARIZONA N 10 10 I 20 30 1- 40 100 -YEAR--20-m 24ISOPLUVIALS -HOUR PRECIPITATION OF 100 -YEAR 24-HOUR 1' f ----- I 0 I MILES PRECIPITATION IN TENTHS OF AN 1- 11.7e 7A INCH s , adjustment procedure to scale down the point precipitation values from the maps to areal precipitation values. The later step, performed only on drainage areas greater than 10 square miles, is accomplished using area -depth curves (Figure 28A) from the U.S. Weather Bureau (1961).

Osborn, Lane and Meyers, (1979) used 20 years of data from the Walnut Gulch Watershed to develop depth -area conversion curves for adjusting point rainfall amounts for given frequencies to areal averages (Figures 29A, 30A, 31A, and 32A). Owing to the limited areal characteristics of the thunderstorms, the reductions from point to area were significantly greater than the curves shown in Figure 28 that are based on national averages. The authors, also developed curves "indicating maximum expected rainfall and typical areas distributions of rainfall depths during major precipitation events" for 31 and 93 square mile watersheds (Figure 33A).

In a paper discussing the topics that an engineer should consider in designing storm drainage for small urban areas, Reich (1978) used thirty -two years of data on rainfall maximum from the National Oceanic and Atmospheric Administration recording raingage at Tucson Interna- tional Airport to develop rainfall intensity- duration frequency (IDF) curves. Though the author's main purpose is to point out some pitfalls commonly encountered by design engineers --such as erroneous extrapolation of mathematical distributions, misapplication of scales involving a logarithmic transformation, and inappropriate use of frequency paper that fits a short duration to a longer duration (where a different process is in operation) --he does develop the IDF curves for Tucson (Figure 34A). The author also presents an array of the rainfall intensities expected for the eight durations and four return periods using, in most cases, several types of probability paper (Table 2A). The best estimates from this table, as indicated by the arrows, were used to draw the IDF curves (ibid.).

RAINFALL -RUNOFF RELATIONSHIPS

Records of precipitation are often used for extrapolation or interpolation of runoff records because there are generally longer records of the former. Runoff volumes and peaks are affected by many factors in addition to precipitation. Therefore, a satisfactory correlation does not usually result from direct plotting of rainfall against runoff. The relation may be greatly improved, however, by taking into account as parameters such factors as storm frequency, initial soil- moisture condition, storm duration, and time of year (Chow, 1964).

Several studies have been conducted using data collected at the Walnut Gulch watershed (see description in "precipitation" section) to develop regression models for predicting onsite runoff from short - duration convective storms. Schreiber and Kincaid (1967) found that

38 1 " L L - : L:: ij.R.r."r- i::::.: L: _. ,a 11 Lu:..= 1T'- WUW.!n - .: u i'".: _ _ 95 11-1 , :..,... {4 _ LLiiio :... t i ::LL ii . is :ia . LL:QIN!'LiL ii impu. '_ n ru , :t_ u L:: :i:iie:i -r fi k u rC.ri. ------}ii!ut . r 1$_ ia !o.ae:L:Lilillli i - hour éliililüllllt:L i ! x::n:=i 24 - f ._.___ ..._._ ` I ,1;'--- 90 1- _ .li 6 - t 1 miwál hour _._ 13T _" = -_`-' .r. 7 R5 MEWT.~ . _ _i ; . + ` ______3 - ü9:=:CiiL:iTiiKw ` # `i1 ? Will- " 4[ _ hour _ 80 MEN Llièa.L;. "EEMME MMREAME::HCilLr. ffin1pm ._.MMEN. _-.. - 1- - . ;._ I..ilr,M Z - i ' + T`,jn a ; ,' M hour r_ -_-MEN -_ 75 E M E+ E MM V E NMEWWVEN®MEmmmi-m mee -EMECi.aI,® M LäT ir.. MM `_ -, . , m;ü M 70 Mm L Aimmhour .ÑL:EmmuummEmm _EME I u l'- 'IME - 65 ::Lïr md:mÇmmom : a -a Mr.r MMnuu : : mm L ü : : = mmC r.r: mmEmmmmu fimmm Amom _:n .. :: ir m n mommMMEMMUMEMEN LMó::.LV . aM l mm=A .. p AIL:LiaME = i r= w. i ii ME-C N EM TT`EE .... 10 eÜ.MEr°9i 20 t-+úMBag 30 "__ 40 i_ Z 50 _dDrainage Area - sq. milesMIN 60 l ñ 70 mEmmiMIEN.EM80 90 MEENENEWAMEM100 110 _ 120 _ 130 140 150 AREA - DEPTH CURVES l i Technical Paper No. 40 Weather Bureau 30-MIN. DURATION <71lu 0.9 !1 11 \ 60- MI N. DU RAT ION W , 1 OtL 0.8r cID \ o \NíJH.. .,?LAS 2 \_ I a \ \-...... , \ NOwt. A7t.S 2 0.7}-- I 0a_ZF- 0.6 \\\\\ 2 -YR 0 0.4 150 ' Fig. 6. minPointquencies duration -to -areaon Walflutrainfalls conversion Gulch. for ratios selected for fre-30- 200 Fig.0 7. minPointquencies duration -to -area on rainfallsWalnut conversion Gulch. for ratios selected50 for fre-60- ARE .:-. ,gym 1002 150 20( 120- MIN. DURATION NOAA ATLAS 2 - 360-MIN. DURATION NOAA ATLAS 2 zF- 0.7- 2-YR o P 2 ó0.6- 0.5-- 10-YR 0.4 0 50 100 100-YR 150 200 0.4 0 50 100 150100 -YR 200 Fig. 8. ciesdurationPoint on-to Walnut',Gulch. rainfalls-area conversion for selected ratios forfrequen- 2 -hr AREA (km2) Fig. 9. ciesdurationPoint on-to Walnut rainfalls-area Gulch.conversion for selected ratios forfreouen- 6 -hr AREA (km2) 4 WALNUT GULCH

FOR ALL DURATIONS UP TO 6 -HR.

km2

AVERAGE RAINFALL

i , km2

0 0 0.2 0.4 0.6 0.8 1.0 FRACTION OF WATERSHED AREA

Fig.1. Fraction of watershed equal to or exceeding average storm rainfall for Walnut Culch.

ALAMOGORDO CREEK 30 MIN. -2 HR. DURATIONS -6 -HR. DURATION

150km2

AVERAGE RAINFALL 50 km2

() 0 0.2 0.4 0.6 0.8 1.0 FRACTION OF WATERSHED AREA

Fig. 18. Fraction of watershed equal to or exceeding average storm rainfall for Alamogordo Creek. 42 4

1111 11111 E

EQRMEIN _ E4A portant for engineers to understand the LN distribution. Engineers soon found that much of their hydrologic which is a special case of the LP III. data had positive skewness.For instance, the highest In Figure 6, the eye fit of this LN to 180 -min rains floods were often of an order of magnitude greater than was an acceptably straight line in the range around 5 to floods that occurred rather frequently.This relative 20 years, for which it was used in Table 3.Graphically largeness in the numerator of Equation 12 was greatly small deviations of points plotted at 20 and 40 years are amplified by cubing the terms before summing. An actually more significant because the log transformation escape from this problem was sought by making a log squeezed the vertical scale. True deviations were less transformation: this was accomplished through the non- when plotted on normal (N) paper.Extrapolation to the linear spacing along the vertical axis of Figure 6. The right side gave the best 50- and 100 -year 180 -min esti- apparent scaling down of larger values was to have mates, as signified by the arrows on the eye N line in drawn the entire annual series of the logarithms into a Table 3. straight line.If this were perfectly achieved. then the One of the earliest probability distributions used was data set would have a zero value for the coefficient of this so- called normal distribution.Its characteristic skewness of the logs, where can be seen from Figure 7 to be a symmetrically changing spacing of the probability lines on either side of CSL =(NE(L- L)3J /1(N- I)(N- 2)(sL)3l (13) P, = 0.5. This symmetry is due to its assumption that data will have a zero skewness coefficient, CSX. The The advantage of the LN or N distributions is the ex- latter statistical parameter can be evaluated, albeit with treme simplicity of fitting a mathematical curve.If a considerable trouble and risk of error, by hand compu- straight line effectively passes through a whole set of tation as follows: points on N paper, the theoreticaLline could be fitted as follows: CSX= (NE(X- X)31 /((N- I)(N- 2)(s,)3í (12) X at P. = 0.5,

Figure 6. Example of S 120 classical log- normal 4 100 analysis for 180 -min LOG-N MALPAPER rainfalls. 3..--tt15EWEIBULLPt.0i71Nm 80 70 1111 60 AN50 40

15 0.5 :' 411111111111111111111 MIMI10 .,93 .e! .9e .93 .9 .a .7 .e.3.4 .3 .2P,_ .1 .05 .02.01

LOOS tat1.72 1.06 1.111 1.2.3 1.3 2 233 345 10 20 50 100 RETURN PERIOD (YEARS)

Table 3. Array of rainfalls expected for Return Period (years)

eight durations and four Preferred S 10 SO 100 return periods from Duration Order or various curves. (min) Curve Comment mm mm/mIn mm mm/min mm mm/min mm mm/min L/

5 Eye EV Good 10.4 -2.08 12.4 -2.49 16.8 - 3.35 18.3 - 3.65 10 Good 17.3 -1.73 21.6 -2.16 30.5 - 3.05 34.0 - 3.40 20 Fair 28.2 -1.41 34.5 -1.73 49.8 - 2.49 56.4 - 2.82 30 S -shape 33.0 -1.10 41.1 -1.37 57.2 -I.90 64.8 - 2.16 Grlrgorten Unacceptable36.3 44.7 63.3 89.6 Eye EV 37.3-0.83 47.5 71.4 80.8 45 Eye LN 38.1 48.3 1.07 74.4 - 1.46 88.4-1.69 Theory LN 34.8 43.4 65.5 75.7 Eye N 39.1 48.8 66.0 71.6 Gringorten Unacceptable37.6 46.0 64.8 72.6 Eye EV 37.6 47.5 70.1 79.0 60 Eye LN 38.1 -0.63 51.1 0.85 83.8 9911 132 Theory LN 35.8 45.2 66.0 76.2 Eye N 50.8 66.5 - 1.11 79.3 Grirgorten Unacceptable41.4 51.8 68.6 82.8 3 55.1 73.2 92.7 Eye EV 45.0 0.36 120 Eye LN 3 43.2 56.61 0.47 94.0 111.8-(Leo Eye N 1 45.5 56.9 76.7f- 83.6 Theory LN 40.6 51.1 76.7 68.7 Gringartee 43.4 55.1 78.2 88.9 Eye EV 45.2 57.7 87.4 99.1 180 Eye LN 45.7 -0.25 80.2 -0.33 96.5 114.3 Eye N I 46.2 59.5 81.8 - 0.45 89.7 - 0.50 L- Grtngorten Unacceptable41.4 55.1 112.0 149.9 Noun: I, m o ain, Mows point ta intensity connpononq ta *N,cred raies. 44 the precipitation accounted for 72 percent of the prediction variance of runoff --that is, it completely dominated their correlation- - and that runoff was strongly correlated to the maximum 5- minute intensity of rainfall. Their regression equation (Q = 0.1290 + 0.5036 P where Q = runoff and P equals precipitation, both in inches) indicates that 0.26 inch of rain must fall before runoff begins.

Osborn and Lane (1969) expanded the efforts of Schreiber and Kincaid to larger and more complex rangeland watersheds in order to determine if other parameters are significant.Osborn and Lane used simple linear regression models to predict the total volume of runoff, the peak rate of runoff, the total duration of runoff, and the hydrograph rise -time and lag -time using three years of data from four small (0.56 to 11.0 acres) watersheds. The independent variables included ten precipitation parameters- -total volume, maximum 5 -, 10 -, 15 -, 20 -, and 30- minute depth of precipitation, two antecedent precipitation indices, the total duration of rainfall per storm, and the duration of runoff- producing precipitation --and three watershed parameters --area, average slope, and straight line segments length.The models indicated that runoff volume was most strongly correlated to total precipitation, that peak rate of runoff was most strongly correlated to the maximum 15- minute depth of precipitation, that flow duration was most strongly correlated to watershed length, and that lag time was most strongly correlated to watershed area. The authors concluded that, while the simple linear regression equations provide the best models for precipitation -runoff relationships for the small brush covered unit - source watersheds, the models may not accurately predict the low -frequency events. This is because the range of data probably represents only approximately 95 percent of the range of precipitation from individual summer thunderstorms.

Osborn and Laursen (1973) built upon the previous successes of using regression to correlate rainfall and runoff variables in Walnut Gulch watershed. Specifically, the authors correlated major peak discharges with the maximum 30- minute rainfall on the entire watershed (58 square miles), a subwatershed 6 (37 square miles), and a subwatershed 5 (8.5 square miles). The maximum 30- minute rainfall was the best precipitation parameter to represent the core of runoff- producing rainfall. The only watershed variable that significantly improved the regression equations was the antecedent channel condition (API), which is based on antecedent streamflow, estimates of channel abstrac- tion, and potential channel loss due to infiltration and evapotrans- piration. The equations in order of decreasing watershed area for the three watersheds were: Qa = (0.02 + 0.010 V1.0 + 0.010 V1.5 + 0.03 V2.0 + 0.15 V2. 5)R

Qa = (0.03 + 0.015 V1.0 + 0.020 V1.5 + 0.05 V2.0 + 0.25 V2.5)R

Qa = (0.05 + 0.10 V1.0 + 0.15 V1.5 + 0.40 V2.0 + 0.60 V2,5)R

45 in which Qa = peak discharge (cubic feet per second per acre), R = multiplicative antecedent channel index (R > 1), and V = volume of rainfall between (x - 2.5) and (x + 2.5) inches. The authors rationalized the increasing coefficients for decreasing watershed size "because of limited channel abstractions and a shorter time base for the flow with decreasing watershed size."

Osborn and Laursen (ibid.) also presented revised equations for the prediction of maximum expected peak discharge from Walnut Gulch and subwatershed 5. These equations were the same as the first and third equations given in the preceding paragraph except that 0.30 V30 was added to the first equation, 0.80 V30 was added to the third, and R was set equal to one. Dry antecedent conditions (R = 1) were assumed since intense, long lasting thunderstorms usually follow hot dry periods. The maximum expected discharge from the 58 square mile and 8.5 square mile watersheds were 23,000 cubic feet per second (cfs) and 17,000 cfs, respectively. The fact that the watershed 6.8 times larger only produced a 35 percent higher maximum flood peak was explained by two factors: "the most intense portion of the core of runoff producing rainfall was not much larger..., and channel abstractions were greater in the larger watershed" (ibid.).

A graph of maximum annual peak discharge versus recurrence interval (Figure 35A) revealed that designs can be based either on frequent floods (10 -year or less) or on the maximum expected flood. Comparison of the Walnut Gulch data with a family of curves based on the flow versus the square root of watershed area (Grove, 1962 and Lewis, 1963) suggests that there may be two families of peak discharge versus area curves (Figure 36A). One family of curves pertains to small watersheds where peak discharges are caused by thunderstorms, and the other family pertains to large watersheds where peak discharges are caused by snowmelt or frontal convective storms. These two family of curves intersect between 100 and 1000 square miles. In this range two probability estimates may be needed (Osborn and Laursen, 1973).

Osborn and Laursen (ibid.) conclude that, while thunderstorm rainfall models developed from Walnut Gulch data should have regional applicability to the Southwest, the rainfall- runoff models can be transferred only to similar -sized watersheds with similar runoff characteristics. This would clearly preclude urban watersheds with physical controls on runoff.

The Atterbury Watershed (see description in "Precipitation" section) has also been a site for the development of rainfall -runoff relationships for convective storms. Fogel (1969) presented a rainfall -runoff relationship for convective storms and examined the relation between rainfall frequency and runoff frequency.He assumed that convective storm runoff is a function of total storm precipitation, the time distribution of rainfall, and the location of the rainfall in relation to the gaging station. His linear regression

46 1138 JULY 1973 HY7 in.peakassanie (76the discharge periodmaximsmm and of m 89(Srecord depth mur)\V). The (18).forare the maximumshown Therefore, storm in thatFig. 30 3.5 -mincould5. in. rainfall (89produce miri) models thein 30 maximum for min 3.0 was in. expected chosenand 3.5 HY7thethanforpeak Walnut SW those discharge storm resultingGulch approaches (SW) and from wassubwatershed the 40,(X)0 Wilson'smaximum cfs 5, criterion (I,100expected respectively. mr that /s)Walnut and"this These 22,(X))Gulch storm values storm. couldcfs (620are Certainlyhappen higher m' /s) THUNDERSTORM RUNOFF 1139 CONVERSION. iNCH X 25.4 NAM MILE X I WALNUT GULCH, here while there is no evidence that a much larger storm can occur" (2I). 35 / KM /' \ 30-MINUTE3 5' INCH, MAXIMUM RAINFALL DivideasFor central the southwest, Arizona, possiblythe SW stormwest of may the beContinental too large; Divide, east of andthe asContinental far westit is more likely because of the possibility of greater moisture aloft 20253C wereandkm3) greater plotted, watersheds, frontal and maximum activity maximumRecurrence (II). expected annual Intervals.-Forpeak peak discharges discharges versus (WG) recurrence were indicated intervals the 58 -sq mile and 8.5 -sq mile (150-km3 and 22- LU WALNUT30-MINUTE3 -INCH, GULCH MA XIMUMRAINFALL (Fig. 6). Smooth curves based on the plotted points and the limits indicated 10000 05 , SOUTHWEST 1 o 3 I t I1 2 1 1 MAXIMUMMAXIMUM EXPECTED PEAK DISCIIRG EXPEC 1E0 PEAR DISCHARGE, WALNUT GULCH DISTANCE4 FROM STORM CENTER 2 0 I MILES ) 3 4 á EAR 100 YEAR CONVER GESSO. MILE X 0.OKXrM/SEC/KM2 ION. SO MHX23qKMz FIG. 5.- Comparison of 3 -in. and 3.5 -in. Rains for Walnut Gulch Model CONVERSION. SO MILE X 2.5911512 R-20-YE AR Hit K)(i000 MAXIMUM 1 EXPECTED PEAK CFS 5002$5 M /SEC f DISCHARGE (WG) i 1 O RECORD PEARS, WALNUT GULCH fOR r O RECORDO RECORD PEAK, PEAKS SAN FROM PEDRO OTHER RIVER ARIZONAAT CHARLESTON 58- SQUARE 10 10 1 . IO1 1 au ..L...(2 - M WATILE ERSHED------x \ -- 85-SQUARE- A DRAINAGE AREA ISO. MI.1 a 00 .lai. 1000 10000 ---- 00 r -- MILEWATERSHED - VersusFIG.10 .i yr, -Comparison Drainage 20 yr, 50 Area yr, ofand for Estimated 100Arizona yr Peak FloodMaximum Discharges Peaks for Walnut Gulch with Peak Discharges Expected Peak Discharge and Estimated 000 Cj TR' rial by the maximum expected peak discharges were then constructed by eye. The _ - -- -- O0 GOODPOORFAIR RECORD RECORD RECORD a checkbasedogyshape problems on ofon these whatfrequent magnitude-shouldmight floods happenfall infrequency-those one with ofwith a twocurves larger, expectancies categories. suggests rarer, flood. Thethatof about most firstThe would10 engineeringsecond yr or be lesswould designs hydrol- -with FIG.,.- Maximum Annual Peak Discharges Versus Recurrence Interval for Subwa- - - RECURRENCE INTERVAL (YEARS) IO roo producedwhichbe designs castle a for thefamily which maximum ofGrove loss curves due expected(5) basedtoand failure Lewis floods on is the (9)relatively (SW familiarpublished and greatWG) relationship reports could(7)- unacceptable be on used.of flood Q versus peaks -in in Arizona. They andappreciabletershed about 5 and 14,000 overbank Walnut cfs Gulch (40(1 Usingflooding rn' Eqs. /s)above for6 and subwatershed 20,(X)) 7 and cfs allowing (570 5, thein for Vs) maximum a for25% Walnut reduction expected Gulch in peak discharge for in.thecurvesvarious fÄ,The estimated inhaveestimate flood which been peaks10 for -yr, Qduplicated, the in20= maximum Arizona C\/A,-yr, 50 with -yr,A plotted expected = theand area, maximum 100-yrwithin peak C thisstorms dischargeexpected relationship. from (WG), peakWalnut dischargesIn for Fig.Gulch watersheds 7, drawn these and coefficient, and showed where equation Q=BO+BIR+B2T+B3S+e;

where Q is storm runoff, R is total storm rainfall, T is a time distribution factor, S is a space factor, the B's are coefficients and e is the error of estimation; reduced to

Q = b0 + b1R = b2T where T is the product of the 15- minute maximum storm intensity (i15) and time to the mass center of the rainfall (t ), the latter to the n power where n is between 0 and 1 denotingthe relative importance of the terms; and the space factor is eliminated because its inclusion did not improve the correlation. T?e coefficients of regression (by)

and coefficients of determination r ) for the runoff prediction equations along with the physical characteristics for the three Atterbury subwatersheds are presented in Table 3A. These data suggest that, while equations containing only mean storm runoff can be used to estimate runoff on small watersheds, a storm location variable may be required on larger watersheds. The mean rainfall exerted the major influence in predicting runoff. The use of one time distribution factor (115) increased the coefficient of determination, and using the combined factor (i15tn1 /3) explained even slightly more of the variance. Fogel concluded that the results "give some credence to the procedure for estimating runoff volumes and frequencies from rainfall data." The effect of antecedent rainfall was studied and produced negative results. This probably reflects the remote likelihood of two or more storms occurring on the same area within a short time.

The studies heretofore summarized present methods to predict runoff from rural watersheds. They are not, however, generally applicable to runoff from urban areas. The effect of urbanization on the hydrologic regimen has long been recognized. Savini and Kammerer (1961) made an analysis of the hydrologic effects during a selected sequence of changes in land and water use associated with urbanization. Their results are summarized in Table 4A.

Kao, et al.(1973) studied the effects of urbanization on runoff from three small urban watersheds in Tucson and one rural watershed southeast of Tucson. The three urban experimental watersheds are shown in Figure 37A. The rural watershed, Atterbury, has been previously described. Through the use of aerial photographs, the land use for each watershed was determined in terms of percent residential, commercial, and industrial. The percent impervious area, referring to "the sum of paved streets and parking lots, institutions, industrial and commercial area, and unpaved but considerably compacted alleys," was also estimated (Table 5A). The average rainfall for every summer convective storm for which the mean rainfall exceeded 0.25 inches was

48 TABLE 3f\

W- 1B W - 2 W - 3

Area (square miles) 7.77 4.49 0.47 Average landslope (percent) 2.1 2.6 3.7 Channel slope (percent) 0.82 0.84 2.20

Channel length (thousand feet) 34 25 10

PREDICTION EQUATION

Q = bp - biR

bp -0.0729 -0.0505 -0.0934

bl .2401 0.1453 0.2208

r2 .61 0.63 0.86

Q = bp + b1R + b2i15 bp -0.1593 -0.1801 -0.1402

log 0.2123 0.1405 0.1918

b2 0.0354 0.0406 0.0299

r2 0.69 0.79 0.89

Q = bp + b,R + b2i15tm1/3

bp -0.1798 -0.1555 -0.1462

b1 0.1468 0.1022 0.1588

b., L 0.0891 0.0788 0.0722 r2 0.75 0.87 0.94

49 INTRODUCTION 20 -3 Table 2.-1. Hydrologic Effects during a Selected Sequence of Changes in Land and Water Use Associated with Urbanization' Change in land or water use Possible hydrologic effect .ansition from preurhan to early -urban stage: Removal of trees or vegetation Decreaseintranspiration and increasein Construction of scattered city -type houses storm flow.Increased sedimentation of and limited water and sewage facilities sirruns. Drilling of wells Some lowering of water table. Construction of septic tanks and sanitarySome increase in soil moisture and perhaps a drains rise in water table.Perhaps some water- loggingoflandand contaminationof nearby wells or streams from overloaded sanitary drain system. Transition fromearly -urbantomiddle - urban stage: Bulldozing of landfor mass housing,Accelerated land erosion and stream sedi- sometopsoilremoved,farm ponds mentationandaggradation.Increased filled in flood flows. Elimination of smallest streams. Mass construction of houses, paving ofDecreased infiltration, resulting in increased streets, building of culverts flood flowsandloweredgroundwater levels.Occasionalfloodingatchannel constrictions (culverts) on remaining small streams.Occasional overtopping or undermining of banks of artificial channels on small streams. Discontinued use and abandonment ofRise in water table. some shallow wells Diversion of nearby streams for publicDecrease in runoff between points of diver- water supply sion and disposal. Untreated or inadequately treated sew-Pollution of stream or wells.Death of fish age discharged into streams or disposal and other aquatic life.Inferior quality of wells water available for supply and recreation at downstream populated areas. Transition front middle -urban to late -urban Stage: Urbanization of area completed by addi-Reduced infiltration and lowered water table. tion of more houses and streets and of Streets and gutters act as storm drains, public,commercial,andindustrial creating higher flood peaks and lower base buildings flow of local streams. Larger quantities of untreated waste dis-Increased pollution of streams and concur- charged into local streams rent increased loss of aquatic life.Addi- tional degradation of water available to duw.uatreant users. Abandonment of remaining shallow wellsRise in water table. because of pollution Increase in population requires establish-Increase in local streamflow if supply is from ment of new water- supply and distribu- outside basin. tion systems, construction of distant reservoirsdiverting water from upstream sources within or outside basin Channels of streams restricted at leastIncreased flood damage (higher stage for a in part to artificial channels and tunnels given flow).Changes in channel geometry and sediment load.Aggradation. Construction of sanitary drainage systemRemoval of additional water from the area, and treatment plant for sewage further reducing infiltration and recharge of aquifer. Improvement of storm drainage system A definite effect is alleviation or elimination offloodingofbasements,streets,and yards, with consequent reduction in damages, particularly with respect to frequency of flooding.t

50 iiY-DR()d..OGY OFF URBAN AREAS

Table 2 . Hydrologic Effects during a Selected Sequence of Changes in LnclandWater Use Associated with Urbanization (Continued) Change in land or water use Possible hydrologic effect Drilling of deeper, large -capacity indus-Lowered water -pressure surface of artesian trial wells aquifer;perhaps somelocaloverdrafts (withdrawal from storage) and land subsidence.Overdraft of aquifer may result in salt -water encroachment in coastal areas andinpollutionorcontaminationby inferior or brackish waters. Increased use of water for an: Overloading of sewers and other drainage ing facilities.Possibly somerechargeto water table, due to leakage of disposal lines. Drilling of recharge wells Raising of water- pressure surface. Waste -water reclamation and utilization Recharge to groundwater aquifers.More efficient use of water resources. * From Savini andKammerer f2). t Added by authors. 3.Increasingiy frequent conflicts wherein two or more types of water users seek the same supply. 4. Diminished streamflow as a result of diversions of water. .5.Declining water levels and pressurein ground water reservoirs.(Also causing pollution of groundwater by leakage from sanitary sewers.l 6. Increasing number of artificial recharge projects, for purposes of water supply and flood control. 7. Increase in amount of wastes disposed to streams and possible increase in pollution when wastes are inadequately treated.,,_ 3. Increased re -use of waste water in agriculture and industry. 9. Land subsidence. Many of the above effects are so interrelated as a consequence of diminishing quality of supply and increasing demands for quantity, that assignment of relative importance to them is not practical.The primary significance probably is that they are interrelated. This section will outline current practice in the use of hydrologic data and met hods in the solution of urban water problems and needs.Stormwater drainage is given major emphasis, not only because of its considerable economic significance, but also because of the growing evidence of dissatisfaction with established methods of runoff determination and the consequent attempts to develop more realistic and accurate. yet practical, engineering designs.In addition, brief mention is made of the utilization of urban hydrology in connection with designs dealing with floods, water supply, pollution, airports, and expressways. II. QL"ALITATIVE DESCRIPTIO\' OF URBAN STORJIWATER RUNOFF The engineer designing facilities for the collection and disposal of stormwatcr can exercise better judgment if he understands what actually occurs from the time a runoff -producing storm starts until the storm and runoff cease.The principal Pita e of this part of the hydrologic cycle are as follows. A. Precipitation Flow in storm sewer systems is principally by gravity.Like natural drainage basins, smaller sewer branches unite with larger branches, and so on, until a main sewer is reached.The smallest catchment area, of the order of an acre in size, is that tributary to an inlet.For most smaller areas in the upper reaches of an urban drainage system the time required to reach peak runoff after the beginning of a storm is a matter of minutes.Hence high- intensity, short -duration rainfall is normally the main, if not sole, type of precipitation contributing to critical runoff rates.This type

51 o

I u -J \^44- crulur j-441,

f,IMA r) 4 1

r.rEEOWAY

5THST N

onnApway

77 NO ST

DAVIS MONTHAN AIR FORCEBASE

LEGEND STREAM ()HIGH SCHOOL WATERSHED %,Arrnsmco souonnY ARCADIAWATCRSHCO -nEconouzz, $TREAm. © RAILROAD WATERSHED FLOW cAcc 0 01 L---J--J MILES

Figure L. Urban hydrology experi_nencal watersheds.

52 "I:ibte 1. DESCRIPTION OF WATkRSII:()

High Watersheds School Arcadia Railroad Atterbury Area, square miles 0.90 3.50 1.90 0.45 No. of raingages (recording) 4 6 4 2 (non -recording) 2 3 3 2

Residential area, % 65.5 60.4 38.7 0.0

Commercial area, % 3.5 6.1 1.5 0.0

Industrial area, i 0.0 0.0 26.3 0.0 Impervious area, % 28.8 21.9 40.3 0.0

Ta4ke"2 =. THE ESTIMATED CURVE NUMBERS FOR DIFFERENT WATERSHEDS

High Watersheds School Arcadia Railroad Atterbury Estimated curve number 87.4 85.9 89.7 72.7 of variince explained by the model 76.3 84.1 95.6 76.2 Number of storm events analyzed 20 27 8 18

fiable 3: VARIABLES DETERMINING FLOW VOLUMES AND PEAK RATES

High Watersheds School Arcidla Railroad Coeff. a -23.10 -31.99 24.26 Coeff. b 996.03 2494.13 926.61 % of error explained 0.94 0.93 0.98

53 computed for each watershed using the Thiessen method, and the corresponding runoff was measured at each outlet using a critical depth flume.

Kao, et al.(ibid.) related runoff to rainfall using the Soil Conservation Service procedure (U.S. Soil Conservation Service, 1972). Using the basic equation of the method,

(P - KS)2 Q (P + (1 - K) S) ' the definition of the runoff curve number,

N = 1000 S + 10 ' and a sensitivity analysis which minimized error by setting K = 0.15; the following relation was derived:

2 1.5 (100 - N) (P N Q 8.5 (100 - N) (P N in which Q is the runoff in inches, P is the mean rainfall in inches, S is the potential infiltration in inches, and K is a coefficient. By use of the data for Q and P, N was estimated from a regression analysis (Table 5A and Figure 38A). This procedure explained at least 75 percent of the variance in all cases. A plot of percentage of impervious area versus N (Figure 39A) reveals a rapid increase in N up to 20 percent impervious area and a slower increase above 20 percent.

The volume -peak relationships for the three urban watersheds were also examined by Kao, et al. (1973). A linear regression model

qp =a +bQ

where is peak runoff in cubic feet per second and a and b are :onstants, accurately described this relationship (Table 5A and Figure 40A). Contrary to the expected results, the watershed with the highest percentage of impervious area produced the lowest peak rate for a given volume of runoff. The authors gave two possible ex- planations for this apparent anomaly: the variability of storm duration was not considered; and the type of street patterns may be affecting runoff.

Kao (1973) investigated the tradeoffs between alternative street patterns with respect to urban drainage. Because most cities in semiarid regions use streets as the drainage routes, the shape of the runoff hydrograph at the outlet of the urban watershed varies with

54 o Data fron üiz.; f;ciiool watershed ' oA DataJ).ti fromfrcn r'.a.Arcadia :lroad waterstiad watcrse d 0. °0 Data fron Atterhury watersaed C 3.40 4 4 ^2 . ..(L1 o A J ; 0.43._- _ÿ, Z. .1.90 1.20 1.60 2.00 Fi;;uro. 'rainfall -- runoff ralationsi?s for small ur'aan and rural watcrs!".eds :a in fall in inches 100

90 Railroad watershed High School watershed Arcadia watershed

Atterbury watershed 70

0 20 40 60 80 100

Percentage of impervious areas

Figure 3. Effect of urbanization on curve number

100

40 o 20 40 60 80 100

Curve number (Dry condition)

Fi;;ure 4. Adjustment of curve number for antecedent moisture conditions O 7.ata ron watersh.ad O 0A ..;aLa;ail fro' n ír'' 1 Kailroad war.arshed watert;i1e1 o% O

0 y; A A A L.- 7.--"'" 0.1 3.1; Q. 0.1 FLI:a[Q atr-.-Iff in inc:te..; t?latiors)1,.: the street pattern within the watershed. Using a model to simulate the runoff hydrographs and flow depths at certain points in a residential subdivision superimposed over a parcel of land near Wilcox, Arizona, Kao found that

"...the peak flow rate resulting from the rectangular pattern is 13 percent higher than that from the curvilinear pattern and 20 percent higher than from the dendritic pattern...time of occupation of high water stages at street intersections is much shorter in the dendritic pattern than that in the rectangular and curvilinear patterns." Kao (ibid.)

Boyer and DeCook (1975) used the method developed by Kao, et al. (1973) to study the effects that a large convective storm might have on the urbanized sections of Tucson. Boyer and DeCook coupled the coefficients (k, a, and b) and the curve numbers (N) obtained by Kao, et al. with the mean rainfall amounts measured during a large convective storm over Atterbury Watershed (Figure l0A) to predict the runoff volume and peak flow that would be produced if such a storm were centered over the urban watersheds. In Table 6A runoff results are given for rainfall means of 2.00 inches (the mean over the entire 13.1 square mile area at Atterbury Watershed) and 2.54 inches (the mean over the six square miles enclosed by the 2.00 inch isohyetal contour), and for the maximum flow recorded in a 5 -year period. Boyer and DeCook concluded that if a storm similar to the one that occurred over Atter- bury Watershed were centered over the urban watersheds, "water levels could rise several feet above normal urban runoff channels and would likely cause severe localized flooding."

Fogel, et al.(1974) proposed a method for evaluating the effect of urbanization of a semiarid area on the return period of storm runoff. A comparison between the model of Fogel, et al. and the annual maximum series of rainfall and runoff fitted to an extreme value (Gumbel) distribution is shown in Figure 41A. The fact that the slopes of the two series differ indicates that the distribution function of rainfall and runoff differ. This is expected since they are not linearily related. The graph of storm runoff versus return period (Figure 42A), which was developed using data from the three experimental urban watersheds (Figure 37A) and Atterbury Watershed, illustrates the increased flood potential brought about by urbanization. Using this figure, Boyer and DeCook (1975) determined that for High School Wash a 1.0 inch runoff (resulting from a rainfall mean of 2.0 inches) has a return period of about 10 years, and a 1.4 inch runoff (resulting from a rainfall mean of 2.5 inches) has a return period of about 20 years.

Arai, et al. (1977) developed a non -linear reservoir model to represent the rainfall -runoff relationships for thunderstorms on the

58 Table2. Results of Transfer of Mean Rainfall to Tucson Urban ',watersheds Using Modified SCS Formula

WATERSHED HIGH SCHOOL ARCADIA RAiLROOAD

Area (Sq. Mi.) 0.90 3.50 1.90 Estimated Curve No. 87.4 85.9 89.7 Maximum Design Flume 5 8 5 Stage (ft) Maximum Design Flume 465 1850 900 Capacity (cfs)

RAINFALL MEAN OF 2.00 INCHES OVER W -1 AREA (13.1 SQUARE MILES )a

Inches Runoff 0.99 0.91 1.12 Vol. Runoff (af) 50 170 115 Peak Flow (cfs) 960 2230 1050 a +b Q max Approx. Stage (ft)b 6.3 8.5 5.2

RAINFFALL MEAN OF 2.54 INCHES ON 6.0 SQUARE MILESa'c Inches Runoff 1.43 1.34 1.60 Vol. Runoff (af) 70 250 160 Peak Flow (cfs) b 1400 3340 1500 b Approx. Stage (ft) 9.6 5.8

MAXIMUM RECORDED FLOW SINCE 1969d

Date 8/12/72 9/1/71 Not available Inches Runoff 0.50 0.40 .Vol. Runoff (af) 25 75 Peak Flow (cfs) 800 980 Recorded Stage (ft) 5.92 5.81 Mean Rainfall (in.) 1.68 1.38 -

aCalculated discharge using equations (3) and (4). Stage extrapolated from flume ratings and includes a reduction because of areal spreading from overtopping structure. CArea is that inside 2.00 inch rainfall contour for storm of 7/16/75 and also within Atterbury watershed boundary. dCalculated discharge using fiume rating tables.

expected to have a return period of about 10 years. Another storm producing 1.4 inches of runoff would have a recurrence interval of about 20 years for the same watershed. The other watersheds show approximately the same recurrence time for runoff generated by the rio artificial storms shown in Table 2. By comparison, the two actual storms shown in Table 2 both have return periods of four years using the method of Fogel et al. (1974).

CONCLUSIONS

The results presented in Table 2 and discussed above indicate that water levels could rise several feet above normal urban runoff channels and would likely cause severe localized flooding. Homes and businesses next to the main drainageways could suffer major damage due to such an intense storm.Par- ticular attention is directed toward possible hazards cn the High School and Railroad watersheds. If the storm were centered such that the areas received 2 inches of rainfall or greater, runoff from these and other washes would.combine and discharge in the Tucson Arroyo beneath co-as and businesses along North Fourth Avenue. This area could be heavily damaged, especially if fences recently installed to prevent access to the concrete channel were closed and clogged with debris. Therefore, persons living and working in this area (as well as others near natural or manmade runoff -channels) should be aware that even in dry Southern Arizona severe storms with large runoff can occur when appropriate meteorol- ogical conditions are present.

ACKNOWLEDGMENTS.

The authors wish to thank the following for their assistance and encouragement inthe preparation of this paper: Byron N. Aldridge, U.S. Geological Survey; Dr. Donald R. Davis, Deoart.rent of Hydrology and 'dater Resources, University of Arizona; Brian M. Reich, P.E., City of Tucson; and Prof. Sol D. Resnick, Director, and William J. Staggs of the Water Resources Research Center.

59 - - -- ANNUAL MAX MODEL SERIES 20 3- i i NITRMPERVIOUSARDAN VARYING WATERSHEDS AREAS 40 RAINFALL 22 %- 29 N. DESERT SHRUB (CN =80) \L 69\ , 6\\ i i i RUNOFF DESERT SHRUBWATERSHED GOjOtp\ IMPROVED 1 O RANGE 0 2 RETURN PERIOD, T 5 10 t 25 YEARSI 50 1 100 200 ./.;,,)RE TURN PERIOD, YEARS 5 10 25 I 50 t 100 t 2W 2 RETURN PERIOD, 5 10 YEARS25 50 100 200 watershed during a season. With the as- andFIG.4 ruuuff. Comparison of model with annual maximum series of rainfall urbanization of a semiarid area on the return period tions'tif rainfall and runoff ag the procedure for dc- that the warm- season rainfall model has asFIG. a result 3 of a proposed grass reseeding program. Estimating the change in the frequency distribution of runoff concerns the tradeoff between model runoffpendent,ofsumption surface variables identically that water, W,V in the M seasonal storm events volume is distributedthe sum of storminde- transformationevent.essarilyThat is, This the 50 -year of rainfall storm tonwidistribution variable. Analyzing of peak now the produce is to be expccton may be consideredthe 50- yeientioned that the excess andciently(Fogelbeen1972). New validated widespread Orleans)The onlyareas, to for(Tucson, however,justify a few anlocal Chicago, attemptare areas suffi- et al. 1971; Duckstein et al. blesimplicityWhereestimationlocal solution data, data and to areifmodel this available, not delemma accuracy.available, to isupdateAexperience topossi- use the of watershed parameters. then(itself random and independent W=of V), VI +V2+...+Vpt offreturni.snon- are the thelinear SCSperiods sanie. (equationprocedure, for both Itowevicecessary.rainfa(- elating storm A linear runoff regres- vol - f If). It ;d data indicates that this k flow rates explained at steinconsidertheregionalization. rainfall et al. the 1973)model effects Onand has of the toelevationthe utilizeother capability hand, the (Duck- dis- to usingattemptstingand moreparameters the approach. explicit will procedures have to prevailin estima- in to reduce uncertainties in (6) urbanizedshedurbanizationin on runoff watersheds volume, of a desert and data the sine f,nsidered.as litions Toduration develop encounteredpredicting ofa constant,theexcess theuse in tisis hydrologicrainof at the - 3 percent vaterslteds. of the varianceIn effect, this someetfalltribution rather areas functionthan is point for rainfall mean (Ducksteinarealal. rain- 1972). A possible limitation for that an event -based ap- areforposed availab estimat tnethotl- -where only rainfallIn data illustrating the use of the pro- 'iug_the-(! Fig. 3 Pesents the results effects of a range im- procedureandsedimentA similar Cornell relationshipyield for (1970) obtaining for havea season. exists thedemonstrated distributionfor Benjamin the total a mineanalyzed.tioned The first the experimental watershediii paratnctvcn watershed, thea prob- step was heated waterslat V and (2tr are linearly in equation 151. eventsproachofconsideration antecedent into for runoffconverting soil of events basemoisture summer isflow. used or Therainfall withprecipita- effect no runoff(Bureausurfaceprovement curve runoff. of programLand numbers Using Management onBLMwere the selected proceduresvolume 1966) for of Mbutionsfunction is of of V the and suns M. WThe from distribution the distri- of generally taken tu be a Poisson bersobtain(1973)was doneused valueswho in used thefor aSCSthe regression runoff et a ng only by a scale factor. study by Kutions for V and Qp are methol .`II' ('' INCLUSIONS comeprocedure.tion by generating This, however, a synthesized can be over-set of is not directly considered by the fairseedingbeingan area proposed of program. herbaceous to The undergo vegetationcondition, a grass thateither re- is is stormvariance(Duckstein events ofper et k, al.season. theDATA average ANALYSIS number ANDof RESULTS 1 972) with a mean and oftheA areSCSthe potential generallydata procedure, indicated infiltration estimated the that initial terni..,it.,ti.m!.,the to elb ab: one ;; ,,; '!' Lou,1 na,dilirations of whichfor cval- is justedentwatershedsentedrunoff moisturefor eventsbyeach Ducksteinparameters eventconditions. using to the reflect etcould al.procedure (1972). anteced-then be pre-The ad- (1972).land.grazingmated Whilepractices as discussed the onlyallowed effectby Ducksteinon of the the range- pro et - al. or good, Rainfall parameters werean indication of the esti- (;l r, of the As a means for determining the suita- I minimumerror in the for regression A _ 0.15 analysisS. Tabl. A more serious problem concerns the grani show is on the volume of surface urban watersheds (High School, Arcadia, and Railroad). The authors used 30 events (Table 7A) that had maximum peak discharges greater than 0.08 cubic meters per second and occurred over a watershed with appropriate measurement systems. They developed two types of computer programs: "a calibration program to obtain a best fit calculated hydrograph; and a verification program to generate storm hydrographs given the watershed characteristics and a hyetograph". The average error to get the best -fit hydrograph was 4.0 percent, and the average error of the prediction of the hydrograph using only rainfall and watershed characteristics was 20 to 25 percent. Examples of hydrographs for the watersheds are given in Figures 43A through 46A.

Diskin and Resnick (1976) performed a statistical analysis of the data from Arcadia Wash and High School Wash. The computed values of average rainfall were used with data on the volume and peak discharge of runoff, and three series of runoff events were determined: one including all events (Series A), one limited to "significant" events (series B), and one limited to "large" events (series C). Significant events, as defined by Diskin and Resnick, include those with an average rainfall greater than 0.2 inch, or an average depth of runoff greater than 0.01 inch, or a peak discharge greater than 10 cubic feet per second (cfs) on Arcadia Watershed and 4.0 cfs on High School Watershed. Large events include those with an average rainfall greater than 0.5 inch, or an average depth of runoff greater than 0.1 inch, or a peak discharge greater than 100 cfs on Arcadia Watershed and 40 cfs on High School Watershed. The number of storms and runoff events for each series is shown in Tables 8A and 9A. The mean, standard deviation, minimum, and maximum of the mean rainfall, depth of runoff, peak runoff, and the runoff ratio (the ratio of the depth of runoff and the total rainfall expressed as a percentage) are shown in Tables 10A and 11A.

Diskin and Resnick (ibid.) also studied the relationships between depth of runoff and mean rainfall, between peak flow and depth of runoff, and between peak flow and mean rainfall for each series and both watersheds. The results are shown in Tables 12A and 13A where R is the coefficient of correlation, Y = AX + B, X = -A /B, and J is the standard error of the estimated value of the independent variable. All relationships could be assumed linear, and the coefficient of correlation was highly significant for all cases.

Foerster (1972) studied the effect of urbanization on the rainfall - runoff relationship by comparing data from the urban Tucson Arroyo - Arroyo Chico Watershed (Figure 47A) with data from Atterbury Watershed (Figure 8A). These data are shown in Tables 14A and 15A.The runoff from the urban watershed was 4.75 times greater per unit area than the runoff from the rural watershed over a 12 -year period (1957 to 1969). The factors shown, by a regression model to effect runoff were average precipitation and intensity of precipitation. The former accounted for 68 percent of the variation, and together, they explained

61 Table7 Events in City of Tucson Area Used in Analysis - Actual Data.

Arai, et al, 1977

Events Total Rainfall (mm) Total Runoff (mm) Peak Discharge (mm /sec) X10 -3

a) Highschool

8-11-70 23.7 9.2 4.7 7-30-71 13.3 2.3 0.8 8-3-71 18.5 4.5 1.9 8-8-71 36.3 14.2 7.6 8-10-71 7.4 1.7 0.9 8-17-71 12.8 2.8 1.0 8-19-71 15.6 4.5 2.3 8-21-71 5.9 0.8 0.6 9-1-71 18.5 3.7 2.0 9-6-71 9.2 1.9 0.9 7-24-72 8.3 0.8 0.5 8-5-72 7.1 0.9 0.4 8-11-72 11.5 1.6 0.9

b) Arcadia

7-11-70 7.6 0.4 0.2 8-9-71 22.7 5.6 1.9 7-15-72 7.4 0.3 0.1 7-16-72 11.2 1.2 0.6 7-24-72 15.3 2.2 0.9 8-12-72 26.2 7.5 2.9 9-9-72 8.3 0.7 0.3

c) Railroad

7-6-70 13.8 1.6 0.8 7-19-70 20.7 3.1 0.8 7-20-70 30.6 15.5 3.5 8-23-70 18.6 4.8 1.4

d) T-3

7-12-66 15.2 0.9 0.4 7-30-66 10.1 0.1 0.1 8-18-67 25.4 0.5 0.2 7-7-67 30.6 0.6 0.1 8-7-69 17.8 0.4 0.2 7-16-71 22.8 0.4 0.4

62 Runott rate(mmisec)x103 ain(a!l jatensity(mmisec) o P x 1 0-2 crl t

oci

-t

'Z-3 63 APPENDIX C/

Examples of Hydrographs WatershedsWl tersheds in the Tucson Area

actual hydrograph

best -fit hydrograph

------predicted hydrograph

fr\

64 Runoff rate(mm /sec)x103 Rainfatltensity( mm /sec ) x10

65 Runoff 'rate C mm/sec.)x10-4 Rainfall ip-t-ensity( mm/sec) co o x102 ow. Runoff 'rate (mmisec) x104 Rainfall intensity( mm/sec) o - x10 ts,)

ro o.

o 3

67 I V() 73' -17 .Ce L1 Çi F t./1 A7dri ?F- 5/ IJ 95- -fr 617 LI ) + 4724 91 7I7 17 DE 11 (c;/ C. SS 9 -17F it 0/ ¿5 t, L E Li Li LV g 9 61 iv ,rae1t111/1/__ )t21441--,,i rti 5 ..ra:31,)73):14=:117'.`> Avi"18 312(721:42,i A :illynos S13441ci 001-27y is 00. S i --' GlICI-LPL CV , . . .11°17to I.J711%If, ItlYrOS..:11,110S Si _6:1 -1 1-a,(1.--a_ ,1-ay St1.1143 OS 1111.-t. -7/0 -vs 7,1,/ A.V.:tier -1 ciff-tIS 7,4 ci,1114441 l

cr) cr)

VI .,, _ tia/-. v

u d j e3.> t 7s.

Va +-L

V/ --- cr cC'j (!;

4,9 Tca--6_ - S c. /tot,/

p v..'" _._ ( A _ c_

6,a.v7 C,37r e$,630 11L I

MeAm St, J.9..?

(44,; iíf 1,

Aft2 í'ct I c,/r2

k-1.40,F-r Si. %v.

AILì , 0,00y- 67,613

Yu, 02_7

Pe-eLLF (e-tu 10-0.0. For' P (_cs t',_% t_ p.p. o 4rtil

tsiS Si- Dey. qí /rS 3-7

70 - e-2 1-eY LTZvi /(a/ 171 k'4 r-ca_.-62A. tJ

_ e,s _4

17k,Cei e.z17g s( 02 V. 62'0q3 1 4 r

_ (,)s-j- eCC2 1.1p1.1 De 2,oZ4- 6).e(10 oì'3

/LC iq) ide I I e , 00 ,1-676 6.474- oq7 e 474--

Me.,04,1 qz:c I 0,0

Pt/. a.(c_ g.06.3

otS I

tg,t)

,vtvc.f. Dcz/;_ _ Pr.( °L)

- 4- 71 _7 k-e, (. qztv(jo,, s J p -: Va.-77 0.14.0 ttu. 14- tni41s

,11,14.p241,4wt-

ß,t,lf L Iamoff !4/Qa w _ (mnç) gf+ ,h)---- ..

k rth eviloff

vA- ch_)

F1 o-voL gt4 (tAnct,o_

107,1- J. R-C,taLe,-2-1s 11-jr-r . ; ''a-i kl"k-í a-147D Pe-r- rcet_oti:ccIA/44-1 -

otzt,t

tio,./vvcvt-62_ - -C. -

C 0,2(1 I piti4 efk)444 cew ,e,eS69 V 4' (5v1c/t1)

0.033 0.041

,70 27

PeAt Floi2 --011( I 02037

.0 1 1,-03 27, 9_ Nos0 0,-7S1 Or744- svi.

NAL Ra -139.0

RA 5.23.3 631.0 '1 o ts .e.o671.1

-73 115::s ca ___C/c.ycrot r\! f.! :.' r:/ i le]; eeee 1'7 , lU ,t ( f tI

t * ' I t e ...r-r I / g ,t3 I 1 1 r e 7 -/ e ' e tIIt -;i a I t ,e F ..- t t e ,C:' ' I ''' - 6 I 7i t..) le: % a t .)e -. : , a .- 1 i 8 , t11..,,t e ce,

/7 *...' **, I '.' -.Y L' e o 1.: In ' 2. Z-

.1-;...".--1-...--!---;;---,tr-1;'-.-i'l t.ec e '!!e .'

...; t ._: : 1 C;!:'C-, e` - c t11, e.:,..',1 i ' e I 11` 1 :-... //' r 1 t /: * I e t '. .! tit! t' * 1, L/ ts e ..,,I 1 ,L11.- eti 1 'Ll O . / i , 1 l t, ''.' '"'l't 1 ; t I .; ' , t' 0 I e ' . :141 :-,-st e:F C/ C:*I 1 C *..,) rt: *,-.1'.); I e t t 1 ".- ,,l.-,., -., Y,' te et, ' ' 'u C-LI l7- /.. I-. e '[ -et 7 ' "1,1111i O 1 ' , 'I" i¡ i '.. /: 1 c ..',' ... it ' 1 , 1. . .-. e:. / r .1 .. t... //:...! . , . i , /-! '------'. - r-, tri t -../,' , I, ,....r.,!! .: ;s. n, , ./ :,e:. , r í....,':*:

L ,I t , C, ..e " . ' Ir:7:7,-; " "..". t \\ \ en / e it I S \ s- * i t . _.\\ .- , LL ' 7 , t r; .. . s C, ...... :. 7 -. \ ' ' o S * e. e. ' --, t.; t. \ se : f- ',.. : e 1-'1 1 *1 -' ',...','*e.s'e.. ' ee I syr

. ' t S t! ' "... t I I. . ; Z (.; ' te--S 1 1 ..;r,o e ,' -7 - . el,me.. e .t. a e ''''' ' ;:e,.`, \ ,... e .' ., ' '_, t t. t. , .,. e r , s ' I e c /-; /,`,s'-'" :::7 L:i , o . t . iter,:e.,: . .. . , - / ' /, ' ,!. .. _.- e , ....-, e a , I I 4 ' . a e \ .. '-' e S e Y 14 íí. C'S'7' ': / e 'í.1 ,, , f . e , / 1 " " ... t. ,...... Le ' l' 1 -1 ' t ., , ,.'e. -,/../ , I e .1' e 1.4 '7' ;r: 1:..._t___. ::. .ts+ L '*. ; '. 1 .. - ',/i ' C -ft; ' (17 ! , : , ' -/' ...-,t r-...t ít e. - i "' s'jr.' f' ' e . , \ ''''. 71 +.: :I."'" ' 8--, t. / e I I 1 I .. r ' 1 \', , t , 1 / o I f; ,...' r 6 i ,,,t \I e ' ' /' /i Nt t t e r: ',- !,,, ,' o It I t i eLt ...:. r! .7 7,, 7 ! ....,- , . !.:g ,:! t: (..): E .., I,'"/ !',

1...... -...--, t : ;".t

8 t:t ,e , ''/

' ' ' e -.1.1 t

'.'-' 7!t!!')-!!. I , , ' --'' . ' .;,/

i!, ". / ;/ o e':el' t' / ,

, g, : .; .\ t. ' .

t.- c::,!! ! 2-2"

Table . Summary of rainfall and r=eCf data for the Tucon Arroyo /1 Watcrhed* -- --- Water ìrecintLtion RnoCf noft Z of Year incher, ncre-fet Procipitation

1957 9.62 320 3.4

1958 1!,.42 903 5.7 1

1959 11_0 781 7.3

1960 10.93 428 4 .1

1901 9.44 1210 13.2

1962 11 .3S 595 5.2

1903 10.00 259 2.7

190:i 10.47 428 4.2

1965 9.25 420 4.8

1966 17.43 1290 S.1

-)7, 1967 8.52 ,. )., 3.2

1908 15.80 410 1.

1969 12.90 340 o

11.67

of :%rizo:In alc! rocords V.S.

A;:': ;I LI', S

H i '` o:

75 73

Table Sum:nary of rainfall ah,.. (1.:La fort-ho. ALtrbury Experiental

ProcipiLaLion Ruooff 1;u:.'xff í of

inches aC17,'.' -17 L

1957 10.10 192 2.0

1953 15.52 416 2.3

1959 6.50 250 3.1

1960 12.05 391 3.4

1951 9.43 447 4.9

1961 11.29 162 1.5

1963 9.63 SO 0.9

1964 12.46 308 2.6

1965 10.30 134 l.4

1966 19.00 400 2.1

1967 9.01 209 2.4

1953 16.19 413

-,,: 1059 ..,...»., 77 1.0

Avc2rac.2 11.60 26S

1:L:1:or l':usourco.7. FJ21-,onl-eh t.) r

76 82 percent of the variation. Deviation of precipitation and the antecedent moisture index did not significantly increase the correlation coefficient of the regression analysis.

RUNOFF

Anderson and White (1979), in cooperation with the Arizona Water Commission, have prepared a statistical summary of the Arizona stream - flow data collected by the U.S. Geological Survey (USGS).The results for the stations that fall within the scope of this study are given in Appendix C. The first set of data includes annual peak discharge, corresponding gage height, and annual volume. Duration tables are then presented to break down the flow distribution into intervals. The next sets of data are the lowest and highest mean values for flow on several series of consecutive days. Finally, statistics are presented on normal monthly and annual mean discharges.

Condes de la Torre (1970) analyzed the USGS data dealing with streamflow in the Santa Cruz River Basin. The author presents a graph (Figure 48A) demonstrating the rapid rate at which water is lost to the subsurface as the flow moves downstream. Condes de la Torre also presented a table (Table 16A) containing statistical parameters developed from USGS data. He points out that the arithmetic average of annual streamflow means little in predicting the flow in a given year because of the large standard deviation relative to the mean. Flow- duration curves developed for the period 1936 to 1963 indicate the streamflow is in direct response to precipitation and that streamflow is highly variable. Condes de la Torre also prepared a hydrograph showing the distribution of the daily high, median, and low flows for Sabino Creek near Tucson (Figure 49A).

Condes de la Torre (ibid.) also performed analyses of low flows and high flows. He found that the low -flow frequency curves revealed little, owing to the long dry periods during the year (Figure 50A). Prefacing his discussion of the high -flow frequency curves, Condes de la Torre points out that on the Santa Cruz River, more than 93 percent of the flood peaks occur in July, August, and September, whereas flood peaks are more evenly distributed on streams having drainage areas extending high into the mountains, such as Sabino Creek (Table 17A). Using two of the figures from Condes de la Torre, (Figures 51A and 52A) the discharge for a flood of selected frequency can be computed. The procedure involves determining the mean annual flood from the drainage area in Figure 51A and the ratio of discharge to mean annual flood from the recurrence interval from Figure 52A where region F includes streams draining from the south and west slopes of the Santa Catalina, Tanque Verde, and Rincon Mountains and region C includes the rest of the basin. Using this procedure for the Santa Cruz River at Tucson, the mean annual flood was calculated at 6250 cubic feet per second (cfs) while the 10 -, 20 -, and 50 -year floods

77 AS WATER RESOURCES OF THE TUCSON BASIN

STREAM FLOW 1lost streams in the upper Santa Cruz River basin are ephemeral and are dry for long periods of time. Flow in the streams is generally in response to precipitation, except in a few places, such as Santa Cruz River near Nogales, Sonoita Creek near Patagonia, and Pantano Wash near Vail, where ground water is forced to the surface. Streamflow is not used for municipal or irrigation purposes, except for small diversions in Mexico; however, the municipal water supplies for Nogales,

5000 -

4000 -

z O U

C!7 w 3000 - a. t- w Santa Cruz River near Lochiel U Daily mean 344 cfs (682 acre -ft). U z i 2000 - s

oÚ ó L/Santa...... -Santa Cruz River near Nogales / Daily mean 192 cfs (381 acre -ft)

1000 - Note: The daily mean at Santa Cruz

{ River at Tucson on September 15. 1965. was 0.8 cfs (1.59 acre- - ft) t t Santa Cruz River at Continental \ Daily mean 21 cfs ,(41.7 acre -ft)

1200 1200 1200 2400 2400 2400 2400 September 12. 1965 September 13. 1965 September 14. 1965 R_ TIME

FIGURE A.-Reduction of the flood peak by channel losses in the Santa Cruz River.

78 TUCSON BASIN A1Q WATER RESOURCES OF THE C 73n r....N :^1Xt. M:JO^l;^...Á ::0^J ryN Ti -'-l C-

-7 c X' _ 7 ^.: cocr I-

OCOCCCO ^1G^.NCOCs-+CCCOC:ON ^-r4xr^^^C^ OC'^.cOC^1^^.N,^:v^c07CM C17

hC CtO^^:....xCC^^1:0 C7...;Cr7..;:..xO Mx ..._

OC C C O C C OO p O C ^C QC NOCN0C1 C c0 ^1 C1 Nx0 -+ C ON^"C3:7 :0 ^ :f_' 00 M C -aN y Ñ v

C CO O O O C O C O O C= CO ïcMiá0 0ó=¡:c1.:3; r.'xx vi -utÑ-îC1

0a Cot C h-OcO0 i.7M . 1 `G^:`*i Ti CO N .y

NO .C.,:M OC NTi^NNUC)C9%Jx x.M CC I C` 0 1O^ C M^ÑC..ÓN V" 0.L7 -Zcir M C1

79 1114 WATER RESOURCES OF THE TUCSON BASIN time ranging from Ito" 1 consecutive days for each year of record ;7.nd give the recurrence intervals, rnagnitttde, and the chronological ..eduences of the occurrence of the low flows. The sustained flow in the basin was sufficient to define the 1 -day and (or)-day curves only at Santa Cruz River near Nogales. Sonoita Creek near Patagonia, and Pantano Wash near Vail. The 1- and T- day means are indicative of the amount of `round -water discharge available to sustain streamflow. At Sabino Creek near Tucson, the l- and 7-day means were less than 0.01 cfs in each year during the period of record. A t the other gaging stations in the basin, the low -Plow frequency curves are of little value as a tool for determining the potential of the streams for a water supply or waste disposal, because the streams are dry for long periods during the year: therefore, curves for these stations are not included in the report. A mean flow of 1 cfs or less for a 1K-day period will have a recurrence interval of -1 years or less at co_

-Highof record

r\\ , ,1 1, , ' Median

r1 ,I

Ji.( ( t; Low of record---rr,

i 0.1

Oct. ' Nov. Dec. Jan. Feb. Mar. Apr. MayJune July Aug. Sept.'

FZGITEE,11:-Distribution of the daily high, median, and low flows, 1936 -C3, for Sabino Creek near Tucson, Ariz.

80 EY- WATER RESOURCES OF THE TUCSON BASIN

PERCENTAGE CHANCE OF OCCURRING IN ANY ONE YEAR

49.0 90.9 66.7 50 20 10 5 3.33 2 1 0.5 380

I Santa Cruz Riverat Continental 360 , rTucson 340_ nea J\`o 320 P -

300 "-`SantaCruzRiver Tucson 280 at c -

SantaCruzRiver 260 at Cortaro 1. - z G t 240 o -

220

200 i 180 o4 Note:Curve forSantaCruzRiverat- Cortarorepresentsnaturalflowand 160 doesnot includewastewaterfrom-_ c irrigationandsewage-disposalplant

140 JA. G. 120- sa J 6C cl

100

80 SJ oeI. 60- ew No ales - ca COQ near

40L Oa 0) R.Ner G

Aa I SonoitaCreeknearPatagonia 20

0 1.01 1 1 1.5 2 5 10 20 30 50 100 200 RECURRENCE INTERVAL. IN YEARS Ficuh- Frequency of days having no flow at selected gaging stations. the resulting winter flood produces a large volume of flow. Figure 0 compares summer and winter flood volumes on the Santa Cruz River at Tucson.

81 UPPER SANTA CRUZ. RIVERBASF,ARIZONA A17 â»s`_?ti8xx

ñV,c VS. c VI V.3

c - C'

^i:1^lpppnry 53§§zP"gH

I jf44.53_

HHHHNHNH+3 I.

82 -UPPER SANTA CRUZ RIVER BASIN, ARIZONA A19 The discharge for a flood of a selected frequency is computed from figures 10 and 11 by the following steps: (1) Determine the discharge of the mean annual flood for the contributing drainage area from figure 10, (2) determine the ratio of the flood of the selected recurrence interval to the mean annual flood from figure 11, and (3) multi-

20.000 I I ( i T iI it 10,000 1 Sites on Sanwa Creek and on Pantano z Wash and its tributaries po 5000

JóW N W J W D 2000 Z <..Z All other sites in basin ti < 1000 U

500

300 I i 10 20 50 100 200 500 1000 2000 5000 CONTRIBUTING DRAINAGE AREA, t I IN SQUARE MILES i f FIouan A.- Variation of.mean annual flood with drainage area in the upper Santa Cruz River basin. (After Patterson and Somers, 1906.)

10 I i 1

iW 7 rO O 6 O Reg.on F s-'ti 5 i J< N 7 z 4 LL < O

= 3 z

0 I L i t LOI 15 2 2.33 5 10 20 50 100 RECURRENCE INTERVAL. IN YEARS

FIGURE 1ct,- Regionalfrequency curves for the upper Santa Cruz River basin. ( After Patterson and Somers, 1966.)

83 were 14,500 cfs, 20,300 cfs, and 33,800 cfs. The variability of annual peak discharges is shown in Table 18A. The flood -volume frequency curves for the 10 gaging stations having sufficient periods of record were prepared. A summary of representative results are given in Table 19A.

The rational formula, an empirical formula for runoff prediction, has gained widespread popularity, owing to its simplicity. Krimgold (1946) gave six rather restrictive assumptions that are inherent in the method (Chow, 1964):

1. The rate of runoff resulting from any rainfall intensity is a maximum when this rainfall intensity lasts as long or longer than the time of concentration.

2. The maximum runoff resulting from a rainfall intensity, with a duration equal to or greater than the time of concentration, is a simple fraction of such rainfall intensity; that is, it assumes a straight line relation between flow Q and intensity i, and Q = 0 when i = 0.

3. The frequency of peak discharges is the same as that of the rainfall intensity for the given time of concentration.

4. The relationship between peak discharges and size of drainage areas is the same as the relationship between duration and intensity of rainfall.

5. The coefficient of runoff is the same for storms of various frequencies.

6. The coefficient of runoff is the same for all storms on a given watershed.

The rational method has been used with satisfaction for small (less than 400 acres) and largely impervious areas such as parking lots and airports. The basic equation is

Q = CiA where Q is the peak runoff in inches per hour per acre (approximately equal to cubic feet per second), C is the runoff coefficient, i is the rainfall intensity in inches per hour, and A is the drainage area in acres. The most difficult aspect of using the rational method is estimating C, a constant that integrates the effects of infiltration, detention, evaporation, retention, flow routing and interception.

84 UPPER gt.N'I'A CRUZ RIVER BASIN, ARIZONA A21

.« oL, -o-.CL Nonn - cM_N C1-..*r.7nM<* - _. .' ' -. -.

xOMNN-+ SCJCL^v^000XN.-+ i..crnnv^x cxL.oconL: ó......

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85 A22)a WATER RESOURCES OF THE TUCSON BASIN

1 TABLE t1 -Flood volumes having 20- and 30 -year recurrence intervals for 1 -, 3 -, and 7 -day periods at selected gaging stations

Flood volume (acre-ft) Station 1-day 3 -day 7 -day 20-year 50-year 20-year 50-year 20-year 50-year

Santa Cruz River near Nogales 4,;60 6.250 9,520 14,300 14,600 2_,200 Sonoita Creek near Patagonia 2,2S0 3,670 2,920 3,690 3,750 5,410 Santa Cruz River at Continental 10,300 13,700 23.600 Santa Cruz River at Tucson 11, 300 15,500 19, 000 29, 200 23,600 37.5(x0 Tucson Arroyo at Vino Avenue, Tucson 770 830 930 Sabino Creek near Tucson 2,480 3,770 4,400 6,340 5,830 9,020 RUlito Creek near Tucson 9, 120 9, 820 17, 300 23, SO0 i8, 700 30, 500 Santa Cruz River at Cortaro 14, 700 15,500 23,600

ride a continuous reservoir outflow and the release of floodflows at lower rates. The summary is presented only as an aid in preliminary planning of reservoirs,-and analyses of the maximum probable floods, which are used for detailed design of reservoir spillways, were not inclu SUSTAINED FLOW The volume of storage required to provide a sustained minimum flow may be determined either by the within- year- stórage method or by the carryover- storage method. The within -year- storage method is based on the assumption that the volume of flow each year is sufficient to replenish the annual storage required to sustain a selected minimum outflow rate. In contrast, the carryover -storage method is based on the concept of Moping water for periods greater than 1 year to sustain a minimum outflow rate. In both methods the amount of evaporation from the'reservoir surface is not included, and it is necessary to add the amount of evali6rätio1rta- the -eet storage requirements. Within-year-storage requirements were ana tized'by. the annual mass -curve method (H. C. Riggs, written commun., 1964) by a digital

1 I 1 I 1 d Note, Computed storage does not include evaporation losses

Santa_Cr.uz River at Tucson ^`-- Sanu..GuzRver. At. Cortaro

100 1.01 1.1 1.5 2 _3 _ 5 10 20 30 50 RECURRENCE INTERVAL IN YEARS

FIGURE 12.- Relation between volume of storage and the average length of time that the indicated storage would be insufficient to sustain a minimum reservior outflow of 1 cfs.

86 Using flood frequency analysis in storm runoff prediction has been severely limited in urban areas owing to the lack of runoff data. This problem is further complicated in Tucson because of the recent urbanization that has altered flow conditions. These limitations have been attacked by relating runoff to rainfall (see Rainfall- Runoff section) and by transposing frequency curves from gaged sites to en- gaged sites.

Roeske (1978) developed regression equations for return intervals of 2, 5, 10, 25, 50, 100, and 500 years for six flood frequency regions in Arizona. His equation for the 100 -year flood in southeastern Arizona is

A100 =1230A0.447 where A is the drainage area in square miles. The watersheds used in developing the equations range in area from 0.15 to 3,610 square miles.

Reich, et al.(1979) tested the equation developed by Roeske on small experimental watersheds at Walnut Gulch (Figure 9A).The authors note that the sparse network of gages in Arizona, coupled with the great spatial and temporal variations in rainfall input, results in large error components in the data. Further, many of the gages statewide, and most of the gages on the small watersheds, are relatively inaccurate crest -stage gages. Reich, et al., point out that Roeske's standard error of estimate of 86 percent means that the range within which two- thirds of the 100 -year flow values for similar watersheds lie is, for a one -square -mile area,(0.86 times 1,230), or 172 and 2,288 cfs. The best fit data from Walnut Gulch is about 70 percent higher than Roeske's curve for 2- to 10- square- mile watersheds. This error is not unexpected because most of Roeske's data are from larger watersheds.

Fletcher et al.(1977) performed a frequency analysis on more than 1,000 data series on watersheds less than 50 square miles using the method of Potter (1961). His equation for southern Arizona is

Q =0.675A0.440R1.268OH0.241 10 where Q10 is the 10 -year flood, A is the watershed area, R is the iso- erodent parameter (the mean annual kinetic energy times the annual maximum 30- minute rainfall intensity), and OH is the difference in elevation along the main channel between the most distant point in the watershed and the location of interest.

As a final note concerning flood frequency analysis, reference is made to an unpublished paper by Reich and Renard (1979), wherein the plotting of flood series on various types of probability paper

87 is recommended as a "viable method for detecting the appropriate distribution for large floods."The authors suggest that the log extreme value distribution appears to provide the best fit for the large floods." The authors suggest that the log extreme value distribution appears to provide the best fit for the large floods, and warn that the smaller half of an annual series is usually not aligned with the larger events. As explained earlier in this report, this phoenomenon is due to the fact that different hydrologic processes are in operation.

The final method for analysis of storm runoff is hydrologic synthesis. As described by Lindsey (1971), the two steps in this method are developing rainfall- runoff relationships and hydrograph synthesis. Most rainfall -runoff relationships are designed to predict the sum of surface runoff and interflow (the flow through the upper soil layers) to which the relatively constant base flow, the third component of runoff, can be easily added. In urban areas, storm flow consists of surface runoff and small amounts of infiltration that occur before the water gets into the drainage system, and when natural channels or ponds are used in the system. As previously mentioned, the large amount of impervious area in urban areas increases the storm runoff and decreases the time to peak flow.

Lindsey (ibid.) discusses three types of rainfall -runoff relationships. Regression, the first type, can take forms ranging from simple plots of rainfall versus runoff to complicated multi -variable relationships. To perform a coaxial correlation, generally the most successful regression technique according to Lindsey, data is needed on rainfall amount and duration, the time of year, and antecedent moisture. Infiltration indices, Lindsey's second technique, are used to express infiltration as an average rate throughout the storm. Since infiltration capacity decreases during rainfall, the index will underestimate infiltration during the first part of the storm and assume too much near the end of it. Infiltration indices are, therefore, best suited for use with major storms occurring on wet soils, or very large storms where infiltration will reach a final constant early in the storm. Analyzing runoff from the summer thunderstorms that occur in the Tucson area is clearly not a situation for which the indices are applicable. The third technique discussed by Lindsey is the water balance approach in which a running account of soil moisture is kept. This final approach is a basis for the Stanford Watershed Model.

The second step in hydrologic synthesis, as described by Lindsey (1971), is hydrograph synthesis. Hydrograph synthesis can be approached using a linear systems analysis.This is a "black box" approach in which a unit hydrograph simply represents the the response of a given watershed to a unit impulse of excess rainfall, and the nature of the process is ignored. While a detailed discussion of the linear systems approach to hydrograph synthesis is

88 beyond the scope of this report, mention is herein made of Clark's work on deriving unit hydrographs using routing techniques (Clark, 1945) and the method of "cascades of linear reservoirs" (Dodge, 1959). The assumption of linearity required in this technique is generally not in effect and inaccuracies are incurred when extrapolating toward large storms owing to the low hydraulic efficiency of channels at low flows, and to the larger relative portion of interflow in the streamflow during low flow (Lindsey, ibid.).

Hydrologic synthesis can also be accomplished by physical analysis of flow. This technique eliminates the need for linearity but a stable solution requires short increments of time and distance, and computation therefore is slow. The complete equations of continuity are used in this approach, and application of the kinematic wave concept has allowed simplification by omitting less important terms. The data needs include the length, slope, and roughness of the reaches into which the stream is divided.The drawbacks to this technique are the need for a great deal of data, and the subjectivity with which the roughness is estimated.

Haan et al.(no date), discussing current hydrological practices, note the trend from the Rational Formula to runoff hydrographs for single storms. The authors also point out that local regulating agencies, in quest of unified hydrologic results, are specifying the type of hydrograph analysis. Haan et al. break down the commonly used hydrograph procedures into three basic steps. The first step, developing the rainfall temporal pattern, can be accomplished using depth -duration- frequency curves or using a severe historical storm (see Precipiation Section). Haan et al. mention three widely varied methods for estimating infiltration losses, the second step (see Infiltration Section). The inaccuracies involved in using a constant loss rate have spurred the development of empirical infiltration equations; another approach employs the Soil Conservation Service runoff curves. Developing a unit hydrograph is Haan et al.'s third step. The development of a unit hydrograph, widely discussed in the literature, involves making estimates of peak flow and time to peak and sketching in the hydrograph using a mathematical function to define its shape. If many unit hydrographs are used in constructing a runoff hydrgraph, the shape of the former has little influence on the latter, whereas if only two or three unit hydrographs are used, the shape is strongly influential.

Renard and Keppel (1966) presented data from Walnut Gulch (see Figure 9A) to "illustrate the unique character of runoff hydro - graphs from semiarid watersheds with absorbent streambeds." The authors found that conventional unit hydrograph techniques are not well adapted to, and flood routing techniques must be modified for, such watersheds to consider the storm pattern, transmission losses, and abrupt transitory waves developed in the channel.A high

89 correlation was found between runoff volume and peak discharge for a simple event. Hydrograph rise time decreased with increasing watershed area. Transmission losses affected hydrograph shape and shortened rise time, especially where a long reach of channel was traversed. And, transitory waves, generally a few inches in height, contributed to the shortened rise time be developing an overriding effect as they travel downstream. The dimensionless hydrographs based on the hydrograph rise time exhibited as a straight line uses "a family of recession curves depending on the antecedent channel moisture conditions and the distance of dry alluvial stream bed traversed by runoff." Figure 52A illustrates the effect of antecedent channel moisture( "low ", "medium ", and "high" refer to the antecedent moisture condition), and Figure 53A reflects both "the increased runoff volume for a given peak discharge at the larger stations" (Watershed area decreases as follows: 1,2, 6, 3, 4), and "the tendency of the rise time to decrease with increasing drainage area." (The ordinate of the dimensionless hydrographs is the quotient of the discharge at time T and the peak discharge, and the abscissa is the quotient of the time from beginning of runoff to the time Q occurs and the time from beginning of rúnoff to peak discharge.)

Doubts as to whether the unit hydrograph concept is applicable to conditions prevailing in semiarid watersheds, where channel losses are considerable and storms do not cover the entire watershed, prompted a study by Diskin and Lane (1976) to apply the double triangle unit hydrograph technique to rainfall and runoff records from the 1975 rainy season on a 4 -acre watershed in the Santa Rita Experimental Range located 30 miles south of Tucson. The characteristic shape of the hydrograph, which starts and ends in a condition of no flow, is a narrow triangular peak followed by a long tail. This shape, coupled with the simplicity of the method, led to the use of the double triangle unit hydrograph. "Reasonable to good agreement" was observed between the observed and computed runoff hydrographs. The mean relative absolute deviation between the two hydrographs was "3.8% when the computed hydrograph was based on individual unit hydro - graphs and 6.0% when it was derived from mean unit hydrographs" (Figures 55A and 56A). The authors suspected that the changes in shape of the individual unit hydrographs (Figure 57A) were influenced by antecedent soil moisture conditions and by the extent of the contributing area.

The City of Austin, Texas (1977) produced a manual for determining storm runoff and constructing a storm hydrograph. Lacking long -term data on urban runoff, the authors recommend the use of the Rational Method for areas smaller than 400 acres, and a combination of unit hydrograph techniques and local flood data for areas larger than 400 acres. This latter procedure begins with the development of the intensity- duration- frequency curves for rainfall analysis. Empirical equations are then developed to correlate physical parameters with

90 EPHEMERAL STREAMS 49

LO f\ 0.8

á 0.6 OP

0.4 HIGH

0.2

0' 2 3 4 7 8 T Tr

FIG. 10.- DIMENSIONLESS HYDROGRAPH WATERSHED 4 ON THE WALNUT GULCH WATERSHED

; G

t ;1 I.0

0.8

Q 0.6 QP

0.4 \ N. ' HIGH \ ` `' \ \. '- \\\...... MEDIUM `' 0.2 \\/-LCw -....

0 I 2 3 4 5 6 7 8 9 T

FIG. 11.- DIMENSIONLESS HYDROGRAPH AT THE OUTLET OF WALNUT GULCH WATERSHED (WATERSHED I)

91 50 March, 1966 HY 2

4 5 6 7 8 T Tr

FIG. 12.- MEDIUM DIMENSIONLESS HYDROGRAPH WATERSHEDS 1, 2, 3, 4, 8:, 6 ON WALNUT GULCH

I.0 `

,, , FLAT TOP------0.8 ` \ SHARP1 I- PEAK , 0 0.6 ,{ 1 OP 1 I \ \ ,,--HIGH

0.4 ! \ \ \ \\, \ ...... ----LOW 0.2 \\

8 10 12 14 16 18 T Tr

FIG. 13.- DIMENSIONLESS IYDROGRAPH ON ALAMOGORDO CREEK WATER- SHED

92 1.2

ODeervadHydrograph / 1.0

/ \ Computed, Using / 0.8 // \ Individual Unit Hydrogroph

0.6 Computed, Using \' Mean Unif Hydrograph. O -J 0.4 STORM 6 8-12-75

0.2

o 0 15 20 25 30 35 40 TIME (MINUTES)

Fig.b --Observed and con,utea runoff hydrographs.'fbr storm of Aug. 12. 1975(lo. 6).

1.2 ,- Computed, Using //\ Mean Unit Hydrogroph

1_0 Observed Hydrogroph \

08- / \

z Computed, Using / \ \\

I` Individuol Unit Hydrograph 06 ¡¡I{' 3 !/ o J \ 0.4 - /1 STORM IO ¡ 9.13-75

0.2-/t

40 10 15 20 25 30 35 TIME (MINUTES)

Fig. 7 -- Observed and computed runoff hydrographs for storm of Sept. 13, 1975 (NO. 113).

134

93 2;5

t7-7 /i fig., 5-- Individual optimal unit hydrographs for the ten storms.

94 unit hydrograph properties. Synthetic unit hydrographs are developed for typical drainage areas with variations in watershed shape, main channel slope, and the overall drainage system conveyance effiicnecy. This latter coefficient takes into account the degree of channel improvement, the roughness, the density of storm sewers, the area and length of streets, and the amount of impervious cover. Frequency curves are then applied to the synthetic unit hydrographs to develop the peak flow versus area curves. The total hydrograph for the 10 -, 25 -, and 100 -year flood is developed using this information along with a tabulation of the total runoff for varying areas and percent of impervious cover, and figures giving the time of rise and base time for the hydrograph from the peak flow and the percent impervious cover.

As an appendix to the Santa Cruz Riverpark Master Plan study, Resnick and Sebenik (1978) developed a descirption of 25 water sources to the park area. Included in this appendix (Appendix E) are descriptions of water source and area of use, quantities and qualities of water, and possible water uses.

The U.S. Army Corps of Engineers has developed flood plain information for several of the rivers and washes in the Tucson area, including Rillito Creek, Pantano Wash, Tanque Verde Creek, Sabino Creek, and Agua Caliente Wash (U.S. Army Corps of Engineers, 1973 and 1975). The authors note that streamfiow in the majority of streams in southern Arizona is negligible except during and immediately after rains. Obstructions to streamflow, both natural and man -made, often result in overbank flows and unpredictable flooding. A surge of water can rush downstream as a result of the breaking loose of debris such as brush and trees that were lodged behind bridges, culverts, pipelines, etc.

This historic peak flows for Sabino Creek and the Rillito at Oracle Road are shown in Table 20A. Defining the intermediate regional flood as "a flood whose magnitude has a one percent chance of being equaled or exceeded in any year," and the standard project flood as the flood that would occur during the "most severe runoff conditions that could be reasonably expected," the authors (U.S. Army Corps of Engineers, 1973 and 1975), using "hydrologic computations" and "consideration of pertinent meteorologic and physiographic conditions," computed the peak flows for Rillito Creek, Pantano Wash, Tanque Verde Creek, Sabino Creek, and Agua Caliente Wash (Table 21A). The authors point out that floods of these magnitudes would cause greater damage than past floods and would result in the destruction of homes, vehicles, water- lines, sewerlines, and streets. Human lives would be lost and certain areas would be isolated creating hazards "in terms of medical, fire, and law enforcement emergencies." Detailed maps are presented showing the areas that would be inundated by the intermediate regional flood and the standard project flood.

95 TABLE 2C A

HISTORIC PEAK FLOWS*

Date Peak Flow

Location Month Year Cubic Feet Per Second

Sabino Creek September 1970 7,730 August 1966 6,400 March 1954 5,110 July 1959 4,240

Rillito River at Oracle Road September 1929 24,000 December 1914 17,000 July 1921 16,000 August 1935 13,400 August 1940 13,200 December 1965 12,400

* "Water Resources Data for Arizona," Part 1, Surface Water Records, U.S. Geological Survey. Flood Descriptions

The following are descriptions of known large floods that have occurred in the vicinity of Tucson, Arizona:

Excerpts from the Tucson Daily Citizen, 23 December 1965

High Water

All river and creek crossings were reported dangerously underwater. Roads closed by high water included, Mt. Lemmon Highway and Golf Links, Pantano, Houghton, Tanque Verde Loop, Sabino Canyon, Silverbell, Trico and Pima Mine Roads.

Bridge Damaged

The bridge spanning Tanque Verde Creek on the Tanque Verde Loop Road also is damaged and sections òf it may have washed out. It was completely under water last night and officials were unable to reach it early today to assess damages.

Flows on the Tanque Verde and Sabino Creek are the highest ever recorded here, officials of the U.S. Geological Survey said today. Both feed the Rillito.

James Ligner of the survey said this area is having what is called a "Chinook" in the northwest. Heavy snows in the Catalina and Rincon Mountains are being turned into torrents of water by warm winds and rain. 96

fo . TABLE _al' k. tr{, 7

PEAK FLOWS FOR INTERMEDIATE REGIONAL AND STANDARD PROJECT FLOODS

Distance Intermediate Standard Upstream Discharge Regional Project from Mouth Area Flood Flood

Cubic Cubic Square Feet Feet Location Miles Miles Per Second Per Second

Tanque Verde Creek:

Above confluence with Pantano Wash 0.00 241 34,000 93,000 Below confluence with Sabino Creek 2.47 215 35,000 99,000 Above confluence with Sabino Creek 3.14 149 28,000 80,000 Below confluence with Agua Caliente Wash 5.80 140 31,000 87,000 Above confluence with Agua Cliente Wash 7.04 98 23,000 64,000 Below confluence with Canyon Del Salto Creek 12.62 51 19,000 43,000 Above confluence with Canyon Del Salto Creek 12.70 43 16,000 36,000

Sabino Creek:

Above confluence with Tanque Verde Creek 0.00 66 18,000 49,000 Below confluence with Bear Canyon Creek 3.20 53 17,000 38,000 Above confluence with Bear Canyon Creek 3.38 35 12,500 27,000

Agua Caliente Wash:

Above confluence with Tanque Verde Creek 0.00 42 13,000 36,000 Below confluence with Molino Canyon Creek 5.52 25 12,000 26,000 Above confluence with Molino Canyon Creek 5.66 18 9,000 19,000

97 2I 4 .L..-,.o- TABLE 3 %?

PEAK FLOWS FOR INTERMEDIATE REGIONAL AND STANDARD PROJECT FLOODS

{U0 -yr. Distance Intermediate Standard Upstream Drainage Regional Project from mouth area Flood Flood

Cubic Cubic Square feet feet Location Miles miles per sec. per sec.

Rillito River above confluence with Santa Cruz River 0.00 934 31,000 81,000

Rillito River below confluence of Tanque Verde Creek and Pantano Wash 11.93 845 34,000 93,000

Pantano Wash above confluence with Tanque Verde Creek 0.00 608 32,000 61,000

Frequency

A frequency curve of peak flows up to the magnitude of the Standard Project Flood was constructed on the basis of available information and computed flows of floods. The frequency curve thus derived, which is available on request, reflects the judgement of engineers who have studied the area and are familiar with the region; however, it must be regarded as approximate and should be used with caution in any planning of flood plain use. Floods larger than the Standard Project Flood are possible, but the combination of factors necessary to produce such large flows would be extremely rare.

Hazards of Large Floods

The extent of damage caused by any flood depends on the topography of the area flooded, depth and duration of flooding, velocity of flow, rate of rise, and developments on the flood plain. An Intermediate Regional or Standard Project Flood in the Rillito River and Pantano Wash would result in greater inundation of agricultural, commercial, and residential sections in the Tucson area than there has been in past floods. Deep floodwater flowing at high velocity and carrying floating debris would create conditions hazardous to anyone attempting to cross flooded areas.I n general, floodwater 3 or more feet deep and flowing at a velocity of 3 or more feet per second could easily sweep an adult person off his feet, thus creating definite danger of injury or drowning. Rapidly rising and swiftly flowing floodwater

98 Comparison of the elevation of the underclearance of bridges with the water level during peak flows shows that the bridges across the Rillito and Pantano Wash would not obstruct the intermediate regional flood but, with the exceptions of the Dodge Boulevard and Swan Road bridges across the Rillito and the Broadway and 22nd Street bridges across the Pantano, the bridges would obstruct, by 2 to 6 feet, the standard project flood. All of the bridges across Tanque Verde Creek and Agua Caliente Wash would obstruct the intermediate regional flood by about 3 feet.

The average velocities for flow in both the channel and the overbank for both the intermediate regional flood and standard project flood are shown in Table 22A for selected locations in the five washes studied. The rates of rise and duration of flooding for the Rillito at mile 3.22 and Tanque Verde Creek at mile 1.95 for the two floods are shown in Table 23A.

Grove (1962) also performed a flood plain study in the Tucson area, specifically along Rillito Creek. The typical topography in this reach includes a low -flow channel 100 to 200 feet wide and 4 to 7 feet deep, paralleled on both sides by swales which, in some places, are as low as the bed of the channel. Grove notes that these swales perform two functions: flows from tributaries flow in the swales until forced into the main channel by an obstruction; and overflows from the main channel are absorbed by the swales. Grove observed that floods have historically occurred between July 25 and August 31 with three exceptions: September 23 and December 23 and 31. In 46 years of record, there were 12 floods over 9000 cfs, 5 floods over 13,000 cfs, and 2 floods over 20,000 cfs. The largest flood ever recorded in the region occurred at Queen Creek (70 miles north of Tucson) in 1954. The runoff that would result from that storm superimposed over the Rillito Creek drainage is 90,000 cfs (ibid.).

The flows on Rillito Creek were analyzed by Baran, et al., (1971) for the purposes of constructing a simulation model for ephemeral streamflow and examining the worth of the data for that model.Although a detailed description of this study is beyond the scope of this report, two graphs developed therein provide useful information. Figure 58A shows the average flow arrival rates for half -month periods over the time period 1930 to 1965. Figure 69A shows the distribution of flow arrivals between August 1 and August 15.

Diskin and Resnick (1976) analyzed the distribution of peak flows using eight years of data on High School Wash and on Arcadia Wash. The short periods of record prohibited the use of a conventional extreme value analysis, so an alternative method, using the highest three or five peak flows for each year, was used. The data are shown in Tables 24A and 25A. The values of peak flows, shown in Table 26A, were read

99 Velocities of flow - Velocities of flow during floods depend largely on the shape of the cross sections, conditions of the stream, and the bed slope, all of which vary in different streams and at different locations in the same stream. During an Intermediate Regional Flood in Tanque Verde Creek. average velocities of channel flow would range from 5 to 20 feet per second (3 to 14 miles per hour), and average velocities of overbank flow would range from 1 to 8 feet per second (1 to 5 miles per hour). During an Intermediate Regional Flood, in the main channel of Sabino Creek and Agua Caliente Wash, velocities would average 13 and 9 feet per second, respectively (9 and 6 miles per hour); and overbank velocities would average 4 and 3 feet per second,'respectively (3 and 2 miles per hour). The velocities of flow during the Standard Project Flood would be slightly higher than those during the Intermediate Regional Flood. The high velocity flow in the channels of Tanque Verde and Sabino Creeks and Agua Caliente Wash would be capable of causing severe erosion to the streambeds, streambanks, bridge piers, and bridge abutments. These velocities would be capable of transporting large rocks and masses of debris. In the overbank areas, water flowing at less than 2 feet per second would deposit debris and silt. Table 5 lists average velocities of flow at representative locations in the study area.

f, 1 'rr ~I¡g TABLE 5' 2 2 c- 7E-

AV ER AGE VELOCITIES OF FLOW 971)

Intermediate Standard Regional Flood Project Flood

Miles Upstream Location From Mouth Channel Overbank Channel Overbank fps* fps* fps* fps*

Tancue Verde Creek

Cross Section No. 1 1.46 g 3 13 4 Cross Section No. 2 4.59 10 2 13 4 Cross Section No. 3 9.58 9 4 12 5 Cross Section No. 4 12.25 15 5 21 7

Sabino Creek

Cross Section No. 5 1.48 11 4 8 3 Cross Section No. 6 3.66 14 8 15 9

Agua Caliente Wash

Cross Section No. 7 1.96 8 2 12 4 Cross Section No. 8 4.54 12 4 17 6

*Feet per second.

100 Velocities of flow - Velocities of flow during floods depend largely on the shape of the cross sections, conditions of the stream, and the bed slope, all of which vary in different streams and at different locations in the same stream. During an Intermediate Regional Flood in the Rillito River, velocities of main channel flow would range from 5 to 17 feet per second, and velocities of overbank flow would range from 1 to 4 feet per second. During an Intermediate Regional Flood in Pantano Wash, velocities of main channel flow would average 12 feet per second; and overbank velocities would average 3 feet per second. The velocities of flow during a Standard Project Flood would be slightly higher than that during an Intermediate Regional Flood. The high velocity flow in the main channels of the Rillito River and Pantano Wash would be capable of causing severe erosion to streambanks and around bridge abutments and would transport large rocks and masses of debris as it has in past floods but to a worse degree. In the overbank areas, water flowing at less than 2 feet per second would deposit debris and silt. Table 5lists average velocities of flow at representative locations in the study area.

TABLE 7, Z/ rG`-r<

AVERAGE VELOCITIES OF FLOW

(feet per second)

Intermediate Standard Regional Flood Project Flood Miles upstream Location from mouth Channel Overbank Channel Overbank

Rillito River Cross Section No. 1 3.60 9 2 11 3 Cross Section No. 2 8.14 12 2 15 3

Pantano Wash Cross Section No. 3 2.46 10 2 12 3 Cross Section No. 4 5.30 14 0 17 10

Rates of rise and duration of flooding - Both the Intermediate Regional and Standard Project Floods would rise from streambed to extreme flood peak in about 32 hours from the beginning of flow. Table 6 gives the maximum rate of rise, height of rise (from flood stage level to maximum floodflow level), time of rise (time period corresponding to height of rise), and duration of flood stage (period of time during which flooding is above flood stagelevel)for the Rillito River at River Mile 3.22. The time versus flood elevation relationships are shown graphically on the stage hydrograph, plate 20.

101 Rates of rise and duration of flooding -Both the intermediate Regional and Standard Project Hoods would rise from streambed to extreme flood peak in about 2.3 hours from the beginning of flow. Table 6 gives the average rate of rise. height of rise (from flood stage level to maximum flood peak level), time of rise (time period corresponding to height of rise), and duration of flood stage (period of time during which flooding is above flood stage level) for the Tanque Verde Creek at river mile 1.95.Thetime versus flood elevation relationships are shown graphically on the stage hydrograph, plate 29. The information presented in table 6 and on plate 29 are based on a peak discharge that was developed fromalocal storm. However, flooding generated by a general storm, of smaller peak discharge,magnitude may rise at a faster rate and its duration may last longer.

M- ./-, ì`" IJS( '` \ TABLE 6 T.r s\A.-.r. i: 1 ,i _p..---` 1a RATES OF RISE AND DURATION Ge'

Tanque Verde Creek at Mile 1.95

Average Duration Rate of Rise Height Time of Flood Feet Per of Rise of Rise Stage Type of Flood Hours* Feet' Hours* Hours

Intermediate Regional Flood 8.8 5.3 0.6 1.3

Standard Project Flood 13.6 10.2 0.8 2.0

'From flood stage to flood crest.

Photographs, future flood heights -The levels that the Intermediate Regional and Standard Project Floods would be expected to reach at various locations on the flood plain are indicated in figures 9 through 11. TABLEe 2

RATES OF RISE AND DURATION

Rillito River at mile 3.22

Maximum Duration rate of rise Height Time of flood feet per of rise of rise stage Location - Flood hour feet hours hours

Intermediate Regional Flood 0.4 2.2 23 58 Standard Project Flood 0.9 5.2 20 64

Photographs, future flood heights- The levels that the Intermediate Regional and Standard Project Floods would be expected to reach at various locations on the flood plain are indicated in figures 21 through 23. --.

-2 ..,C L. --,- , a_ N\ t"4 Li 5 .1. v. \ c.) ..) ç. ..., ,s , i:--, K\ .1-3 i. ii."' -1 ""-, 2 N.-./ ....._5 c, d z ,.. I D t.,.. 0, x ;ii i 0 F; 5 ...P* - .:'`- ::"..4.., i:. ..7,...7 ,..., .; < .f), 2.5 - ,i) 1 03 --% La, U.. z o ir to 0.1 SA107.d AO 83E MIN 3DVAV 207

104 10- 8- RILLITO CREEK1930 THRU 1965 4-6-

0 Ó I 2 3 4 5 6 7 8 NUMBER OF FLOWS BETWEEN AUG.I THRU AUG.15 , 't7.ur 1 Film -.& 3, Aug.Distribution 1S for the ofperiod 0, 1, 1930 -1965 on Ri }litoi: Creek. 2, flow arrivals between Aug. 1 and - s -% I,, Sc,C1cn 5

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108 from the eight cumulative distribution curves. For both washes curves were prepared on plain probability paper and log probability paper for three events per year and five events per year. The eight estimates of the peak flow were averages for each return period (10th, 20th and 50th years). The average of the eight estimates was computed and divided by the square root of the drainage area. This final parameter is generally constant over an area with similar conditions.The values for High School and Arcadia Washes were within 10 percent of each other.

As part of the 208 Project of the Pima Association of Governments (1977) members of the University of Arizona Water Resources Research Center (WRRC) and College of Agriculture prepared a report on urban storm runoff in Pima County. Even though urban runoff is unusually visible in Tucson owing to the extensive use of streets for drainage, the authors found information on volumes and quantities to be sparse. They combined the seven -year record of rainfall -runoff relationships developed on the WRRC experimental watersheds (High School, Arcadia, Railroad, and Atterbury), the 80 -year record of rainfall from the University of Arizona station, and land -use descriptions to develop estimates for annual runoff and peak flow for each of 84 watersheds in Tucson area (Figure 37A). Using the unit area annual runoff values for each land use category (Table 27A) with the land use information, the annual runoff values for the 2 -, 10 -, and 100 -year event were computed for each watershed (Table 28A). The peak flows for each watershed in the metropolitan area (Table 28A) were estimated using Zeller's (1977) modification of the Soil Conservation Service (SCS) method.

The method of predicting peak discharges from surface runoff on small watersheds for 2 -year to 100 -year flood recurrence intervals, developed by Zeller, is described in a hydrology manual for flood plain management within Pima County (Zeller, 1977). His 18 -step procedure solves, by an iterative process, the equation 0.3 Nb (LcLca) -0.4 - Tc S S(0.4) o c where Tis the time of concentrations (the time required for water to travel from the hydraulically most remote point in the watershed to the location under question); Nb is the visually estimated roughness coefficient; L is the length of the longest watercourse within the watershed, incfeet; L is the distance up the longest watercourse from the outlet to acpoint opposite the center of gravity of the watershed, in feet; S is the mean slope of the longest watercourse; q is the runoffcsupply rate, in inches per hour; and 50 is a conversion factor. Three iterations are

109 F) Iz

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*4-EAS..ED C TY =CA 1:11- XL? D4AP L.2,:cp-k.l. LANDFILLS AND WATERSHED B(;UNAR17'S THE TUCSON AREs. SEPTEMBER. 1977. \ Y. Y.J.N IDCNIrv,Tom humeEpl SPA);ve.3.wo

PLATE 1

FIGURE .rZ

110 / c? 7 7 TABLE 3-4-4. 27A4 THE ENTIRE URBAN WINDOW,AVERAGE PIMA ANNUAL COUNTY. RUNOFF ARIZONA (ACRE -FEET) GENERATED WTIHIN Land Use Category WATERSHEDCATEGORY - (Acres) Surface Area* (Sq. Mi.) Sum of Each Water- shed Category (Sq. Mi.) (Ac- Ft /Yr /Sq.Mi.) Unit Area Runoff Annual Runoff Average(Ac- Ft /Yr) MobileSingleRanch HouseHome&Multiple Family SuburbanUrban -Urban 3597910505 5157 56.216.5 8.1 56.216.5 8.1 956075 5340 610990 GovernmentMisc.TCUCommercial (Buildings.& Institutions Assoc. Materials) InstitutionalCommercial 494734371824 5.42.87.7 10.5 120 1260 MilitaryIndustrial & StructureReservations PavedIndustrialInstitutional - Desert 11348 2642 125 17.7 0.24.1 17.7 4.15.6 115 50 70 890470390 StreetsAirportsGovernment- - Non- Structure PavedPaved- -SuburbanSuburban 18951 1452 597 29.6 0.92.2 29.6 3.1 130 80 3850 250 HorticultureParks,Feedlots,Resource Cemeteries ExtractionPens GrassyBareFarming 19874 28527510 908 11.731.1 4.41.5 11.731.1 5.9 20 83 100120 90 VacantNaturalNonIndustrial -Horticulture Areas Vacant Desert 281220 24462921 228 439.4 4.60.33.8 448.1 15 6720 *AsTOTALSDrainage supplied (Rounded) by the City of Tucson, not rounded. Stream Channel 429000 14287 670 22.3 670 22.3 ( `' t, 0 %'<``'%`/``'/.f 1.1 7 7 21000 0 Table 3:-+7..20).(CUBIC FEET /SECOND) GENERATED FROM ALL WATERSHEDS CONTAINED2.0 4THE ENTIRELY URBAN WINDOWWITHIN AND THE URBAN WINDOW PORTION OF THOSE THAT EXTEND SUMMARY OF ANNUAL RUNOFF (ACRE- FEET /YEAR) AND STORM PEAK FLOWS OUT OF THE WINDOW, PIMA COUNTY AlDesignationWatershed Surface Drainage Area (sq. mi.) 35.0 70 2yr.Annual Runoff (Ac- ft /yr) 950 10 yr, 2600 100 yr, 2 yr. Storm Peak Flow (cfs) 10 yr. 100 yr. recur. intervals 8281A4 63.513.514.5 190 6040 2000 550480 147059001350 1448 437532 601143671963 1736616494 5655 8584B3 4.63.3 201510 190160110 510430279 709522534 20281930 57034886 ÑH Cl86 2.15.65.2 25 5 220 45 610140 697 2105?1052643 494849487047 C4C3C2 4.21.41.0 254010 230120 60 640350150 278645162 2435 914667 223065741805 C7C6C5 0.6 3.1 102030 200110 55 150440560 417501595 16512196 998 211141975527 C10C9C8 5.81.41.8 651015 366 8090 1010 230240 1025 451479 373514331638 926133703897 E2ElD1 14.4 7.94.7 204035 210270340 580820770 137370 40 1522 770501 243521474300 (" 7)/ MAI c ;iC 7C)S'$(.?C../ i4 7.70f /c;r'V/'` ,( f oII7f generally sufficient to find the two variables, T and q. The peak flow is then found by multiplying q by 645.33 times the watershed area in square miles. Zeller presents his 18 -step procedure along with general guidelines and examples to aid the user.

METHODS OF DIVERSION AND DETENTION

Detention of urban storm runoff can reduce flooding and the size of drainage facilities, enhance aesthetics, and increase ground -water recharge; but detention requires large areas of land, and often presents maintenance problems. Poertner (1974) conducted a nationwide survey of engineering firms to determine the present status of urban detention facilities. Poertner found that the Rational Formula, unit hydrographs, and rainfall- runoff simulations were the pre- dominant methods for predicting runoff. He also found that weirs and spillways were the most often used mechanisms to control release rates, followed by orifices, hydraulically limited outlets, and control gates. The problems most often associated with detention facilities included operation and maintenance, sedimentation, administration, safety of children, property loss, mosquito breeding, and aquatic vegetation.

The engineering firms indicated that 184 parking lots had been designed as detention facilities. Shopping centers, office buildings, apartment complexes, and industrial plants are particularly attractive sites. The basic scheme involves using depressed areas near throttled drains. The problem of steep slopes can be somewhat modified by using the least -used areas for detention, and pending can be decreased by channeling the runoff to recharge areas.

Materials have recently been developed that provide the load carrying capacity needed for roadway surfaces, are easy to repair, and hard to damage, but are porous to allow runoff to pass through. Several materials fit these criteria, such as a porous asphalt with a crushed rock base, and lattice work concrete block.

Basins in residential areas were the second most often designed by the engineering firms surveyed by Poertner (146 facilities) and ponds in parks and playgrounds were third (120 facilities). There were also 18 ponds designed in conjunction with school grounds. Design of basins and ponds is based on land cost, space available, physical and aesthetic characteristics, topography, climate, and whether the facility serves multiple purposes (such as flood control and recreation). The major

113 considerations in designing detention basins are the volume of storage that is needed and the maximum permissible release rate.

Poertner (ibid.) discusses three facets of the engineering design of detention facilities: criteria, factors, and procedures. Poertner's criteria for design include keeping the excess water away from proposed habitable areas, and providing a positive outlet for discharge in case of clogging. The slopes needed for complete drainage are 1% for paved surfaces, 0.4% for paved channels, and 2% for grassed areas. The deeper portions of storage should be at the least - used areas of the site, and multiple purpose facilities are desirable. The design should be based on the hydraulic gradient, and the outlet works should provide for uniform discharge regardless of depth.

The design factors include rainfall curves, the size and location of (and the hydrologic data from) the tributary area, the inflow and outflow hydrographs, the storage volume required, and the means of releasing excess flows. Other factors include the type of facility, safety precautions, factors pertinent to operation and maintenance, and the cost and useful life of the facility. Possible time limitations for releasing runoff without causing secondary problems should also be considered, along with providing the proper slopes and pumps to allow the complete and timely release of stored runoff. A flood routing study should be carried out to determine the runoff rates when the design capacity is exceeded.

Poertner laid out a general set of design procedures. The first step is to delineate property lines, and the areal limits of the watershed. Topographic maps are then used to route excess flow through the site. The next steps are to examine the path of stormwater flow upon discharge, and determine the discharge capacity of the downstream channel. Using the most reliable rainfall data available, hydrographs for runoff are produced, using several return frequencies, showing both peak flows and durations. Designers should then evaluate the conditions created by on -site storage, when the release rate exceeds design capacity, both on site and downstream. The location and method of outlet restriction is then selected, and the structural design is completed with special attention to the emergency spillway (Poertner, ibid.)

Several governmental agencies in Maricopa County have policies requiring the retention of a specified volume of runoff following land development. Erie (1979) examined the effects of these policies on runoff. He found that a storage volume greater than that required to retain a 10- year -24 -hour storm was required in order not to

114 increase the undeveloped peak flow of a 100 -year frequency or less. Increases in volume reduced the peak flow for all storms, up to the 100 -year event, with a linear relationship. The maximum retention policy studies (100 -year -24 -hour) reduced the 100 -year flow from a single family residence by 50 percent. Another way to look at it is that the policy reduced the 100 -year event to the 10 -year event prior to development. Erie concluded that even limited retention reduced the peak from smaller storms, such as the 2- year -5 -hour storm, but that retention up to the 10- year -2 -hour capacity has little effect on the large (100 -year) storm. Erie points out that basins may, if full at the time of the storm, increase the peak flow downstream by decreasing overland flow times. Finally, the author estimates that a storage volume large enough to retain the 10- year -24 -hour storm is required to reduce the runoff after development to the natural runoff.

CHANNEL HYDRAULICS

Natural alluvium channels are unstable, hence any consideration of erosion control or changes in capacity, for example, requires special knowledge of channel hydraulics and careful study.

A paper by Schembera, 1963, contained the following synopsis: "A study for the design of a stable channel on the Rio Grande is presented. The channel rectification was accomplished through the use of a steel jetty system. Statistical equations were derived from numerous water and sediment measurements. The equations related velocity and Manning's "n" to several measured or computed variables. Combining the derived equations with Manning's formula and the general flow equation resulted in an equation from which the floodway width between the jetty fields could be computed. The designed channel was then checked for sediment transport ability and the estimated amount of degradation was determined for future conditions."The equations were developed based on the general concept of river morphology by

Maddock and Leopold ( ).

Maddock (Personal communication, 1979) *, in continuing studies regarding the hydraulic geometry of natural alluvial channels, gives consideration to the width of the water surface; the mean depth of flow; the mean velocity of flow; the slope of the stream water surface; and the concentration, size, and size distribution of the transported sediment. Using a systematic analysis of field data, he finds there are certain relations among the variables. Dr. Maddock

*Dr. Thomas Mddock, Jr., retired from the U.S. Geological Survey and presently a Distinguished Scholar with the Hydrology and Water Resources Department, University of Arizona.

115 has improved considerably on the earlier studies by considering sizes of transported material and stream slopes. A minimum of four equations are required to describe the geometry of a stream: (1) The equation of continuity, Q =AV; (2)a resistance of flow equation; (3)a sediment transport equation; and (4) a width equation, which according to Dr. Maddock is the least understood.

CHANNEL MODIFICATIONS

Historic

It is safe to divide the discussion of the history of surface water use in the Tucson Basin into pre- historic or pre -european, and historic or european influenced channel modifications.

Before the arrival of the Spanish Missionaries the channels of the Santa Cruz, Rillito, Pantano and Canada del Oro were used to a small (relative to present and other pre- historic uses) extent to irrigate the crops consumed by the Hohokam and their predeces- sors.

Archaeological evidence for irrigation systems exists for all of the pre- historic sites shown on Figure 110 (Arizona State Museum, 1980).

The utilized stream channels were characterized by the very high water table associated with this Basin before the advent of ground -water use. The channels were broad and shallow with low flows often inundating large areas. Although evidence indicates that flow was not uniformly perennial throughout the Basin, the streams were intermittent with the areas of shallowest bedrock enjoying the perennial flow of water (Betancourt, 1978).

The diversions usually constructed by the former residents of this Valley consisted of brush and rock dams built in the streambed feeding a canal which carried the water to the crops and then back to the stream. During large flow events the dams would be destroyed by the water and reconstructed or abandoned (Castetter and Bell, 1942).

The small scale of these diversions placed little demand on the water resources of the Basin.

Channel modification and surface water utilization increased with the appearance of european influenced agriculture.Father Kino and his replacements, both Jesuit and Franciscan, encouraged the irrigation of lands in the vicinities of the Tucson area missions; San Xavier, San Augustin and Tumacacori (Cooke and Reeves, 1976).

116 When settlers began to tap the Basin's resources, the geo- morphologic changes which are responsible for the present confir- mation of the streams was initiated. Cattle and sheep along with mining and milling became important users of the areas' water resources (Cooke and Reeves, 1976).

In 1957 the Rowlett brothers' Flour Mill began operation uti- lizing the water stored behind the recently constructed Silver Lake for power. After 1860, W. S. Grant, the Mill's new owner, expanded the Rowlett Mill and built an additional mill. The Silver Lake mills enjoyed a virtual monopoly as the nearest mills outside of Tucson were at El Paso, Texas.

In 1875 Solomon Warner began operation of his mill at the foot of Sentinel Peak, now "A" Mountain. Warner's flour mill and a stamping mill for processing of ore were powered by a diversion of the Santa Cruz in the vicinity of and across the land of the San Augustin Mission and the Catholic Church. In 1883 Warner built a dam and utilized a 300 -acre lake to power his mills. Tail waters from the mills were ultimately put to agricultural use in the Acequia del Rey, Acequia Missional and the Acequia del Cumaro; all occurring downstream in T14SR13E Sec's 10, 11 and 2.

In addition to the above mentioned diversions for use, several canals were constructed solely to provide irrigation water. Farmer's ditch which was originally headed at Silverlake Road (T14S, R13E Sec 23) on the east side of the Santa Cruz; Manning Canal originating in Sec's 14 and 23 of T14S, R13E from the west branch of the Santa Cruz; a canal originating opposite the Farmer's ditch which was ultimately combined with Manning Canal; and Sylvester Watts' Tucson City water supply which originally intercepted subsurface flow at T15S, R13E Sec. 14 are all depicted to the nearest section on Figure 110 along with many other ditches and canals (Betancourt, 1978) .

Once the surface supply became completely utilized, the windmill and pumping plant began to lower the ground water level and guarantee the ephemeral nature of the area streams.

Present and Planned Projects

Projects that have been completed by the U.S. Army Corps of Engineers within the Tucson area include the Tucson Diversion Channel and emergency bank protection. The former, completed in 1966, in- tercepts flow from the upstream part of the Tucson Arroyo and Railroad Wash and diverts the flow around the south edge of Tucson to Julian Wash. The bank protection included the placement of dumped and grouted stone along the abutment of the Valencia Road

117 /2

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118 bridge over the Santa Cruz River to prevent undermining, and the installation of pipe and wire revetment along the Santa Cruz River- bank at City well number 12 to prevent erosion (U.S. Army Corps of Engineers, 1979).

Large projects completed by Pima County include the construction of an earth -bottom channel with stone - revetted side slopes along a one -mile reach of Rillito Creek near Swan, and similar work along a 2.5 -mile reach of the Cañada del Oro.

Two major privately funded projects have been constructed on watercourses in the Tucson area. Golder Dam, though located north of the Pima County Pinal County border and not, therefore, within the boundaries of this study, has an impact on flood conditions along the Canada del Oro. The 130 - foot -high earthen dam, located about five miles east of Oracle Junction, presents a danger to more than 4,000 Pima County residents located in the flood plain and to property valued at $120 million (1979 value)(Pima County Flood Control District, 1979). Seepage through the dam wall and underlying sands and gravels prompted the State of Arizona to order the breaching of the dam in 1966. Litigation has continued since that time.

A 100 -year flood on the Canada del Oro at Lambert Lane is approximately 33,000 cubic feet per second (cfs). If Golder Dam were to fail when filled to capacity of 12,720 acre -feet (elevation at 3,410 feet) a peak flow of 116,000 cfs would reach Lambert Lane 2 -1/2 hours after failure, filling the main channel to a depth of 11 -1/2 feet and a width of 3,300 feet, according to a computer model study conducted at the National Weather Service Flood Forecasting Center in Salt Lake City, Utah. Failure with the reservoir filled to approximately half of capacity (6,550 acre feet) at the elevation of the pipes (3,385 feet) would cause a peak flow at Lambert Lane of 63,000 acre feet, three hours after failure. Failure with the reservoir filled to a frequent depth (3,360 feet) would produce a 29,000 cfs flow at Lambert Lane. Not only would floods resulting from dam failure be larger than the 100 -year flood, but the water would rise much more quickly as a result of failure.

Two other pertinent facts about Golder Dam are of hydrologic importance. Even if the dam were adequately designed for flood control, it would regulate only 48 of the 255 square mile drainage area of the Canada del Oro at its confluence with the Santa Cruz River. And, at maximum discharge under present conditions, it would take five weeks to empty the reservoir. Recent developments indicate that the dam may soon be breached.

119 The second privately funded project is the Kinnison Reservoir (now called Lakeside Park). Originally built as a stock tank, it was first modified for safety purposes by raising the flanks and constructing a concrete spillway. In this stage, the dam detained the runoff from Atterbury Watershed but the reservoir was dry except following a rain. The final modification was made by the Tucson Parks Department for the purpose of forming a wet park. The reservoir was filled with dirt to form an impermeable base and ground water was used to supplement the surface runoff. As Dr. Brian Reich has pointed out (Personal communication, 1980), the spillway, designed for a nearly empty reservoir, is not adequate with the reservoir full.

There are numerous examples of channel modifications on the smaller washes in the urban area. Many of them were formed as urbanization engulfed the native land on which surface runoff was the rule and washes were constructed. Detailed plans showing the channel modifications can be obtained by consulting the City of Tucson Engineering Division and the Pima County Flood Control Dis- trict.

Failure of the channel modifications has been the rule in the smaller washes because of the failure to design for increased volumes and rates of flow due to the urbanization effects. The failure in the larger drainages is due to lack of knowledge regarding channel hydraulics.

Dr. Thomas Maddock, II (Personal communication, 1980) stresses the need for studying the river in sections starting at the upper end and proceeding downstream. One section in the interior of the river cannot be modified without the changes affecting the sections above and below in the river. It is highly recommended that appropriate authorities be consulted, at least until the theory is understood, when dealing with the difficult concepts of alluvial channel hydraulics, and when modifications are being considered in the larger drainages.

In response to the need to prevent possible inundation due to flooding, the desire to utilize flood waters, and the demand for recreational facilities, the U.S. Army Corps of Engineers (1970) studied the relative feasibility of many possible channel improvements on Rillito Creek, the Canada del Oro, and the Santa Cruz River; detention dams on Sabino Creek, Tanque Verde Wash, and Pantano Wash; and check dams near Tucson International Airport. Reports on those studies outlined the major problems with floods and silt in the Tucson Basin. Erosion can cause the rapid cutting of banks and can change the shape and locations of channels. Damage has been caused by inundation and by the destruction of communication

120 and transportation facilities, and other utilities.The channel improvements that have been made by location interests, including earth levees, dikes, and rock and wire revetments, are neither continuous nor adequate for large floods.

The two most promising of the 39 improvements considered were a 4 -mile stretch of the Santa Cruz River from Silverlake Road to Grant Road, and a 10 -mile reach of Rillito Creek from Swan Road to Interstate 10. Both involve the combination of the construction of earth -bottom channels (EBC) with stone -revetted banks (SRB) and flood -plain management. The Santa Cruz River project would be designed for the 35 -year event of 33,000 cfs and would preclude habitable structures from being built in the 50 -year flood plain. The authors estimate that 150 acres of right -of -way would be needed for channel improvement, that 20 electrical transmission towers would have to be relocated, and that new bridges would be needed at Speedway, Silverlake, and St. Mary's Road. They calculate the ratio of benefits to costs at 1.9, and predict that 88 percent of the potential flood damage would be prevented.

The Rillito Creek project would be designed to control the 50 -year flood of 24,000 cfs, and would also prohibit new habitable structures in the 50 -year floodplain. A right -of -way encompassing 450 acres is needed for channel improvement of which 325 acres are presently channel, 17 acres are agricultural land, and 108 acres are vacant. One new bridge will be needed and eight buildings will need to be removed. The benefit -cost ratio is approximately 1.3, and about 83 percent of the potential flood damage would be prevented.

Three other projects on the Santa Cruz River are proposed. Two of these projects involve the construction of EBC and SRB. The third proposed project is a small multiple purpose dam near the San Xavier Mission, and EBC and SRB from Congress Street to Grant Road. The authors estimate that a safe yield of 6,000 acre -feet per year (a.f. /yr can be developed from the annual average runoff of 13,310 a.f. /yr using 8,630 a.f. impoundment).

Three of the four economically justified projects on the Rillito River -Tanque Verde Creek -Pantano Wash are designed to control the 50 -year flood. One project involves 17.4 miles of EBC and SRB. A second proposed project involves 17.4 miles of trape- zoidal concrete channel coupled with a spreading basin along Ril- lito Creek. A third project involves 12 miles of EBC and SRB. The fourth project, designed for the 100 -year flood, involved providing non - structural protection. The other proposed projects involve the placement of EBC and SRB, the construction of rectangular concrete channels, flood plain zoning, and flood - proofing on the Canada del Oro, Rodeo Wash, Airport Wash, and

121 Cemetery Wash.

The U.S. Army Corps of Engineers (1979a) distributed option papers dealing with flood damage reduction options for Tanque Verde Wash, Pantano Wash, Agua Caliente Wash, Rodeo Wash, Airport Wash, Cañada del Oro, Rillito Creek, and the Santa Cruz River at Green Valley, Tucson, and Marana. For each of these watercourses, descriptions of the watercourse, the watershed, and the flood areas are given, along with information about flood flows and previous studies and projects. The authors point out that the Corps of Engineers will decide upon one of three options for each watercourse. The extreme options are "no action" and "channel modification." The third option is "flood plain management." This third option may include limited structural solutions such as the raising of bridges, but the thrust of it is non -structural solutions such as floodplain land purchases, flood -proofing of structures, and strict control of development. Emphasis shall be given to providing recreation, preservation of vegetation, wildlife, and historical sites, groundwater recharge enhancement, and urban storm runoff. As it is these last two concerns that prompted this study, no further discussion of the option papers will be included.

As a part of the Southwest Area Plan, the Pima County Flood Control District is studying the possibility of using detention parks along the western slopes of the Tucson Mountains. Even though this area is not strictly within the scope of this report, a discussion of the principles seems relevant. The plan involves using elevated sports fields and play terraces to dam washes draining 1.5 to 15 square mile watersheds. Implementation of a project such as this will involve purchasing land for the channel rights -of -way and detention parks, constructing the inlet and outlet works and outlet pipes, excavating the basins, installing fencing, and performing the engineering studies. The benefits would include flood protection, additional ground -water recharge, recreation areas, sand and gravel for possible sale, reduction of the number and size of culverts, and elimination of dip maintenance.

Cluff (1978) has presented the compartmented reservoir as an efficient method of storing water in areas of Arizona having flat terrain where the evaporation rate is high. The evaoration losses are reduced by concentrating the water, thereby minimizing the surface area -to- volume ratio. In terrain with slopes less than four percent, pumps must be used to transport the water from one compartment to another. A computer program has been developed for selecting the optimal design configuration. Inputs to the model are the watershed area, daily precipitation, daily and maximum depletion, three sets of season modifying coefficients, the surfce water evaporation rate, and the type of consumptive use. The design parameters are volume, area, depth, and slope of the embank- ment around each compartment. Several variations have been studied

122 such as the use of impervious or recharging reservoirs,and the use of a floating cover over the last (most often full)reservoir. In a simulated example, a cover placed over the last ofsix reservoirs (16 percent of the area) increased the dependablewater supply by 50 percent.

Engineering studies conducted by Smith (1979) on the effects of the IBM plant and future urbanization on flows in Julian Wash were prompted by fears of increased flooding as a result thereof. An estimation of peak flow for both existing conditions and with full basin development in accordance with approved area plans was agreed upon by Pima County Flood Plain Management and Smith. Ten - minute unit hydrographs were developed both for the existing conditions and assuming that the IBM plant, and an interceptor channel by- passing the plant, were in place. A third hydrograph was developed assuming complete development of the Basin. The assumptions used in applying the technique of Espey, et al.(1977) are as follows:

1. The 1% probability precipitation for the area under consideration was 2.45 inches per hour.

2. The vegetative cover for the existing condition consists of 15% vegetative cover with 80% Type B soil and 20% Type D soil.

3. The curve number for Type B soil is 83 and for Type D is 92. This resulted in a weighted curve number of 85 for the natural conditions.

4. The improved condition was assumed to consist of 55% curve number 98 and 45% of curve number 85. This resulted in a weighted curve number of 92 for the improved condition.

5. The impervious percentages were assumed to be 28 and 72 for the original and developed conditions respectively.

6. A conveyance factor of 1.1 was assumed for the natural state (Natural channel conditions with light channel vegetation). This factor was reduced to 0.7 assuming complete channel improvement with no vegetation, extensive use of curbs, pavement and storm drains for the fully developed condition.

7. An improved channel with a bottom width of 80 feet, side slopes of 3 to 1, depth as required, and a Mannings "n" factor of 0.025 was assumed to intercept all of the storm water entering the site.

12-3 The predicted runoff peak for the 100 -year storm both for the natural state and for the IBM site only was 2,800 cfs with one peak occurring one hour and 50 minutes after the start of the storm in the former, and two peaks occurring at 50 minutes and 2 hours in the latter. Under completely developed conditions, a peak of 8,400 cfs was predicted to occur one hour and five minutes after the start of the storm. The discharge of approximately 200 cfs and velocity of 11 feet per second (fps) at Rita Road were reduced to 37 cfs and 5 fps by an on -site detention facility one acre in area and four feet deep. The cost of land used for detention was approximately equal to the money saved by downsizing the Rita Road drainage structures. Although detention increased the total runoff time from 2 hours to 8 hours, the benefits accrued due to decreased flows downstream are great.

Condes de la Torre (1970) conducted a preliminary analysis on the volume of storage required to provide a sustained minimum flow at 15 gaging stations in the upper Santa Cruz Basin. He concluded that

"Because of the high evaporation rates and the extremely low flows in some years, streamflow in the upper Santa Cruz River basin is not a likely source for a continuous water supply of any magnitude. Streamflow, however, could be used in ways other than as a continuous draft. For example, streamflow could be stored and used in a few months to supplement existing ground -water supplies; the short -term storage would reduce the evaporation losses in the reservoirs."

EVAPORATION AND TRANSPIRATION

Evaporation

Cooley (1970) used records of evaporation from sunken insulated evaporation pans near Phoenix, records of evaporation from a Class A evaporation pan at the University of Arizona Mesa Experimental Farm, and evaporation maps of the United States to develop a procedure for estimating evaporation from open water surfaces in Arizona. Figure 120 is used to estimate the normal daily and average monthly evaporation. For extremely hot, windy periods, the curve for maximum daily evaporation curve is more accurate during cool, cloudy periods. The evaporation values read from the graph must be multiplied by a location factor which, for Tucson, is approximately 0.93. Cooley suggests multiplying the evaporation

124 IIIr,.i,:, APORATION FROM 4 0 '- J ?ENI WATER SURFACESARIZONA 35 - EXa.'.:P!.E "A" \ FIGURE. Maximum, No Keith R. Cooley ) J 30 .- MAX i\1U:d -,° A_.,-\JF7.uLi I °\ tionand Minimum Daily Evc and Average MI S. Water Convservotion Laboratory, Soil Research-HO-Fora-gist and Water 25 - . - Ij ° Evaporation Frolic Research j/ I " Water Surfacas (Adju. ,nservation Research Division, Agricultural / I \ Factor = 1.00). rvice, U. S. Department of Agriculture. / /MIVIMUM \ \\ o \ 1 \ / / EiAPORATIGN // AVERAGE ANNUAL // " 72.4'\ N. \ \ \° Most people know that a considerable amount of water / 9 9 i ï 919" \ N. wever,ost by evaporation they are amazed from open that, water from a stock tank con- surfaces in Arizona...... 5-0" 6.6" 90° 1 I 9.-0" 6.9" 5 3 N. \° i 2"i 2 .05 ! . -- i i r- \\ or'sning time water could 7 be feet as deep, much as 6 feet, leaving only one the loss to evaporation in o 00 //. 5 .5 25 I. 5 IS 25 5 15 25 S 15 25 5 15 25 5 I5 25 S IS 25 \ 5 I5 25 5 i5 25 )t for livestock. On the other hand, declines in water 4 5 .52i 515 Î5s 1525JAN. ` MA3. APR. MAY JUNE JULY Iltl AUG. SEPT. OCT, NOV. DEC. :el of 3 or inches per day from fish ponds and 3. F:8. / 1 UsingMiming pools cannot be due entirely to evaporation. the method outlined in this folder, the home above to obtain the estimated evaporation for the time -iMultiply the values obtained in steps and 2 ;en,rimate'net, unfrozen water surfacefarmer, during .rancher,the any amount part of ofthe evaporation year expected from an contractor, or consultant can and location in question.For facilities with exposed walls, such os above -ground .SISthind for any location in Arizona. Results will generally10 bepercent of actual evaporation on an annual exposedaveragethestock value tanks -wall coefficient obtained and exposed in for step the -wall 3entire above swimming state by 1.25, pools, which multiply is an i structures. for all types of . Estimation1w to Estimate of evaporation Evaporation consists of three steps. Examples: ¡-iporotion on whether lyfor evaporation, youthe periodwant maximum, inchoose question1. one normal, fromof the Figure threeor minimum curves,1. For depend- Select the average daily or overage monthly A. Wanted:StepStepfrom Average2.a swimming daily pool normal in Tucson evaporation during July. from 1. .lulyFrom _=From 0.32Figure Figure inches 2, adjustment/day. factor .= 0.95. 1, average evaporation for J:)ectOClJalues evaporation. of IJCIIaverage gioph normalc15 Ínchu, evaporation are shown in 111anlh. Stop 3. 2Multiply ululvrr values 0.32 x obtained 0.95 In steps 0 3 M(1144(141)/ 1 and -imotens.Use However, dieof expected curve, for rcpre.d:ntinll evaporationextremely nrxmrllhot under windy uvaporntiorn average periods, condi- or for cool an par B. In Tucson. uve!argo daily evaporation during July .mate.:udy:y The also1imum curves be evaporation,of valueof maximum when considering and minimum the evaporation possible rangeperiods, the curves representing maximumrespectively, and will give a better Wanted:Steppond in Average Phoenix normalduring Mayevaporation and June. from a fish 1. MayFrom andFigure June 1, average evaporation for 9.0 and 9.9 inches, crestseepagethe losses from2. water storage facilities.locationthe inlocation question.Determine in which Read youfroman adjustment are the interested. map the factor factor from Figure 2 Step 2. Phoenixrespectively.Adjustment = 1.0. (See over) factor from Figure 2 for FIGURE 2. Evaporation Adjustment Factors IE.iro f estimate by 1.25 for facilities with exposed walls.

Transpiration QUALITY (DIVERSION AND DETENTION)

Laney (1972) has discussed the chemical quality of water in the Tucson Basin. His description of the surface water quality is as follows:

In the Tucson basin the water in the major streams is of excellent chemical quality; the dissolved solids consist mainly of calcium, sodium, and bicarbonate. The streamflow, however, generally contains large amounts of suspended sediment; at times, the sediment concentrations is almost 47,000 mg /1 (milligrams per liter) in the Santa Cruz River. Surface water is not used for irrigation or public supply because of the erratic occurrence and quantity of the flow and because of the lack of storage reservoirs.

Chemical Constituents

In the Tucson basin, water in the major streams generally contains less than 400 mg /1 of dissolved solids and commonly contains less than 200 mg /1 of dissolved solids (Table 100). Streamflow in the Santa Cruz River and Pantano Wash generally contains larger amounts of dissolved solids than the flow in Rillito Creek. Cal- cium and bicarbonate are the principal ions in solution, although flows in Pantano Wash and the Santa Cruz River may contain large amounts of sulfate. The flows in Rillito Creek and its tributaries have about the same dissolved solids concentrations, except the tributary flows contain greater amounts of sodium and sulfate.

Suspended Sediment

Sediment data are vital in the design of flow -retarding structures intended to increase the amount of ground -water recharge from streamflow. In the Tucson basin the accumulation of fine sediment deposited by floodflows behind the structures probably would reduce the infiltration capacity of the streambed.

127 1712 NV ATE It. 1(1A.11I1CGS OF 'P1I1: TUCSON BASIN CI1b.Ml:CAI. QUALITY OF WATER,TABLE 2. --11 tiler suspended- scdinte+lt dí.:chururt, Tucson basin BASIN, ARIZONA D13 T.+111.1; ,11:::t1. Kit 1y1: l,)an! ratean of cheulieal constituents, cnlciunnUlf Lit, lo ratios in sur)it,'t: tcaler in atajar LLI streams in A, ,(Milan ratios, turd Tuc un Lusin and 1 III _...... -..__SII,¡n.ndrll .._._._.. slìl.,enl ...._. ., .:uusUtuauU ta 1 t'nuu p,r lila) 1.:,...pl. u.a ' flit point eull.twuI,,,tl, Í'l'Ila. \uw1 '_I- ;1.. 1°.I:r i,rfsl lI:tl0,n (I.: - ti .r lu:utllt. t,t MungeS:ua.t Cruz River IIeuu Ruug,+ l'.tnt.,ne stt Jlrutl tti.l Santa. Cruz River at 12-20-67 17011 1::, i1111 :32, 000 1, 174, IIUU Culti100Sílirs tl'tu_ . _-- 2511 ' - 'JO46 4724 7 1721 8 -102- 21 742215 station.Continental gaging 5.13 Sodium13irurLt,tnttc\I:nn.::iuut t(11 C(,) .. (\al_-.-_---- l;;)-__.. . _ O81S13 -194- 4414 137 6528 171 68:i(i -261- 56 11321S 46 :' Santa (aU'L River at .ìttitWtl.Tucson gaging 8-7-7-16 162-65 -65 215013151020 .1, IlI)t)1:55 20 13, 200 4,7, 15(1300 19, 400 .'., 62(1 232 FluorideCltloridoSulfate1)t.>lVUtl (F) lStI,I--- (l'1)___- 1,6,1,_ -- -- 102 81. 32-. 1 - --160 38-585 2. 59 .7 198 16 1. 99 .5 133 12 1. :i0-.4 -- -327--218 16 2. (ill S 1.9ti 14 2. .b 10 12 -23 652-112-11-662 66 8-66 0945ISO))15351225 1, 100 4:30350 20,200lt),30,41, 3(1051)0100 4S l, 000 23,811,19, 50040() 2()0 1IC(1-'Sl)t----Ca/Na__ .95- ltlllito Crock 8.03 3.20 'l'rlbuturfrs to Rillito1.97- C:Rok except Puritan() 11'avh 9.73 5.85 9-13-668-22-6688-19-668-1S -19-66 66 0915103511(10144'51145 1,I, 7(111 9(10200 120160 18,28,46,44,39, (SUI) tiUO3(1080O000 227,214, (1(10126, 000 000 12, 4006, 090 Silica )Si():).. ______.. 12 _Runge _.._------.. _.---- 15 ------14Mean 67 Rungo - 25 Die3n 1816 10 - 8-8-20-9-15-6(3 8-69 liS 3 67 130(115:301500113501200 203 7876atl41 11,25,12,21, 15, !;OO100..00I'M 100 11, 9002,:i, 4302501, 9:iO670 StlllilllllMagnt.

Streamflow that contains a sediment concentration of 46,600 mg /1 is almost 5 percent particulate solids. The sediment concentrations in flows of 1,000 cfs (cubic feet per second) or more are equivalent to sediment discharges of from 100,000 to more than 700,000 tons per day. The sediment discharge, in tons per day, given in Table 110 was calculated using the instantan- eous stream- discharge rate at the time the sediment sample was collected. Although tons per day is a common measure for reporting sediment- discharge data, it may not represent the actual daily sediment discharge because the irregular streamflow may cause the sediment - discharge rate to decrease or increase considerably within a few hours. The actual sediment discharge for a given day would require many more measurements than were made during the sampling period.

On February 14, 1968, sediment samples were collected at Rillito Creek near Tucson and Tanque Verde Creek at Sabino Canyon road (pl. 1B, sampling points 7 and 5); the samples were collected at nearly the same time of day, and there was no flow entering the reach from Pantano Wash. Tanque Verde Creek had a sediment concentration of 894 mg /1, but at Rillito Creek near Tucson, about 7 miles downstream, the concentration had increased to 1,440 mg /1; the sediment concentration increases as a result of the contribution of silt and clay from the bed of Rillito Creek. The flow in this reach decreased from 400 cfs at Sabino Canyon road to 250 cfs near Tucson. The decrease in flow in this reach is due to infiltration.

On August 22, 1966, samples taken from the Santa Cruz River at Tucson and at Cortaro (pl. 1B, sampling points 2 and 10) had nearly equivalent sediment concentrations and

129 '1'.\lu1)11 I: 11:1'l'I:l; ,,t,l,t ,:dt'tl-oudinu,)IfR dischtu / T111: 'rUCsOti nAS[N s, 1't(cs()t bn,+in -l'untinnetl (1l1.Allc:11, Qt" %1.11`1" gF WATER, 'rU('SUN nASI':, A111ZON.A 1)15 2.- 11'utr,' I)..tc uf 't'ime 1 S:t.i. sI'('Un(Iat 1)odg' limaoll lioul'c:u'd (111. 11;,,>:uul,li11g point (1) pit l:-'; toe second ilu(ttl puke was di-lei-mined I, \- 111 vVu:; Ial.Un llulin1, a a ci,n1- .'u1L,:nnu 09211hour)1'=i trl.ì) tr,w011unoü1) Ui>ir,rt.,,ltotna per d.t, ,t The,1111la:ll'I51a11 (lll'"' that l't'llCtillllt; at 'Famine of the \\';tIL'r samplesVerde discharge ('r1'el; taken du\111:11'rfllll at kWh() ('I''L'I; at :--iabi110 (':l11yun road \\'1'e from IIoo11lio\\' I)1I;l' 1iU11le\.it'll It:ll,l, :).' Itillit., l'n rh :at t)ra1l ruu11. 12 22--657-27-50Sti- - 17--5U t S-5U 093016111115011ltiUll 61_',715, 01111 000 568123 shovl:lrmthat s preceded anny(lilncut increase the discharge in second sediment d(a\\flood disch:u'g' 11a pulse. ream An vvitheven analysis thoughvata'r of (Ii.;1'Il:lwa'Ih' Illc water sediment IliseJl:n'tn'. and Il.ttu :t 9-13-66'?--1--15-69 6-06 = 21301413 tilJ. 300 t. 2301, 120 measurementsderreaS'à becults' ihovr that sediment concentrations tend to of lltldh'atiull. III ( lie Tucson basin Io' I111d1'1'll;tln,alt5 incll ,te a'll:, sodiw,ul,t::,1mr¿ r.Ite Iu4s c:IlauIateati using the lusLUttam,,us stre.wrdlscliarye raleltillitu ut Um Cn,l: time at Uotit, 1-15-tiU 2 13311 al)0 '2, 53t1 2, 030 ),lIliilllltS uf sedimentslightly are transported in relation during to tut periods incr'as' of ill high Ilutv. GROUND í1':11'lac vv'ater (li,clt:u're :uui that large -J ' triGnturylhu :."liment :.u.i(daa IRg l'.ntpUp c,;Il,ct1 A1;t,,h d.Ott Na:; F'hrttalemitttLutü!t v' 1111 inllulc. Euept for the lntluW Iraut JabLw inaoa'Creek, Gort the amountthu S..ct:a of Ca;.il.nu \luuutains Is maim lva. 1.1, 10(18, sediment samples vv-ere collected at Iiillitu foi' utost,"`--- purposes. -- .1..s(}round used invValet' this r'',url, in the the Tucson tenu "shtlluvc ground basill is of snit :t110 (i'nlicn( quality the('role sumacll'l. near 111. tittle Tucson sampling Of day, and pointsand'Famine there 7 and Verdevrus 5) II() ; Creekthe 1101v' samples at enteringSabin() were the ("tutvottcollected teach frontmail at neatly grOtllttldepthslaudvvat"'" surface, of ul)i)li'smore and t Iuthe water term tu "deep t(el)(((s ground. of its Water- owe!' as applies 7uu feel to 700 feet Belovv' tlin land surface. The shall,) lei:; (1ì'(l11 ,il )II In'lur; the vv ;her :Il theS9tration1 I concentration ttllltll)nnlg /I, increases but\Vet at -)ì Itillito had as increased at'['celc result near of to the'l'ttcsott,1, -1.10 coutributiolt aboutnlg /I; 7 the )Hiles of sediment silt duvv tutd nst concen-clay ream, front '1':uuiuc Verde ('reek hurl a sediment concentration of Offluoride.Tellesolids, dissùlvetl vvulet. aunt 'Ile deepthe isstlids, hart( principal ground thetu moderately Iniucilrtiwetter I(')lls geuer:tlly' are ions h:u'tl 'altillitt,- are andcult luiuiIsodilllll, less Ih:111 and bl'al'bolt,ill'. :100 111:;,'I V'tt el' generally contains ;oalili ut :lin, small :(Moulu -- of and lltr!' /1 of dis-oiled Iicarhullule, un(l ut'l'ucsoninatthe Sabha)this hell reach of and (':tttv'unItlilit() is :it due ('ortaro ('reek.The toroad infiltration.On (1)l.to At,ust250 1luvv' I1;, efs san11)ling 22, innear this 190(1, 'l'ucson. reach points samples decreased 'Ile 2 toil decrease taken10) from haul front in301) nearly Ilow- eisthe Santa ('luz 1tiv'er thekielovv-(hy vv-utet'recommended t11C:land is soft ; maximum surfaceThe groundcontains amounts water fluoride l'or of¡midi,. poorest rince(; Atpply. rationsduality inis cv'ssat shalltivv of depth along the lit, 'tirer, \Nater at clelltbs ulVtaure than 1,000 fleet wereabouttiondischargeequivalent and muchequal erosion. rates; sediment largersediment this_Although than 1)rolrlblyconcentrations comcelltl'utions those the on samplesindicates _11tgust awl at taken sediment-dischargethea '?2;balance two on the _augustsite, water between the 19, dischargeconcctttrt 11)0(1, stdituenitt-and water- ionsalsohail groundcentrationsnarrowmarginSanta U'atet' ('ritz zoneof thealong "liver, ofthat basin, calcium, the trends 111:110('in at the depth northwestward sulfate, l'aut:nlu st in reams. ry- nitrate, Formationl,sif'rotls Telle across alltulllllSand uludstt)ie, tocbicarbonate afk&r oysin. the analLorure northeast occur :don, con- in:t SUtllllill, chlo- onwas _August greater 19 on at. _1uhnst Cortaro 10vvas than almost onAugust _august double 22.the 'l'hesediment se(lina'llt, discharge discharge at nearride, the fluoride, Santa ('raz sulfate, fault :nulbecause iicarionaa' (il' the illtl.case u1,1vard iu the'grouttd \v'alor ; 11' of poor- Tucson owing to the increase( )n January ill water 15, 10611,discharge live tlot'it51reuln. sediment samples were collected in 'Fatigue (lu:tlity 1Vatcr. 11(E.1I, 1)1STRIIIUT1(.)N Ot' 1ISSOI.A'EI) SO1.11)S IN 1 IIALLOW ('reel:.\\lienVerde there and'('Ire wasIiillitu tie( no linl'ml 1kí1\'('rctI:s, cuncenlFtion lit whenl' :titauto the Washstreantllu\r in the at sample its continence of Sabin()from 1äIIlto 11'itli ('reeksu"tai11'd Iiillitu('reel: wits by runup' front the Santa Catalina \lottntains tuttl 111'the major the basin, sedimentary much of the fat'ies luground general, in v%ate Clue the 'bahn. contains areal In distribution theless norl)leustcrnIhan Wit of 111g,''1 tli :,;ulveilhalt' of soli(;., is r'lalt(l tu GROIINI) sediment- discharge and water -discharge rates; this probably indicates a balance between sedimentation and erosion. Although the samples taken on August 19, 1966, had about equal sediment concentrations at the two sites, the concentrations were much larger than those on August 22; the water discharge also was greater on August 19 than on August 22. The sediment discharge on August 19 at Cortaro was almost double the sediment discharge at Tucson owing to the increase in water discharge downstream.

On January 15, 1969, five sediment samples were collected in Tanque Verde and Rillito Creeks, when the streamfiow in Sabino Creek was being sustained by runoff from the Santa Catalina Mountains and when there was no flow in Pantano Wash at its confluence with Rillito Creek. The sediment concentration in the sample from Rillito Creek at Dodge Boulevard (pl. 1B, sampling point 6) was taken during a second flood pulse; the second flood pulse was determined by a comparison of the water discharge at Rillito Creek at Dodge Boulevard and that at Tanque Verde Creek at Sabino Canyon road (Table 110). The three remaining samples taken downstream were from floodflow that preceded the second flood pulse. An analysis of the sediment data shows an increase in sediment discharge with water discharge and a large sediment discharge downstream even though the water discharge decreases because of infiltration. In the Tucson basin the miscellaneous measurements show that sediment concentrations tend to increase slightly in relation to an increase in water discharge and that large amounts of sediment are transported during periods of high flow.

The quality of runoff from Tucson urban watersheds was studied by bharmadhikari (1970). In his conclusions he discussed the parameters that appeared to be a cause for concern.

Turbidity is likely to reduce as the area becomes more developed residentially, but even in totally residential areas it may range from 156 to 1400 JCU. In industrial areas, it may reach 3100 JCU. Some degree of treatment will be necessary to reduce the turbidity to an aesthetically

131 acceptable value. pH will be especially important for runoff from industrial watersheds since the observed range of 6.6 to 11.2 is very wide. Unless this evens out in storage, neutralization will be required before this source is considered for use. This problem is not likely to arise in runoff from residential and commercial watersheds.

Urban runoff shows very high values of COD, even more than that of the secondary sewage treatment plant effluent. In residential and commercial watersheds, this appears to be due to the suspended organic matter. Range of values in such watersheds is from 91 to 347 mg /l. The range observed in runoff from the industrial watershed is considerably higher and wider, 141 to 1693 mg /l. Careful investigations may be necessary to trace and control the source of these high values.

Urban runoff contains phosphates in concentrations above those considered necessary for prevention of algal blooms. Storage of these waters may reduce it slightly due to uptake by organisms. Heavy doses of alum or lime will be required to reduce these further.

The densities of indicator organisms obtained in all the watersheds in the Tucson area are very high, in fact much higher than those observed elsewhere in the nation. The highest densities are observed in the residential watershed. Adequate disinfection will be necessary before these waters are used.

The ratio of fecal coliforms to fecal streptococci is more than 3.0 in all the watersheds. This indicates that most of the pollution comes from human sources. This also emphasizes the need of adequate and efficient garbage collection.

The results obtained to -date are not a cause for alarm. Phenolics may prove to be unimpor- tant in runoff from residential and commercial

132 areas since they may originate from asphalted road surfaces and roof -tops. But the phenolics need continuous attention in runoff from industrial areas since industrial activities may contribute toxic phenolic compounds.

The final section on Nonpoint Source Pollution by Pima Associa- tion of Governments (1977) deals with estimating the pollutant loads for each of the watersheds delineated in Figure 60A. In Appendix D, a series of tabulations shows the loading of each pollutant in a ranked sequence from highest to lowest, by watershed.

Appendix E is from the appendix to the Santa Cruz Riverpark plan, ( "Water Resources Report ") where Resnick and Sebenik (1978) presented information which is highly technical but may be of special interest to this study.

Two inexpensive treatment techniques that are related to diversion and detention and to ground -water recharge are grass filtration and soil - grass filtration. Resnick and Sebenik (1978) also discussed these methods in the appendix to the Santa Cruz Riverpark Master Plan.

133 »4 .;

0.1tig the T,:ality st,rin runot f or sewage effluent hgrass f-!itra ;;..r1 w,!! ,In:ented techniouePoplcm, 1973, Barfield. líao. and Fitv1k1 Wa(C1 thrOtlilil eier re u,r bermuda grass 3.1) aLre-icet per acre per day during SUMIlle 111011(11s. and 3.0 to 7. e-i oet oer ,icre per day during winter months. can significantly e cjientical oxx gen demand, turbiditv, and bacterial densio.. From mole it can he seen that grass filtration can upgrade cool-season urban storm runoff especially with regard to the concentration of fecal colitorm organism so that both contact irrigation and recreation uses of urban storm water can he accomplished. With lower hydraulic loadings, acre-feet per acre per day, further significant reductions in suspended solidand bacterial populations can be obtained as compared with grass- H7,-red iter sampled 1)%Bnokin (1973). For example. l'orges and ll.picuis 119551 reported that suspended solids and bacterial populations %%etc :educed by 99 mid percent, respectively., with a hvdrattlic loading ,tcre_teet per .ti.re per day. and Lehman kl9tieu used three f,.raic..1 Bermuda grass strips to test the effectiveness of grass filtration of !:,.-atet sewage et fluent from an oxidation pond. The% found that coarse and s.,ispentied solids were el lecmely removed by. bermuda grass with a hdratilic loading of approximately 1.3 acre-feet per acre per day. Warm-season urban storm runt)! f can also he upgraded. The hydraulic rate needs to he loty enough to remove the larger concentrations ut leLai conform organisms and suspended solids found in sinniner urban r,,!,,,twaters. III r(lel ti) St,itleVilat alleviate these water Tiara the W;11111-SCaSollUrban111111)1t. generally should not be used. This initial runoff eventifl have a large concentration of both organisms and . solids.I 1,rough the po.oer 1)N -bass management technique. ate s. and clihainat u m, W:11111-NeaNtill urban suu it t can be used for at east tion-c-ourrc'rfnci probablv contact recreation ÇtIId !iglu!, Pr )14:111t 1973i, sce(Fable 2. used hydraulic loading i ales d' t.t extreme:\ high and lituited-theliitration action ut the gt-ass. !setglitary sewage et fluent can also be upgraded throughrass Filtration. \k t.,,rding to Searle il .,t.191, the City ot elbourtie. Australia has emploY ell ;Ilion for donieiic sewage ti eatment folloyving Nettling since 1932. an average hydraulic loading of- about 0.1 acre-leet per acre per (lac. biochemical oxygen demand (.1()1)1 was reduced during filtration limit 12:2 milligrams pet liter to less than 20 milligrams per liter, and suspended reduced to21,) milligrams per liter. \\Ikon and Lehman 119661, as pitouslv discussed, found that BO() and suspended solids were re- L(hman t bum(' that large quantities ut iron. manganese and ton:)e taken tit)v giass hum the filtration ol dtimestic sewage ilnent flout ail oxidation 1)1)11(1. Of course. coliform organisms will .,11.0 utiectixely rc(Iticril. F,cr the grass filtration technique, the following physical parameters are ::cccle(l: A ..ee,, ;tcnl. to resist 'enuring, (_') dense grus growth ,,Í at l(.ts[ t'.: inches [11 11Cig1t. 1.3) ability to recover growth subsequent to y,... sediment. s Uri .1Ce slope of approximately one per - cut- :utci, tat song;,tr hydraulic loadings for the season during the Year that o(curs, :Itt(i for the quality of vPater needed. u cvicetlent_:ass filtration method would include the utilization or rasseti terraces.í hest grassed terraces would he level across unit0,tIt'ispe along their length.1Thete'in he etiectiveiy ued for the creation of greenbelts parallel to the river channel as +.cfli as :or remoy ing acciinn':ntt front storm runotf. Concrete curbing would provide;t 1.11 for captürlilg the coarse se(timent, and a method ti,r cfeliyerin <, the water uniformly onto the broad -based terraces. C ;lass loll "¡Hit otioo -- grass -covered soilfilter could effectively be used as a water quality treatment. Flood water filtering through either rye or bermuda grass and five feet of natural soil at applied rates of 0.1 to 3.0 acre -feet per acre per day during summer months and 3.) to Ti) -acre -feet per acre per day ;luring winter months can significantly reduce chemical oxygen demand. :1-neu,tcu socl(fs. tumidity and bacterial density. To use grass -soil filtration. the following requirements are needed:( l) A deep root system lo resist scouring. (-.L; dense grass growth of at least two inches in height. (3) vetov er gt ()will subsequent to inundation with sediment. (4) a surface slope of approximately one percent. (5) at least seven days of storm

runoff . irrigation are nettled for grass establishment and grass -soil stabilization, and ítì) proper hydraulic loadings for the season during the ear that urban storm runot f occurs. and for the quality of water needed. .Assuming grass -soil stabilization has been completed. Fable `_'sfi)ws the estimated quality of grass -soil tittered, urban storm runoff. As the (Lila indicates. grass-soil filtration can etfectiyely remove almost allt ecal col - ifornc organistrt, and suspended solids from cool- season urban runott. The resulting filtered water can he used for all the possible recreational and irrigation uses. In the future. domestic uses of filtered, urban runoff water nta\ also be feasible depending on the results of the continuing research in potential virus removal of various soils. Warm- season urban storm runoff is more highly polluted than cool -season ruaof fu nit excessive concentrations of both fecal conform densities and suspended solids. Consequently. grass -soil filtration must be more effective during the summer months to obtain the same relative water quality is obtained during cool season flows. As previously indicated in the ,grass filtration section. the first warm season runoff should not be filtered, but diverted downstream. The hydraulic loading should also be significantly lowered to remove the larger concentration of fecal conform organisms and suspended solids. InFable 2 under warm- season flows, grass -soil filtered water has fecal conform numbers greater than 1000 conforms per Pm nil of water sampled as Popkin (1973) applied extremely large quantities of highly polluted water to his grass -soil filtration system with expected, limited soil filtration action. If a' more reasonable hydraulic loading rite of urban runoff ís applied, fecal colitonn organisms will be greatly reduced. .Intl probably wane- season urban runoff waters could also be used tor ail Tice! po,sihk rrccatiouaf ;Ind irrigation uses. Secondary sewage of fluent can also be upgraded by grass -soil filtration, see L able _).sit(h{flatthe concentrations offecal conform organisms and iii s ter, :ie.tlun,titlientS trc reduced. It should he {toted that removal of mutt tents in 'c'.. ;.,e diluent will be discussed later. Fecal conforms as bacteria can be expected to he removed h\ sedimentation, entrapment and adsorption .is the polluted vrater moves through a soil complex. Notable e. ork, by ,"tce .nutf ;artierc 1051) on test plots at Whittier and .Azusa. (Allot-ma, using secondary sewage effluent. led to the conclusion that water of a hat Lelia quality suitable for drinking purposes can be obtained

135 V ; t;;H f, ;;;7 ,`[`,.11. lí1. H Ltr'.,( .ccacte H i \s.o.;ak) aPplac( i lulottut i Ita'tott "'alt.\\*awll'o;antion 1)ata stio,e,1 that ,a--

;11H.1 ;. ate:Nailoat.- !lad tuao otaz gamsni per lt ilrite ,c;;.cal-Hot is le-, than thatrectum-et.'tor the di inking ;act.,tartd.odk of uc1 'itate. 1)f-paiuncut. ( Is!wlHet !It..-;;To conducted subseThtent icsi:tieter1 1uÉkS UT:ticeaatt;;mita

an ti ; ! ; e v found a ot ()noun( rtmocai ot,,tilltale, jr h)(il

; (197-h tumid,1[11,1 intactItt,crate of it(' c_leet per c:;11- 01 1)..,.4; ,.:CIC-;:t2t2'._pet;ture per,LIN;; cattilent into infiltration hasins, that dir Tralit ¡towied ;a; on! Heathy %cells \cas excellent. IThe concentrationttllutal mtif decieasc-d ti um 30 to 10 rmlitgrams per literUICiecal coltiormer e

,thsent, except tor counts of I tu 10 organisms per I00 lc hen samples cere tit-st otnaillecl. ;Therefore, soil-tittered secondall sec\ - age et fluent could he used tor all recreational and irrig-cition applications, arid c\ ;01 chlorination or ozontztwort could Ite recharg,edNVmeaus of 'elk gt wind v.:1[cl ttastn.

11(1111.11,1l.! . I

' '' ` . ! I.. 71

111.4. 114 \ 11'N

.r.,,,t,,i,.111111-,ii Isr,.I °I .1[I.) :11/.it irducc,uliturtu tlen, Ut [[J[ :41r, Mische (1971) conducted a detailed sutdy of "The Potential of Urban Runoff as a Water Resource ". With respect to treatment, Mische concluded as follows:

1. The impoundment and subsequent storage of urban runoff is an excellent means of improving the storm water quality. Quality of the detained water varied with the character of the watersheds. After a period of a week, it was determined that approximately 99.9, 65, and 95 percent removal of bacterial indicators, turbidity, and COD, respectively, was possible. It was determined that the optimum storage of water is for a three -day period since the small quality improvement which occurs with further time would not justify larger storage facilities. Following three days of storage, quality of the supernatant was approximately 62 mg /1, 7 mg /1, and 70 -3200 organisms per 100 ml for turbidity, COD, and total coliform concentrations, respectively.

2. Coagulation of the runoff waters is effective as a rapid means of treatment. Optimum doses of alum were found to be about 100, 50, and 100 mg /1 for Arcadia, High School, and Rail- road Watersheds, respectively. At the optimum doses, it was found that effluent quality of approximately 22 mg /1 turbidity, 23 mg /1 COD and 1 -600 organisms per 100 ml could be obtained.

QUALITY (GROUND WATER RECHARGE)

Laney (1972) studied the chemical quality of the water in the Tucson Basin. In his summary he discussed the quality of ground water as follows:

Most of the ground water in the Tucson basin is of excellent chemical quality and is suitable for most uses. In places, ground water contains excessive amounts of dissolved solids and fluoride, and the fluoride content may be large in the water in the deep parts of the aquifer.

About 75 percent of the shallow ground water - water at depths of less than 700 feet below the

137 land surface - contains less than 500 mg /1 of dissolved solids, which is the maximum recommended concentration for public water supplies. Dissolved -solids concentrations generally are less than 300 mg /1 in the ground water in most of the Cañada del Oro drainage south of the Pima - Pinal County line and in the area bounded by Rillito and Tanque Verde Creeks, the Southern Pacific Railroad Co. tracks, and the Rincon and Tanque Verde Mountains. Dissolved -solids concentrations of more than 500 mg /i occur in ground water along the Santa Cruz River and in the narrow zone that trends northwestward across the center of the basin. In places along the Santa Cruz River northwest, west, and southwest of Tucson, ground water contains more than 1,000 mg /1 dissolved solids.

The dissolved- solids content of the deep ground water - water at depths of more than 700 feet below the land surface - is comparable to that of the shallow ground water and in some areas may be less than that of the shallow ground water where the aquifer is mainly sand- and gravel - sized material. In the southwestern part of the basin west of the Santa Cruz fault and in the eastern and north- central parts of the basin, water at depths of more than 2,000 feet below the land surface contains less than 500 mg /1 of dissolved solids. The dissolved -solids concentrations may exceed 2,000 mg/1 in the water in the hypsiferous mudstone in Tps. 15 and 16 S., R 14 E., and in the southern part of T.13S., R.14E., along Rillito Creek.

In general, shallow ground water that contains less than 500 mg /1 dissolved solids is a calcium sodium bicarbonate type, and deep ground water that contains less than 500 mg /1 dissolved solids is a sodium bicarbonate type. Shallow ground water that contains more than 500 mg /1 of dissolved solids is either a calcium sulfate or calcium sodium sulfate type, and deep ground water that contains more than 500 mg /1 of dissolved solids is a sodium sulfate type.

Most of the ground water contains fluoride concentrations that are below the maximum recommended limit for public water supplies.

138 The maximum recommended fluoride concentration, which varies indirectly with the annual average of maximum daily air temperature, is 1.4 mg /l. The optimum fluoride concentration is half the maximum, or 0.7 mg /1. In most of the basin, fluoride concentrations in shallow ground water are less than 0.5 mg /1; along the Santa Cruz River, fluoride concentrations generally are more than 0.5 mg /1, and northwest of Tucson they are more than 1.5 mg /1. Deep ground water contains more fluoride than shallow ground water. In the central and northern parts of the basin, fluoride concentrations increase from less than 0.5 mg /1 in the upper part of the aquifer to as much as 5.0 mg /1 at depth in the mudstone. In the rest of the basin, water contains less than 1.0 mg /1 fluoride to depths of as much as 1,000 feet below the land surface.

Excessive hardness of water is a near -surface phenomenon and, as a result, the shallow ground water is moderately hard to very hard. The deep ground water is soft in most of the basin. Most of the moderately hard ground water is in the northeastern part of the basin. Hard ground water occurs in the south -central part of the basin and along Pantano Wash and Rillito Creek. Very hard water is in the upper part of the aquifer along the Santa Cruz River, in a zone of poor -quality water that trends northwestward across the basin, and along parts of Rillito Creek and Pantano Wash. Most of the deep ground water is soft to depths of more than 1,000 feet below the land surface, where the aquifer material is coarser than mudstone. Deep water in the mudstone, however, generally contains large amounts of calcium and is extremely hard.

Most of the water in the aquifer contains less than 0.3 mg /1 iron, which is the maximum recommended limit for public water supplies. Shallow ground water generally contains less than 0.05 mg /1 iron, and deep ground water generally contains less than 0.3 mg /1 iron; in places, however, deep ground water may contain as much as 0.5 mg/1 iron.

139 Sulfate concentrations are less than 150 mg /1 in most of the aquifer. In a small part of the basin, sulfate concentrations in ground water exceed the recommended upper limit of 250 mg /1 for public supplies. The distribution of sulfate in ground water is similar to that of the dissolved solids. Sulfate concentrations are less than 50 mg /1 in the shallow ground water in the southern and northeastern parts of the basin and may be as small as 10 mg /1 in the northeastern part. Sulfate concentrations are more than 250 mg /1 in the ground water in places along the Santa Cruz River northwest and south of Tucson and in the zone of poor -quality water that trends northwestward across the basin. In these areas, shallow ground water is not suitable for use as a public supply. Sulfate concentrations generally are not more than 150 mg /1 in deep ground water, except where the aquifer material is gypsiferous mudstone. In these deposits water may contain as much as 2,000 mg /1 sulfate.

140 RECHARGE ENHANCEMENT

INTRODUCTION

The enhancement of ground -water recharge can be associated with a wide variety of beneficial effects. The most straightforward effect is the utilization of unfilled pore space in the vadose zone for the storage of water. In areas where ground water is being mined, recharge enhancement can either decrease or reverse a declining water table, thereby decreasing pumping costs and prolonging the economic life of the aquifer. Water conservation will be accomplished by recharging sources which otherwise would have been lost by evapo- transpiration or outflow from the basin. Furthermore, the area of land needed for surface storage can be reduced if underground storage is used conjunctively. The potential damage that could result from land subsidencé can be avoided if recharge enhancement stabilizes the water table. Flood damage can be mitigated by recharge enhancement in two ways: directly, by reducing the volume of surface flow; and indirectly, by opening up surface storage volumes that can retain the flood waters. While recharge enhancement can be used along with flood control techniques, it is not a viable substitute.

Water stored underground is protected from most catastrophic events. As an example, the effect of an earthquake on ground water may be minimal, whereas an earthquake could cause the failure of a retention dam used to store surface water which could result in widespread damage. Another positive feature of underground storage is that aquifers comprise a distribution system which decreases the need for surface piping.

As the recharged water moves through the porous soil structure, filtration can improve the physical quality of the water. The chemical properties may also be improved by some type of reaction. The recharging operation provides an opportunity to mix or dilute water containing an undesirable constituent with water that has a low concentration of that constituent, resulting in a usable source.A third quality consideration is that underground water is generally protected from chemical and biological pollution that can degrade surface water. Recharge enhancement can also be used to create a barrier against the entrance of some undesirable fluid into an area of useful ground water. This commonly is done to prevent salt water from encroaching into potable aquifers.

In addition to the benefits associated with recharge a number of problems must be recognized. The aforementioned filtering action of the porous soil structure causes the most important problem associated with recharge enhancement. The clogging by particulate matter that inevitably occurs in a recharge operation can only be

141 controlled by continual maintenance. Another inherent negative factor associated with recharge enhancement is that, due to cohesive forces between water molecules and soil particles, an aquifer can never be completely dewatered. Under certain conditions, water that is stored underground can be susceptible to chemical pollution from salts and minerals. Two resources that must be committed to a recharge operation are energy, which is needed to return the recharged water to the surface for use, and land area, which is needed for the recharge site.

METHODS

Spreading - Basins /Pits

A commonly used recharge method involves spreading water in basins and allowing it to filter through the soil surface and percolate through the vadose unsaturated soil) zone to the water table. This method is most suitable where vadose deposits are coarse with no impeding layers of low hydraulic conductivity. Successful basin operation requires that, following infiltration through the soil surface, the recharged water can quickly move out of the zone immediately below the basin to make room for incoming water. The rapid lateral movement of recharged water will be better realized when the vadose zone and aquifer are transmissive and the aquifer is unconfined (U.S. Army Corps of Engineers, 1979). In other words, the best location for a spreading basin is where the flow profile is least restrictive, and the lateral aquifer is most continuous. Further, the water table in the vicinity of a recharge basin must be deep enough so that the mound of water that generally builds up above the water table does not reach the surface, but shallow enough so that large volumes of water are not required to wet the materials in the vadose zone to field capacity or saturation.

Several spreading methods are variations of the basin technique. Where land slopes are gentle and uniform, flooding may be a viable method. The infiltration rate may be high due to the fact that it is not necessary to disturb the soil, but it is difficult to regulate the water flow using this method. Slopes should be large enough so as not to allow rapid settling of fines, but not so large as to cause erosion. Structures may be required for diversion, ditches, and flow measurement (U.S. Army Corps of Engineers, 1979; Bianchi and Muckel, 1970).

Farmers have long known that infiltration occurs in canals and ditches. Using canals or ditches for recharge enhancement is feasible only where land and water are inexpensive and land conditions are appropriate. The benefits of the lateral subsurface flow are maximized (the basins are very long and narrow) but the ratio

142 of wetted area to total area is very low - generally around 1:10. Three layouts have been envisioned: contour, where ditches are molded to the land profile; tree -shaped, where ditches get progressively smaller as they branch out from a central canal; and lateral, where an orthogonal pattern is developed. As in the flooding method, slopes must keep the velocities between depositional and erosive values.

In areas where a thin layer of low permeability near the surface precludes surface spreading, or where land area is scarce, a recharge pit may be a practical solution. Generally, an excavation deeper than five feet is termed a pit rather than a basin. Abandoned gravel pits may provide ideal sites for recharge enhancement facilities, albeit they may need some modification and repair prior to use. It may be conceivable to operate a gravel pit and recharge facility conjunctively, thereby defraying the cost of recharge. With the proper design and operation, infiltration can occur primarily through the sides of the pit while the sediments settle to the bottom. Provisions should be made for easy removal of bottom sediments.

Factors That Affect Basins and Pits

The initial infiltration rate for a given source of water being recharged through a given layer of soil is dependent upon a wide variety of factors. These factors, along with several others, also control the rate at which infiltration changes, usually decreasing, with time. Included among these factors are the physical structure of the soil and the chemical and biological reactions that take place between the water and the soil. These elements are, of course, dependent upon the physical, chemical, and biological make -up of both the water and the soil. Two observations should be kept in mind throughout the following discussion. First, as the wetting front advances, the viscous forces increase requiring more energy input. Second, even a thin layer of low permeability can have a devastating effect on recharge rates.

Bianchi and Muckel (1970) discussed the soil characteristics that generally are accompanied by a high hydraulic conductivity. The intake rates are highest where soil particles are coarse -sized and size distribution is uniform. In an non -uniform soil, the matrix of coarse particles will be filled in with finer particles, leaving little pore space. Water intake rates are affected by pore size and distribution. Large and continuous pores are generally necessary for a high hydraulic conductivity. Bianchi and Muckel observed a direct proportional relationship between the percolation rate and the noncapillary pore space. The relationship between porosity, specific retention and specific yield for California soils is shown in Figure 1B (ibid.).

An aggregate soil structure usually produces high recharge rates. A high rate of infiltration and percolation may occur in a

143 4050 - O POROSITY - 5 4 30 SPECIFIC YIELD 7 j- 10 SPECIFIC RETENTION- -> O 10." 0 T >, a) C Ca) tiC O a.N C -v N v .= E l"; ' a) O -o oC C ou) oN 17 o- C N 0 oi CO .b o . ` C . O U 1/16 oN Ú 1/8 1/4. v- 1/2 E MAXIMUM 10% GRAIN` UO N 2 oO N 4 8. SIZE (mm) 32 Ea) o, 64' c.).oO Ufo 128 256. .n7 SIZE IN , . ( THE GRAINWITH THE COARSEST WHICH THE CUMULATIVE. TOTALMATERIAL,. REACHES .10 % OFSAMPLE) BEGINNING THE TOTAL clay soil if aggregation occurs. Due to the large surface area in clay soils, inter -particle forces become important. If these forces are attractive, an aggregate structure will develop. If, on the other hand, these forces are repulsive, the fine particles will disperse, creating a nearly impermable soil (ibid.).

Bianchi and Muckel use the term "particle realinement" to define the process whereby sediments in the water become lodged in the soil pores. This process makes the pores smaller causing finer sediments to be trapped. Again, the pore size is decreased, finer sediment is trapped, and so on. The conclusion is that clogging will inevitably increase, causing a concomitant decrease in recharge rates. This process generally takes place within the first few feet, or even the first few inches of the soil profile.

Bouwer (1978) points out that clogging of coarse materials has occurred using recharge water with suspended sediment concentrations below 50 milligrams per liter (mg /1). Wilson (U.S. Army Corps of Engineers, 1979) adds that the clogging layer can be as thin as one centimeter. In a tilting bed flume experiment, performed using Rillito River bed materials, Matlock (1965) found the infiltration rate to be inversely proportional to the suspended solids concentration in the water. In Matlock's experiment, a thin layer of sediment significantly reduced intake rates, and the degree of silt- ing increased with decreasing particle size.

The presence of air can affect infiltration in two ways. It can become confined ahead of the wetting front thereby offering resistance to flow, or air can impede flow by becoming entrained in the pores. Wind can indirectly affect recharge by causing waves that erode the banks of the basin. This will cause sediment to be introduced into the water (U.S. Army Corps of Engineers, 1979).

Water temperature and water viscosity are inversely related; therefore, percolation rates should increase with increasing temperature. The temperature dependence of recharge rates was demonstrated in the Leaky Acres Project in Fresno, California (Bianchi, et al., 1978). Average winter infiltration rates were 40 acre -feet per day (a.f. /day) whereas summer rates averaged 58 a.f. /day. More water is lost, however, due to evaporation in warm conditions.

Biological organisms can affect a recharge operation directly or indirectly. The direct effect is the clogging that is caused by biological by- products or dead organisms. Not only can organisms in the water die as a result of the sudden change of the environment upon infiltration, but soil organisms can die due to lack of oxygen as recharge water floods the soil. Recharge rates can be indirectly affected by microorganisms if they change the chemical properties of the soil -water environment. In the absence of oxygen, some

145 microorganisms will function anaerobically. This process results in the formation of acids that can increase the solubility of soil minerals and salts (Bianchi and Muckel, 1970). Another example is algae which can increase the pH of the water resulting in the precipitation of carbonates (U.S. Army Corps of Engineers, 1979).

The degree of aggregation of soil particles is affected by the chemical constituents that are found in the soil profile. Organic remains or by- products of plants, inorganic products of precipitation of salts, and evaporation products of previous high water tables can act as a glue to form an aggregate structure (Bianchi and Muckel, 1970) .

All but the most insoluble salts will be quickly leached by large volumes of recharge water. The dominant cations to consider are sodium, potassium, calcium, and magnesium. The dominant anions are sulfate, chloride, carbonate, and bicarbonate. As the recharge water comes into contact with the soil and ground water, chemical equilibrium is unlikely to exist, and high initial recharge rates can quickly di- minish. Precipitation is most likely to occur between sodium or calcium, and carbonate or sulfate.

In general, the monovalent cations (osdium and potassium) cause dispersion of soil particles due to high levels of hydration, whereas the divalent cations (calcium and magnesium) cause aggregation of soil particles due to low levels of hydration and the sharing of the double charge between clay particles. Therefore, a high relative concentration of sodium could lead to decreasing intake rates.The relation of sodium to calcium and magnesium is expressed by the adjusted sodium adsorption ratio (SAR). An SAR greater than 0.15 will generally cause deleterious affects, although soil and water conditions affect the degree of sodium selaing. An SAR as low as 0.09 can cause problems in clay soils. Precipitation of calcium or magnesium carbonate will increase the SAR, and should be minimized in a recharge operation. A high salt concentration in the recharge water can temper the effect of a high SAR by decreasing hydration.

Design and Operation of Basins and Pits

Recharge basins and pits can be designed and operated to minimize the adverse effects that have been discussed. It is important to choose a site with favorable characteristics such as continuous high permeability from the ground surface to an appropriately deep water table, and space for lateral movement of recharge water. Brown, et al.(1978) suggest a minimum surface infiltration rate of one foot per day and a minimum percolation rate in the vadose zone of 0.2 feet per day. This latter value can be smaller than the former because horizontal permeabilities are usually several magnitudes larger

146 than vertical permeabilities, so, as the water moves down, it spreads out horizontally. Bianchi and Muckel (1970) recommend choosing a location where there are several hundred feet of unsaturated sediments above the water table, but point out that it may take a long period of time before recharge occurs. Recharge facilities should be located so that the recharge water will flow into an area with a large storage capacity. A particularly useful receiving area is a recently dewatered aquifer. Such an area is very likely to have desirable hydrogeologic characteristics, and the vadose zone should have a small moisture demand. Final considerations in site selection are that the recharged water should be up- gradient from and hydraulically connected to the water recovery wells, and that the recovery wells should be near the point of use.

Since water intake rates are often controlled by the first few feet or inches of soil, it is logical to allow for the periodic removal or reworking of this impeding layer. The basin must be allowed to dry before such an operation can be carried out. Intake rates can be impaired by working the surface if the soil does not have a water stable structure.

Clogging can be minimized by removing some of the sediment prior to recharge. Settling basins may be adequate, or flocculents such as alum, ferric chloride, or poly -electrolytes may be needed. Rapid sand filters can also be used to remove sediment.Wilson (1967) and Popkin (1973) demonstrated that grass basins are effective in removing silt from water. The grass slows the velocity allowing the sediment to deposit around and between the plants.

The reduction of water intake rates caused by air confinement can be minimized by de- aerating the recharge water or by venting the subsurface air. Air clogging has not been a significant problem at spreading or pit recharge facilities. The indirect adverse effects of the wind can be lessened by aligning the long axis of the basin or pit perpendicular to the prevailing wind direction (Brown, et al., 1978) .

Water is more viscous at warm temperatures than at cool temperatures. Heating the water prior to recharge would increase recharge rates. The energy cost of heating the water coupled with the higher evaporation rate outweigh the benefit of slightly higher intake rates, and there may be undesirable secondary effects such as the formation of air bubbles or chemical precipitation. It might be reasonable to intensify recharge during the warmer months of the year to take advantage of the higher viscosity during that period. Bianchi, et al.(1978) point out that control of evaporation seems impractical with current technology.

147 Wet -dry cycling is also an effective method for controlling biological clogging. Algacides and bactericides, such as copper sulfate, may be necessary if cycling is ineffective or undesirable. (If properly operated, cycling can also eliminate insect activity).

Remedies for chemical clogging are as varied as the possible problems that could occur. In general, an attempt should be made to match the recharge water with the soil and native ground water so that problems do not occur. Sodium clogging can be lessened by adding a source of calcium or magnesium, such as gypsum.

An example of a basin is shown in Figure 2B (U.S. Army Corps of Engineers, 1979). The standard design includes multiple and parallel basins to allow for the continuous use of the facility. One basin, or series of basins, can be serviced while another basin, or series of basins, is being operated. Wet -dry cycling of basins has been found to be advantageous for the purpose of improving infiltration, as well as helpful in controlling the growth of aquatic plants and in minimizing insect problems. The regulation and monitoring of flow rates is desirable to allow flexibility in operation and to determine the performance characteristics.

The first basin is often used for sedimentation with succeeding basins used for recharge. For a given surface area, a long and narrow basin will generally allow more water to be absorbed than a square basin due to the effect of lateral flow. This effect is less for large basins than for smaller ones (Bianchi and Muckel, 1970). In existing facilities, ratios of wetted area to total area average 0.75 but can be as high as 0.90 in urban areas.The remainder of the land surface is needed for support facilities such as roads, fences, dykes, and buildings for offices and laboratory. Side slopes average 2:1 to 1:1 and the freeboard allowance is one to three feet. Rip -rap or grass is used where high velocities are anticipated and roads are commonly placed on top of the levees. Flow between the basins can be provided for using pipes, gated culverts, weirs, and spillways. Facilities are usually needed to smooth out inflow fluctuations and to allow for returning the outflow to a stream or wash. Finally, provisions must be made to allow for scarifying, disking, or otherwise removing the sediments that accumulate in the basins.

Brown, et al.(19781 presented a graph for determining the dimensions of spreading and settling basins (Figure 3B). For the example infiltration basin design, a basin area of 96,000 square feet was required for a basin with an infiltration rate of two feet per day (ft /day) and a pump capacity (inflow rate) of 1,000 gallons per minute (gpm).

148 CANAL DIVERSIONSTRUCTURE FLUME-- BYPASS LINE DIVERSION DITCH RECHARGE SEDIMENTATION POND FLUME VALVE DISTRIBUTION DITCH TOBASINS BASIN "El CHAIN LINK FENCE (LI IN) SHOP - L ABOR ATORY LP Vtworr.v...t.tors. Roch.,mo UosSuo U. Z. COMPLEX 3111NIW/SNOì1V9 i Si1f1OH '31V8 MOIdNI x 31v11 NOI1N3138 O O o O O o 0 O O o I I I I I I I ( 1111 1 1 1 ¡I fl f I

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150 Figure 3 Examples of Basins and Pits

Recharge basins and pits have been used in many locations throughout the world (IASH, 1970). Perhaps the most extensive and sophisticated system is in Israel where an integrated system of recharge basins and wells is used to conjunctively manage surface water, sewage effluent, and ground water.

A second hub of recharge endeavors is Southern California. Over 100,000 a.f. of Colorado River water has been recharged by the Metro- politan Water District using basins and channel spreading. The Los Angeles County Flood Control District operates water spreading facilities. Intake rates for several spreading systems during period of continuous wetting are shown in Figure 4B. Alternating wetting and drying periods have been used in recharging more than a million acre -feet (a.f.) of Colorado River water. Operational problems have included insects, algae growth, weed infestations, and silt build -up where storm waters have entered the basins( Bianchi and Muckel, 1970).

A great deal of data on basin recharge has been collected at the Leaky Acres facility in Fresno, California. The facility occupies 145 acres, of which 117 acres (81 percent) is pond surface. The remaining area is occupied by dykes, fences, easements, and landscaping. Unlike other recharge operations in California, this facility does not overlie a coarse sandy or gravelly soil. This has led, according to Bianchi, et al.(1978) to the use of "land preparation and water control procedures...more related to irrigaton practice than to flood or stream channel control." The facility overlies recently dewatered aquifer materials. The water table dropped from a depth of 68 feet in 1960 to a depth of 81 feet in 1970.The long term infiltration rate was 0.5 ft /day and the yearly (300 days) recharge volume, using the ten -basin system was 17,500 a.f. Of the 19,600 a.f. of canal water delivered, 14,400 was recharged. Canal water containing over 20 milligrams per liter (mg /1) suspended solids was rejected from the facility. This accounts for 16.4 percent of the loss water. The need to dry the basins because of sudden proliferation of midges accounted for 6.2 percent of the loss, and a 1.8 percent loss was due to low flow in the canal. Only 2.3 percent of the loss was due to evaporation (Bianchi, et al., 1978). Significant air entrapment was present but did not adversely affect recharge operations.

Bouwer and his associates, in cooperation with the Salt River Project and the City of Phoenix, have constructed and operated several recharge facilities in the Phoenix area. The basic thrust of these efforts has been the land treatment of sewage effluent using a well- monitored system of shallow basins. In order to minimize the mixing of the effluent with native ground water, a series of wells was installed at the 23rd Avenue facility to

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152 Fig. 4t, capture the filtered effluent. The layout and flow paths are shown in Figure 513(Wilson, 1979).

Several recharge tests have been conducted at the University of Arizona Water Resources Research Center (WRRC) facility located adjacent to the Santa Cruz River west of the intersection of Inter- state 10 and Miracle Mile. The 110 -foot long pit, with a V- shaped cross- section 50 feet wide at the top, was surveyed to develop relationships between depth and volume, and depth and surface area. The intake rates during a 142 -day continous flooding tests, conducted in 1966 and illustrated in Figure 6B, decreased from 25 ft /day to 5 ft /day after one month, and to less than 1 ft /day after five months. Using bore hole moisture loggers, a bulge in the water content was detected at a depthof 30 feet, the location of the interface between very coarse alluvial sediments and the underlying gravel (Figure 7B). Wilson (1979) concludes, from this evidence, that perching has occurred at this location "even without the presence of an underlying tight layer." All that was required, Wilson continues, "is that the permeability at the underlying layer is less than the vertical flow rate." This perched water drained very quickly, imply- ing the existence of rapid lateral movement of water, possibly in excess of 100 ft /day.

Wet -dry cycling improved the recharge rates at the WRRC facility. Only 45 a.f. of water was recharged in the 142 days of continuous flooding, whereas, in 80 days of cyclic recharge, 40 a.f. was recharged. Wilson (1971b) attributed the improvement to the regenera- tion of open surfaces that occurred during the dry periods.

In 1973, the recharge pit was reshaped by digging a rectangular cross -sectioned interior trench 45 feet long, 20 feet wide, and 6 feet deep. This modification increased the volume and bottom surface area of the pit and made it possible for earth working equipment to operate in the pit. Over a 185 -day test period, the intake rate decreased from an initial value of 16 ft /day to a final value of 3 ft /day (Figure 813). Simultaneous to the cessation of recharge, rapid recession was observed in the water levels of nearby wells. This localized recharge test was not believed to significantly affect the regional water table declines (Wilson and Rasmussen, 1976).

Wells /Shafts

Recharge wells and injection wells are generally more expensive to construct and operate than spreading facilities. Choosing wells over other techniques must, therefore, be justified by other considerations. Recharge wells are defined as boreholes through which water is introduced into the ground -water zone by gravity, whereas,

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157 if water is forced under pressure into aquifer, the preferred term is injection well. Recharge wells may be the chosen method where there is an impermeable layer, expensive or limited areas of land, a deep water table, or the need for a pressure head. "Draw -ups" are found around a recharge well that approximately mirror the draw - downs that occur around pumped wells.

Boreholes that do not reach the ground -water zone are called shafts or dry wells. They are less costly than recharge wells, and there is less chance of biological hazard, sediment damage, and air binding in the ground -water zone if the well does not reach the water table. The main problem with dry wells is that they cannot be re- developed (U.S. Army Corps of Engineers, 1979).

Factors That Affect Recharge Wells

The factors that affect recharge wells are, for the most part, similar to the factors that affect recharge basins and pits. Infil- tration takes place across a vertical right circular cylinder rather than across a horizontal or inclined surface, and percolation through the vadose zone is absent or occurs over a short distance. Again, the structure and composition of the soil in the recharge zone, the characteristics of the recharge water, and the interaction between the two control recharge rates. Recharge wells are generally more sensitive to clogging and quality problems than basins and pits.

The recharged water should have low concentrations of both suspended solids and dissolved air. Air binding can be induced if the water is allowed to fall freely or if a cool water with a high dissolved gas content is recharged into a warm water aquifer. In the latter case, the air will come out of the water (U.S. Army Corps of Engineers, 1979).

Recharged water and aquifer water, when mixed, will generally not be in chemical equilibrium. Salts can precipitate, or clays could be influenced to disperse. Either of these events could result in conditions detrimental to the movement of the recharged water. Pre- cipitation of calcium or magnesium carbonate will increase the SAR which could cause the soil particles to defloculate. Chemical clogging can also result from the accumulation of encrustation and corrosion products (Bouwer, 1978). Biological sources of clogging include the organism itself, or its by- products. Algae and slime forming bacteria can be particuarly troublesome in recharge wells.

Design and Operation of Wells and Shafts

A schematic representation of a recharge well and its appurtenances is shown in Figure 9B. A cross -section of a recharge well is presented

158 CHAIN- LINK FENCE K x FLOW METER RECHARGE WELL f"-(\ A X E SEDIMENTATION POND FLOW METER X CHLORINATOR N K N 4PID FILTER SAND ¿ALV Figure 10 -6. c, Schematic Representation ,Recharge Well and Appurtenances. in Figure 10B (U.S. Army Corps of Engineers, 1979). The preferred drilling technique is the cable -tool method wherein no mud is used and samples can be obtained at various depths during the drilling. For a well drilled using the rotary method, the migration of sand into the well, upon redevelopment in the case of a recharge well, can be minimized by gravel packing the casing. A concrete seal may be a necessary addition to a recharge well to prevent flow up the casing (Bianchi and Muckel, 1970). Screens or slotted perforations are used throughout the permeable zone to reduce clogging (Brown, et al., 1978).

Successful operation of recharge wells requires the presence of very coarse sediments or secondary openings in the recharge zone. Initial well yields should be greater than 500 gpm and recharge rates should be less than the potential yield. Wilson (U.S. Army Corps of Engineers, 1979) recommends recharge rates equal to 80 percent of the potential yields. In contrast, Brown, et al.(1978) suggest using the maximum recharge rates possible in order to force sediments as far into the soil as possible. Brown, et al.(1978) developed a graph for designing injection wells (Figure 11B).In the example shown, a well diameter of 2.9 inches was derived for a recharge rate of 500 gpm and an ordinary iron pipe.

Wells can be designed specifically for recharge, or they can be used for both recharge and pumping. As described by Wilson (U.S. Army Corps of Engineers, 1979):

"Osborne (1969) reasoned that information on the intake characteristics of a pumping well could be obtained from the theoretical specific yield of the well. In other words, he assumed that well and formation losses were the same for both pumping and recharge in a well. To test his hypothesis, he conducted a series of step drawdown tests by pumping an experimental well. These tests were followed by a parallel series of step intake tests by recharging the well. Using data from these tests he then determined the coefficients B, C and n in the Rorabaugh equation:

Where Sw = drawdown in a pumping well, or rise in a recharge well B = the aquifer loss coefficient C = well -loss coefficient n = an empirical constant Q = discharge rate

160 /WELL CASING

DEEP WELL TURBINE PUMP

PRE- MILLED SLOTS

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Figure 10 -7. Cross- section Idealized Recharge Well.

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INJECTION -PIPE DIAMETER, IN INCHES

162 This equation may be manipulated into the form:

Q 1 Sw + CQn-1) =

where Q /Sw is the specific capacity or specific intake of the well. For the well studied by Osborne, values of B and C were about the same for both recharge and pumping cases after 200 minutes. However, the value of n was lower during recharge. At any rate, he proved his hypothesis that the theoretical specific capacity of a pumping well could be used as a first estimate of the specific intake. Solutions (of above equation) are also a useful method for determining the long -term effect of recharging of well characteristics. That is, step -drawdown tests could be conducted periodically and the coefficients B, C and n calculated. The relative effect of recharging on aquifer and well losses could thus be determined."

Both recharge rates and the life of a recharge well will be greatly increased if the well is periodically pumped. This operation, called redevelopment, can be a daily operation, where the well is pumped for an hour everyday, or a weekly operation, where the well is pumped several hours once each week. Where there is extensive plugging, it may be necessary to pull the pump and redevelop the well by surging and bail- ing, followed by step - drawdown pumping cycles (U.S. Army Corps of Engineers, 1979). Other redevelopment techniques include jetting and air surging.

Successful recharge well operation also requires the use of high quality water. Sediments can be removed using settling alone, settling in conjunction with prior flocculation, or filtration.Air binding can be reduced by deaeration prior to recharge. Free fall can be eliminated using a well header, or a foot valve with a conductor pipe (U.S. Army Corps of Engineers, 1979). A disinfectant such as chlorine can be used to prevent microbial binding, and chemical problems can be minimized by using the appropriate treatment scheme such as pH adjustment. In situations where contact between recharge water and aquifer water would have unfavorable consequences, a zone of non -reactive water could be placed between them (U.S. Army Corps of Engineers, 1979).

Adequate storage space for the recharged water, and proximity to recovery wells are other necessary conditions for successful operation. An equilization basin may be necessary to smooth out inflow hydrographs.

163 Recharge wells operate more efficiently under constant rate conditions. The basin also could be used to hold water during well redevelopment. If the inflow is uniform, it may be worthwhile to have two wells to allow for continuous operation (Wicke, 1976).

Examples of Wells and Shafts

Recharge wells have been used in many locations to form a barrier against salt water intrusion.The Metropolitan Water District of Southern California has been recharging 4800 a.f. per year through 17 wells for that purpose. Massive pumping operations on Long Island are only possible with the associated sea -water barrier formed by recharge wells. There are many other examples of recharge well operations throughout the country (LASH, 1970).

A well recharge experiment was conducted in 1969 at the WRRC experimental facility (Wilson, et al., 1969). A 50.8 -cm diameter well was drilled using the cable -tool technique. The drilling rate was logged, a sieve analysis was performed on the cuttings, and the visual appearance of cuttings was recorded. Milled slot perforations were made in the steel casing opening at two discrete locations, one above and the other below the water table. The total surface areas were 1890 square cm in the upper zone (6.1 to 11.9 m depth), and 4554 square cm in the lower zone (24.4 to 39.6 m depth). A liner and packer assembly was installed so that the vadose zone, above the 24.4 m deep table, could be recharged independently of the ground -water zone.

Using a deep well turbine pump, a two -week constant discharge pump test was conducted to determine the well and aquifer properties. The results indicated a specific capacity of 15 square meters per hour per meter of drawdown, a transmissivity of 487 square meters per day, and a storage coefficient of 0.0218. The maximum pumping rate was 113 cubic meters per hour (ibid., 1969). Fourteen gravity head recharge tests were conducted using only the lower set of perforations. The recharge water was industrial waste effluent with a suspended solids concentration less than 100 mg /1, and an average total dissolved solids (TDS) of approximately 1200 mg /l. The TDS of the native ground water was 1100 mg /l. A settling basin was used to remove sand particles. Flow was measured using a propeller flow meter, salinity was monitored, and a full pipeline was maintained to limit air entrapment. The well was surged 30 minutes each day.

Over recharge periods of 1 to 28 hours, recharge rates varied from 23 to 102 cubic meters per hour, and intake volumes varied from 82 to 1062 cubic meters. As expected, the intake rates decreased continuously, and the specific intake was less than the specific capacity due to hysteresis. No deleterious effects on well characteristics were observed, and the maximum head loss across the casing

164 was 15.2 cm. Clogging was observed on the perforations and aquifer materials due to microorganisms, chemical precipitation, and entrain- ment of air bubbles. As a consequence of recharge, the local water table rose 10 feet. The authors concluded that well recharge is an effective tool in the Tucson Basin, but periodic redevelopment is needed (ibid.).

Percious (1969) and Wilson (1971a) used the wells at the WRRC facility to study the mixing characteristics of recharged water with aquifer water. The concentration of chloride ion was used to distinguish recharged water from the native ground water.

Tests using a single well were conducted in three different modes (Percious, 1969). In the first mode, the well was pumped immediately following recharge. After a quantity of water equal to that recharged had been pumped, the percentage of the total water pumped that was recharge water, as indicated by the relative concentration of chloride ion, was 50 (Figure 12b). This is the value predicted by the dispersion theory. The second mode differed from the first in that the well was not pumped until seven days following the recharging. The percentage of recharge water decreased throughout the test from an initial value of 20. The initial value was lower in the second mode than in the first due to indigenous ground -water movement, percolation from above, density migration, and molecular diffusion (ibid.). The tagged effluent was effectively mixed using the third mode, pulsing.

A pair of wells 260 feet apart was used for the two -well tests (Wilson, 1971a). Two hundred gallons per minute was simultaneously recharged at the up- gradient well and pumped at the down -gradient well for a period of 14 days. The relative chloride ion concentration in the pumped well increased gradually from an initial value of 0% to a final value of 26 %. Wilson concluded that underground mixing was effected by hydrodynamic dispersion (ibid.).

Dry wells have been used over the Ogallala Formation in Texas; near Fresno, California; and in Phoenix. The purpose of the dry wells in Phoenix is to dispose of stormwater runoff from parking lots, parks, hospital grounds, and residential developments. In these "Maxwells" (Figure 13b), of which there are over 700 in operation, water is channeled through a settling chamber with a five -minute detention time, and then into a six -foot diameter cavity. The shaft is drilled to a depth at least five feet into a permeable strata. The average depth is 85 feet (U.S. Army Corps of Engineers, 1979).

As previously mentioned, the recharge well at the WRRC facility can be set up to recharge the vadose zone, separately from the groundwater zone. Tests have been conducted to examine the role of shafts in intermittent recharge of urban runoff. This was done by determining

165 loo 0 o Well Yavne(after 20,Harpaz, sandstone et al, 1968) o WRRC Well R -1 , test no.5 4020 0.5 1.0 PUMPED 1.5 VOLUME 2.0 RATIO 2.5 (Vp /Vi) 3.0 3.5 4.0 Type I Fully -lined MaxWell

FIGURE 1- CROSS-SECTION 0"MAXWELL" DRY WELL

167 the head loss during recharge, and by examining the microbial changes during percolation through the vadose zone.

Augmenting Streambed_Infiltration

Infiltration can be augmented using streambeds by locating spreading basins within the banks, or by in some way improving conditions so that a greater quantity of the natural flows in the stream will infiltrate. Streambeds are usually the most efficient recharge areas in a ground -water basin. Ephemeral streams are particularly useful sites because wet -dry cycling is automatically achieved. The bed materials can be reworked during no -flow periods. Two inherent ad- vantages of streambed facilities are the low cost of land, and the shape of the channel which, being long and narrow, maximized lateral flow.

Factors That Affect Streambed Infiltration

All of the factors that control infiltration and recharge rates in basins are also important in streambeds. Additional factors, which can be organized in three categories, are also influential.

The first category is channel characteristics. The channel width, bedslope, and straightness control the flow characteristics, such as velocity and degree of turbulence, of the flood waters. Higher velocities are generally found in narrow, steep, and straight channels. There are optimal widths and slopes for the most efficient infiltration conditions. The effects of soil structure was discussed in the section on basins /pits. Again, a necessary condition for high recharge rates is, generally, coarse materials to great depths void of even thin impeding layers. The antecedent moisture content below the streambed must be in the acceptable range. If the moisture content is-too low, large volumes of water will be required to reach field capacity. If the moisture content is too high, problems may arise if the saturated mounds reach the land surface.

Flood flow characteristics, the second category, also influence streambed infiltration. Both the velocity of flow and the silt load are controlled by the source of the runoff and the channel properties. Runoff from snow melt tends to have low velocities and sediment loads. Due to freezing in the mountains, these flows usually oscillate diur- nally. Winter frontal storms can be of long duration, produce moderate velocities, and carry fairly high concentrations of sediment.Summer thunderstorms produce rapid but shortlived flows and carry large amounts of sediment. Using a test flume, Matlock (1965) found that the infiltration rate increased with decreasing sediment concentration and increasing velocity (Figure 14b). In another flume study,

Marsh (1968). found that increasing the sediment concentrations from 10,000 to 30,000 parts per million was highly effective in reducing

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169 44b infiltration, whereas increasing the flow from 300 to 600 gpm only moderately increased infiltration.

The flow- channel relationship, the third category, can produce a condition of deposition at low velocities, scour at high velocities, or equilibrium where the sediment load equals the capacity of flow for transport. If deposition occurs, infiltration rates will decrease, and if erosion occurs, infiltration can increase.

Design and Operation of Streambed Infiltration Enhancement

Significant increases in streambed infiltration can often be realized by scarifying the streambed or removing the top few inches of soil. The low -flow channel could be reworked to give it the optimal width, slope, and straightness. Low dams could be constructed to pond water over a high recharge area, and to spread the water out areally (Figures 15b and 16b). Acceptable performance of low dams generally requires that the flows into and the releases out of the pond area are controlled. Even then, large flash floods can cause the failure of low to moderate sized facilities. Collapsible dams could be used in order not to create a hazardous condition during very large flows. Diversion structures could be used for two purposes --to force water into normally dry parts of the channel, or to keep flows with an unusually high sediment concentration away from efficient recharge sites. Structures upstream from the recharge area could be used to decrease the velocities and smooth out the peaks.

TECHNICAL INFORMATION REQUIREMENTS /COTLECTION TECHNIQUES

The four stages in a recharge operation are: infiltration, percolation, storage, and recovery. Data and information must be collected and developed in these four areas in order to attempt to predict the response of the geologic system to recharge enhancement. These data and information are then used to select both the site and recharge technique, and to design the facility. The data and information can consist of general material from previous studies and reports, and site specific material that is developed as part of the recharge operations. The most useful method for the collection of data and information is, of course, a demonstration project.

Infiltration

Infiltration refers to the phenomenon of water entering the soil surface. Techniques for predicting infiltration rates fall into three categories.

The first set of methods involves collecting information about the general nature of the soil and inferring infiltration rates there- from. Soil augers can be used to dig holes in the soil profile, but

170 Figure 15

171 TERRACE OUTLET WEIR FLOW CONTROL CHECK INLET WEIR o o o f CHANNEL FLOW o o e o o o o ln-channa\ RocetsrSpa üs ln . TERRACE the soil is disturbed by the auger and hardpan layers can not usually be penetrated. Information that is provided includes the ease of penetration and the appearance of the soil. Particle -size analyses can be made on the samples that are brought up. Mechanical augers can also be used, but the soil is more greatly disturbed, and the samples are quite mixed. An inexpensive but useful technique for providing information about the upper soil profile is jetting. The procedure is to drive a 3/8 to 1/2 inch pipe into the ground, pumping water through it at successive depth intervals. Information can be obtained about the force needed to move the pipe downward, the amount of water lost in the hole, and the properties of the soil that is washed out of the hole (Bianchi and Muckel, 1970).

The second set of methods involves making actual field estimates of the movement of water into the soil. Basin intake rates are determined by keeping track of water levels or by monitoring inflow to and outflow from the basin. Water budget techniques are also used to estimate streambed infiltration. Care should be exercised to include all components of water flow, including evaporation and transpiration, and the interception of precipitation. Intake rates in small basins may be used to estimate the infiltration rates in full scale basins, but rates are usually overestimated in the former due to the greater effect of lateral movement (U.S. Army Corps of Engineers, 1979). Infiltrometers can also be used to estimate infiltration rates. The standard dimensions of a double -ring infiltrometer are an inner ring diameter of 6 to 14 inches, an outer concentric ring diameter of 16 to 30 inches, and a height of 6 inches. Both of the rings are flooded and the rate of recession in the inner ring is measured. This set -up limits flow to the vertical direction but also tends to overestimate infiltration rates (ibid.). Bouwer (1978) recommends using larger diameter, single -ring infiltrometers.

Geophysical techniques, the third set of methods, are discussed in the following section of this report. Those most applicable to shallow soil layers are seismic and surface resistivity techniques.

Percolation

Percolation refers to movement of water through the soil below the surface layer. The methods discussed in the infiltration section are, of course, applicable to percolation in the vadose zone, especially in the upper levels. Indeed, there is no sharp line of separation between infiltration and percolation. The methods outlined in the following discussion have been developed specifically to describe the characteristics in the deeper soil zones.

The most direct method for obtaining information about the nature of the layered deposits is to construct a well and obtain samples

173 while drilling. The cable -tool technique is preferred inasmuch as clean samples can be obtained at discrete intervals. The drill cuttings can be analyzed for size distribution, and information can be obtained on potential perching zones, storage, and transmissivity (U.S. Army Corps of Engineers, 1979). Previously conducted drillers' logs can provide useful information, although many are not complete or accurate.

Bore -hole logging techniques can be used to provide information on the geological deposits (see Keys and MacNary, 1971). The natural - gamma nuclear logging technique measures the natural gamma activity of rocks, a parameter that has been calibrated according to the composition (i.e., clay content) of the soil. In the gamma -gamma method, the intensity of radiation generated by a down -hole source is measured after it has backscattered and attenuated in the well casing and surrounding medium. It is generally used to estimate bulk density and porosity (U.S. Army Corps of Engineers, 1979).

The parameter used to describe the ease of water transmission in a soil zone saturated with water is the hydraulic conductivity. It is equal to the flux divided by the hydraulic gradient. Several methods have been used to measure the hydraulic conductivity in unsaturated zones (see Bouwer and Jackson, 1974). These techniques generally involve bringing the soil to or near saturation at the measuring point. Methods include the shallow well pump -in method, the cylinder permeameter method, the infiltration gradient methods, and the air entry permeameter method. Transmission values in the deep vadose zone can be obtained using laboratory permeameter tests on drill cuttings. The results may not accurately represent soil conditions due to disturbance of the samples. The hydraulic conductivity can also be estimated from grain size. The U.S. Geological Survey (1977) has developed two methods to estimate the transmissive properties in the deep vadose zone. One involves pumping water into a bore hole and measuring the rate needed to keep the water level constant; and the second involves the use of an intake well and several observation wells. Weeks (1978) developed a method for obtaining the vertical air permeability by measuring the air pressure changes due to barometric pressure. The relation between air permeability and hydraulic conductivity is not always clear. Wetting does alter the soil structure, and increasing moisture reduces the air permeability (Weeks, ibid.; and U.S. Army Corps of Engineers, 1979).

Several methods are available to estimate the hydraulic conductivity in a perched ground -water body. The auger hole, piezometer, and well -point methods involve measuring the rate of recovery in cavities after the water level has been artificially lowered. The multiple well method involves equalizing the water levels in a set of wells( Bouwer and Jackson, 1974; U.S. Army Corps of Engineers, 1979) .

174 Storage

In the previous section of this report, water movement in the vadose zone was termed percolation. This process can also be thought of as "in- transit" storage (Wilson, 1971b). Water can be stored in a saturated or unsaturated condition, above or below the water table. The main thrust of the techniques described in this section is to determine storage properties in the vadose and ground -water zones.

It is difficult to determine the dimensions of a ground -water reservoir using direct methods. Information obtained at a well is limited to a line running through the aquifer. Even with a network of wells, there are complicating circumstances. The base of an aquifer may be a sharp decrease in permeability, or the decrease may be gradual. The lower limit to the reservoir may be a barrier of saline or otherwise unusable water, the point where subsidence becomes a problem, or the economical limit to pumping. The lateral boundary can also be hazy, and could be poor quality water, or even a political boundary. The upper limit can be the ground surface, or an impermeable boundary below the surface (Bianchi and Muckel, 1970).

The capacity of vadose zone to receive water is also controlled by the level of the water table, which can be determined from well levels, piezometers, or moisture logs. Water levels in unpumped wells may not accurately reflect the indigenous water table level during transient flow. Well levels tend to lag behind water level changes. Water levels in wells can also be influenced by short circuiting from perched water bodies.

Geophysical techniques can be used to supplement well data by providing indirect information about the aquifer. As Bianchi and Muckel (1970) point out, however, "interpretations are from statistical inference rather than engineering definition."

Seismic surveys are generally the most useful geophysical methods but also the most expensive. The technique involves using geophones to measure the arrival times of refracted and reflected compressional waves produced by vibrations that are artificially induced in geologic bodies. The geophysicist induces the elastic nature of the formation. This method is excellent for predicting the thickness of the overlying sediments, the location of buried stream channels, and the depth to the water table( U.S. Army Corps of Engineers, 1979); Bianchi and Muckel, 1970; and Davis and DeWiest, 1966).

Electric methods provide useful information and are less expensive than seismic techniques. The usual procedure is to measure the natural potential between two electrodes, and then the resistivity by passing electricity through the soil between the probes (Davis and DeWiest, 1966). This method can be used to detect the amount

175 of water in rocks, and the salinity and distribution thereof.It can also indicate the presence of clay and other conductive materials. The vertical location and lateral extent of underground stream channels can also be mapped (U.S. Army Corps of Engineers, 1979).

The strength of gravity varies over the surface of the earth due to variations in densities and thicknesses of underlying materials. The gross geologic properties of a formation can be measured using a gravity meter. A base station of known gravity is needed, and it may be necessary to apply several corrections (U.S. Army Corps of Engineers, 1979; Bianchi and Muckel, 1970; and Davis and DeWiest, 1966).

The water retention and release characteristics in the upper vadose zone can be determined using the techniques of soil scientists. The value of the saturation capacity can be obtained by oven -drying a saturated soil sample. It should be noted that saturation will not be attained due to occlusion of air bubbles. Specific retention (or field capacity) can be estimated by obtaining a sample during drainage and oven -drying it, or by subjecting a saturated core to a pressure of 1/3 atmospheres. If the moisture content is below the specific retention, the soil will exert a moisture demand that will not be released upon drainage. These methods are not viable where the sediments are very coarse, and cannot be used in the lower zones due to the difficulty in obtaining undisturbed samples.

The moisture content in the vadose zone can also be measured using tensiometers. Tensiometers consist of ceramic cups connected to tubes, in turn joined to mercury reservoirs. A network of tensiometers can be used to monitor the moisture conditions in the vicinity of a recharge facility. Tensiometers are limited in usefulness due to contact problems and the fact that only point measurements are made.

Neutron logging involves lowering a source of high energy neutrons and a detector of slow (thermalized) neutrons into a well.Neutrons are most effectively slowed by hydrogen nuclei, which are present in water but not, to any great extent, in dry soil. Therefore, the number of slow neutrons that are detected is related to the water content in the vadose zone, or the porosity in the ground -water zone. Calibration is required to define the relationship. Neutron logging can also be used to detect perched ground water, and, by placing the source of neutrons in one well and the detector in another well, the lateral extent of perched ground water bodies can be mapped (U.S. Army Corps of Engineers, 1979). Wilson and DeCook (1968) pointed out that this technique gives no information on the direction or rate of water movement, and may not differentiate between water in the vadose zone, the phreatic zone, and the capillary fringe.

176 Using proper timing, neutron logging can be used to estimate the saturation capacity, the specific retention, and the moisture deficit. Continual measurements of moisture content in the vadose zone are made before and throughout a major runoff event in a stream channel. The water content before the event is approximately equal to the drained water content. The moisture content immediately after the event will be at saturation if recharge is large enough, and the values during drainage correspond to the specific retention.The difference between the drained profile and the specific retention indicates the moisture deficit (U.S. Army Corps of Engineers, 1979).

Storage properties in the ground -water zone can be measured using many of the techniques used in the vadose zone. In addition, pump tests can be used to determine the storage coefficient which is the volume of water taken into or released from storage per unit surface area per unit change in head.

Recovery

Many of the physical soil properties that have been discussed control the recapture of recharged water. In addition, two other properties relate specifically to recovery. The specific yield is the portion of water that is released from soil due to gravity.It can be determined in the laboratory or vadose zone by saturating a sample, allowing it to drain, and measuring the volume released. It can be determined using data taken simultaneously on water table elevations and pumping or recharge volumes. It can also be estimated from mechanical analyses or indirectly by centrifuging (Todd, 1963). Cehrs (1978) developed a computer technique for transferring descrip- tive well logs to estimates of specific yeidl for each strata.

The product of the hydraulic conductivity and the thickness of the ground -water zone is called the transmissivity. It defines the rate at which water will flow through a vertical strip of an aquifer one foot wide and extending through the full saturated thickness, under a unit hydraulic gradient. The transmissivity can be estimated from core samples or grainsize distribution analyses, but a pumping test is the preferred technique. The procedure involves pumping the well, and determining the discharge rate and the response of the water table. Many authors have presented step -by -step procedures for determining the transmissivity and storage coefficient from pump

tests (Theis, 19 ; Jacobs, 19 ; Hantush, 19 ; and Boulton, 19 ).

Flow techniques can also be used to determine the transmissivity. Flow nets consist of two sets of orthogonal curves: equipotential (equal head) lines, and stream lines (direction of water movement). The three most significant assumptions made in using this method are that the distribution of the vertical hydraulic head does not vary,

177 that the aquifer thickness is constant, and that the transmissivity is isotropic. Transformations are available for anisotropic conditions (Cooley, Harsh, and Lewis, 1972; Lehman, 1972, and Bouwer, 1978).

The recovery of recharged water is also affected by the direction and magnitude of the hydraulic gradient. This can be determined from tensiometer measurements in the vadose zone, and measurements from observation wells in the ground -water zone (U.S. Army Corps of Engineers, 1979).

DATA AVAILABLE

Infiltration

Burkham (1970) made estimates of the average annual volume of infiltration for the time period 1936 to 1963 along seven normally dry alluvial channels in the Tucson Basin (Figure 17b). Using USGS stream flow data, Burkham first developed average relations between rates of inflow and infiltration for the seven reaches using the form:

(infiltration rate) = constant (inflow rates)0'8

The constant includes the effect of many parameters. Burkham assumed that channel evaporation and interception of precipitation were negligible. An effort was made to determine the constants during a time period when there was no tributary flow along the reach. For short duration flows, the duration was taken as the time that the flow was greater than 10 cubic feet per second. For long duration flows, in- stantaneous infiltration rates were calculated by determining the time to translate from the inflow point to the outflow point.

For the reaches on the Santa Cruz River and Rillito Creek, the inflow -infiltration rates were determined from flow measurements at the end points of the reach. A least- squares line of best fit was drawn on the log -log graph of inflow rate versus infiltration rate (Figures 18b, 19b, and 20b). Due to the scarcity of data for the reaches along Tanque Verde Creek, Pantano Wash, Rincon Creek, Sabino Creek, Agua Caliente Wash, Canada del Oro and Big Wash, the constant was estimated from the flow data by comparison with similar reaches along the Santa Cruz River or Rillito Creek.

The values of the constant, along with other information, for the seven reaches are presented in Table lb.

Burkham notes a high initial infiltration rate on Sabino Creek, Agua Caliente Wash, and upper Tanque Verde Wash due to the coarse materials in the streambeds. This rate dies off due to the intercon- nection between surface water and ground water in the area. The low infiltration rate along the upper 4.8 miles of Rincon Creek, due

178 .,/ 6 -5 { FINAI. COUNTY -- l'IMA COUNTY á \\ 2:'J

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Pantano Wash near Vail -I Irene Pantano Wash near Irene

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179 10,000 QI =1.6 (Q inflow )0.8 I 1000 - O o da // Co ca , 100 EXPLANATION o InstantaneousAverage values values for short for - duration flows I 1 I 1 t long- durationI_ flows I I I I 10 10 INFILTRATION RATE, IN CUBIC FEET PER SECOND l i l 100 I I 1000 il 20 INFILTRATION, IN PERCENTAGEOF INFLOW 10,000 1 1 i l l t I I 1 1 i 1 T 1 t 1 i 1

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181 ^ _ - 2 -. , ` 4p(Qinflow , ation(Aercet)= n{i1t , 1

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1 1 i 1 1 1 titt t lt l 1 1 _I1 1 I t J 1 1 8 o ONO03S ti3d 1333 ammo Ni 131X8 MO-UN!

182 Table 1A Average annual inflow, infiltration, outflow, and maximum possible increase in infiltration by total regulation of inflow in the Tucson basin R E A C H Reach (see p1. 1) of Lengthreach, from the equation Variable (C) acreInflow, -feet in Acre-feet AcreInfiltration -feetper mile Percentageof inflow Acre -feet Outflow Percentageof inflow 1- 1 in miles 28.5 Qi t(4inflow ) 1.6 0.8 22,450 9,030 320 40.2 13,420 59.3 5432 117.5 21.5 9.57.8 1.7 13,99016,740 7,1503,790 7,7805,1603,5007,540 820240450430 72.292.345.0 9,200.1,990 290 27.855.0 7.7 76 Total 137.5316.6236.1 4 1.4 26,850 9,940 46,980 8,0305,940 340480160 29.959.855.6 1.8,820 4,0006,210 70.140.244.4 B A S I N Maximum possible increase in Inflow point (see pl. 1) Acre- Percentage Inflow Infiltration Outflow at Cortaro infiltrationtion, in percent by total regula- feet of total Acre-feet Percentage of inflow Percentageof total Acre-feet Percentageof inflow Percentageof total atoccurringby rallyIncreaseinflowinfiltration from pointnatu- divided water sevenrallyoccurringbyIncrease infiltration reachesin the dividednatu- 2-21 -1.7.- TanqueSantaSabino Cruz Verdeand RiverBear Creek Creeksat near Continental atTucson confluence., 9,150 11,420 4,360 13.817.3 6.6 4,0807,2807,490 79.693.665.6 15.515.9 8.7 1,8703,930 280 20.434.4 6.4 20.7 9.81.5 25.752.5 6.6 4.08.3 .6 4 -1.6 -1. Pantano Canada Wash del atOro Vail at base of mountain Remaining small tribute!iesTotal 66,09031,090 5,0205,050 100.0 47.0 7.67.7 47,08018,990 4,4604,780 71.261.188.894.6 100.0 40.310.2 9.5 19,010i2,100 560270 28.838.911.2 5.4 100.0 63.7 2.91.4 63.712.6 5.6 40.425.1 1.2 .6 2 I Includes 3 Includes 12 miles of Big Wash. miles of Sabino Creek and 4 miles of Agua Caliente Wash. 4 Applicablethe gaging to stationsthe 12.25 at -mile Tucson long and channel at Cortaro, of Santa Arizona. Cruz River between 3 lnr i r ,t , , to the absence of thick and permeable alluvium, was found to be in sharp contrast to the high rates in the lower three miles, the latter due to spreading of water over the floodplain.

Burkham used flow -duration curves previously developed by Condes de la Torre (1968) for gaged streams, and, where streams or tributaries were ungaged, synthetic flow- duration curves (Figure 21b) were derived from "simple relations between measured daily streamflow and size of the contributing basin for flow that is equaled or exceeded 0.1, 0.5, 2.0, and 10 percent of the time." The data used in developing these relations consisted of summer flow data for ten southern Arizona streams. These streams were mostly below an elevation of 6,000 feet, and more weight was given to those similar to the study area reaches. The degree of correlation between flow and basin size was fair for flows of rare occurrence, but decreased with more common flows (Burkham, 1970).

Burkham then coupled the inflow -infiltration relationship with the flow - duration curves to produce infiltration- duration curves (Figure 22b). Applying inflow- infiltration relations (based on events) to flow duration curves (based on average daily flows) should produce values that underestimate the actual infiltration( Burkham, 1970).

Burkham's final step was to calculate a water budget of stream - flow and infiltrate volume. Determining the infiltration for each source independently could have produced some bias.This error should be small, as Burkham points out, due to erratic spatial and temporal behavior of runoff producing streams, the slope of the basin (in which tributary flows should be gone before the main flow arrives), and the smallness of the rate of change of infiltration in relation to the rate of change of runoff.

The composite results for the seven reaches indicate that the main channels are efficient natural infiltration galleries. Of the average annual inflow of 66,000 a.f., 19,000 a.f. flowed out of the basin, and 47,000 a.f. or 70 percent of the inflow, infiltrated. Infiltration varied from 29.9 to 92.3 percent of the inflow as shown in Table lb. A more complete breakdown into sub- reaches is shown in Table 2b. The most efficient reaches were, in order of decreasing infiltration percentage:Rincon Creek, Pantano Wash, Cañada del Oro, Big Wash, and Tanque Verde -Rincon Creek. The percentage of this infiltration that eventually becomes recharge, i.e., finds its way to the ground -water zone is, according to Burkham, probably greater than 90. Burkham estimates that the average annual infiltration can range from zero to four times the average annual value.

184 10,000 I 1 T l i 1 1 T 1 I 1 T I T I I I i i i 111 ' EXPLANATION x x16 4 15.15 isPercentage equaled or of exceeded: time that flow x - 0.1 lx 1 l a2 2 14x 3. 16 15 5 Ao - o- 0.5 - 10 2.0 70 7x °12x12 12 1 o 11011° ° 2 140 3 ' °16 , 4 NOTE: Numbers nextindicate to symbol station 7° °12 l ° 14A 15. 70 1 4 110 . 40 0.1 10 1 1 I 1 t i t DRAINAGE100l AREA, IN SQUARE MILES I I I i_L 1 j 1000I I I t t L 1 1 10,000 1000 I _ I 1 I 1 I I 1 I Z , í 1 \ __\ - \V)ó . 6 1 \. O7 100 i\ \y

- \)O- , _ , y\,7

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0.1 I I I I 1 I 1 1 A 1 1 I 1 1 ^ ' 1 1.0 N LO 00 0 0 0 0 O O O u") co oN c001 .r Q1 010l 0 OOO NR7 d tn tp n co ol. Cr; O1 CA 0 O OA ON Cri PERCENTAGE OF TIME FLOW IS EQUALED OR EXCEEDED

186 Matlock (1965) used USGS streamflow data to develop relations between discharge and infiltration rate (Figure 23b). He noted that the largest relative infiltration occurred at the point where the wetted surface was just large enough to fill the entire streambed. Above this flow, the increase in infiltration rate is due only to the effects of velocity and depth. The loss along a given reach was greater than 50 percent over 61 percent of the reaches in the valley, and less than 25 percent over 13 percent of the reaches in the valley. Infiltration is probably larger than calculated due to the contributions of ungaged tributaries. Matlock (1965) also made direct measurements of the infiltration rate in the Rillito Creek channel using a cylinder infiltrometer. The infiltration rates during a test made with clear water in the dry channel at Alvernon Road decreased exponentially from an initial value exceeding 100 feet per day to 30 feet per day in one hour.A 1/16 to 1/8 inch thick silt layer reduced infiltration markedly, and a 3 to 4 inch thick silt layer completely eliminated infiltration. Matlock also ran a series of tests while the channel was running. The infiltration rates decreased from upstream to downstream, or from 6200 gallons per day per square foot (gpd /ft2) at Pantano Road to 200 gpd /ft2 at Oracle Highway. Matlock concluded that the infiltration rates per unit area decreased with distance from the mountains because the bed material is coarse near the mountains and fine downstream.

A valuable source of information on soil properties pertinent to infiltration are the U.S. Department of Agriculture Soil Con- servation Service Soil Surveys (USDA, SCS, 1972).

Recharge

Another set of studies focuses on recharge rather than infiltration alone. This is generally done by studying the effect of flow events on water table elevations as evidenced by water levels in wells. Matlock and Davis (1972) divided the basin into four districts, three of which are in the scope of this report. Within the Tucson District, the water level in a well at Rillito Creek fluctuated wildly in response to streamflow, whereas wells in the Catalina Foothills, the inner basin, and near Vail were not sensitive to channel flow.Water levels in bottomland wells in the Cortaro- Cañada del Oro District flucturated with flow in the rivers, while wells located up in the bajadas showed a steady decline regardless of the condition of the stream. Similar bajada- bottomland distinctions were found in the Sahuarita District. Assuming an average specific yield of 12 percent, and equality between underflow entering the basin and under - flow leaving the basin, Matlock and Davis calculated the average annual recharge between 1961 and 1968, using the Thiessen polygon method, as 55,000 a.f.

187 Table 2J -Water budget of average annual synthesized streamflow and infiltration volumes for the main channels of the Tucson basin (1936 -6)) DEPLETION OF STREAMFLOW BY INFILTRATION of reach Length Average annual inflow Average annual infiltration2 Santa CruzAverage River atannual Cortaro outflow at Inflow point (see pl. 1) Squaremiles Percent- age of point of toinflow end fron Acre -feet Acre-feet Percent -' Acre- Percent- Percent- age of infiltrationinflow minus Measured (acre - CO total of inreach, miles sq mi per totalage of feet age of infiltra- total tion Acre-feet outflowPercent-age oftotal feet) 1 -2-1. to Santa 1 -111. Cruz Ungaged River tributariesat Continental to SantaCruz River from Continental to Tucson 1,662.0 560.0 47.516.0 40.75 211,030211,420 6.9 16.717.3 6,2607,490 56.865.6 13.315.9 '3,9304,770 25.120.6 2 -2-7.-1. to SabinoTanque2 -6, andVerde Bear Creek Creeks near near Tucson Tucsonto Tanque Verde Creek from gaging 2 -8, 2 -9. Ungaged tributaries 125.7 51.843.0 3.61.51.2 22.028.5 29,15024,360 3,230 177.0101.0 13.9 4.96.6 2,7407,2804,080 84.879.693.6 15.5 5.88.7 1,870 490280 9.82.61.5 Canyonstation road. near Tucson to Sabino . 34 -2,-1. RinconPantano Creek Wash nearat Vail Tucson 3 -3. Ungaged tributaries to Rincon 457.0 44.8 13.0 1.3 37.535.8 22,61025,050 58.211.0 7.73.9 2,6104,780 100.0 94.2 10.1 5.5 270 0 1.5 0 54 -2-3 to 54 -7.-5. Ungaged tributaries toalongPantanoCreekRillito from Wash Creekgaging from from Vailstation Sanbino to mouthto Canyonmouth 66.836.6 1.01.9 1,8101,180 2.71.8 1,4701,180 100.0 81.2 2.53.1 340 0 1.8 0 6 -2-1. to Canada 6 -7. delUngaged Oro attributaries base of mountains of Canadadelroad Loro to gagingfrom base station of mountains near Tucson 214.4 41.589.7 6.11.22.6 26.7 4,9205,0202,850 121.0 7.47.64.3 4,4601,8801,630 38.288.857.2 4.09.53.5 1,2203,040 560 16.0 2.96.4 Composite7 -2 to 7 -13.of all Ungaged reaches 'tributaries to SantaCruzto mouth. River from Tucson to Cortaro 3,500.4 107.1 100.0 3.1 66,090 3,460 100.0 5.2 47,080 1,220 71.235.3 100.0 2.6 19,010 2,240 100.0 11.8 218,990 21 Measured.Net difference betweenvolume volumesis taken of precipitation as the volume of depletion of streamflow. on and evaporation from the flowing water is assumed negligible; therefore, the infiltration -r- AVERAGE DAILY. AT UPPER STATION (cfs)

:189 Fig. 23b Davidson (1973) pointed out that the effect of pumpage on the water table level near the Santa Cruz River is less than the effect under the urban area due to significant recharge along the former. He also pointed out that about one -half of the recharge in the basin, which he estimates at 100,000 a.f. /yr, is due to infiltration through stream channels during the rainy seasons. The second largest source of recharge, according to Davidson, is seepage along subsurface fracture planes along mountain fronts.

Anderson (1968) developed an analog model of the Tucson aquifer. His model indicated that recharge along the stream channels increased from 19,000 a.f. in 1940 to 35,000 a.f. in 1964. He concluded that this was due to the falling water table.

Clyma and Shaw (1968) studied the effect of the runoff events that occurred in the usually wet years of 1965 and 1966. Significant groundwater recharge through the Santa Cruz River bed to the water table were found as exemplified by rises of more than 10 feet extending 1 to 3 miles wide and as much as 10 miles along the river. Clyma and Shaw estimate that the water table recovered up to 40 percent of the total decline that had occurred along the river between Amado and Rillito. They also estimated the 1965 recharge through the Santa Cruz River and Rillito Creek at 15,000 a.f. The water table rose over 40 feet during the year at the confluence of the Tanque Verde Creek and the Pantano Wash. The recharge along Rillito Creek was estimated at 50,000 a.f. /yr. Clyma and Shaw predicted that with controlled pumpage, up to 500,000 a.f. /yr could be recharged through the Rillito Creek bed.

Fogg (1978) set up a model to simulate water level declines between 1940 and 1965 in the Cañada del Oro area. He concluded that the recharge from the Canada del Oro river in the study area is negligibly small.

Belan and Matlock (1973) studied the mountain front recharge from a seven mile stretch of the front range of the Santa Catalina Mountains. They found a complex transition zone between the mountains and the lower basin. The high variability is partly explained by the presence of buried stream channels that changed course from time to time. Using a flow net analysis, they calculated annual recharge at 50 a.f./ mile. This is in sharp contrast to the estimate of Anderson (1973) of 325 a.f. /mile /year.

Osterkamp (1973b) summarized the work of Anderson (1973) on mountain front recharge and Burkham (1970) on streambed recharge, by preparing a map of recharge in the Tucson area.Areas with annual recharge between 600 and 800 a.f. /mile include Sabino Creek, and Tanque Verde Creek from Sabino Canyon Road to First Avenue. Areas with annual recharge between 400 and 600 a.f. /mile include Rincon

190 Creek and the Pantano Wash upstream from their confluence, the Tanque Verde Wash upstream from its confluence with Agua Caliente Wash and from First Avenue to the Santa Cruz River, and the Santa Cruz River downstream from Congress Street. Estimates for annual recharge between 200 and 400 a.f. /mile were made for the Santa Cruz River upstream from Congress, the Canada del Oro River upstream from its confluence with Big Wash, and for most of the mountain fronts along the Santa Catalina, Tanque Verde, Rincon, Empire, Sierrita, Santa Rita, and Tortolita Mountains. The Agua Caliente Wash and portions of the Santa Catalina and Empire Mountains fronts were designated as areas with 100 to 200 a.f. /mile of annual recharge. The Pantano Wash between Rincon Creek and Tanque Verde Creek, and Big Wash were designated as areas with 50 to 100 a.f. /mile of annual recharge. Areas with annual recharge less than 50 a.f. /mile included the Tanque Wash between Agua Caliente and Sabino Canyon Road, the Canada del Oro between Big Wash and the Santa Cruz River, and the mountain fronts around the Tucson Mountains.

Recharge is commonly estimated using data on water table changes and estimated specific yield. Wilson and DeCook (1968) demonstrated the existence of saturated or nearly saturated zones above the water table at the WRRC field lab adjacent to the Santa Cruz River near Miracle Mile. Three days after a December 22 -27, 1965 runoff event, the water table rose four feet (from 80 to 76 feet deep), but moisture logs indicated an additional 40 feet of materials were saturated or nearly saturated. The 5- foot -thick upper mound (30 to 35 feet deep) dissipated by January 14th, but the 35- foot -thick lower mound (41 to 76 feet deep) was less than half drained by April 20th. The lower mound was still 28 feet thick on May 6th. Wilson and DeCook observed that well measurement accounted for only 33 percent of the volumetric change in subsurface water contents and pointed out that several months may elapse before the maximum value of specific yield is approached. Clearly, estimating recharge from water table measurements alone could introduce large errors, and any water balance should include this "in transit storage" in the intermediate vadose zone.

Hydrogeologic Conditions

A number of geophysical investigations have been conducted in the Tucson area to characterize underlying structural and hydrological- ly- related features. Davis (1967) established a gravity network over the Tucson Basin on a nominal one -mile spacing to determine the major hydrologic boundaries. He supplemented his gravity values with data from magnetic, seismic, and borehole geophysical surveys. Thus, refraction surveys were conducted to refine gravity data at sites around the basin margins, in areas of shallow pediments. His studies revealed a pronounced linearity in structural patterns which correlated well with trends noted by other researchers.

191 In addition to defining the structural features, Davis used the gravity technique to define the volume of saturated sedeiments in the Tucson Basin. The method is based upon the application of Gauss' Theorem to the gravity effect of the "anamalous" mass of the basin. According to West and Sumner (1972), "The anomalous mass occurs because a density contrast exists between low density alluvium and high density bedrock, which defines the surface and subsurface boundaries of the basin....Mathematically, the anomalous mass is equal to the product of the alluvium- bedrock density contrast and the volume of the alluvium. The anomalous mass can be uniquely determined using Gauss's Theorem provided that an accurate residual gravity map of the gravity effect of the anomalous mass is available. Furthermore, if the basin surface area is determined and average values of alluvium and bedrock density and water -table depth can be estimated, then the volume of saturated sediments can be calculated. Ground -water volumes are determined from the volume of saturated sediments if the storage coefficient and porosity of those sediments are known." Based on this approach, Davis (1967) used his gravity data to estimate that the volume of water in storage in the Tucson Basin was 129 cubic miles.

West (1970) conducted a gravity survey in Avra Valley to determine the major subsurface structural features; the volume of ground water available in storage within the basin; and the center of mass of the sediments contained in the basin. West established 298 gravity stations in the valley and surrounding mountains, at a density of one station per square mile. From his gravity data, West excluded the possibility that any extensive shallow buried pediment surface extends in a northerly direction from the Sierrita Mountains. In contrast, a buried pediment surface was detected extending westward from the Tucson Mountains. The deepest part of the basin was observed near Ryan Field, where bedrock was detected between 4000 and 5000 feet. Using the "anomalous mass" approach, as described above, West estimated from his gravity data that the volume of ground water in storage in Avra Valley was 58 million acre -feet. West emphasized that it has not been determined if it is technically and economically feasible to extract this entire volume from storage.

Goodoff (1976) conducted a residual gravity survey to characterize subsurface structural features in the Cortaro Basin. Her studies were enhanced by data from tests conducted on 12 holes in the area of the City of Tucson. The latter tests included grain -size analyses on drill cuttings, and the following types of bore hole geophysical logs: self potential, resistivity, caliper, dipmeter, temperature, acoustic, gamma ray, neutron, and a formation density log.

Goodoff showed that the Cortaro Basin is a separate subsurface basin within the northern section of the larger Tucson Basin. The southern boundary of the Cortaro Basin appears to be located a few

192 miles north of the Roger Rd. Treatment Plant.The northern end coincides with the Rillito Narrows. The Cortaro Basin is a typical basin and range block - faulted structure with a large downdropped structure in the middle of the basin. The basement complex is uplifted to within 1700 feet of the land surface near the southeastern entrance to the basin. The depth to bedrock then increases rapidly to a maximum depth of 5000 feet near the Catalina Mountains.At the northwest outlet from the basin the basement complex is uplifted again. A geologic cross - section of the Cortaro Basin is shown on Figure 24b.

The structure of the Cortaro Basin appears to be such that only water within 500 feet of the surface flows from the basin. That is, the Cortaro Basin is potentially a closed hydrologic basin. Ac- cording to Godoff: "If Cortaro Basin becomes a closed hydrologic basin, the water flowing from the Tucson Basin would be dammed there and there would be little subsurface flow from the Tucson Basin northward."

The Exxon Company conducted an extensive exploration program to characterize the Cenozoic stratigraphy of the Basin and Range province of southwestern Arizona (Eberly and Stanley, 1978). The program includes seismic mapping and stratigraphic drilling. The Tucson Basin was found to be one of the five anomalously deep troughs in the study area. Cenozoic deposits may be more than 3000 meters in thickness. The structure beneath the wide valley floor is "...composed of a narrow central graben between broad sloping mountain pediments. The profile suggests that a once - narrow valley between broad ranges has grown in width at the expense of the eroding surrounding highland."

Davidson (1973) described the hydrological characteristics of the various geologic units in the Tucson Basin. The rock units along the margins of the basin are composed primarily of metamorphic and intrusive igneous rock. Low porosities and permeabilities are the rule along the Santa Cruz, Rincon and Tortolita Mountains. Some areas of moderate permeability are found along the Sierrita, Santa Rita, and Empire Mountains. The margins of the Tucson Mountains are generally composed of low permeability volcanic rocks with the exceptions of some north and east slopes and the Black Mountains where the volcanic and sedimentary rock have moderate porosities and permeabilities.

The sedimentary units in the Tucson basin form a single aquifer. The units are distinguished by the differences in hydrogeologic characteristics. Fogg (1978) summarized the information from Davidson (1973) in a tabular form (Table 3b).Both the Tinaja beds and the Fort Lowell Formation grade from gravel near the margins

193 tti..yoreirih

3000 RillitoCreek

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1500

Tos miles

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Tos - PantanoFormation

TKv - Tucson Mountainvolcanicrocks

194 Fig. '24f} Table 3. --Summary Information of hydrogeological from Davidson characteristics (1973). of geologi.._.1 formations described by Pashley (1966) and Davidson (1973). (determined from well cuttings Composition Thickness b 2.1. Pcrmr_abilityPorosity c Unit Dame and Age and logs and coring' ; ) 0 -? (feet) 1.3. Transmissivity.2 -.27 (sandstone /Specific and gravel)Capacity c TDSdWater > Quality3000 mg /I in yields of wells Comments b_,ds)Pantano (Typea Formation I Aillito mudstoneconglomerate,weaklyvolcanic to interbedded strongly flows sandstone, and cemented withtuffs and 2.3. wellsthe? /at.5 tappingunits; -15least ft up/day3840500 to -1,000ft37700 /day ft3 feet /ft /day offor /ft mostfluoride1000 wells; in some >and wells> 1 mg /1 approx.inchesgreaterhaving rangediametersthan300 to12from 5000 sandy gravel dominant at basin 0 to greater 1. .26-.35' TDS < 500 mg /1 may unconformablyft3gpm /day)(57,600- 86,400 over- TinajaRillito(Type beds beds)a I S II mudstonegypsiferousmargins --along gradesclayey central intosilt and muchperhapsthan as 2000as5000 and 2.3. 1,300-20,0001-50 ft/day ft /day 2 presentmgbe silt/1more where ofthan fines abundant 1000 are lies the Pantano mationFortfill Lowell (basindeposits)a For- siltymarginsaxis of sandgravel --basin grladesand near clayey basinto a - most300 places -400 in 1. wellsmaterial.26 in -.34;which was average: 50%sand or and more gravel of .30; .50 for 4 general,TDSsuited < 500 isformg well /1public in liesunconformably Tinaja beds over- cementedisparts;silt loosely in the the sediment packedcentral to weakly 3.2. -/190020 -100 -19000ft /day ft3 /day /ft supply Surficial deposits areandmainly fluvialgravelly composed in sand origin of and gravel 100,no5 tomore avg.probably than 30; 3.2.1. -- dry in most places aCorreasponding name used by Pashley (1966). 40along to 100streams (avg. 50) dTotalcVerybDotermined roughdissolved fromestimate solids.formation determined density from logs. aquifer test. of the basin to silt and mudstone in the interior. Generally, cemen- tation and compaction increase with depth and age, and porosity and permeability decrease with depth accordingly (Fogg, 1978). The well yields in the Fort Lowell Formation vary from 10 to 110 gpm per foot, and from 1 to 40 gpm per foot in the underlying Tinaja beds (Davidson, 1973) .

The surficial deposits underlie three main topographic benches and the present day stream channels and flood plains. Even though they are drained of ground water, they are highly transmissive formations that allow a high rate of infiltration to underlying sediments.

The deposits along the streams are loosely packed and generally not well cemented. They were transported and deposited by north and northwest flowing streams. This is a drastic change from the basin - confined drainage that deposited the Tinaja and Fort Lowell units. The alluvium is saturated along some of the Rillito Creek, but its general function is to receive flood water and to store it temporarily, allowing natural recharge to occur. Some of the water replenishes the moisture demand of the alluvium, and some is evaporated or trans- pired, but most moves downward.

Matlock and Davis (1972) reported the water levels in 800 valley wells. In the Tucson district, water levels in wells in the Catalina Foothills were gradually declining, while wells in the inner basin were steadily declining. Water level depths ranged from 500 feet near Vail to 10 feet adjacent to Rillito Creek. In the inner basin, water levels dropped 10 to 20 feet between 1965 and 1972, and up to 75 feet since 1947.

The depth to the water table in the Cortaro- Cañada del Oro Dis- trict was 100 to 200 feet in bottomland wells, and 300 to 500 in steadily declining bajada wells. Between 1965 and 1972, declines of 5 to 10 feet were noted along the Santa Cruz bottomlands, while, except for the depression at Tucson National Country Club, the water levels along the Cañada del Oro rose 10 to 20 feet. Between 1947 and 1972, declines of 25 to 50 feet observed along the Santa Cruz River and lower Cañada del Oro, but little decline was evident for the upper Cañada del Oro area.

Depth to water in the Sahuarita District was 30 to 120 feet along the Santa Cruz River, and over 250 feet along the bajadas. Water levels declines from 1965 to 1972 were up to 50 feet in the northwest, but less in the south. A decline of 75 feet was observed in the area west of Sahuarita.

The depths to water in selected wells in various locations are shown in Figures 25b and 26b (Arizona Water Commission, 1973). The

196 00

220 - D-19-16)15. ' Stockwell, epth 300' 240-_Water-tableaquifer. .Cienega ,Creekdrainage

---- F 1 #_ F . f # !_ - :20-'(D-24-15) 14.: Observationwell,depth47' -Water-table aqulfer. ' SantaCruz River flood pain 40 _v 200 3 220 o 240 - (D-I9-13) 5.Stockwel ,depth 260 -- .µfater-table aquifer . 1

60 I- < èó D-17 -14) 18.. Observation well depth124' DO"Water -tableaquifer.1/2 mile eastofSanta Cruz River

260 .1- 280-` (D- 14 -15) 16,_ Unused 'well,depthunknown :0 Water -tableaquifer 300.

40 Vr VU Y1-111 --"/-V1AvrW 80--(D-15-12)3.Observationwell, depth 106 AN' .Water-table aquifer.East bank ofSantaCruzRiver 100. 9501i51.1'521'51'541'55I'56I'571'58 I`59 I'61I'62'63'64'65'6667'68'69'70'7I'72 ( blankspacesIndicate YEAR nomeasurement made)

197

Fif 25b 26b University of Arizona Agricultural Experiment Station prepared maps showing the depth to water (Figure 27b) and ground -water level contours (Figure 28b) in 1970. Osberkamp (1973a) prepared a map showing depth to water in Tucson area wells. The water table is roughly parallel to the land surface but with gentler gradients. It slopes from the margins toward the outlet near Rillito, and ano- malies exist due to faults and fractures (Davidson, 1973). Belan (1972) estimated the ground -water gradients as 60 feet per mile near Craycroft Road and Rillito Creek, and 400 feet per mile near Oracle Road and Ina Road. Davidson (1973) estimated the ground -water gradients at 10 to 20 feet per mile in the central valley, and 20 to 30 feet per mile in the south and northwest regions.

The three major cones of depression are: 1) in the Sahuarita area where total declines exceed 70 feet and annual declines are 5 feet;2) below metropolitan Tucson where total declines exceed 64 feet and annual declines are 3.5 feet; and 3) at the confluence of the Rillito Creek and Santa Cruz River where maximum declines exceed 60 feet.

Davidson (1973), in making estimates of the hydrogeologic properties of the Tucson aquifer, noted that the horizontal area decreases with depth. The porosity varies from 20 to 35 percent with a basin average of 28 percent. The specific yields vary from 10 to 25 percent with an average of 15 percent. The specific yield is generally higher in the stream alluvium, averaging 25 percent. Trans - missivities ranged from 1000 to 500,000 gpd per foot and the average value was 50,000 gpd per foot. Wells in the Tucson basin are pumped at 500 to 4000 gpm and the specific capacities range from 5 to 100 gpm per foot of drawdown.

The areal variations of transmissivity were mapped by Anderson (1968 and 1972)(Figure 29b). He found transmissivities ranging from 7.2 x 10-4 to 4.3 x 10-2m2 /s but noted that most values were less than 50,000 gpd per foot. Larger values of transmissivity indicate that the water table decline for a given withdrawal will be less deep and extend over a wider area. The mapped values are more accurate where the well pattern is dense and less representative where sparse. The transmissivity declines as the water table drops. (It is equal to product of the hydraulic conductivity and saturated thickness). It can decline rapidly with depth if a geologic boundary is crossed. This phenomenon is evident in the Tucson Basin where the water table has dropped into the Fort Lowell Formation. Anderson's model assumes that there is a single layer of sediments. This is not representative of the conditions where, as an example, stream courses overlie older aquifer materials.

Site - specific geophysical /geologic studies were conducted at the WRRC research site to facilitate the selection and design of artificial recharge facilities and associated monitoring facilities.

199 .5 t \ -" ' .... . \ ...... 1111

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GROUNDWATER LEVEL INN CONTOURS TUCSON BASIN It es UR k SANTA CRUZ VALLEY SPRING 1970

11111111111121MIMAIIIIII SOOTPOOpot °Awl.* it 'tit NOTITlISAS sea austvost esoemsteass ososatwast r 1 VTITVIIIMITOf 440 .....1.1 4 i MI - MIME 4111"1.1111111111.M%IPA. 111111IIMO *155 rs cfrow-70111111,1111111111M111 111.f/1111.

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1-1c;uxF. lN\rçiUn,tlrrun.rvuixtibilirt j,.utrrn andr.cltvrr rif madded crtu

.-Óf7-... 202 Specific reasons for conducting these studies were to characterize: (1) The vertical and spatial distribution of strata; (2) the storage properties of the vadose zone, and (3) estimated hydraulic properties of the vadose zone and ground -water zone. Geophysical methods included surface resistivity and seismic refraction tests, and borehole logging, such as natural gamma logging and neutron logging. The results of these geophysical tests were correlated with grain -size analyses conducted on drill cuttings.

Dumeyer (1966) obtained resistivity profiles at 10 stations in the vicinity of the proposed recharged facilities to characterize the spatial distribution of layered materials. He correlated his results with grain -size analysis of drill cuttings, and natural gamma logs. The latter logs were obtained in three, eight -inch diameter observations wells, and the smaller diameter access wells. Dumeyer used the results of resistivity, grain -size, and natural gamma data to develop the geological description of the three stratigraphic units at the site, discussed elsewhere in this report, and to construct a fence diagram (see Figure 30b).The data also provided clues on the hydraulic properties of the layered units. Four observations were of particular interest: (1) The stratigraphic units appear to be uniformly distributed throughout the area; (2) the most favorable zone for recharge is a coarse layer at the base of the uppermost unit;(3) perched ground water probably develops during recharge at the interface between the upper two units (i.e., in the vadose zone); and (4) perched ground water probably develops during recharge above the main water table, which coincided with the interface between the second and third units. Subsequent neutron moisture logs (see, for example, Figure 7b) verified that the two perched ground water regions do in fact develop during recharge events.

Details of the seismic refraction studies at the WRRC field site were reported by Osborne (1969). The purpose of these studies was to locate the major breaks in alluvium. A line of geophones was set out in northwest- southwest line through the recharge well. Five separate charges, comprising 15 pounds of dynamite each, were deto- nated. The traces of the 12 geophones were recorded on Polaroid film for each shot. The first arrival times were picked off the traces and plotted on a travel time diagram.

The seismic survey indicated three major regions in which changes in velocity occurred. According to Osborne, the upper 25 feet of deposits had an average velocity of 1800 ft /sec, indicating unsaturated media. The deposits from 25 to 150 feet had an average velocity of 4700 ft /sec, indicating saturated or nearly- saturated material. Finally, the material below 150 feet had a velocity of 8300 ft /sec, indicating inundated material.

203 RECHARGE PIT

E -50 rE -25 E-75

E - 100-7

r-RECHARGE WELL

M1 ``.,. P ' \, ÿ.r 2 0 . / 9°0a,7ÿ,. tit - S F1tl ßp$1¡ -twos OtpEß A MEN r. T75 9\:\i. -4-50 \, +25 LEGEND B 25,1\ GRAVEL OR COBBLES 7V/ 25\k SAND SILT AND CLAY FEET 5 \ - -- CONTACT. DATUM ELEVATION 2147 FEET 75- DISCONFORMABLE Fig.1. Fence diagram of the recharge area, Water Resources Research Center, theUniversity of Arizona, showing location of recharge facilities and appurtenances.

Figure 30B Wilson, 1971

204 Subsidence

Land subsidence occurs for a variety of reasons and under a variety of names (Figure 207). Slumping occurs into a subterranian cavity or void. A mine or a natural cave provides an excellent area into which surface soil may collapse if triggered by the failure of supporting structures. Particular subsurface geologic structures like salt domes can dissolve naturally or be mined and encourage the slump of soils.

Deep changes in subsurface geology can also effect subsidence. An active range -bounding fault in the Basin and Range provinces of the world can shift enough to cause gravitational re- organization of the alluvial fill in the adjacent valley. Such fault activity would be associated with seismic or earthquake activity.

Seismic vibration without active fault motion may also serve as a trigger to re- consolidation of alluvial materials, again with gravity providing the force for movement.

In areas with soils deposited in an intermittent riverine environment, subsidence can occur with application of a large amount of water to the soil profile through the re- consolidation and compaction of the wetted soils.

Subsidence also occurs through the drying or dessication of a saturated soil. The pattern of cracks seen in a dry mud bed are analogous to such subsidence fissures.

Last, but certainly not least, the withdrawal of water stored underground can cause subsidence for purely structural reasons as opposed to the shrinkage defined above. In alluvial soils typical of the southwestern United States, clay is not common below the surface except in lenses or intermittent layers. While these layers are saturated, hydrostatic pressure supports the layers of clay as well as the recently deposited soils overlying the clay. Once water is removed, both the clay layers shrink and the overlying soils lose structural support and can subside (Chow, 1964) .

Research done in the Basin and Range province attributed land subsidence in valleys with confined, deep aquifers to groundwater withdrawal in excess of natural recharge (Peterson, 1962). The Tucson Basin seems to fit the criteria making it susceptible to land subsidence. Further research is necessary to determine the probability and likelihood of such an occurrence.

205 1 c:

, (-)0.1.

206 SOURCES AND USES

207 SOURCES AND USES

CENTRAL ARIZONA PROJECT

The Central Arizona Project (CAP) is one of the nation's largest and most controversial public works projects ever to be constructed. It consists primarily of a pumping station at Lake Havasu, behind Parker Dam on the Colorado River, and a series of canals, lift stations and pressure aqueducts which will utimately deliver water to the major urban centers and irrigated agricultural areas in south -central Arizona.

History

When first proposed in 1947, the CAP was a much broader system than that being built today, and was intended primarily to provide supplemental water for agricultural irrigation. The CAP would have delivered only one percent of its water for municipal and industrial use. The 1947 version of the CAP included dams at Bridge Canyon (Hualapai) and Marble Canyon on the Colorado River as well as Charleston Dam on the San Pedro River, and Hooker, Buttes and Maxwell (Orme) dams on the Salt -Gila system.

The State of California successfully postponed consideration of the Project by the House Interior Committee in 1951 based on the lack of binding quantification of rights to the waters of the Colorado River. One year later, 1952, the State of Arizona filed suit in the United States Supreme Court against California and California water users to force a judicial solution to the quantification of rights question. The State of Nevada and the federal government joined the suit as intervenors and the states of New Mexico and Utah were joined by a motion brought before the Court. A Special Master was appointed by the Court and his decree was issued in March 1964. The decree quantified the rights of the Lower Colorado River Basin States to Colorado River Water as follows:

0.3 million acre -feet per year (mafy) to Nevada 2.8 mafy to Arizona 4.4 mafy to California.

The Upper Basin States retained their rights allotted by the Colorado River Compact of 1922, which had first split the Basin at Lees Ferry on the Colorado River. The Upper Colorado River Basin States were apportioned water by the Compact projected to be at least 7.5 mafy. The first 50,000 acre -feet per year go to Arizona. Colorado then receives 51.75 percent, New Mexico 11.25 percent, Utah 23.00 percent and Wyoming receives 14.00 percent of the water remaining after Arizona's portion is deducted. Thus the binding

208 quantification of water rights was established.

In 1968, the final version of the CAP bill was enacted by Congress. Major changes in the bill from those introduced earlier were the result of increases in population beyond those projected in 1947 and pressure from environmental and political groups with special interests in the Project. Two dams on the Colorado River, at Bridge and Marble Canyons, were deleted after nationwide protest by the Sierra Club. A moratorium on even the study of water importation from the Pacific Northwest was included to pacify the fears of Columbia River Basin politicians who felt the threat of diversion from the wet Columbia Basin to the booming, semi -arid Colorado Basin (Metropolitan Utilities Management Agency, 1974; Bureau of Reclamation, 1962).

In 1977 President Carter successfully deleted Orme Dam from the Project for environmental and social reasons. The Presidential review also suggested elimination of Hooker and Charleston Dams. The Central Arizona Water Control Study, with Bureau of Reclamation funds, is studying alternatives to Orme Dam. Alternatives to Hooker Dam are scheduled to be studied in 1980. The fate of Charleston Dam remains to be determined (Bureau of Reclamation, 1978). Previously, the San Pedro -Tucson Aqueduct which would have brought waters from Charleston Dam and Reservoir to the Tucson Area was deleted as a concession to the growth of urban areas to the south and east of the city of Tucson (Metropolitan Utilities Management Agency, 1974).

The Plan at Present

The delivered quantity of CAP water to the Tucson Area depends upon three inter -related factors:

-the allocation of waters to be delivered by the CAP (which is in process,) -the use priorities which govern the allocation of CAP water, and -the water available to the CAP.

Water users who contract to receive CAP water do so with the Central Arizona Water Conservation District (CAWCD) which in turn contracts for water with the Secretary of Interior through the Bureau of Reclamation, (recently re- titled the Water and Power Re- sources Service). By law, agricultural users of CAP water cannot be charged for the interest repayment costs associated with the construction of the Project. This means that these costs will be borne by the municipal and industrial water users, making municipal and industrial CAP water more expensive. The cities of Tucson and Phoenix will pay the same unit costs for purchased CAP water( Bureau of Reclamation, 1979(2)).

209 Use priorities were established by the Secretary of the Interior in 1972. To avoid ambiguity, the text of the Secretary's decisions are quoted directly:

"After careful review of all interrelated factors affecting Indian and non -Indian lands and evluation of the comparative benefits allowed by law, and in recognition of my trust responsibility, I hereby conclude and announce the following interrelated decisions:

(1) Delivery of project irrigation water to Indian lands will not be required to be offset by diminished ground water pumping.

(2) Project irrigation water may be delivered either to developed lands or to new lands with no restriction on increased ground water pumping in either or both areas to firm up irrigation water supply in times of shortage, so long as all such activities take place within established reservation boundaries.

(3) In the allocation of project irrigation water, Indian land shall receive a relative advantage over non - Indian land, the percentage of water allocated to Indian lands to be determined by the Secretary.

(4) All contracts and other arrangements for Central Arizona Project water shall contain provisions that, in the event of shortages, deliveries shall be reduced pro rata until exhausted, first for all miscellaneous uses and next for all Central Arizona Project agricultural uses, before water furnished for municipal and industrial uses is reduced.

210 (5) In times of water shortages the Secretary will exercise his rulemaking authority to require assurances satisfactory to him that appropriate water conservation measures have been adopted by project water using entities.

In accordance with the decisions set forth herein, the contract with the Central Arizona Water Conservation District has been approved."

Rogers C.B. Morton Secretary of the Interior December 15, 1972

(Federal Register, 1972)

The implication of these priorities is that Indian agriculture and then non- Indian municipal and industrial uses have priority over non - Indian agricultural uses of CAP water.

Allocations are presently being made. Those announced for the Tucson Area thus far are shown in Table 10.Table 10 also indicates the sliding allocations which reflect projected further development of the Colorado River water source by entitled states into the 21st century and the projected trend toward population growth in municipal areas.

Based on projected averages, it is anticipated that the CAP Colorado River source will have approximately 1.8 million acre -feet of water available for delivery in 1985, and only approximately 1.2 million acre -feet of water available for delivery in 2035 (Bureau of Reclamation, 1979). The estimates have been the subject of considerable controversy.

Owing to seasonal fluctuations in flow and fluctuations in other diversions, the CAP will not deliver water at a constant rate. This dictates regulatory storage in the aqueduct to smooth these pulses of delivery by storing water during periods of high flow and releasing from storage during periods of shortage. These regulatory reservoirs are intended to provide additional benefits as flood control structures which will enhance both the quantity of deliverable water and the cost effectiveness of the Project as awhole.In addition to regulatory storage, terminal site storage will be necessary for both the regulation and distribution of Project water at a delivery point. Various sites have been suggested to serve this terminal storage purpose for the Tucson Area. These sites and the canal turn -outs may ultimately be a part of the Pima County portion of the CAP (Bureau of Reclamation, 1979).

211 CAP Water Allocation Delivery Schedule and Priorities TABLE X Acré-f.eet Pima CountyTUCSON AreaDIVISION péxf ypár..: (8 W (' (-1/1--C C`4.c. Priority6/Entity Water Exchan9sSec. 304(e) First -- Agricult.-Indian Second h18.I-Tuc9n Third FourthMining- Agriculture-Non -Indian Fifth J a Total 1987Year None Identified 0 56,050 35,900 74,433 166,383 1990 H 0 58,650 35,050 68,741 162,441 ÑN 200a1995 II 0 67,35063,000 33,60032,150 49,76959,255 149,269155,855 20102005 " 0 76,05071,700 29,25030,700 40,28338,550 142,583143,850 20202015 " 0 80,40084,750 26,35027,800 35,08336,816 146,183145,016 20302025 0 89,10093,450 12,45024,900 31,61633,350 137,516147,350 See2035 next paye for footnotes. " 0 97,800 0 29,883 127,683 (continued)

Footnotes:

"Section 304(e),Public Law 90 -527, Colorado River Basin Project Act, specifies that "in times of shortage or reduction of main stream Colorado River water for the Central Arizona Project...users which have yielded water from other sources in exchange for main stream water...shall have a first priority to receive main stream water, as against other users...which have not so yielded..."

Inaccordance with the October 12, 1976, allocation of Project Water for Indian Irrigation Uses, by the Secretary of the Interior, ill Sttick].är. published in the Federal Register on October 18, 1976. 4i9 CAP water /-.2,100 was requested by, and no water allocated to, the San Xavier Unit of the Papago Indian Reservation.

3 ./Inaccordance with the Arizona Water Commission recommendations to the Secretary of the Interior in a letter dated June 22, 1977. Assumes straight -line proration between 1985 and 2035 allocation points.

"Seefootnote 3, above. In addition, the data shown is from working file data supplied for this study by the Arizona Water Commission and is not final. Priority assignment is inferred and subject to change.

"Inaccordance with the Arizona Water Commission recommendations to the Secretary of the Interior in a letter dated August 31, 1979. Assumes straight -line proration between 1985 and 2005, and 2005 and 2035 allocation points.

6'Prioritiesexclusive of Section 304(e) and mining priorities, are as established by the October 12, 1976 Indian allocation order or the Secretary of the Interior's December 15, 1972, notice of CAP Water - Use Priorities and Allocation of Irrigation Water, published in the Federal Register December 20, 1972.

213 Quality of Delivered CAP Waters

Appendix Z summarizes the chemical composition of Colorado River water in the Colorado River Aqueduct to Los Angeles and com-

posite City of Tucson ground -water quality values . The quality of the water delivered may differ from that upon which these data are based. The average annual salinity of CAP water planned for delivery to the Tucson Area is expected to be about 755 milligrams per liter (mg /1). This value will be affected to an unknown extent by water which is delivered from sources other than the Colorado River. Water quality and comparisons of data are discussed further in the section of this report titled Beneficial Use.

Delivery Sites

Current debate in the Tucson Area involving the terminus of the Water and Power Resource Service's (WPRS or Bureau of Reclamation's) construction of the CAP aqueduct revolves around several points. The WPRS has announced its intention to study environmental impact of the aqueduct construction to the vicinity of the intersection at Ina and Silverbell Roads in northwest Tucson. This decision, since modified, did two things; first, it implied that proposed alignments of the aqueduct around the west side of the Tucson Mountains were not to be constructed by the WPRS, and second, that no provision for WPRS construction and therefore delivery of CAP water was being made for any users south of the City of Tucson. These users include the Farmers Investment Company, the San Xavier Indian Reservation, and Duval, Anamax and Cyprus Pima mines, among others. This also slightly handicaps the City of Tucson in that distribution of water is more costly from the Area's lowest point in northwest Tucson than from the higher elevation site south of town.

Following intervention by the Secretary of the Interior and the Solicitor General, the WPRS has proposed to the Eastern Pima County Water Resources Coordinating Committee (EPCWRCC) that a two -stage environmental impact statement (EIS) be prepared. The first stage would cover (or be "scoped" to include) both a possible site near the Cortaro -Marana Irrigation District from which a branch or bend could proceed along the west side of the Tucson Mountains and the Ina -Silverbell site previously mentioned. The second stage would be scoped farther south to the southern edge of the San Xavier Indian reservation south of Tucson. An additional consideration which will be taken into account in both stages of EIS preparation is the possibility of co- mingling or mixing treated sewage effluent from the Ina Road wastewater treatment facility with CAP water for delivery to potential users south of Tucson (mining and agriculture, not domestic use).

214 This will delay delivery of water to areas south of Tucson until approximately 1988. The sites north of Tucson can still expect CAP water in 1987 (Preliminary Presentation to EPCWRCC, January 21, 1980, by WPRS). Potential routes for the CAP- Tucson Aqueduct are shown on Figures 200 through 203 (Bureau of Reclamation, 1979). Final distribution of water from the aqueduct will be the responsibility of the entitled user.

Summary

The Central Arizona Project will deliver approximately 170,000 acre -feet of Colorado River water to Eastern Pima County in 1987. The delivered water will be readily treatable for all potential uses including domestic drinking.

The aqueduct itself will manifest associated environmental and social changes as will the necessary regulatory and terminal reservoirs and pump stations.

The final decision on location of the aqueduct terminus has not been made but is expected to be public knowledge before the end of 1980. This terminal location decision may affect when CAP water is delivered at the terminus by as much as one year and as little as not at all.

BENEFICIAL USE

Legal Definition

By Arizona State Law;

"any person may appropriate unappropriated water for domestic, municipal, irrigation, stock watering, water power, wildlife, including fish, mining uses, for his personal use or for delivery to consumers. The person first appropriating the water shall have the better right." (ARS45 -141).

When two users come to conflict about the appropriation of waters which both desire to use;

"...preference shall be given by the Commission (Arizona Water Commission) according to the relative values to the public of the proposed use(s). TOSSONCC NV/VAL DIVISION- ANISONS PROJSCSANIZON Id Or SCLANINYIONROUTE <>- CAP PUMPINGU REGULATORY ALTERNATIVE PLANT RESERVOIR SITE ROUTE SO.Atf Of MILES DeleINIS TUCSONLOCATION AOLICOUCT MAPALTERNATIVES GOMEZ -BOYLE ROUTE (MOOIFIEW /.0.1.4"11,corecort. ANISON TF 444rT114KI.. '". Fi44-330-1350 O REGULATORY RESERVOIR CA.P ALTERNATIVE ROUTE 11,CSONTUCSONLOCATION AQUEDUCT MAPALTERNATIVES ROUTEAnl.rphla owroJtcr -- GOMEZ-BOYLE' ROUTE 04001AELB PUMPING PLANT SITE SCALE Of Olt la Oroa c.. .11..VATTPIC," , Apoo,,v.u..orreu 4n000. oostaaao. A.0.0 T., I .1 044-330-1350 , .1 o

' CIE , 71.:TUGSONlcHl M41. NOVI EAtItIZONA WeCt."4,104141"r;tal"1: AMI.IONA 000. o REGULATORY RESERVOIR C A.P ALTERNATIVE ROUTE 1- rucsoNLOCATION MAPA Auut-otICT '<> PUMPING Pt ANT SITE GOmEZ -1JOYLE ROUTE TMOOITTEN -4 ScALI Ir MIL 5* ,RN 1344- 330-13tio N

O ñ

3 3[Il1 '321-Y 3t1'Î 301Y 3011 lt u

219 ...The relative values to the public for the purposes of this section shall be: 1. Domestic and municipal uses. Domestic uses shall include gardens not exceeding one -half acre to each family. 2. Irrigation and stock watering. 3. Power and mining uses. 4. Recreation and wildlife, including fish."

(Laws of 1979, chapter 139) (ARS45 -147).

Beneficial use can be defined as any use of water of value to the public. The highest use of water would be domestic use or consumption by the public directly.

In addition to beneficial use itself, use of water can provide benefits to the public not directly related to the water itself; flood control is such a benefit.

Uses

Table 20 summarizes present and projected water uses and consumption demand for eastern Pima County.

Reduction of Flood Damage

It has been said among hydrogeologists in the Tucson Area, that flooding has not truly occurred here except perhaps once since before the first english speaking people settled here in the 1800's; and that it is curious that when no water flows in our channels they are called rivers and when water does flow, it is called a flood.

Flooding can be defined as a situation in which water flows over the banks of its channel. Floods, more often than not, result in a few feet of slow moving water inundating a broad flood plain adjacent to the low flow channel and depositing large quantities of mud and silt upon the lower portions of the unfortunate residents' homes and properties. This process is quite natural and is in fact responsible for the fine quality soils which attract humans to floodplains in the first place. Initially, agriculture established itself in these bottom lands and as the City of Tucson grew such land became more and more valuable. Every few years a slow- moving winter storm will dump precipitation into the Tucson Area and soon the rivers begin flowing and generally eroding their banks in an attempt to dissipate all of the energy generated by a fall from the sky and flow down a gradient. The desires of man and the processes of nature once again appear to be at odds. Flood damage reduction with maximization of flood plain productivity and utility is predictably difficult.

220 Flood Damage Reduction by Diversion and Detention of Storm Runoff

Flood control may take a variety of paths to reach its ends. One is the do- nothing option in which man does nothing and simply runs away from an impending flood. Unfortunately, this option is of little help to the family which is forced to watch its cherished possessions floating off to be deposited elsewhere or to the farmer who may stand on his doorstep and watch his cotton acreage dissolve as the Santa Cruz tears across his farm.

Another option, more commonly considered, is the levee system, sometimes referred to as the "pile up dirt around everything important" option. This may be more useful on small, slow flowing streams common in the eastern United States, but in the Southwest the energy available to waters in a large flow event may overwhelm even a sophisticated and expensive pile of compacted earth.A third option, related to the levee idea, involves piles of dirt around the low flow channel reinforced with concrete or soil- cement (which is, perhaps obviously, a mixture of soil and cement). Such a channel is designed to carry large flows safely within its banks. Several problems result from such a plan; sterile, hard banks are not usually very pleasant to look at and discourage growth of plants and flowers, low flows may become even more dangerous than those which presently occur in that flow velocity is likely to increase reducing recharge and transferring the problem to a resident of an area downstream from the channelization who may experience flooding or erosion much worse than the conditions faced before the upstream efforts at controlling floods were constructed. Partial channelization or simple bank stabilization can protect from erosion but does little or nothing to protect property from inundation in a large flow event.

An administrative option might provide a solution in that zoning decisions often reflect the economics inherent in flood damage estimation. An area can be zoned to minimize the possibility of flood damage. The problem is that citizens are less likely to re -elect a politician who claims to be saving the taxpayers 10 million dollars in flood damages from a flood that may not occur for 35 years by voting for a restrictive floodplain ordinance, when a developer is offering to provide homes for persons who want to join this community now and stimulate the local economy on floodplain lands now, not in 35 years.

The final option, to be examined in some detail in later sections, is the primary topic of this report: diversion and detention. Divert- ing floodwaters and detaining them for use or later release can serve many valuable purposes. A flood or large flow even in Tucson Area channels can be plotted, with time, to show graphically the intensity of flow. Flooding occurs when the flow rate of the channel is at

221 TABLE 20 EASTERN PIMA COUNTY EXISTING AND PROJECTED CONSUMPTION (Acre -Feet /Year) Indicated at location where applied. Numbers reflect a 7% conservation by 2000 for all users except for the City of Tucson and the San Xavier Indian Reservation agricultural projections.

1980 2000 2030

UPPER SANTA CRUZ BASIN

Agricultural Tucson District (1) 10,855 8,442 (2) 8,020 (2) San Xavier Indian Reservation 2,925 38,725 65,339 Farmers Investment Company 21,450 19,949 19,949 Subtotal 35,230 67,116 93,308

Municipal City of Tucson 68,641 115,105 172,938 Green Valley 2,400 4,092 4,859 San Xavier Reservation 100 372 1,023 Misc. Private Companies 9,740 (3) - (4) - (4) 80,881 119,569 178,820

Industrial Arizona Portland Cement 1,000 2,139 3,069 Cortaro -Canada del Oro District (1) 300 372 558 Tucson Electric Power Co. 6,754 6,281 6,281 ASARCO Inc. 6,930 (5) 6,445 (5) 6,445 (5) ANAMAX Mining Company 17,000 (5) 29,760 (5) 23,250 (5) Cyprus -Pima 17,500 (5) 16,275 (5) 16,275 (5) Duval Corporation 27,905 (5) 25,952 (5) 25,952 (5) Subtotal 77,389 87,224 81,830 Recreational /Other University of Arizona 1,200 1,100 1,100 Davis -Monthan AFB 2,074 1,929 1,929 Subtotal 3,274 3,029 3,029

Total 196,574 276,938 356,987

NOTES: (1) Reference to districts is to USGS surface drainage subunit. (2) Assumes that 5% of agricultural acreage will be converted to urban development by 2000 and an additional 5% of 2030. (3) Metropolitan Water Company, 3,900 ac -ft; Flowing Wells Irrigation District, 2,840 ac -ft; other miscellaneous small water companies, 3,000 ac -ft. (4) City of Tucson projections for Upper Santa Cruz basin include private water companies in the metropolitan Tucson area. (5) Assumes PAG Mines Task Force report of no significant return.

222

(Eastern Pima County Water Resources Coordinating Committee, April, 1980) its greatest. If this peak can be attenuated, the flood will be less severe. Figure 204 is a comparison of such an attenuation with a natural flow event.

The Tucson Area does not offer many favorable sites for construction of large dams. It is safe to assume that if it did, there would be little problem today, for large dams would surely have already been built. However, small dams or diversion structures feeding into detention basins which would control floods are more feasible because they do not rely on the bedrock upon which large dams must rest for strength. Such structures are discussed in other sections of this Report. The benefits to such structures include; protection of land and property from inundation in large events provided the diversion and detention structures are designed to withstand large events or pass waters not detainable safely; protection of agricultural and residential land from erosion by reducing the velocity and volume of channel flow downstream from the structure; and probable enhancement of natural recharge processes by removing suspended sediment in detention and allowing low velocity flows to spill and percolate to the water table without rushing out of the Basin. A diversion - detention- recharge project can provide many flood control functions necessary for the Tucson Area as well as providing sites for wet - parks, greenbelts and other water -based recreational areas.

Municipal and Domestic Uses

Domestic use is use in private homes for drinking, cooking, washing, cooling, recreation, irrigation and sanitation.Municipal use refers to use in public places for the same purposes as domestic use with the possible inclusion of firefighting.

Estimates of consumption of municipal and domestic water for eastern Pima County appear in Table 20.

Municipal and domestic uses of water require, for public health reasons, water of very high quality. Table 30 provides a brief summary of water quality standards and criteria. Table 40 displays measured ground -water quality in the Upper Santa Cruz Ground -Water Basin.

The Tucson Metropolitan Area occupies roughly 300 square miles. Distribution of water presently occurs thorugh a network of wells and above- ground reservoirs throughout the metropolitan area and Avra Valley.

223 Z` Pt FIGURE 1958

(Leopold, L., and T.Maddock jr., 1954, "The Flood Control Controversy," Ronald Press, New York)

WITHOUT DAMS

3,000 ...--bUTFLOSr AT MOUTH WITH 3DAMS GO SO km AREA fi WRHODT pAMS CONTA tuTION Or á UNCONTROLLED F.0 AREA 2P00 TOTAL CONTRteUTgN OOTFEC:I AT N,OOTN Oí CF AREAS, E;i.r+ 10 SO Aa, 60 Sn süAREA C SEFJRE CONSTRUCTION OFOA.Mç CC+Tsc:c:O3 Da.ts, ó CONTRT uTICN ERCHGhTRCW:Z 10 SO Nn. F t;NCONN4OLLED ß IA AREA

TOTALCCNTR'.',T ,'! FR:,si 3 AREAS CONTRCCED ST DOIS 12 i6 20 24 0 4 8 12 16 20 24 Time, in hours offer h2gnniTy cf runOf f FLOOD HYDROCRAPH UNCONTROLLED "Y DAMS (LEFT), AND CON- TROLLED RY THREE DAMS ( RTCnT) Table ,K (Bovet, 1970.

TREATED WATER QUALITY STANDARDS AND GOALS

Parameter Unit PHS1962 AWWA WHO1971 EPA 1973 Mand. Desir. 1968 Mand. Desir. Health Esth. (a) (b) (c) (d) (d)

Physical Param.

Color PCU - 15 3 50 5 - 15 Non -filt.solids mg /1 - - 0.1 - - - - Odor TON - - None Unobj. Unobj. - 3 Taste - - - Unobj .Unobj .Unobj . - - Turbidity JTU - 1 0.1 25 5 1 -

Biological Param.

Coliforms filter No /100 ml 1 or 4 - None - - 1 or 4- (e) (e) ferment No /100 ml - - None - - - - Fecal coliforms No /100 ml - - None - - - - Macroscopic organisms No. - - None - - - -

Inorganic Chemicals

Alkalinity (CaCO3) mg /1 - - (f) 6.5 -9.2 7.0 -8.5 - - Aluminum mg /1 - 0.05 - - - - Arsenic mg /1 0.05 0.01 - 0.05 - 0.1 - (g) Barium mg /1 1.0 - - - - 1 - Boron mg /1 5.0(h)1.0(h) - - - - - Cadmium mg /1 0.01 - - 0.01 - 0.010 - Calcium mg /1 - - - 200 75 - - Chloride mg /1 - 250 - 600 200 - 250 Chromium, hexavalent mg /1 0.05 - - - - 0.05 - Copper mg /1 - 1.0 0.2 1.5 0.05 - 1 Corrosion mg /sq cm - - 5.00 - - - - (i) Fluoride mg /1 (j) (j) - (j) (j) (j) - Hardness mg /1 - - 80(k) 500 100 - - Incrustation mg /sq cm _ - 0.05(1) - - - - Iron, filter mg /1 - 0.3 0.05 1.0 0.1 - 0.3

225 Parameter Unit PHS 1962 AWWA WHO 1971 EPA 1973 Mand. Desir. 1968 Mand. Desir. Health Esth. (a) (b) (c) (d) (d)

Lead mg/1 0.05 - - 0.1 - 0.05 - Magnesium mg/1 - - - 150 30-150(m) - - Manganese, filterable mg/1 - 0.05 0.01 0.5 0.05 - 0.05 Mercury mg/1 - - - 0.001 - 0.002 - Nitrates & Nitrites(N) mg/1 - 45 - 45 - 10 - Selenium mg/1 0.01 - - 0.01 - 0.01 - Silver mg/1 0.05 - - - - 0.05 - Sulfate mg/1 - 250 - 400 200 - 250 TDS, filt. residue mg/1 - 5.00 200 1500 500 - - Zinc mg/1 - 5 1.0 15 5 - 5

Organic Chemicals mg /1

CAE - - - - 7.. 3.0 - CCE - 0.2 - 0.5 0.2 0.7 -

Cyanide 0.2 ' 0.01 - 0.05 - 0.2 - Herbicides 2, 4 -D - - - - - 0.02 - 2,4,5-TP(Silvex) - - - - - 0.03 - MBAS - 0.5 - 1.0 0.2 - 0.5 Mineral Oil - - - 0.30 0.01 - - Pesticides ------Aldrin 0.001 Chlordane 0.003 DDT 0.05 Dieldrin 0.001 Endrin 0.0005 Heptachlor epoxide 0.0001 Lindane 0.005 Methoxychlor 0.1 Org. phosphates and carbamates (parathion) 0.1 Toxaphene 0.005 Phenols - - - 0.002 0.001 See odor -

Radioactivity (n) pc/1 Gross alpha - - - 3 /10(o) - - Cross beta 1000(p) - 100 30 /1000(q) - Radium 226 - 3 - - - - - Strontium 90 - 10 - - - - -

226 Unobj. = Unobjectionable

(a) If the concentrations of any of these constituents are exceeded, the further use of this water for drinking and culinary purposes should be evaluated by the appropriate health authority because water of this quality represents a hazard to the health of consumers.

(b) If the concentration of any of these constituents is exceeded, a more suitable supply or treatment should be sought.

(c) For all health- related constituents not stated herein, these goals shall require complete compliance with all recommended and mandatory limits contained in current USPHS Drinking Water Standards. Unless other methods are indicated, analyses shall be made in conformance with the latest edition of Standard Methods for the Examination of Water and Wastewater.

(d) Mandatory limits are called "allowable "; desired limits, "acceptable ".

(e) Water quality fails the standard if: (1) arithmetic average of samples collected is greater than 1 per 100 ml; or (2) two or more samples (5% or more if more than 20 are examined) contain densities more than 4/100 ml.

(f) Alkalinity should not change by more than 1 mg /1 (decrease or increase in distribution system, or after 12 hours at 130 °F. in a closed plastic bottle, followed by filtration).

(g) Although the recommended arsenic concentration is 0.01 mg /1, because of interferences in some waters, the concentration of arsenic was only determined to be less than 0.03 mg /l. For the purposes of this study, these waters were considered not to exceed the recommended standard.

(h) Proposed for inclusion in the Drinking Water Standards.

(i) Loss by corrosion of galvanized iron by coupon tests.

(j) Public Health Service limits are as follows: Temperatures shown for fluoride concentrations are annual average maximum day temperatures for 5 years or more.

227 \, i

Limits(mg /1) Temperature Mandatory Desirable

50.0- 53/7°F 2.4 1.7 53.8- 58.3°F 2.2 1.5 58.4- 63.8°F 2.0 1.3 63.9- 70.6°F 1.8 1.2 70.7- 79.2°F 1.6 1.0 79.3- 90.5°F 1.4 0.8

The World Health Organization recommends the following upper and lower control limits which should be considered mandatory:

Annual average of maximum - Limits (mg /d) daily air temperatures Lower Upper

10 - 12° C 0.9 1.7 12.1- 14.6°C 0.8 1.5 14.7- 17.6°C 0.8 1.3 17.7- 21.4°C 0.7 1.2 21.5- 26.2°C 0.7 1.0 26.3- 32.6°C 0.6 0.8

EPA's limits are, for temperatures of 65° F or less, 1.5 mg /1; 66 - 79° F, 1.3 mg /1; 80° F or over, 1.2 mg /1.

(k) A balance between deposition and corrosion characteristics is necessary; a level of 80 mg /1 seems best, generally, considering all the quality factors; however, for some supplies, a goal of 90 or 100 mg /1 may be deemed desirable.

(1) By 90 -day coupon tests on stainless steel.

(m)If 250 mg /1 of sulfate are present, not more than 30 mg /1 of magnesium are desirable; with less sulfate, magnesium up to 150 mg /1 may be allowed.

(n) The unit for radioactivity is the pico -curie or micro -micro -curie per liter, expressed by pc /1.

(o) If radium 226 activity exceeds 3 pc /1, 3 pc /1 of alpha radiation is the mandatory limit; if radium 226 activity is below 3 pc /1, 10 pc /1 of alpha radiation are permissible.

228 (p) Acceptable in water in the known absence of strontium 90 and alpha emitters.

(q) If strontium 90 activity exceeds 30 pc /1, 30 pc /1 of beta radiation is the mandatory limit; if strontium 90 activity is below 30 pc /1, 100 pc /1 of beta radiation are permissible; and if strontium 90 activity is below 30 pc /1 and iodine 129 activity is below 100 pc /1, then 1000 pc /1 of beta radiation are permissible.

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231 Mining and Industrial Uses

Mining and industrial uses of water include mineral processing, manufacturing processes, plant cooling and electricity generation.

Projected quantities of consumptive use of water for these purposes in eastern Pima County are summarized in Table 20. Estimates are that approximately 50% of water pumped for mining purposes returns to the water table as recharge. The consumptive use figures represent the total amount pumped minus the amount which returns to the ground water (Pima Association of Governments, 1978, Task 6330).

Manufacturing and Industry demand various qualities of water. Table 60 is an attempt to summarize these demands. A more detailed list of industries and their water quality tolerances was published in Report of the U.S. Study Commission -- Texas, 1962 and was reprinted in the American Water Works Association Journal, March, 1970, pp. 150- 151.

Conspicuously absent from Table 60 are the qualitative demands of the froth -flotation copper separation process common to the Tucson Area. Some scientific research has been done in examination of the potential effects of treated municipal waste water or sewage effluent on the forth -flotation process. Based on laboratory experiments, four conclusions were drawn regarding this reuse of water:

"1. Secondary treated sewage effluent from the City of Tucson activated sludge treatment facility causes a small decrease in copper recovery and a large decrease in molybdenum recovery when it is substituted for normal process water in a laboratory flotation test. It also causes the formation of a voluminous, unmanageable froth that has little mineral carrying ability.

2. Isolation of the surfactants in sewage effluent by foam fractionation eliminates the unmanageable froth, but has no effect on metal recovery.

3. The component of sewage effluent responsible for the loss in molybdenum recovery is an organic substance attracted to a cation exchange resin.

4. The effect on flotation response of sewage effluent and humic acid added to standard water are the same. (Fisher, W.W. and S. Rudy, 1978)"

232 Table,' Quality Requirements of Water at Point of Use for Steam Generation and Cooling in Heat Exchangers [Unless otherwise indicated. units are mg /I and values that normally should not be exceeded. No one water will have all the maximum values shown.]

Boiler feed water Cooling water Quality of water prior to the addition of substances used for internal conditioning Electric Industrial utilities Once through Makeup for recirculation Inter- Low mediate High pressure pressure pressure Oto150 150 to 700 700 to 1,500 1.500 to Characteristic psig psig psig 5,000 psig Fresh Brackish Fresh Brackish

Silica (SiO:) 30 10 0.7 0.01 50 25 50 25 Aluminum (AI) 5 0.1 0.01 0.01 (3) (=) 0.1 0.1 Iron (Fe) 1 0.3 0.05 0.01 (3) (3) 0.5 0.5 Manganese (Mn) 0.3 0.1 0.01 ç) (3) ( ) 0.5 0.02 Calcium (Ca) (3) (3) (3) 200 420 50 420 (3) (3) (3) Magnesium (Mg) (`) (2) (3) 0 (2) Ammonia (NH,) 0.1 0.1 0.1 0.7 (3) (3) (3) (') Bicarbonate (HCO3) 170 120 48 600 140 24 140 Sulfate (SO,) (3) C) (3) (a) 680 2,700 200 2,700 Chloride (CI) (=) (3)' 0 (a) 600 19,000 500 19,000 Dissolved solids 700 500 200 0.5 1,000 35,000 500 35,000 Copper (Cu) 0.5 0.05 0.05 0.01 (2) (3) (3) (3) Zinc (Zn) (`) (3) (3) (a) (3) (3) (3) (3) (3) Hardness. (CaCO:) 20 (3) (3) 850 6,250 130 6,250 (3) (3) (3) (3) (3) (3) Free mineral acidity (3) (3) (CaCO::). Alkalinity (CaCO..) 140 100 40 (3) 500 115 20 115 pH, units 8.0 -10.08.2 -10.0 8.2 -9.0 8.8 -9.2 5.0-8.3 6.0-8.3 (3) (2) Color, units C) O O (3) (3) (3) (3) (2) Organics: (3) Methylene blue active 1 1 0.5 (3) (3) 1 1 substances. Carbon tetrachloride 1 1 0.5 (1) (3) (') 1 2 extract. (3) Chemical oxygen demand 5 5 0.5 75 75 75 75 (0,). Dissolved oxygen (O,) ____ 2.5 0.007 0.007 0.007 (2) (2) (3) (3) Temperature, F (3) (3) (3) (2) (3) (3) (3) (3) (3) Suspended solids 10 5 (3) 5,000 2,500 100 100

' Brackish water -dissolved solids more than 1,000 mg /I by a Controlled by treatment for other constituents. definition 1963 census of manufacturers. s No floating oil. 3 Accepted as received (if meeting total solids or other limiting values); has never been a problem at concentrations en. NOTE.- Application of the above values should be based on countered. Part23. ASTM book ofstandards(I).or APHA Standard a Zero, not detectable by test. methods for the examination of water and wastewater (5).

Quality Requirements of Water at Point of Use by the Textile Industry (SIC 22) (Water quality prior to addition of substances used for internal conditioning.Unless otherwise indicated. units are mg /I and Quality Characteristics of Surface values that normally should not be exceeded.) Waters That Have Been Used by the Textile Sizing Industry (SIC 22) suspen- Characteristic sion Scouring BleachingDyeing [Unless otherwise indicated.units are mg /Iand values are maximum. No one water will have all the maximum values shown.1 Iron (Fe) 0.3 0.1 0.1 0.1 Manganese (Mn)_ 0.05 0.01 0.01 0.01 Copper (Cu) 0.05 0.01 0.01 0.01 Concen- Concen- Dissolved solids 100 100 100 100 Characteristic tralion , Characteristic tration Suspended

solids 5 5 5 . 5 Iron (Fe) 0.3 Suspended Hardness Manganese solids 1,000 (CaCO,) 25 25 25 25 (Mn) 1.0 Hardness pH, units: Copper (Cu) ___ 0.5 (CaCO,) 120 Cotton 6.5 -109.0 -10.52.5 -10.57.5 -10.0 Dissolved pH, units 6.0 -8.0 Synthetics 6.5 -103.0 -10.5 (') 6.5 -7.5 solids 150 Color, units Wool 6.5 -103.0 -5.02.5 -5.03.5 -6.0 Color, units 5 5 5 5 ' Accepted as received (if meeting total solids or other IVmit ingvalues);hasnever been a problematconcentrations ' Not applicable. encountered. NOTE. -Application ofthe above va!,.es should be based NOTE.- Aoohc3tion of the above values should be based on upon analytical methods:nPart23ofthe ASTM bookof Part23. ASTM book ofstandards(1).or APHA Standard standards (1). or APHA Standard methods for the examination methods for the examination of water and wastewater. (5). of water and wastewater (5). 233 C Table T (Cont.)

Quality Characteristics of Surface .Quality Requirements of Water at Waters That Have Been Used by the Pulp and Point of Use by the Pulp and Paper Industry Paper Industry (SIC 26) (SIC 26) [Unless otherwise indicated, units are mg /I and values that [Unless otherwise indicated.units are mg /Iand values are normally should not be exceeded. Quality of water prior to the maximums. No one water will have all the maximum addition of substances used for internal conditioning.] values shown.] Chemical pulp and paper Chemical pulp and paper Mechanical Mechanical Characteristics pulping Unbleached Bleached Characteristics pulping Unbleached Bleached Silica (Si0_) (') 50 50 Silica (SiO) (I) 50 50 Aluminum (AI) (r) (') (') Aluminum (AI) (') (I) (1) Iron (Fe) 0.3 1.0 0.1 Iron (Fe) 2.6 2.6 2.6 Manganese (Mn) 0.1 0.5 0.05 Manganese (Mn) (') (') (1) Zinc (Zn) (') (1) (') Zinc (Zn) Cl (') C) Calcium (Ca) (') 20 20 Calcium (Ca) (') C) C) Magnesium (Mg) (') 12 12 Magmesiurn (Mg) C) (t) C) Sulfate (SO,) (') (1) C) Sulfate (;50,) (1) (t) C) Chloride (CI) 1,000 200 200 Chloride -(CI) 1,000 200 200 Dissolved solids C) (1) (') Dissolved solids 1,080 1,080 1,080 Suspended solids (') 10= 10' Suspended solids (') C) C) Hardness (CaCO3) (') 100 100 Hardness (CaCO,) 475 475 475 pH, units 6-10 6-10 6-10 pH, units 4.6 -9.4 4.6 -9.4 4.6 -9.4 Color, units 30 30 10 Color, units 360 360 360 Temperature, F (') (') 95 Temperature, F (') (1) 95 ' Accepted asreceived(ifmeetingtotalsolidsor other t Accepted, as received (if meeting total solids or other limit- limiting values); has never been a problem at concentrations ingvalues); hasneverbeen a problematconcentrations encountered. encountered. :No gritty or color- producing solids. NOTE. -Application of the above values should be basedon NOTE. -Application of the above values should be based on Part23. ASTM book ofstandards(1).or APHA Standard Part23, ASTM book ofstandards(I),or APHA Standard methods for the examination of water and wastewater (5). methods for the examination of water and wastewater(5).

. Quality Characteristics of Surface Waters That Have Been Used by the Hydraulic Quality Requirements of Water at Cement Industry (SIC 3241) Point of Use for the Hydraulic Cement Industry [Unless otherwise indicated,units are mg /I and values are (SIC 3241) ma:umurns.Noone waterwill have allthe maximum values [Unless otherwise indicated,units are mg /I and values are shown.] maximums. No one water will have all the maximum values shown. Quality of water prior to addition of substances used Concen- Concen- for internal conditioning.] Characteristic tration Characteristic tration Concen- Concen-

Characteristic tration III Characteristic tration Acidity (CaC(1) (r) Iron(Fe) 1.8 Alkalinity Manganese (CaCO3) 240 (Mn) 5 Acidity Organics: Chemical oxygen Organics: (CaCO.) Carbon demand Carbon Alkalinity tetrachloride (Q) (-) tetrachloride (CaCO:,) extract 1 Coliform bac extract 1 Chemical oxygen Iron (Fe) 25 teria (count/ pH, units 6.9 -8.8 demand Manganese 100 ml) (`) Silica(Si0_) 16 (O.) (Mn) 0.5 Color, units (") Dissolved Coliform bac- pH, units 6.5 -8.5 Hardness solids 1,120 teria, (count/ Silica(Si0_) 35 (CaCO,) 500 Suspended 100 mi) Dissolved Calcium solids 200 Color, units solids 600 hardness Sulfate (S0,) 235 Hardness Suspended (CaCO3) 150 Chloride (CI) 100 (CaCO,) solids 500 Calcium Sulfate(SO,) 250 Zero. not detectable by test. hardness Chloride (CI) 250 Acceptedasreceived(ifmeetingtotalsolidsor other (CaCQ) limiting values); has never been a problem at concentrations encountered. r Zero. not detectable by test. trOTE.- Concentrations are based on limited data. Applica- Accepted as received(ifmeetingtotalsolidsorother tion of the above values should be based on Part 23. ASTM limiting values): has never been a problem at concentrations book of standards(1)or APHA Standard methods for the examination of water and wastewater (5). encountered. NOTE. -Concentrations are based on limited data. Applica- tion of the above values should be based on Part 23. ASTM book ofstandards(1)or APHA Standard methods forthe examination of water and wastewater (5).

234 Table TCont.)

.Process Water Intake by Chemical Quality Characteristics of Surface and Allied Product Industries With Total Water Waters That Have Been Used by the Chemical Intake of 20 or More bgy During 1964 and Allied Products Industry (SIC 28) [Unless otherwise indicated,units are mg /Iand values are Process water intake maximums. No one water will have all the maximum values shown.] SIC Industry group and industry Bgy Percent Concen- Concen- Characteristic tration 2812Alkalies and chlorine 16 2.8 Characteristic tration 2815 Intermediate coal tar products 9 1.6 Silica (Sip:) ___ (,) Suspended 2818Organic chemicals, n.e.c.' 314 55.5 Iron (Fe) 5 solids 10,000 2819 Inorganic chemicals, n.e.c.' 74 13.3 Manganese Hardness 2821 Plastic materials and (Mn) 2 (CaCO3) 1,000 resins 25 4.4 Calcium (Ca) 200 Alkalinity 2822 Synthetic rubber 11 2.0 Magnesium (CaCO3) ____ 500 2834Pharmaceutical prepara- (Mg) 100 pH, units 5.5 -9.0 tions 3 0.5 Ammonia (NH,)_ (' ) Color 500 2841 Soaps and other deter- Bicarbonate Odor (') gents 2 0.4 (HCO3) 600 BOD (Or) (') 2851 Paints and allied Sulfate (SO.) __ 850 COD (O:) (i) products 1 0.2 Chloride (CI) ___ 500 Temperature (I) 2861 Gum and wood Dissolved DO (Of) (') chemicals 2 0.4 solids 2,500 2871 Fertilizers 32 5.6 2892 Explosives 2 0.4 I Acceptedas received(ifmeeting totalsolidsorother limiting values); has never been a problem at concentrations Subtotal 491 87.1 encountered. Nonlisted industries' 73 12.9 NOTE.- Application of the above values should be based on Part23. ASTM book ofstandards(1),or APHA Standard 28 Chemicals and allied methods for the examination of water and wastewater (5). products 564 100.0

Not elsewhere classified. r Although the industries selected for study probably determine the range in values of the various quality criteria for process waters for chemical and allied products.itis noted that 3 industries(SIC2823,CellulosicMan -MadeFibers; SIC 2824, Organic Fibers Noncellulosic; and SIC 2891, Glue and Gelatin) use 23, 8, and 6 bgy, which is more than several of the industries under consideration.

. Quality Requirements of Water at Point of Use for Petroleum Industry (SIC 29) . Quality Characteristics of Surface [Unless otherwise indicated, units are mg /I and values that Waters That Have Been Used by the Petroleum normally should not be exceeded. Quality of water prior to the Industry (SIC 29) addition of substances used for internal conditioning.) [Unless otherwise indicated,units are mg /Iand values are maximums. No one water will have allthe maximum values Concen- Concen- shown.] Characteristic tration Characteristic tration

Concen- Concen- Silica Nitrate (NO,) __ (1) Characteristic tration Characteristic tration Iron (Fe) 1 Dissolved Calcium (Ca) 75 solids 1,000 Silica (Sí0:)____ 50 Chloride (CI)___ 1,600 Magnesium Suspended 10 Iron (Fe) 15 Fluoride (F)____ 1.2 (Mg) 30 solids Calcium (Ca) 220 Nitrate (N0,) __ 8 Total sodium and Hardness Magnesium Dissolved potassium (CaCO:) _ 350 (Mg) 85 solids 3,500 (Na, K) (' ) Noncarbonate Total sodium and Suspended Bicarbonate hardness potassium solids 5,000 (HCO,) (' ) (CaCO,) 70 (Na, K) 230 Hardness Sulfate (SO,)___ (' ) Color, units (i) Bicarbonate (CaCO,) 900 Chloride (CI)___ 300 pH, units 6.0 -9.0 (HCO,) 480 Color, units 25 Fluoride (F) (`) Sulfate (SO,) 570 pH, units 6.0 -9.0 t Acceptedas received(ifmeetingtotalsolidsorother limiting values): has never been a problem at concentrations NOTE. -Application of the above values should be based on encountered. Part23. ASTM bookofstandards(1).or APHA Standard methods for the examination of water and wastewater (5). NOTE.-Application of the above values should be based on Part23, ASTM book ofstandards(1),or APHA Standard methods for the examination of water and wastewater,(5).

235 c Table T (Cont. ) Ne j c .N N o n H

ÿ .? 3 n I nu.0- OMNOOOQOtt70o000^:. 00Ô.NM...v....p ^^ô O-..^J-1f) CQ1^' Y u n.y.C.. J Ô NNÓE N O 1 ° UE3y - ti c r tci 4 C ,-, N 36 7, t.6 j q ' J 7 . . Qn: ,H, 7 o ñ r' _Q3 n 9 ú Ë NN;:C , - ,. . U V E -q o O Ñ t< 3 ! O. '. CO N 6 N ç .-c ..9 Oc a o O 'u q v ,- ñ ; 1:: > n _ 3 ÿ9 C U:3 Ó , ,._.Ô "C °- .> -' u c C. _ O _ '

. fA , C ,NC

ä '. :3 =ó= V .541'3 L .f 7 , E r7 G x a,.., ' ' S' - y xm E V c cE ó -m=o YC m 'j .oó ,.

;V ! óccM°áa Zr .8..E1, < M ? ` O ñ ^p ...----..-sa, ^^p 4-.4-, 1 N I Cñ n .yv I vQ v, C U W f C. r Y i V vL7v - 7 C C Y 1/1N tD o Ey 0 Y Ú N V - N J Z x Y Q C Y Drq9 7,07N . E e u R > ; .0 -Oá C ó N - O.

L iY -C .30 .3.n ÑJ O .. .. . -. -. :. ., ...... v » : Ovvv .Ov i - U Ñ - UÇ^+ >y N=ú coOOC ,J',N E: .. -O n...... 4' .00W " - N á.0ú

, ~ Lc U6- le/ N u C

Ì -o

oO ..-..-...--z l ^0UvVOVZ" O O^n -o u 0..>, rñ co^_ =cO H =Q>`a.. vv.O -G.= ` N C1 .. cu:v7=0'?., 7 -. 'oQpOv+mO r3,0 ,Ti= N_LU2LDfnUZf-Z.n- , 7 aUInOinUOSO r ONY

236 Table ,TCont.)

Quality Characteristics of Surface Waters That Have Been Used by the Food Canning Industry .,.cress otherwise ind.cated. unitsare mg /Iand vues that normaly shouldnot be exceeded.] Quality Requirements of Water at Concert- Concen- Point of Use by the Canned, Dried, and Characteristic tration Characteristic tration Frozen Fruits and Vegetables Industry (Unless otherwise indicated. units are mg /I and values that AI alinity (CaCO :)300 Fluoride (F) C) normally should not be exceeded. Quality of water prior to the pH. units 3.5 Organics: Carbon ad ttion of subst: nces used for internal conditioning.). Hardness chloroform extract 0.3 (CaCO.1 310 Canned specialities (SIC 2032) Calcium (Ca) 120 Chemical oxygen Canned fruits. vegetables, etc. (SIC 2033) Chiorides (CI) 300 demand (02) C) Dried fruits and vegetables (SIC 2032) Sulfates (SO.) 250 Odor, threshold Characteristic Frozen fruits and vegetables (SIC 2037) number (i) Iron (Fe) 0.4 Taste, threshold Manganese (Mn)_ 0.2 number (i) Acidity (H,S0,) 0 Silica (SiO2). Color. units 5 Alkalinity (CaCO.,) 250 dissolved 50 Dissolved solids 550 pH, units 6.5 -8.5 Phenols (') Suspended solids_ 12 Hardness (CaCO,) 250 Nitrate (NO ) 45 Conform, Calcium (Ca) 100 Nitrite (NO) count /100 ml (') Chlorides (CI) 250 Sulfates (SO.) 250 Iron (Fe) 0.2 Asspecifiedby NTA Subcommittee on Water Quality Criteria for Public Water Supplies, in this volume.- Manganese (Mn) 0.2 - Acceptedasreceived .f meetingtotalsolidsor other Chlorine (CD (i) I.oiii g values); has never been a problem at concentrations Fluorides (F) 1 encountered. - Zero, not detectable by test. Silica(SiO,) 50 Phenols ('' NOTE. -Application ofthe above values should be based ) on Part 23. ASTM book of standards (1).or APHA Standard Nitrates (NO) 10 methods for the examination of water and wastewater,(5). Nitrites(NO.) (') Organics: Carbon tetrachloride 0.2' n Odor, threshold number__ (') Taste, threshold number__ C) Turbidity ( ") Color, units 5 Dissolved solids 500 Suspended solids 10 Conform. count /100 ml C) Total bacteria, count /100 ml (r) Quality Requirements of Water at Point of Use by the Leather Tanning and ' Process waters for food canning are purposely chlorinated toa selected, uniformlevel. An unchlorinated supply must Finishing Industry (SIC 3111) be available for preparation of canning syrups... !Unless otherwise indicated. units are mg /I and values that - (Waters used in the processing and formulationof foods normally should not be exceeded. Quality of water prior to the for babies should be low in fluorides concentration. Because addition of substances used for internal conditioning.] high nitrate intake is alleged to be involved in infant illnesses, the concentration ofnitratesin waters used for processing baby foods should be low. General Zero. not detectable by test. Tanning finishing ' Because chlorination of food processing waters isa desir- Characteristic processes processes Coloring able and widespread practice, the phenol content of intake -..itersmust be considered. Phenol andchlorineinwater can react to form chlorophenol, which even in trace amounts can impart a medicinal off flavor to foods. Alkalinity (CaCO ) (i) C) (i) -.Maximum permissible concentration may be lower depend - pH. units - 6.0 -8.0 6.0 -8.0 6.0 -8.0 ing on type of substance and its effect on odor and taste. Hardness (CaCO ) 150 (') (" ') As required by USPHS drinking water stcndards. 1962 (8). 60 (`) (3.3) The total bacterial count must be considered as a quality Calcium (Ca) requirementforwatersusedin certainfoodprocessing Chloride (CI) 250 250 (') operations. Other than esthetic considerations. high bacterial Sulfate (SO,) 25& 250 (') concentration in waters coming in contact with frozen foods may significantly increase the count per gram for the food. Iron (Fe) 50 0.3 0.1 Waters used to cool heat -sterilized cans or Jars of food must Manganese (Mn) (`) 0.2 0.01 he low in total count for bacteria to prevent serious spoilage Organics: Carbon duetoaspirationoforganisms throughcontainerseams. Chlorination is widely practiced to assure low bacterial counts chloroform extract C) 0.2 C) on container Cooling waters. Color, units 5 5 5 NOTE. -Application of the above values should be based on Conform bacteria 'ç') C) C) Part23. ASTM book ofstandards(1).or APHA Standard Turbidity (') C) C) methods for the examination of water and wastewater.(5).

Acceptedasreceived(ifmeeting totalsolidsor other limiting values): has never been a problem at concentrations encountered. - Line softened. Zero. not detectable by test. Cemin- rai,zed or distilled water. Concentration not known. ' 1352it S. Ptbhc Health Service Drinking Water Standards, Pub.956;8). NOTE. -Above valuesbased onPart23, ASTM bookof standards '.i;APHA standard methodsforexaminationof water and wastewater, (5).

237 r

Table /T (Cont.)

Quality Requirements of Water at Point of Use by the Soft Drink Industry (SIC 2086) Unless otherwise indicated. units are mg /1 and values that normally should not be exceeded. Quality of water prior to the addition of substances used for internal conditioning.)

Concen- Concen- Characteristic tration Characteristic tration

Alkalinity(CaCO:.) 85 Fluoride (F) (a) pH, units (') Total dissolved Hardness solids (CaCO) (,) Organics, CCE Chlorides (CI) 500 Coliform bacteria_ Sulfates (SO.) 500 Color, units Iron (Fe) 0.3 Taste

Manganese (Mn)_ 0.05 Odor _

Controlled by treatmentfor other constituents. Ifpresent with equivalent quantities of Mg and Ca as sulfates and chlorides, the permissible limit may be somewhat below 5C0 mg /I. , Not greater than USPHS Drinking Water Standards. Ingeneral,public water supplies are coagulated, chiori nated, and filtered through sand and granular activated carbon to insure very low organic content and freedom from tasteand odor. 'Zero, not detectable by test. NOTE. -Application of the above values should be based on Part23.ASTM book ofstandards(t).or APH4 Standard methods for the examination of water and wastewater(5).

238 The implication of this research is that the froth - flotation ore recovery process is somewhat susceptible to water contamination. Conclusions as to production and economic impacts of impure water use by the Southern Arizona copper mines cannot be made.

Additional information from the laboratory experimentation is included as Appendix K.

The distribution of water to Area industries is presently accomplished with well fields and relatively short pipelines.Metropolitan industry buys water from the City of Tucson.

Distribution of CAP or surface water to mines or other entities will require above -ground pipelines which have not yet been designed.

Agriculture

Water consumptively used in agriculture varies with the crop, the soil and the efficiency of irrigation. Consumption of irrigation water in Eastern Pima County is displayed in Table 20.

Projections about agricultural water use in the future are particularly controversial during the process of revising Arizona's ground -water law. Agriculture historically has accounted for almost 90 percent of the water pumped in the State of Arizona.This ratio of usage between agriculture and urban centers will surely shrink -- the question is how much? Projections of agricultural demand for water are also shown in Table 20.

Agriculture demands varied qualities of water depending upon, again, the crop, the soil and the irrigation efficiency. In arid and semi -arid regions the prime qualitative problems with agricultural irrigation are Total Dissolved Solids (TDS or salts) and Suspended Solids (silt and clay). Salinity (high TDS content) may affect the plant itself (Figure 206) or the soil. Experimentation continues to attempt to develop salt tolerant crops to avoid the high energy costs associated with desalting water.

Agricultural soil can be affected both positively and adversely by high salinity of irrigation water.A complicated relationship exists between the sodium adsorption ratio (SAR) of the soil and the bicarbonate hazard or capacity for precipitation of calcium carbonate when soil and water are combined.The problem is that at high SAR values, interaction between soil and water can lead to aggregation of clay particles and a sizable decrease in soil permeability. Even at low SAR values a high bicarbonate content can allow precipitation of calcium carbonate which cements particles of soil together, eventually forming caliche which is

239 FIGUREv,1-1'. Salt tolerance of field crops~ (Federal Water Pollution Control Admin.,1968) EC, IN MILLIMHOS PER CM. AT 25 C ñ 8 10 12 1:1 16 18 20 22

Bar.ey 5u.::rbr.e[s C ;ton Safflower wheat Sorghum ::;_: o;:;:::.4; Soybean Sesuara 'The indicated salt tolerances apply to the period ofrapid plant growth and ...... Riceí Paddy) . . maturation, from the late seedling stage .ionv.ard.Cropsineachcategoryare Crr. rankee .n orner cf decreasing salt tolerance. Width of the bar next to each Broad bean crop indicates the effect of Increasing salinity on yield. Crosslines are placed at10 25 ,and 50- percent yieldre-

eans . ductions. 25% 10% 50% YIELD REDUCTION only if that threshold were exceeded? Most studies causing 10. 25. and 50- percent yield decrements aldirated that some damage began with any in- for a variety of field and forage crops from late creaseandthatthere was no threshold where seedling stage to maturity, assuming that sodium damage first apreared or became markedly worse. or chloridetoxieityisnot a growth deterrent. Recent data by Bernstein(14)give EC values These values arc shown in figures I, 2, and 3. The

Salt tolerance of forage crops* EC, IN MILLIMHOS PER CM AT 25 C 4 6 8 10 12 11 16 18 20 22

Bermuda grass Tall wneatgrass Crested wheatcrass -fah fescue Barley hay Perennial rye fi 3 r ill n'i. r ass B.rdsfoct trefoil .... The :norcated salt tolerances apply to af::r::»:::7».7::,:.: the period of rapid plant growth and Eearless wridr,e maturation, from the late seedling stage Alfalfa onward. Cropsineach category ,are rankedInorder of decreasing salt tol- Orc rardi;rass erance. Width of the bar next to each crop indicates the effect of increasing Meadow foxtail salinity on yield. Crosslines are placed at10 ,25 .and 50- percent yieldre- Clovers. císrke E. red ductions. 25°-0 10% 50''.o YIELD REDUCTION

240 Salt tolerance of vegetable crops" ECe IN MILLIMHO;, S 10 12 14 16 PER CM. AT 25 C

Beets f Sp'nach Ta:nato

...... [;roccoll Ì -- Clhba'e

. ot.3t 7777777777=Ellin

_ 0,:rn . . ;:r [pota[o ...... The indicated salt tolerances apply to the period of rapid plant growth and .;tace maturation, from the late seedling stage onward. Cropsineach categoryare Bt-,I pepper ranked in order of decreasing salt tolerance. Width of the bar next to each Onion P7S3a1131 crop indicates the effect of increasing Carrot salinity on yield. Crosslines are placed at 10 ,25 ,and 50- percent yield reduc- Beans rT tions. 25% : 10%50% YIELD REDUCTION

241 common in arid and semi -arid areas (Federal Water Pollution Control Administration, 1968).

Table 80 reflects additional quality considerations for irrigation waters.

Generally, agriculture must use irrigation water of a quality which is appropriate for the crop's ultimate use. Sewage effluent, for example, should not be applied directly to lettuce which will be consumed raw by humans. Table 90 provides a summary of uses and qualitative demands.

Distribution of irrigation water is presently done with on -site wells and a small quantity of diverted water from the Santa Cruz River (effluent).

CAP water or surface water will have to be distributed above ground unless storage is feasible below ground (artificial recharge) which would allow the use of the present distribution system.

Summary

Agriculture in the Tucson Area occupies an appreciable acreage of land, consumes moderately large quantities of water and places fairly small demands on water quality when compared with municipal use and mining process water. The use of treated sewage effluent, which is rapidly increasing in quantity, for irrigated agriculture should be given strong consideration.

The role of agriculture in the American Southwest is changing and its future demands are diffucult to estimate.

Recreational Use

Recreational use can be divided into two uses, secondary contact, which does not involve significant risk of ingestion of water, and primary contact, which generally involves some such risk. In addition, whether human contact is primary or secondary, an esthetic use or benefit can be attributed to most surface waters.

Water consumed by parks, golf courses, recreational lakes and public swimming pools represents recreational use.

Estimates and projections of present and future use for eastern Pima County appear in Table 20. These figures reflect primarily urban or developed recreational uses of water.

242 Herbicide Site of use TABLE type of formulation Levels of herbicides jnTreatment Irrigatioii tate Waters ' irrigation OvalerLikely concculr.riionreaching ui crop or held irrigationCrop u,lury water threshold (mg /I)'in rtcn,nrM. Acrolein In water frone cylinderspressure.under nitrogeil gas Soluble liquid __. 15 trig /I X 4 hours. 10 tu 0.1 nei; /I._ _. Flood or furrow: bcanscottonbeans 80,G0,20, soysugarcorn - 60, Canals up tu cenhabi:nnules.Ilunrnlluu ui :'f-i(,reduced 10 cf: to ,,r,ri- 20 to 0.6rng '/IX8 hours. 0.4 to 0.02 rng /I_- __Sprinkler: corn 60, soybeansbeets 60. -15, sugar Cariais, concentration reduced to 200 to 500 cfs 0A mg /I X 48 0.05 to 0.1 mg /I_ _ Lets 15. Canals 1,000 cfs and largermiles.minimum in 20 to 30 Aromatic solvents (xylene). Emulsified in flowingwater. Emulsifiable liquid. Cr - 10 gal /cfs in 30hours. 60 mini- 700 ntg /I or less -_ Alfalfa 1,200, carrots 1,600, beans Cuncentiation reducedconcentrationidlyin 30 Ruin to 50 point miles.to minimum ul applica, b.; rap- 750mum ingil). (300 toes-1,300,oats-2,400,sorghumcotton-1,600,1,600,>1,200. corn-3,000- wheat-;-800, pota- grain - 6taon loand 10 within almostruiles. 2 completely in 6 smiles Copper sulfate ____In flowing water canals or in reservoirs. Coarse penta- crystals.hydrate 0.51/3 to 3.0 to nog /I (slue).(continuous). 1 Ib /cts 9.00.8 to 0.080.04 nig.'mg /II in 10IO tovoiles. 20 miles. Apparently above con-centrationsfor weed control.used ConCentrahon reduced slugmurerapidly applications. with distance from in. AnutroleT _.__.___On bank weeds along drainandirrigation on canals. cattail canals In Foliage spray ____6 to 16 Ib /A___Usually less than , 0.1 nlg /I.' Beets (Rutabaga) - -3.5, corn->3.5. Registered westerntrotdrainbut of canals actuallybank Oritation andweeds used marshes, canals. along for cun for use only DiquatDa la pon In water or over Sur- reservoirs.face of canals and I oliageLiquid ..__ _3 5 mg/1 or15 to 30 lb /A....'_ Usually less1 -1.5than Ib /A. Usually less than 0.10.5 nogmg /I./I.' BeansBeets 5.0, <0.35. 1.0, corn - corn 1'25.O__Diquat used Sanie as anutrole -T. Doweedscontrol not and use floating for 10 weeds. days. of in Floridasubmersed for Diuron On bottoms arid banks inwhenof canal.small no canals water is Wettable powder sprayed.suspension 64 lb /A Below crop injury threshold. No data Used mostly in waterditchesgationNot flow. used with systems. in western irri- intermittentsmall fame Table I' (cont.) Monuron Same as for (boron_ _Same as forLiquid or diuroo. 64 Ib /A do Corn -2 5, du field beans - MustSame wait as 7for days diuron after except treatforafterfirst - irrigation. treatment not used water through canal Endothall lia and K salts. In ponds and roser Easternvours mostly States. in t-iquid granule. 1 -4 mg/1 _ _ -.. Same as for Na Probably little or ingrione period. after wait- 1.0, alfalfa- >10.0. purposes.forment before ruin irrigation or domestic 7 water 2,4-DDimethylamines __In water control canalsWeeds along canal banks.canals.jugin Florida. use in westernPromise Liquid spray __ _ _1 to 4 lb /A uso 0.5 2.5 nigh ally as amine. and K salts.3.0 to 1.0 r.g /I, 2 to 1O ruiles CorrlField -''25, beans- soybeans- >3.5, 25. sugar beets- WaitRegistered for ingafterpending water. treatment on concentration) before us- to 25 daysprecaution: (de. Do Floating and emersedweeds in southern do do 0.1 mg /I or less to none in 3 weeks. ment.below treat- SugarGrapes- beets 0.7 -1.5. -3.5 <10. A minimum waiting periodtreated3 ofbenot used contaminate for irrigation. water to weeks water before for irriga-using Silvex Phreatophytes on andcanals,floodways,canals. streams. reservoirs, along Liquid spray as ester. 2 to 4 lb /A No data. Probably mgless /I. than 0.1 No data _Silvex 4controltion. lbDoin /l00 not gallons use in ofwater water. to be nontiowing registered of aquatic: weeds wateronly for at Floating and emersedwaterwaysweeds in southern Liquid spray over surface. 2 to 8 lb /A From 10 to 1,600 70application.r.g /I,fig /I, 5 weeks 1 day after 1 to do dornusticused purposes. for agricultural or Dichlobenjl _____.._Promising bottom water.canalstreatments without in Granules or wet. spray.table powder 7 to 10 lb /A after treatment. Alfalfa 10, corn.¡` -10, beets-1.0soybeans-1.0, to 10. sugar Registered for control of usedditchessubponds,mersed - where weeds water not for and agricultural in drainage lakes, or Fenac _Sanie as dichlobenjl _Same as benil. dichlo- 10 to 20 lb /A__._0.66 to 1.8 rug /I area.below 0.007treated to Alfalfal.0, corn-10, sugarsoybeans10. beets -0.1, -0.1 to Sarre as d chlobenil. domestic purposes. Pichloram For control of brush watershedand weeds areas. on Liquid spray or granules. 1 to 3 lb /A No data _ 20.100 hours mg later. /I _Corse -10, field beans - ':1.0.0.1, sugar beets - Gives Canadabank weeds, thistle butand use other near excellent control of tionsion, IS ARS, indicated USDA (unpublished).for acrolein.c Data submitted Threshold byData ofF. injuryare for is flood lowest or furrowConcentration irrigation that for allcaused herbicides except when sprinkler irriga- L. Timmons, Crops Protection Branch, Crops Research Divi- reductioneither temporary in crup yield or permanent or quality. injury.Estimates Often based this concentration upon very 6mitcd did data not andcause extensive final observations. canals hazardous. ;

Tab le ,(f

EFFLUENT QUALITY GUIDELINES FOR VARIOUS USES°

_ E 900 -oral Total Toxic Total j Total 3acterio- SS dissolved Sub- Pnos- nitrogen logical

solids stance ohorus I

R GER ROA0 1 30.5 29 731 1 13 { 30 58

..,., ï.Cr2 3.4 2- 528 -5 '20 7.3/2.4 i

ri :rous or forage crops For intended for human consumption ,3 30 709 5 c C

Groner-a cro Cs -no direct opl'catidn of water to fruit of foliage 30 30 709 b C C C

.CCC crops- product suo- ected to physical or

chemical processing 30 20 709 h c - c i 1000 sufficient to destroy pathogenic organisms

0rcnard crops- direct aCpiicat1Cn to fruit or foliage 30 30 709 o c c 1000

Food crops which may he consumed in their raw 10 10 709 h c c 200 state

Golf courses, cemeteries and similar areas 30 30 709 b c c 1000

School grounds, playgrounds, etc. wnere 10 10 709 o c C 200 children are expected to play

farm animals other than producing dairy animals 30 30 709 D C c -

Procucing dairy animals 30 20 709 b c c 1000

°E_REA,;O'tAL .MPOUNCMENTS Cestnetic enlcyment or invclviny only 30 20 709 b .15 1000 secondary contact

nary contact recreation 10 10 709 b 0.5 c 200

GRC;;`aCWATER REGARGE " 2onding on surface 30 30 409 b c C 1000'.

:ell -point 10 10 409 b 0.5 10 200

-Concentrations expressed in terms of mg /1. -Bacteriological figures expressed in terms of fecal conform group density (count) Per :00 .milliliters. a) Based on the State of Arizona Administrative Rules and Regulations, Title 9, Article 4. R9 -20 -406 and U.S. Environmental Protection Agency befinition of Secondary Treatment, FR Document 73- 17194. b) Not to exceed United States Health Service Drinking Water Standards. c)No limit on concentration. ') Obtained by telepnone. ") Recommendations only based. on the assumption that existing groundwater - quality is to be maintained, and they are not intended as specific standaras of any kind, since none currently exist.

245 EFFLUENT QUALITY GUIDELINES FOR VARIOUS USES

(RGA Consulting Engineers, 1979).- In 1968 the National Technical Advisory Committee to the Secre- tary of the Interior recommended the following criteria for esthetic/ recreational water quality:

"All surface waters should contribute to the support of life forms of (e)sthetic value...Surface waters should be free of substances attributable to discharges or waste as follows: (a) Materials that will settle to form objectionable deposits. (b) Floating debris, oil, scum, and other matter. (c) Substances producing objectionable color, odor, taste, or turbidity. (d) Materials, including radionuclides, in concentrations or combinations which are toxic or which produce undesirable physiological responses in human, fish and other animal life, and plants. (e) Substances and conditions or combinations thereof in concentrations which produce undesirable aquatic life. Substances and conditions referred to in (e), above, would include factors such as excessive nutrients and temperature elevation. Undesirable aquatic life would include objectionable abundance of organisms such as a bloom of blue -green algae resulting from discharge of a waste with a high nutrient content and an elevated temperature. We would encourage the use of numerical limitations on nutrients in specific waters where present or future knowledge may permit or other water use requirements (e.g., public water supply) justify such actions. However, the Subcommittee fells their recom- mending numerical limitations that would meet the many varying requirements of aesthetics for individual waters and regionswould result in nothing more than a welter of numbers...Species available for harvest by recreation users should be fit for human consumption. In areas where taking of mollusks is a recreational activity, the criteria shall be guided by the U.S. Public Health Service manual "Sanitation of Shellfish Growing Areas," 1965 revision...In water designated for recreation uses other than primary contact recreation, the subcommittee recommends that the fecal coliform content, as determined by either multiple -tube fermentation or membrane filter techniques, should not exceed a log mean of 1,000/ 100 ml, nor equal or exceel 2,000/100 ml in more than 10 percent of the samples...Fecal coliforms should be used as the indicator organisms for evaluating the micro- biological suitability of recreation waters. As determined by multiple -tube fermentation or membrane filter

246 procedures and based on a minimum of not less than five samples taken over not more than a 30 -day period, the fecal coliform content of primary contact recreation waters shall not exceed a log mean of 200/100 ml, nor shall more than 10 percent of total samples during any 30 -day period exceed 400/100 ml...In primary contact recreational waters, the pH should be within the range of 6.5 -8.3 except when due to natural causes and in no case shall be less than 5.0 nor more than 9.0. When the pH is less than 6.5 or more than 8.3, discharge of substances which would increase the buffering capacity of the water should be limited...In primary contact recreation waters, except where caused by natural conditions, maximum water temperature should not exceed 300 C (85° F)...For primary contact recreation waters, clarity should be such that a Secchi disc is visible at a minimum depth of 4 feet. In "learn to swim" areas the clarity should be such that a Secchi disc on the bottom is visible. In diving areas the clarity shall equal the minimum required by safety standards, depending on the height of the diving platform or board...In waters designated for recreation use, optimum conditions for recreation based upon utilization of fish, other aquatic life, and wildlife should apply, with specific and limited exceptions. The Subcommittee endorses by reference criteria for these purposes recommended by the National Technical. Advisory Sub- committee on Fish, Other Aquatic Life, and Wildlife.... Surface waters, with specific and limited exceptions, should be of such quality as to provide for the enjoyment of recreation activities based upon the utilization of fishes, waterfowl and other forms of life, without reference to official designation of use. The Sub- committee recommends by reference criteria developed by the National Technical Advisory Subcommittee on Fish, Other Aquatic Life, and Wildlife for guidance relative to various species and waters...."

Recreation waters generally occur either in urban areas, where distribution to the recreational use is of little consequence, or in natural and man -made reservoirs and lakes. Distribution of water to recreational uses may only be a problem when associated with other problems such as reduction of natural distribution to a wildlife habitat.

Summary

Recreational use is generally a product of convenience. Humans enjoy swimming and boating and having parks and playing fields and

247 courses. The demands, both qualitative and quantitative, on the region's water supplies for recreational consumption are small and may be met by many potential sources, such as, urban storm runoff and treated sewage effluent in addition to the traditional water sources.

Other Benefits

Benefits are often difficult to evaluate when discussing a large project which affects many square miles of land and 500,000 people. Benefits which might be attributed to a diversion -detention -recharge enhancement project in the Tucson Area other than those already mentioned include the following:

1. A reduction in ground -water level declines. A systematic project which will improve the quantity of water recharged to ground water annually will reduce the rate of water table decline and net overdraft.

2. Small change in riparian flora and fauna. Some changes in vegetative and wildlife patterns can be expected in the vicinity of a longer term supply of surface water. Many old timers in the Tucson Area talk of the days of year -round flow and express regret at not being able to appreciate the animals and plants that depend upon this constant source of water. While a diversion -detention - recharge project would by no means turn back the clock, a small stream flowing through the Santa Cruz Linear Park would certainly be esthetically pleasing.

Exchanges

As mentioned under a previous topic, the downstream water user or flooding victim must be considered by the upstream group discussing some alteration of a river's flow. Those residents downstream from Tucson would be happy to be relieved of the worries which beset them in 1965 and 1978 when flows from this Basin, after doing their damage here, careened through the Lower Santa Cruz Basin eroding agricultural lands, threatening homes and public buildings and generally creating a nuisance. However, it is not, under law, fair for the Upper Santa Cruz Basin to alter the flow of the River enough to deplete those waters which support irrigation, plant and animal life or ground water recharge in downstream basins without compensation. This leads to the option of mutually beneficial exchanges. Once a project of diversion, detention and recharge enhancement was proposed, the eastern Pima County water users who would benefit in this Basin might offer to exchange their allotment of CAP water or to withdraw a claim for some source of water to the benefit of downstream entities with rights to flood flows on the Santa Cruz River. Another possible exchange, perhaps best

248 suited for an agricultural user, might involve municipal wastewater from the Tucson Metropolitan area. These exchanges might best be realized under a contract agreement. LAND USE INVENTORY AND PROJECTIONS

250 LAND USE INVENTORY AND PROJECTIONS

Area land use has historically been dominated by agriculture, grazing and mining. Recently, urban use has become a fourth dominant use. Of the total 3,800 square miles of land that comprise eastern Pima County, 60% is used for grazing, 29% is used for enjoyment and recreation (mountains), 8% is urban, 2% is agricultural and 1% is used for mining (City of Tucson, et al., 1975). Table 100 summarizes land use and ownership in eastern Pima County as of 1975.

NATURAL DRAINAGE SYSTEM LAND USE

Before the influence of intensive agriculture, mining, and urbanization, the Tucson area enjoyed a high water table which resulted in marshlands and perennial streamflow along the watercourses of the Basin. Aquifer storage and ground -water levels were in a natural state of dynamic balance. Floods, or more appropriately, high flows on area streams, resulted in inundation of broad flood - plains. Such areas are those which today exhibit the finely textured soils underlain by more coarse gravels characteristic of stream environments. These floodplains might be completely inundated in- frequently and the subsequent deposition of silt during medium frequency floods would encourage the low -flow channel to meander throughout the floodplain seeking an ever changing path of least resistance.

During the latter portion of the 19th century a variety of changes to the stream channels occurred for reasons which have only been speculated upon. Several researchers have worked on the subject and potential causes have been identified.

The influx of grazing livestock affected the streams in that erosion became prevalent without the range grasses present before grazing. Subtle changes or fluctuations in climate may have occurred, affecting rainfall and runoff. An earthquake in 1887 may have affected the subsurface geology of the Basin, thereby changing the patterns of surface -and ground -water flow.

Once the effects of the above circumstances became evident, the perennial source of water became a thing of the past. Many attempts at increasing the supply of surface water only compounded the problem and hastened the onset of groundwater pumping (South- west Environmental Service, 1980). Because the stream channels of the Basin downcut as they did, the broad flooding that occurred previously was confined to the downcut channels and only in large flows was overbank inundation or erosion likely. This explains the situation at present in which a family may live on a floodplain which was once covered with water once every five years but is now

251 Table

Summary of Generalized Land Use in Eastern Pima County

Land Use Square Mile Percent

Grazing 2,500 60 Mountains (conservation and recreation) 1,100 29 Urban 250 8

Mining 50 1 Agriculture 90 2 Other 50

Total 3,800 100

Land ownership in Eastern Pima County is divided into that held by public bodies and private entities. Federal and state agencies administer a major part of the land in Eastern Pima County. There are approximately 3,846 square miles in Eastern Pima County. 1,221 square miles or 31.8% are owned by the federal government, 1,446 square miles or 38.8% are owned by the State of Arizona and 29.4% are owned by City, County, and private interests.

Eastern Pima County Land Ownership

Federal Lands

Coronado National Forests 545 square miles East Saguaro National Monument 85 square miles West Saguaro National Monument 24 square miles Davis Monthan A.F.B. 18 square miles U.S. Department of Defense Lands 4 square miles Santa Rita Experimental Range 85 square miles San Xavier Indian Reservation 109 square miles Bureau of Land Management 350 square miles

Total Federal Lands 1220 square miles State Lands 1446 square miles City, County and Private Lands 1180 square miles

Grand Total 3846 square miles Comprehensive Pian, 1975

252 covered once in fifty years. Thus the residents of the Tucson area have a problem - much flat land with good soil lies in what was once a regularly wetted floodplain. The dynamic nature of the geo- morphologic changes which have occurred in this Basin remains to be understood. During recent high flows area streams have done damage through both inundation and erosion.

The lands within the Tucson area's historic floodplains are of concern in this study primarily for their value as sites for diversion and detention of floodwaters and the enhancement of natural recharge.

Land use in these floodplains is currently a mixture of all possible uses. Gravel mining and recreation both occur in the stream channels and use on the floodplains ranges from residential through agricultural and public buildings, including hospitals.

In addition, floodplains and water -associated areas often provide a necessary oasis for native wildlife.For similar reasons, a high concentration of archaeological sites occur within area floodplains - again the availability of water providing motivation.

LAND USE PROJECTIONS

Tucson area land use planning has characteristically been as dynamic a process as the channel changes described above. Only relatively recently has land use planning become a strong public concern in reflection of the fact that only recently have land use conflicts and flood dangers become evident. The Tucson area has grown rapidly since 1960. Between 1960 and 1975, population increased 67 percent, from 266,000 to 444,000 (deGennaro, 1979), and the demand for central city land has increased owing to these increases in population. Tucson itself has attracted many white collar workers with the influx of light industries and related service businesses. This has led to a demand for middle to upper -middle income housing and the economic climate has favored development and construction.

In the last twenty years, however, increased development in the floodplains has increased the number of persons and the value of property damaged by the flows on Area streams. Therefore, the projections about land use in the Tucson Area in general and in relation to flooding may safely extrapolate from present trends. The floodplains may expect more sensitivity from land use planners to protect the public from flood damage.Floodplain land use planning will probably include the present uses of gravel mining and recreation but will probably be much more restrictive about residential use and may require that development for residential use be much more restricted in the floodplain.

253 REFERENCES CITED

254 REFERENCES CITED

Diversion and Detention

Anderson, T. W. and N. D. White, 1979, "Statistical Summaries of Arizona Streamflow Data," U.S. Geological Survey.

Arai, _. S. Ince and S. D. Resnick, 1977, "Urban Flood Water Management Systems in Semi -Arid Regions: Model Extension Design and Application," Water Resources Research Center, University of Arizona.

Baran, N. E., C. C. Kisiel, and L. Duckstein, 1971, "A Stochastic Analysis of Flows of Rillito Creek," Hydrology and Water Resources in Arizona and the Southwest, Proceedings Arizona Section American Water Resource Association and Hydrology Section of the Arizona Academy of Science, Vol. 1.

Boyer, D. G. and K. J. DeCook, 1975, "The Effect of an Intensive Summer Thunderstorm on a Semi -Arid Urbanized Watershed," Hydrology and Water Resources in Arizona and the Southwest, Proceedings Arizona Section American Water Resource Association and Hydrology Section of the Arizona Academy of Science, Vol. 6.

Chow, V. T., 1964, Handbook of Applied Hydrology, McGraw -Hill Book Company.

City of Austin, Texas Engineering Department, 1977, Drainage Criteria Manual.

Cluff, C. B., 1978, "The Compartmented Reservoir: Efficient Water Storage in Flat Terrain Areas of Arizona," Hydrology and Water Resources in Arizona and the Southwest, Proceedings Arizona Section American Water Resource Association and Hydrology Section of the Arizona Academy of Science, Vol. 8.

Clark, 1945.

Condes, de la Torre, A., 1970, "Streamfiow in the Upper Santa Cruz River Basin, Santa Cruz and Pima Counties, Arizona," U.S. Geological Survey Water -Supply Paper, 1939 -A.

Dharmadhikari, V. V., 1970, "Quality of Runoff From Diversified Urban Watersheds," M.S. Thesis, University of Arizona.

Diskin, M. H. and L. J. Lane, 1976, "Application of a Double Triangle Unit Hydrograph to a Small Semi -Arid Watershed," Hydrology and Water Resources in Arizona and the Southwest, Proceedings Arizona Section American Water Resource Association and Hydrology Section of the Arizona Academy of Science, Vol. 6.

Diskin, M. H. and S. D. Resnick, 1976,

Dodge, 1959.

255 Erie, L., 1979," Stormwater Retention Criterion for Urban Drainage Basin Management," Extracted from M.S. Thesis, Arizona State University.

Foerster, E. P., 1972, "The Effect of Urbanization on Watershed Runoff," I.S. Thesis, University of Arizona.

Fogel, M. M., 1969, "Effect of Storm Rainfall Variability on Runoff from Small Semi -Arid Watersheds," Transactions of ASAE, 12(6), pp808 -812.

Fogel, M. M. and L. Duckstein, 1969, "Point Rainfall Frequencies in Convective Storms," Water Resources Research, 5(6).

Fogel, M. M., L. Duckstein and C. C. Kisiel, 1974, "Modeling the Hydrologic Effects Resulting from Land Modification," Transactions of ASAE, 17(6).

Grove, G. T., 1967, "Rillito Creek Flood Plain Study Report to the City - County Planning Department, Tucson -Pima County, Arizona."

Haan, C. T., B. J. Barfield, and T. Y. Kao, no date, "Urban Storm Water Management in the U.S.," University of Kentucky.

Hickok. R. B., 1965, Water Management on Semi -Arid Watersheds."

Kao, S. E., 1973, "Effect of Urban Street Pattern on Drainage," Ph.D. Dissertation, University of Arizona.

Kao, S. E., M. M Fogel, and S. D. Resnick, 1973, "Effect of Urbanization on Runoff from Small Watershed:. Arizona and the Southwest, Proceedings, Arizona Section American Water Resource Association and Hydrology Section of the Arizona Academy of Science, Vol. 3.

Laney, R. L., 1972, "Chemical Quality of the Water in the Tucson Basin, Arizona, Water Resources of the Tucson Basin," U.S. Geological Survey Water -Supply Paper 1939 -D.

Leopold, L. B. and T. Maddock, 1953, "The Hydraulic Geometry of Stream Channels and Some Physiographic Implications," Geological Survey Professional Paper No. 252.

Lewis, 1963.

Linsley, R. K., 1971, "A Critical Review of Currently Available Hydrologic Models for Analysis of Urban Stormwater Runoff," Hydrocomp International.

Mische, E. F., 1971, "The Potential of Urban Runoff as a Water Resource," Ph.D. Dissertation, University of Arizona.

256 Osborn, H. B., and L. Lane, 1969, "Precipitation- Runoff Relations for Very Small Semi -Arid Rangeland Watersheds," Water Resources Research, 5(2).

Osborn, H. B., L. J. Lane and V. A. Myers, 1979, "RainfalÏ Watershed Relation - ships for Southwestern Thunderstorms."

Osborn, H. B. and E. M. Laursen, 1973, "Thunderstorm Runoff in Southeastern Arizona," ASCE - Journal of the Hydraulics Division.

Osborn, H. B., W. C. Mills and L. J. Lane, 1972, "Uncertainties in Estima- ting Runoff -Producing Rainfall for Thunderstorm Rainfall- Runoff Models," International Symposium on Uncertainties in Hydrologic and Water Resources Systems.

Pima County Flood Control District, 1979, "Summary of Information on Golder Dam's Flood Impact Upon Pima County."

Poertner, H. G., 1974, "Practices in Detention of Urban Stormwater Runoff," American Public Works Association.

Potter, 1961.

Reich, et al., 1979.

Reich, B. M., 1978, "Rainfall Intensity - Durations Frequency Curves Development from (not by) Computer Output," Transportation Research Record 865, National Academy of Science, Washington, D.C.

Reich, 3. M. and K. G. Renard, 1979, "Application of Advances in Flood Frequency Analysis," American Water Resources Association, unpublished.

Renard, K. G. and R. V. Keppel, 1966, "Hydrographs of Ephemeral Streams in the Southwest," ASCE Journal of the Hydraulics Division.

Resnick, S. D. and P. G. Sebenik, 1978, "Water Resources Report for Use in Preparation of a Master Plan for the Santa Cruz Linear Park, Tucson, Arizona," Water Resources Contribution No. 1, University of Arizona, Water Resources Research Center, Tucson, Arizona.

Roeske, 1978.

Savini and Kammerer, 1961.

Schembera, R. E., 1963, "Development of Hydraulics and Sediment Transport Relationships and Their Use for Design of Middle Rio Grande Channelization," paper presented at Water Resources Engineering Conference of the American Society of Civil Engineers, Milwaukee, Wisconsin, May 13 -17.

257 Schreiber and Kincaid, 1967.

Sellers, W. D. and Hill, R. H., 1974, "Arizona Climate 1931- 1972," University of Arizona Press, Tucson.

Smith, R., 1979, "Storm Flows Management in Relation to Industrial Development."

U.S. of = _ _ . _ __ =__ -' _ __._-- Proposed Wet Park at the Tucson Detention Basin, Pima County, Arizona.'

U.S. Army Corps of Engineers, 1973, "Flood Plain Information, Rillito River and Pantano Wash, Vicinity of Tucson, Arizona," Prepared for Pima County.

U.S. Army Corns of Engineers, 1976, "Flood Plain Information, Tanque Verde Creek and Tributaries, Vicinity of Tucson, Arizona," prepared for Pima County.

U.S. Army Corps of Engineers, 1970.

U.S. Army Corps of Engineers, 1979, Option Paper: Flood drainage reduction options for ...Tanque Verde Wash, Pantano Wash, Santa Cruz River at Tucson, Santa Cruz River at Green Valley, Santa Cruz River at Marana, Aqua Caliente Wash, Canada del Oro Wash, Rodeo Wash, Airport Wash, and Rillito River.

S. Army Corps of Engineers, 1979, "Water Resources Development by the U.S. Army Corps of Engineers in Arizona."

U.S. Department of Agriculture, 1972, Soil Conservation Service.

U.S. Weather Bureau, 19611

The University of Arizona, 1977, "Nonpoint Source Pollution," Water Resources Research Center and the College of Agriculture, Pima Association of Governments 208 Project.

Wood, 1979.

Woolhiser, D. A. and H. C. Schwalen, 1959, "Area -Depth Frequency Relations for Thunderstorms Rainfall in Southern Arizona," AEA 4527.

Zeller, M. E., 1977, "Prediction of Peak Discharges from Surface Runoff on Small Semi -Arid Watersheds for 2 -year Through 100 -year Flood Recurrence Intervals," Flood Plain Management Section, Pima County Highway Department.

258 ADDITIONAL REFERENCES CITED

DIVERSION AND DETENTION

Anderson, C. A., 1955, "Memorandum on: Potential Development of Water Resources of the Upper Santa Cruz River Basin in Santa Cruz County, Arizona and in Sonora, Mexico," Arizona State Land Department.

Arizona State Museum, 1980, Computer Listing of Archaeological Sites in Tucson Basin, Confidential.

Betancourt, J. L., 1978, "Cultural Resources Within the Proposed Santa Cruz River: ark Archaeological District, "' Arizona State Museum Archaeological Series X125.

Castetler, E. F. and W. H. Bell, 1942, "Pima and Papago Indian Agriculture," University of New Mexico Press, Albequerque.

Cooke, R. U. and R. W. Reeves, 1975, "Arroyos and Environmental Change in the American Southwest," Clarendon Press - Oxford.

Ölberg, C. R., and F. R. Schank, 1913, "Irrigation and Flood Protection, Papago Indian Reservation," (San Xavier), Senate Document No. 973, 62nd Congress, Third Session.

Schuyler, J. D., 1901, "Reservoirs for Irrigation, Water Power and Domestic Water Supply," Wiley and Sons, New York

Smith, G. E. P., 1910, "Groundwater Supply and Irrigation in the Rillito Valley," University of Arizona, Agricultural Experiment Station, Bulletin no. 64.

259 REFERENCES CITED

Recharge Enhancement

Anderson, T. W., 1968, "Electrical Analog Analysis of the Hydrologic System in the Tucson Basin," International Association of Scientific Hydrologists, 80 Vol. 1.

Anderson, 1973.

Arizona .`later Commission, 1;73, "Bulletin 5, Annual Recort on Groundwater in Arizona - Spring 1971 to Spring 1972," U.S._ Geological Survey, Phoenix.

Belau, R. A., 1972, "Hydrogeology of a Portion of the Santa Catalina Mountains," M.S. Thesis, University of Arizona.

Belan, R. A. and W. G. Matlock, 1973, "Groundwater Recharge from a Portion of the Santa Catalina Mountains," Hydrology and Water Resources in Arizona and the Southwest, Proceedings, Arizona Section American Water Resources Association and Hydrology Section of the Arizona Academy of Sciences, Vol. 3, Tucson.

Bianchi, W. C. and D. C. Muckel, 1970, "Ground -Water Recharge Hydrology," U.S. Department of Agriculture.

Bianchi, W. C., H. I. Nightingale and R. L. McCormick, 1978, "A Case History to Evaluate z .e Performance of Water Spreading Projects," Journal of the American Water Works Association 70 Vol. 3.

Boulton, 19

Bouwer, H., 1978, Groundwater Hydrology, McGraw -Hill Book Co., New York.

Bouwer, H. and R. D. Jackson, 1974, "Determining Soil Properties," In: Drainage for Agriculture J. Van Schilfgarde, editor, Agronomy No. 17, Americian Soc. of Agronomy, Madison, Wisconsin.

Brown, R. F., D. C. Signor and W. W. Wood, 1978, "Artificial Ground -Water Recharge as a Water Management Technique for the Southern High Plains of Texas and New Mexico," Texas Dept. of Water Resources.

Burkham, D. E., 1970, "Depletion of Streamflow by Infiltration in the Main Channels of the Tucson Basin," U.S. Geological Survey Water Supply Paper, 1939 -B.

Cehrs, D., 1978, "Geological Relationships to Groundwater Recharge in the San Joaquin Valley," Presented at Ground Water Symposium on Recharge and Regulation, University of California Extension Service.

260 Clyma, W. and R. J. Shaw, 1968, "Natural Recharge in the Tucson Basin," AES, Progressive Agriculture in Arizona, 20 Vol. 2.

Condes de la Torre, 1968, "Streamflow in the Upper Santa Cruz River Basin, Santa Cruz and Pima Counties, Arizona," U.S. Geological Survey Water Supply Paper 1939 -A.

Cooley, 1970.

Cooley, R. L., J. F. Harsh and D. C. Lewis, 1972, Principles of Ground - Water Hydrology, Hydrologic Engineering Methods for Water Resources Development, The Hydrologic Engineering Center, U.S. Army Corps of Engineers, Davis, California, Vol. 10.

Davidson, E. S., 1973, "Geohydrology and Water Resources of the Tucson Basin, Arizona," U.S. Geological Survey Water Supply Paper 1939 -E.

Davis, R. W., 1967, "A Geophysical Investigation of Hydrologic Boundaries in the Tucson Basin, Pima County, Arizona," Ph.D. Dissertation, University of Arizona.

Davis, S. N. and R. J. M. DeWiest, 1966, Hydrogeology, John Wiley & Sons, Inc., New York.

Dumeyer, J. M., 1966, "Stratigraphy and Hydrogeology of the Water Resources Research Cneter Recharge Area, Special Problem," Dept. of Geology, University of Arizona.

Eberly, L. D. and T. B. Stanley, Jr., 1978, "Cenozoic Stratigraphy and Geologic History of Southwestern Arizona," Geological Society of America Bulletin, Vol. 89.

Fogg, G. E., 1978, "A Ground -Water Moedlling Study in the Tucson Basin," I.S. Thesis, University of Arizona.

Goodoff, L. R., 197,5, "Analysis of Gravity Data from the Cortaro Basin - Area, Pima County, Arizona," M.S. Thesis, University of Arizona.

Hantush, 19

International Association of Scientific Hydrology (IASH), 1970, Artificial Ground -Water Recharge, Gertbrugge.

Jacobs, 19

Keys, W. S. and L. M. MacCary, 1971, "Application of Borehole Geophysical to Water- Resources Investigation," in: Techniques of Water Resources Investigations of the United States Geological Survey, Chapter El, Book 2, Collection of Environmental Data.

261 Marsh, J. A., 1968, "The Effect of Suspended Sediment and Discharge on Natural Infiltration of Ephemeral Streams," M.S. Thesis, University of Arizona.'

Matlock, W. G., 1965, "The Effect of Salt -Laden Water on Infiltration in Alluvial Channels," Ph.D. Dissertation, University of Arizona.

Matlock, W. G. and P. R. Davis, 1972, "Groundwater in the Santa Cruz Valley, Arizona," AES Technical Bulletin 194.

Osborne, P. S., 1969, "Analysis of Well Losses Pertaining to Artificial Recharge," M.S. Thesis, University of Arizona.

Osterkamp, W. R., 1973b, "Ground Water Recharge in the Tucson Area," U.S. Geological Survey.

rkamp, --W.-R.-, -1974,, "Map Showing Groundwater Velocities in the Uppermost Saturated Alluvial Deposits of the Tucson Area, Arizona,"

U.S._ Geological Survey. ,

Percious, 1.69.

P opki , 3. P.,i.:r 3 , f Ni: -:ed -Grass Cover and Na ive -= .__ on Urban Runoff Quality," M.S. Thesis, University of Arizona.

Theis. 19

Todd, 1963.

U.S. Army Corps of Engineers, 1979,'Plan of Study for a Demonstration Recharge Project in the Salt River Valley, Prepared by Water Resources' Research Center and School of Renewable Natural Resources, University of Arizona.

U.S. Department of Agriculture, Soil Conservation Service, 1972, "Soil Survey of Tucson -Avra Valley, Arizona."

U.S. Department of Agriculture, Soil Conservation Service, "Soil Survey of

U.S. Department of Interior, Geological Survey, 1977. ( ?)

Weeks, E. P., 1978, "Some Principles of Flow in the Unsaturated Zone as Related to Artificial Recharge."

West, 1970.

West, R. E. and J. S. Sumner, 1972, "Ground -Water Volumes From Anomalous Mass Determinations for Alluvial Basins," Groundwater, 10 Vol. 3.

262 wicke, H. D., 1976, "A Preliminary Feasibility Analysis of Artificial Recharge in Avra Valley, Arizona with Santa Cruz Flood Flows," M.S. Thesis, University of Arizona.

Wilson, L. G., 1979, "Case History - Groundwater Recharge in Arizona."

Wilson, L. G., 1971a, "Management of Artificial Recharge Wells for Groundwater Quality Control," Hydrology and Water Resources in Arizona and the Southwest, Proceedings, Arizona Section, American Water Resource Association and Hydrology Section of the Arizona Academy of Science, Vol.1, Tempe.

Wilson, L. G., 1971b, "Observations on Water Content Changes in Stratified Sediments During Pit Recharge," Ground Water 9 Vol. 3.

Wilson, L. G., 1967, "Sediment Removal from Flood Water by Grass Filtration," Transactions of the American Society of Agricultural Engineers, 10 Vol. 1.

Wilson, L. G. and K. J. DeCook, 1968, "Field Observations on Charges in the Subsurface Water Regime During Influent Seepage in the Santa Cruz River," Water Resources Research, 4 Vol. 6.

Wilson, L. G., M. M. Fogel, K. J. DeCook and P. S. Osborne, 1969, "The Design of an Experimental Artificial Recharge Well at Tucson, Arizona," Arizona Water Resources Research Center, Annals of Arid Zone, 8 Vol. 2.

Wilson, L. G. and W. O. Rasmussen, 1976, "Feasibility of Modeling the Influences of Pit Recharge on Ground -Water Levels and Quality in Alluvial Basins," Arizona Water Resources Research Center.

263 REFERENCES CITED

CENTRAL ARIZONA PROJECT

Bureau of Reclamation, 1962, "Appraisal Report, Central Arizona Project," United States Department of the Interior, Bureau of Reclamation, Region 3.

Bureau of Reclamation, 1978, "Re :CAP, information packet number 1," United States Department of the Interior, Arizona Projects Office.

Bureau of Reclamation, 1979, "Preliminary Central Arizona Project Alternatives," United States Department of the Interior, Arizona Projects Office.

Bureau of Reclamation, 1979(2), "Re:CAP, information packet number 2," United States Department of the Interior, Arizona Projects Office.

Federal Register, 1972," Notices, Department of the Interior, Office of the Secretary: Central Arizona Project, Arizona; Water Use Priorities and Allocation of Irrigation Water," Federal Register, V37,N245,12/20/72.

Metropolitan Utilities Management Agency, 1974, "The Central Arizona Project; a Staff Report," City of Tucson.

Preliminary Presentation, 1980, " Tucson Division CAP EIS Scoping," January 21,1980, Water and Power Resources Service, to Eastern Pima County Water Resources Coordinating Committee.

Strickland, W., 1980, statement to the Eastern Pima County Water Resources Coordinating Committee regarding past history of Papago Tribal requests for CAP allocations, January 21, 1980.

264 BENEFICIAL USE

Arizona Revised StatutEs, 45 -141

Arizona Revised Statutes, 45 -147, Laws of 1979, Chapter 139.

Federal Water Pollution Control Administration, 1963, "Report of the Committee on Water Quality Criteria," United States Department of the Interior.

Fisher, W.W. and S. Rudy, 1978, "Investigation of Municipal Wastewater Constituents Detrimental to Froth Flotation Recovery of Copper and Molybdenum Sulfides," Project Completion Report, OWRT number A -074 -Ariz.

Pima Association of Governments, 1973, "Projected Water Use and Water Budget Calculations for Pima County, Arizona," Element 6, Task 6330.

Pima Association of Goverments, 1978, "Water Use Information for Pima County, Arizona," Element 6, Task 6320.

RGA Consulting Engineers, 1979, "Report on the Feasibility of Wastewater Reuse Options," Los Angeles District, United States Army Corps of Engineers, Tuson Urban Study.

265 REFERENCES CITED

Subsidence

Peterson, D. E., 1962, "Earth Fissuring in the Picacho Area, Pinal County, Arizona," M.S. Thesis, Department of Geology, University of Arizona, Tucson.

Chow, V. T., ed., 1964, "Handbook of Applied Hydrology, Section 13," McGraw -Hill Book Co., New York.

266 REFERENCES CITED

Land Use Inventory and Projections

City of Tucson, Pima County, City of South Tucson and Pima Association of Governments, 1975, "Comprehensive Plan for the City of Tucson, Pima County, City of South Tucson and Pima Association of Governments, A Draft," Department of Housing and Urban Development.

deGennaro, N., 1979, editor, "Arizona Statistical Abstract, 1979 Data Handbook," Northland Press, University of Arizona. Southwest Environmental Service, 1980, "Flood and Erosion Hazards in Tucson," Southwest Environmental Service, 115 West Washington, Tucson.

267 BIBLIOGRAPHY

268 APPENDIX A

276 CLIMATOLOGICAL SUMMARY M La,TM RANCH LATITum .32 07' MEANS FOR PE5IJO 1941 -1970 EXTREMES FCR PF0100 1141 - 1972 LONGITUDE: 1 O61' 5436 ELEV.IFT.} 3050

Mean number or days ..mperamre rn Pre. ptation Totals (Inches) Estimated mean reiative Temperatures

¡ humidity Max . Min. 4tans i _i:remes Snow, S1eeL Hail (percent)

1 i i _ E oc

, H r - ó - vv v °

_ I < e a ce- 1 r ; < E S ^ o. Sii?. .n a.-. ao S

;AI 30 31 29 J1 79 ILI

aaN 1.75 1.29 1946 0.4 10.0 1951 JAN =ca 0.53 1.56 1358 3.2 1.3 1945 1 FEO na 0.85 1.25 1165 0.1 4.0 1952 MAO icQ 0.35 3.5T 1952 T T 1957 APO

.AT 0.14 0.65 1967 1.7 0.1 1 MAY ,uN 3.22 0.66 1955 0.0 0.3 JUN

1JL 2.60 1.90 1955 0.0 0.3 7 JUL 1JG 2.55 1.73 1946 0.0 3.0 7 LUG SEP 1.21 2.12 1966 0.7 0.3 3 SEP :21 0.72 1.51 5951 0.0 0.3 2 1CT .Y 0.65 1.23 1955 T 1957 2 NOV 1.15 1.40 1965 3.5 3.3 1941 4 OFC

SF° JAN ,t1 Y 12.35 2.12 1966 5.2 10.0 1951 16 TEAR

IJTALPRECIPITATION IIN,:NES)FOR NLAZT MiA4CN

!EAR JAN FS5 MAR APRIL MAT JUNE JULY tUG SECT OCT NOV OEC ANNUAL TE1R :9.1 1.37 0.5. 0.15 2.56 3.41 4.31 3.33 0.48 2.55 1941 942 0.75 ..64 0.45 3.60 3.03 3.37 2.72 1.13 0.70 1.05 0.00 0.36 9.F1 194? :9r3 1.11 0.25 1.32 1 7 0.25 3.64 1.56 0.79 9.39 0.00 1.21 7.25 1943 ;9r 7.51 1.:8 1 . . 2 0.46 3.26 0.17 2.45 3.21 1.58 0.72 7.42 1.15 15.19 1944 :945 3.35 0.58 3.05 :.45 0.00 0.30 Z.62 4.81 0.05 1.90 0.30 0.<0 12.24 1945

946 2.69 2.21 7.56 1 .12 7.37 0.34 1.76 3.99 2.45 0.79 1.84 0.55 14.40 1946 r 0.31 0.13 3.60 0.04 0.02 0.13 0.94 J.56 0.75 0.54 0.74 1.14 9.07 1947 .0 0.77 2.39 1 .14 0.10 3.30 0.36 3.62 1.51 0.76 9.73 0.05 1.22 .46 1945 :9.9 1.02 ...5 7.36 0.33 0.00 0.35 1.71 1.05 1.11 0.04 0.31 1.41 10.66 1949 950 3.43 t.45 7.30 1 .73 7.07 0.55 6.57 0.51 0.35 0.00 0.30 0.00 10.31 1950

.551 2.61 ..21 0.56 2.04 0.38 7.30 1.16 3.66 0.95 2.33 1.11 1.70 15.46 1951 952 0.33 7.03 3.33 1.43 0.11 0.29 1.47 2.56 0.36 0.00 2.20 0.50 12.77 1952 .453 0.75 1.49 t.OJ 3.11 0.25 0.34 2.50 0.86 0.00 0.08 0.26 3.13 5.82 1953 .954 3.15 0.65 1.J6 0.42 0.55 4.73 2.65 0.91 3.01 0.00 0.07 12.52 1954 :155 2.22 3.36 0.01 0.12 0.09 7.04 5.09 Z. 52 0.00 1.12 9.09 0.38 17.06 1955

:956 0.62- 7.32 ..71 0.45 0.30 0.46 3.26 1.96 0.24 9.50 0.77 o.32 8.99 1956 :951 3.21 3.54 1.03 7.11 0.15 0.15 1.80 3.32 0.34 2.57 1.09 0.51 1,¢.95 1957 ...958 T 0.97 2.54 7.69 0.11 1.23 2.15 3.21 1.09 1.70 1.27 0.00 14.76 _ 1950 :959 0.32 1.33 3.01 0.37 0.00 0.10 3.91 5. ?5 0.13 1.17 0.49 1.55 11.68 1959 '.960 2.51 7.96 3.31 3.70 7.15 T 2.00 1.35 0.42 1.07 7.05 0.47 9.67 1960

.961 1.37 0.74 0.31 0.00 3.07 0.10 1.62 4.15 1.71 1.20 0.72 2.42 11.66 1961 :962 1.23 0.46 47 T 0.00 0.14 2.44 0.59 t.35 T 0.11 1.51 e.6 1962 563 1..5 1.62 0.82 0.46 7 T 3.13 3.95 0.93 0.59 1.51 0.24E 14.93 1953 564 0.97 0.32 0.95 0.65 0.00 T 2.49 0.53 3.99 0.75 0.71 0.65 12.34 1964 :965 0.52 0.83 0.29 0.40 T 0.10 1.68 2.71 0.56 0.11 1.16 7.14 14.53 1965

.940 1..9 2.37 0.10 1.10 T 0.17 4.57 0.79 1.12 3.74 n.56 7 14.61 1956 -967 0.19 0.25 0.38 3.40 3.33 3.69 4.74 2.81 0.84 3.72 3.79 0.55 15.09 1957 :466 ..73 2.63 ..57 ..67 ..05 - 1 1.16 1.71 0.20 0.24 1.10 0.87 12.44 1954 :969 0.15 0.57 0.41 T 0.22 T 1.54 1,41 3.01 0.05 0.85 1.14 12.2^ 1969 '.970 0.00 0.29 1.09 0.19 5.37 3.33 1.86 2.14 2.70 0.25 0.00 0.64 9.69 1970

571 0.37 3.92 0.00 7.11 0.33 T 1.69 6.26 1.66 1.64 1.12 1.91 15.35 1971 :972 T 0.00 7 0.33 0.39 0.51 2.55 1.24 0.90 4.41 1.15 0.69 11.84 1972

277 CLIMATOLOGICAL SUMMARY MCUHT FAGAH RANCH LATITUDE 314 56' MEANS FOR PERIOD 1941 -1967 EATREHES FOR PER100 1940 -1967 LONCl1UDE 1105' 5129 ELfÌ. iFT.} 3 7 6

Mean (lumber otdays lem;ratureì'R 7recipil3timTotals llnthes) Estimated mean relative Temperatures "umrditr Max . 1Im. Means ü:remes Snow. Sleet. Had percenU

Ì = 1 E. E ,, + o `. c ii l a a A e- o °. .. -, $' 3 ö c c'. c .c 2 a- 1 .-. 0É <ï > TpcÉ > ó .-. a--á«.-. ar. a 1 1 (Al 22 15 15 15 14 IA1

JAM 1.26 1.36 1960 1.9 11.5 1949 3 JAN FEB 0.63 1.11 1956 0.5 5.0 1955 2 FES MAR 0.68 1.10 1950 1.1 16.0 1952 WAR APR 0.49 1.26 1951 0.2 2.0 1956 APR MAT 3.17 3.36 1954 T T 1950 MAY JUN 0.44 1.80 1957 7 T 1952 JUN

JUL 3.23 2.55 1944 T T 1954 e JUL AUG I.27 2.30 1961 - t T 1952 7 AUG SEP 0.65 0.92 1954 0.0 C.0 2 SEP Oct 0.91 1.71 1951 7 T 1961 2 OCT MOM 0.55 1.44 1952 0.5 7.3 1958 1 ROY DEC 0.96 1.22 1949 0.6 4.0 1949 . OEC

JUL MAP TEAR 13.66 2.55 1946 4.6 16.0 1952 33 TEAR

TOTALPRECIP1rAUI0N(INCNESI FORROUNT FAGANRANCH

TEAR JAN FE3 MAR APRIL MAY JUNE JULY AUG SEPT OCT NOV DEC ANNUAL YEAR 19.0 1.72 1.62 3.47 4.20 1.17 1.56 2.86 1940

1941 2.16 2.15 1.71 1.61 0.56 0.00 1.75 2.47 3.04 7.56 0.24 2.47 20.72 1941 1942 1.12 1.13 0.54 0.96 0.00 0.00 1.64 2.53 1.45 1.30 0.00 0.29 11.12 1942 1941 0.76 2.31 1.26 0.00 0.00 0.27 1.07 3.00 0.06 3.94 0.00 1.07 9.53 1943 1944 3.57 1.21 1.36 3.35 0.16 0.00 2.99 7.99 1.15 0.92 2.23 1.12 20.35 1944 1945 0.76 0.3c 7.50 0.00 0.20 2.30 3.60 0.30 0.82 4.00 0.65 1945

1946 3.34 0.33 0.81 0.11 0.07 0.00 ' 4.18 4.75 0.59 1.S7 0.66 1946 1947 0.40 0.00 0.54 0.17 0.30 0.86 1.10 3.79 0.68 0.69 1.44 1947 1948 0.00 2.50 0.51 0.00 0.00 0.10 4.33 1.23 1.15 1.17 0.00 1.46 12.50 1944 1949 2.84 0.62 3.70 0.14 0.00 O.t0 6.56 1.4Z 1.27 0.86 0.20 Z.96 16.79 1949 0.41 0.43 7 1950 1.41 0.18 1.59 6.85 0.46 0.02 0.02 0.00 T 11.37 1950

1951 2.56 0.27 0.12 3.01 0.22 T 2.11 5.32 0.4i 2.51 1.11 2.02 20.03 1951 1952 7.I0 0.10 2.54 1.39 0.32 1.06 1.77 3.67 1.03 0.00 2.97 0.26 15.7-3 1952 0.25 0.72 1951 1.52 0.44 0.24 3.24 3.54 1.27 0.00 0.14 0.34 3.20 6.70 1953 1954 1.06 0.76 t.46 C.00 0.80 0.59 7.47 2.23 1.56 1.02 0.00 0.30 16.66 1954 _2.56 7 r T 1955 0.64 T 4.05 4.34 0.08 1.45 7 0.42 13.54 1955

1956 1.13 1.12 0.00 2.53 T 0.60 1.70 1.61 0.33 0.27 T 0.08 . 6.07 1956 1957 0.25 0.10 0.77 0.48 0.43E 2.05 2.55 4.30 T 1.30 0.40 0.20 " 12.26 1957 1558 1 1.60 3.13 1.00 0.20 0.09 1.45 5.74 1.82 0.43 0.75 0.00 16.23 1956

1959 , 0.57 0.00 0.13 0.00 1.54E 3.06 2.27 3.25 1.23 0.66 . 2.12E 12.63 1959 1960 2.37 0.16 0.74 0.03 0.00 0.10 1.12 2.79 1.10 0.93 0.20 1.02 11.03 1560

1961 1.55 3.15 3.14 ..00 0.00 0.35 3.27 6.26 0.75 1.97 0.49 2.31 17.24 1961 1962 2.37 0.67 3.70 T 2.66 0.36 1.34 1962 1963 1.28 0.66 0.00 0.00 0.00 1.54 3.41 0.60 1.42 1963 1964 1964 3.965 1965

1966 1966 1967 0.35 0.78 4.93 1967

278 CLIMATOLOGICALSUMMARY nE LmE1 PEAK LATITUDE J157 CAMS E9100 1941 - 1954 ExT+EMES 10P 9E9100 1940 - 1954 lC;1C11UDE 1111 03' 1973 )220

Estimated Meannumberotdays ',moor tute!'f7 P15cmitSbonTotals (Inches) mean - relative Tempetatures humidity Max. Mia_ 'ears `.st:emes Sion. Sleet. Hail ',percent)

1 o i ¡ -

cc.a r c # £ I > S g .óá +.-iI' d.-. oo f tAl 3 9 4 4 1 3 3 3 (AI

JAV 52.5 36.1 41.5 55 1153 71 1947 403 9.60 0.62 1141 0.4 4.3 1951 59 41 2 0 0 6 0 JAN stg 55.5 37.9 52.1 17 1141 23 1953 361 0.49 0.57 1942 3.2 2.3 1953 53 37 3 1 1 0 7E9 MAR .,.E. .2.5 55.6 13 1950 32 1451 315 0.71 0.74 1543 0.3 2.1 1954 46 33 3 3 5 5 MAP e..< 51.2 51.1 111: 1+.1 14 11547 61 0.45 0.75 1951 i ' 19511 37 22 5 0 0 0 APP -.-T 51.1 55.1 72.1 136 1951 35 1955 15 0.25 1.65 1944 77.1 2.1 31 11 17 0 0 0 .AT J1;n 46.3 5-.2 60.1 135 1454 50 1951 0 3.29 0.50 1950 r 1952 10 20 25 0 9 0 JUN

JUL 57.1 73.I 53.7 135 1942 50 1946 0 3.15 Z.30 1146 r _T 19541 45 14 7 27 0 n 0 JUl AuG 9I.5 65.1 81.3 155 1944 56 1451 0 3.39 1.74 1452 7 7 1151 61 42 1 25 0 0 0 AUG 51P 92.1 63.0 77.5 107 1990 47 1950 3 1.81 1.45 1944 T T 1952 55 19 5 28 3 0 0 SEP OCT 63.7 53.3 65.5 95 19521 37 1951 20 7.61 2.01 1151 1.0 1.3 48 36 2 17 0 n 0 OCT 404 72.7 41.0 57.4 91 1952 25 1146 295 3.40 1.22 1952 0.3 3.3 48 41 Z 1 3 3 0 NOV U1G 55.5 33.7 51.9 .. 1950 23 1145 467 1.84 0.99 1941 T T 1941 59 49 3 0 0 9 0 DEC

JUN EEO ^CT JAM RAS 07.5 51.9 56.4 126 1154 23 1451 1950 13.24 2.37 1451 1.9 4.3 1951 48 14 15 139 1 14 0 YEIP

AvEcAGE NCMTMLY TEMPEaATURES t71 FOR HELMET PEAX

YEAR FEO +A7 APRIL MAT JUNE JULY 4JG SEPT CCT NOV CEC ANNUAL TEAR 1940 55.7 55.21 1940

1941 50.9 55.0 56.2s 59.6$ 72.3$ 78.9 84.0 80.2 75.1 55.2 59.4 52.8$ 55.9 1941 1942 51.4 49.5 54.5e 62.5$ 71.6 81.6 57.2 712.41 79.51 67.6 62.51 53.81 67.1 194, 1943 52.4 56.5$ 52.2 56.5 75.2 81.06 84.6 79.A 75.4 67.6 55.21 50.4 67.3 1943 194. .7.7 45.6 54.61 60.9' 70.6 77.7s 84.2 82.3 76.4 69.6 1944 1945 46.Z 52.2 51.5 57.3 4A.4 1945

1946 43.5 49.57 56.1 67.6 69.61 82.4 30.7 71.3 75.5 52.5 52.0 52.6 64.5 191.6 1947 45.3 53.91 51.3 65.2 1947 14448 1948 1949 1949 1950 51.31 65.6 73.2 80.3 79.31 80.2 73.8 73.4 62.6 57.7 1950

1951 .9.6 53.7 57.4 62.9 71.6 75.1 04.8s 89.51 79.2 57.5 56.0 50.9 66.0 1951 1952 51.3 51.0 51.7 63.5 75.1 81.6 e4.4 82.4 75.9 74.3 54.6 48.6 66.5 5952 1953 5-.6 51.6 1953 1954 59.3 73.0 00.7 83.9 1954

51144 PRECIPIT:TIOM (INCHES' FOR HELMET PEAK

Tt AR JAY fill MAR APRIL nY JUNE JULY AUG SEPT OCT NOY DEC ANNUAL YEA? 1340 0.31 1.57 1940

1.1 1.11 1.52 1.21 0.50 0.67 1 1.66 2.47 2.44 1.51 0.31 7.02 14.64 1941

19.2 .... 3.15 0.25 3.65 0.00 0.00 0.39 Z.11 1.33 1.29 0.00 . 7.27 1942 14,3 1.39 1.74 3.12 t 1 2.68 6.G1 1.99 T 0.00 0.47 12.40 1943 v.4 3.61 1.32 3.73 0.15 0,.65 T 1.58 3.48 2.27 1.35 2.97 1944 1945 1.55 0.1Z 0.51 0.00 T 1945

11,5 3.17 7.22 '0.24 0.70 0.00 5.72 2.92 2.11 1.45 5.46 0.41 15.11 1946 1947 3.32 3.54 0.03 1947 1945 1948 1.744 1949 1953 0.39 3.00 0.33 1.31 5.78 1.75 0.11 3.30 0.00 0.00 1953

1951 3.35 1.72 T 0.00 2.18 2.60 1.32 2.29 3.70 1.75 13.55 1951 1452 1.46 3.13 1.00 0.47 3.07 5. 89 2.11 3.30 1.51 0.41 15.57 1952 :153 1953 1154 .76 0.30 0.93 0.51 4.52 1954

279 CLIMATOLOGICAL SUMMARY RUBI STAR RA'C, LAMM 31 55' _s95 FORpE2I00 1944 -1974 E%TPF.+cS FOP PE91O0 1945 -1972 Lcti',ITUOL __ 05' 7310 :.,_4 tï1} 3640

Estimated Mean number of days Temperalu:e;`Ti ?rec pitahvn Tows (inches) mean r.la ive Temperaturei humdity Max. Nezls mes $rvw, Sleet. Had percent) Min .

i h I {

i _ C ' _ o ó +' _ - { ; { e_ v E '0 1 `~ - 33 . s ( 4 ^ö1 r. .`, . S. I .``5 _ ' ! ^ Ç c 1 ) !^; 2 c^E ... c 5 .cc > 2£ c3 a :Ë E > a. . ° I: i o` .-a _r o S^c L

t.l 2 21 22 25 23 23 2 7 2 2 (At

11.5 45.4 54 1153 13 o 0.1 JAN 57.1 1449 0.94 1.51 1966 5.5 1449 15 22 3 14 0 JAN FEd 63.5 16.9 50.2 51 0948 25 19490 0 3.66 1.16 1950 r T 1462 75 16 ? 0 0 5 0 rE9 84 10 T T NAR 57.4 .J.2 54.1 1949 1143 0 0.42 0.71 1956 1470 ?7 5 2 2 3 2 NA7 65.2 95 1948 3 3.24 r APR 80.2 E0.1 34 2944 0.76 1953 5.5 1951 19 i 5 9 1 0 APR 55.2 72.1 110 42 0 1.467 NAT 55.3 1949 1949 0.11 0.40 5.0 1.2 12 95 I2 1 d o NT 95.3 54.1 111 1945 4d 1449 0 1.0 P6 JUN 55.1 3.36 1.01 1154 0.1 12 97 1 0 0 0 JUN

95.0 70.2 52.6 104 1443 63 1345 0 3.52 T T JUL 2.93 1946 1949 25 12 7 25 1 0 0 JUL AU6 67.5 11.2 1949 61 0 94.5 102 1944 2.70 2.13 1f'55 0.J 0.3 15 15 6 27 0 0 0 AUG 64.9 77.5 101 S7 0 SEP 90.6 1949 1945 1.35 2.50 1470 0.0 9.1 32 11 1 19 1 A 0 SE* OCT 75.6 53.1 65.9 it 19490 36 1949 0 0.66 2.49 1951 T 7 19590 ?1 15 2 2 2 3 0 OCT 42.7 55 NOV 73.0 57.1 1944 29 1948 0 0.53 1.10 1963 r t 1971 25 15 2 ^ 2 1 0 NOV OEC 62.5 37.9 43.2 77 1943 19 t949 0 1.12 2.08 1967 1.1 6.0 1971 14 ?3 3 4 0 9 0 gc2

JUL JAN JUL JAN TEAT, 78.8 51.6 65.2 104 :945 13 1349 0 12.91 2.9.1 1948 0.4 6.5 1949 ?7 11 12 116 37 0 TEA,

AvE910E NCNTNLY TENPEPAT'JRES (FI F3R RUSTSTAR RA4CN

TEAR JAN FES NAR APRIL HAY JUNE JULY AUG SEPT OCT tiOV CFO A N!:1:=L TEAR 1945 50.r, 51.5, 65.6s 73.3 50.11 53.5 77.11 67.1s 5?.5 50.1 1945 1949 41.2 46.7 55.4 64.4 71.1' 50.3 51.4 51.2 75.4 64.6 61.2 50.2 55.. 1444 1950 50.5 1950

TOTAL PRECIPITATION (INCHES) FORRUBY STARK ANCLA

TEAR JAN FE7 9AR APRIL NAY JU:OE JULY 1JG SEPT O ^,T NOV CEC 1NNUAt, YEA* 1945 1.63 2.40 0.03 0.00 0.11 4.73 1.18 2.04 1.06 0.04 1.04 1944

1949 1.55 0.21 0.12 0.06 0.00 0.06 - 2.20 2.09 : 3.29 1.06 0.06 1. +1 12.16 1949 1950 0.20 0.79 2.15 0.03 2 1.25 5.72 1.10 0.40 T 0.00 0.10 10.71 1950

1951 1.08 3.14 3.09 1.31 0.00 3.00 1.77 2.2e 0.97 2.54 0.71 1.40 14.79 1451 1952 0.84 2.35 1.12 0.00 0.67 1.50 3.55 0.75 9.00 1.51 1.59 12.19 1952 0.00 1953 :.3G ..50 0. 0.00 1.30 5.09 3.07 0.00 T 0.00 5".96 1155 1954 1.26 3.32 1.'8 2.20 1.04 1.56 2.9? 3.25 2.93 0.45 0.09 1 .3A 15.+5 1154 1955 2.14 0.00 1.03 0.03 2.30 0.03 5.06 5.16 0.55 1.10 0.00 r 11.21 1955

1956 0.30 3.15 ..00 0.14 0.00 0.00 5.20 0.19 0.05 0.21 0.81 0.12 5.21 1956 1957 2.33 ..58 2.79 0.25 0.44 7.30 3.15 ,.54 0.00 1.53 0.43 0.46 17.11 1957 1956 0.30 1.36 2.JL 0.59 0.00 1.60 1.42 t.56 2.10 7.00 1.14 0.00 13.59 1955 1959 5.13 3.51 1.32 0.10 4.30 0.30 5.85 3.54 7.11 1.25 1.45 1.96 15.11 1959 1960 2.29 0.70 ..24 0.00 0.00 0.40 L.12 2.23 0.52 0.50 0.00 1.66 9.56 1960

1961 1.40 3.00 2.i5 0.33 0.00 0.54 4.68 2.27 1.91 1.43 0.47 1.53 12.55 1951 1962 - 1.22 5.25 0.63 0 0.00 0.30 1.81 0.10 2.95 0.05 0.37 1.11 .53 1962 t961 0.74 3.90 0.36 0.76 0.00 0.00 1.90 3.37 1.94 0.66F 2.41 0.00 13.04 1963 1964 1964 0965 1.57 0.10 4.75 6.75 1965

1966 2.15 2.19 3.63 0.04 0.00 0.66 2.91 5.12 2.9+ 3.60 1.50 0.77 19.27 1965 1967 0.14 2.25 1.20 ' 0.49 0.60 0.37 5.57 1.04 0.69 0.31 0.48 4.71 15.15 1967 1955 0.55 0.79 1.25 0.26 0.00 0.30 1.42 3.45 0.23 3.22 1.0t 0.74 11.95 1968 1969 0.53 0.45 0.34 T 0.25 T 4.16 4.75 1.15 0.27 1.17 0.44 13.57 1969 1970 0.00 1.46 1.04 0.34 0.00 0.55 1.66 4.17 1.20 3.19 0.94 0.62 12.26 1971

:971 2.15 2.65 0.00 0.25 0.00 T 4.73 6.57 2.70 1.36 0.96 2.35 70.11 1477 1972 0.00 0.30 T 0.10 T 1.t2 2.43 0.65 1.19 4.22 1.45 0.48 11.74 1972.

280 CLIMATOLOGICAL SUMMARY :nYtt41vC.. ;aTttt)DE 3159' 'FANSFUR 'E?IOO 1942 -1479 ExTKE'-ES °94 °E *400 1142 -1972 LO)1CtTi;DE: Ill. 23' .267 2750

Estimated Mean number 01 dan Temperat:ne tr) Prec'píta6on Totals (Inches) i mean

' re!7tive Temperatures homey i Ma1. Min. i Means Extremes Sr.o. Sleet. Hail (percent)

! i n

..,e-7, 7,3 2 ° L .i 3 ñ 1 i ¢ _t. r 1 < < .=Á, .oM .oa f

II, 23 25 15 27 2n ?5 >1 25 19 71 15 20 (4)

J:N o5.7 JI.5 41.7 39 1971 1 1967 489 0.65 1.45 1462 1.1 7.0 54 41 7 0 9 16 1 JAN 7f3 _..e 57.5 13 1357 11 1972 355 7.59 1.41 19i J.'. 2.3 1146 51 36 2 5 12 0 FE3

'r:t 7..3 33.2 ,. 45 1450 15 1351 261 1.60 1.15 1170 0.t 1.1 19°2 45 75 2 1 5 7 0 M34

.Fa 13. 4..7 ..1 104 1i65 22 1345 94 .31 i.44 t9S1 7.7 71 73 1 ' n l 0 Apo ..ir t... ,..., .7 111 1)` 23 1959 19 9.14 ..10 1147 1.0 7.0 31 21 21 J 0 MAY

T.:`. 1.0.3 "1.3 1.1 116 1461 42 1355 a d.16 1.'5 1150 5.1 0.0 25 IS 1 29 1 0 0 JUN

JJl 111.1 .44 35.5 114 1955 56 1455 0 2.r5 1.65 1946 r (152 44 22 7 21 n 5 0 Alt AUG ,6.1 t4.7 12.4 113 1162 50 1468 J 2.29 2.95 1971 1.0 0.7 59 31 6 30 1 0 Q AUG 4.17. vá.6 b5.3 7í.s 11: 1455 38 1965 1 1.55 ..13 1462 1 T 1951 54 16 1 28 5 0 0 SEP OT 36.4 .).4 61.3 101 1151 20 1971 74 J.62 2.20 195t 1.1 0.0 49 34 2 l' S 0 9C1 NOY 75.6 38.1 56.4 14 1967 id 1956 241, 9.47 0.31 1172 0.1 3.0 1151 49 11 1 1 n 6 0 NOV 711 47.3 32.1 49.7 16 1954 8 1954 471 0.46 1.12 1967 t 5.3 1971 61 41 7 5 1 16 0!tEt

JUN DEC SE* DEC r(A4 e4.. .'.3 60.4 1t. t)66 a 1954 1974 10.61 4.30 1142 0.1 5.3 1971 45 31 29 162 0 56 0 YE4R

CLIMATE OF ANVIL RANCH, ARIZONA

Anvil Ranch is located at an elevation of 2750 feet in the northern section of the elongated Altar Valley,29 miles southwest of Tucson. umerous dry washes are found in the valley, emerging from mountains to the east and vest. The normally dry Fresnal wash, descending from higher elevations to the east, follows a west -southwest course just south of the ranch.Three miles to the vest Altar '.:ash :lows northward, ultimately emptying into 3rawley Wash. The valley floor is encircled by the Baboquivari Mountains to the vest, the 2oskruge,MOuntains to the northwest and the Sierrita, Cerro Colorado and San Leis Mountains to the east. The hignest elevations within 30 miles of Anvil Ranch are Oaboquivari Peak which rises to 7730 feet, 20 miles to the southwest, Kitt Peak at 3575 !cot. 15 miles to the west and Keystone Peak at 6206 feet, 10 miles to the southeast. Mt. Wrightson in the Santa Rita Mountains soars to a majestic height of 9432 feet, 35 miles to the southeast. Probably the best -known site in the area is Kitt Peak National Observatory which attracted approximately 50,000 tourists yearly in the mid- 1960's.The San Xavier del Sac Mission, famous for its architectural design and historical background, líes 25 miles to the east -northeast.Creosote bush and salt brusn are the most common types of vegetation on the valley floor at Anvil Ranch, although mesquite does exist along the northern Altar Wash bottoms. Creosote bush is replaced by desert grass at lower elevations and by chaparral and oak woodland in the higher elevations of the neighboring mountains. Sections of yellow pine prevail in the southern Daboquivari Mountains. In an average year slightly less than eleven inches of precipitation falls at Anvil Ranch, about half of it during the months of July, August and September. In 1955, almost 95 percent of the annual total occurred during this three month period. The basic mechanism triggering summer-rains is thunderstorm activity which is set off by the incursion of warm, moist air from the Gulf of Mexico and the development of extensive cumulonimbus clouds over the mountains, particularly to the east. The most severe rainfall at Anvil Ranch is associated with northeasterly- moving weak tropical disturbances or surges of moisture that tr.7vo -1 across the state from the Pacific and the Culf of California. The region is driest in May and June. Precipitation amounts exceeding three- tenths of an inch were recorded in June only four times during a 27 year span extending through 1970.

winter precipitation at Anvil Ranch does not normally exceed a few inches. Occasionally, Pacific storms move far enough south co produce a noticeable increase in rain. However, under such circumstances, most of the heavy,precipitation is limited to the western .Mountains. Only trace quantities of snow have been recorded, although considerable amounts can fall at higher elevations in the surrounding arcas.

Suring tr.e summer months at Anvil Ranch, while daytime temperatures commonly surpass 100 degrees, the nights are pleasant,

with readings in the sixties. Diurnal variations of almost 40 degrees exist in June and September, the cool nights counter- - acting the intense heat of the day. Even with the increased relative humidity of July and August, resulting in warm evenings, daily temperature ranges remain in excess of 30 degrees.

For must of the rest of the year a mild climate exists at Anvil Ranch, the possible exceptions being December and January. During these months. on about half of the days, early morning temperatures drop below the freezing point, although daytime maxima ace frequently in the upper sixties and occasionally higher. Average temperatures for this period are slightly under 50 degrees, certainly not unpleasant for the residents of the area.

281 1YE43Ct..1(:41MLY _'C?ASJ+'S Sfl .ANV¡L .4NCH FtG y4/ S L 4.37 JUNE 131Y SU; SFPT n;T Nov rEC 4NNU*L 'E4á it 4.7 J4N 67.3 74.71 .1..^.t 14.46 5 2.91_ 79,41 59.16 45.5t 1443 194J 57.. 60.2 51.ít 45.51 43.1, 5... ó7.1t 76.71 5$.41 54.4 77,5 1144 19 47,71 045 4..34 52.51 51.6, 75.36 5+.6t 55.4 55.1 1945

5 7 .a, 66.2, e.3.11 93.4r '9.1 52.6 194. 1946 45.6, 45.2 55.6 ..t 79.9, 15.2, 1147 1947 ...7t 55.6, 54.21 1945 1346 1944 1949 65.46 7G,7í 61.31 13.1 51.8 77.3 75.3 61.4 15.51 1950 1950 57.6 56.56 61.76 72.0 7..41 55.1 11.61 1.5 70.5 49.9, 1951 1951 49.Cí 529, ..4t 5t.16 67.16 75.16 50.3 5'..4t 81.6: 79. lt 72.36 51.41 47.4t E5.. 1152 1952 51.16 49.56 57.5 63.16 67 3.51 06.1 66.0, 3t.-:r 54.36 46.6: 1951 1953 52.26 65.01 73.51 11.26 54.5t 41.41 52.66 71.61 59.51 49.71 65.1 1154 1154 51.51 57.., 57.7 51.66 71.26 60.66 52.2. 79.6: 76.7: 69.6s 56.2 52.31 64.9 1955 1955 .1.5s 46.5, 57.26 73.26 54.46 12.51 49.26 1956 :5..t 57.76 84.íf 57.86 53.61 1956 11.5, .'1.7t 56.71 47.2 1957 51.9, 56.56 53.1/ C4.36 65.11 55.41 57.41 51,76 51.01 1957 95.4: 16.71 51.1: 77.07 70.56 57.1: 54.41 1154 1955 48.5, 51.96 52.46 52 2r 55..6 :5.51 55.56 55.26 79.96 50.76 1958 1959 52.1, 71.21 72.76 44.6: 06.9 63.8 71.56 55.8! 55.5: 4í.1r 66.6 1960 1910 46.3, 45.56 51.66 64.66

1961 51.87 52.9' 64.66 71.51 85.9, 15. 81.8t 56.3 53.41 45.1, 1961 .'..2, 55.Cí 2.9t 71.76 30.06 55.5 57.2 +0.7r 51.2 41.66 62,71 1962 1962 71.56 71,., 1961 47.3 57.06 57.16 62.9 76.4. 7..1 57.5 51.2 57.51 49.06 57.2 1961 70.56 75.51 50.9r 1964 .4../ . 5 . 8 6 53.. 63.46 71.2, 50.5, 55.71 51.16 1964 77.3, 16.9 85.. -77.1 71,76 51.91 1065 1965 49.71 54.3 51.31 66.71 50,ór

1966 46.. 47.1 59.01 64.66 73.9 82.1 56.51 51.3 75.24 67.11 54.66 41,11 56.4 1966 :967 ..66 52.46 55.26 61.16 69.2, 78.11 84.1 .2.1 79.21 5..1 61.16 4F.1: 65.5 1967 061 49..ìf 57.06 57.31 61.0: 72.4: 61.í,s 7'1.3 77.56 48.76 55.26 06. .5.1 1964 4î.8r 52.b1 64.16 75.26 77.41 55.3 75.5 54.9 55.16 50.31 1969 54.71 19 70 197. 45.31 55.01 55.56 59.16 73.5, 81.51 56.71 75.16 63.3: 51.11 50.36 1971 4'.5' 57.11 49.5, 16.41 77.21 62.76 55.41 1971 1.72 68.94 53.46 64.01 73.5t 40.66 56.7; 51.9: 7.21 57.Z1 52.21 45.1t 1972

1C141a2CC1.IT:110N 1I`+:1'ESSFOR SNV1L 9UtCH

Ti 4R JAN 71.9 MAR APRIL NAY JUDE JULY SUC SFPT 351 NOY CEC 4N411141 FEAR 1942 042 1943 0.35 13 0.61 T 0.03 0.09 0.91 1.60 2.23 1.46 O.23 0.40 7.91 1941 1944 0.24 1.52 0.42 0.33 0 .96 T 3..0 2.11 7 .52 1.13 2.24 1.17 27.61 1944 1945 ..77 1.51 2 .07 4.00 3.30 1.19 3..9 0.110 1 .2 6 3.00 '.OS 1945

1946 0..9 1.53 0.19 0.04 0.00 4.15 3.67 3.25 0.12 0.46 0.35 1946 1947 7.15 1.31 0.1b 1.15 0.12 0.41 1.40 1947 1946 0.30 0.00 2.00 0.16 1.03 1.37 C.45 1945 1949 2.25 2.35 0.42 3.21 9..94 0.05 1.20 1949 1954 0.74 0.05 0.30 T C.55 3.73 C.51 0.10 1.00 1.17 0.00 6.90 195n

1951 0.93 1.15 1.11 1.32 i 0.00 1.52 3.36 1.27 7.10 0.50 .50 01.15 1951 1952 0.75 0.13 1.65 1.21 1 0.20 2.12 3.3 1.55. 0.10 1.22 0.72 11.14 1952 1153 0.31 0,96 0.34 1.44 0.01 0.01 2.05 0.587 1.00 0.01 7 0.05 5.45 1951 1954 1.066 0..1 1.43 7.03 0.91 0.15 S.22 1.59 0.69 3.25 0.00 0.17 9.15 1954 1455 1.68 0.15 0.0 3 7.2C 3 0.00 4.85 1.59 0.04 9.09 0.00 0.12 13.52 1955

1956 0.31 C.15 7.02 2.21 1.79 0.25 1.61 0.12 5.17 3.16 0.75 7.25 L.26 1956 1957 1.12 0.4t 0.71 4.19 0.41 0.01 2.60 1.45 0.12 1.60 0.57 0.79 9.57 1957 1958 0.11 1.97 1.92 0.50. 0.30 3.10 2.48 1.53 0.53 1.21 0.51 0.50 11.46 1958 1959 0.00 0.75 0.00 0.05 2.00 0.44 2.77 4.51 1.51E 1.34 0.76 1.72 1 ?.41 1959 1960 2.63 4.26 1.23 0.00 0.30 0.10 1.29 3.92 2.10 0.60 0.30 1.19 13.12 1960

1961 0.94 0.50 2.13 0.00 0.00 0.15 4.17 2.17 2.16 3.50 0.51 1.9 11.73 1961 1962 0.06 0 .26 .37 0.:/ 0.00 0.62 7.14 1.0' 5.97 0..0 0.1 1.24 11.64 1967 1961 0.11 0 ..3 0.25 1.57 0.30 C.10 3.00 4.24 1.5 7 7.70 0.90 2.17 12.40 1961 1964 0.10 C.03 1.04 3.68 0.33 0.15 I.26 2.74 2.35 t.52 O. .1 0.527 14.01 1964 1965 0.69E 0.90 0.11 1 .48 T T 1.61 2.31 1.45 0.10 1.27 4.21 11.07 1965

1966 1.66 2.00 5 1.35 0.10 0.91 3.22 7.69 1.71 3,29 0.20 0.51 13.61 1146 1967 0.15 0.00 ..71 1.12 1.20 0.15 2.71 1.74 0.63 0.10 0.55 4.33 11.19 1967 1966 1.15 1.15 1.77 1.17 0.00 0.00 2.74 2.95 0.15 0.79 0.65 1.00 10.15 1965 1969 0.63E 0.36 0.35 0.17 0.17 0.00 2.93 1.50 1.96 0.00 1.65 0.45 10.44 1969 1970 0.70 0.25 1.91 0.13 0.00 0.23 L.65 1.14 4.61 0.t2 0.03 0.47 10.71 1970

1911 0.06 C.15 1.10 0.45 0.23 0.10 2.95 5.91 1.51 1.59 0.66 1.95 1'.73 1971 t372 0.70 0.10 0.00 0.10 0.02 1.16 2.41 1.47 1.62 3.47 1.37 0.16 I1.78 1972

282 CLIMATOLOGICAL SUMMARY CORtARO 3Sa LATITUDE 12 20' -ERNS F04 PERIDO 1945 - 1970 ETT0E.T5 FOR PE9ton 1945 - 147? LoHClNDE.' 111 or 7159 ELEV. írT't. 2270

Mean number at days Temoeratc:e('ni Preapitati0nT0talst.nthes) Estimated mean relative Tempe. atures humidity Max. Min. Means t E3L'emes Snow, Sleet, Hail (percent) ._

f i i _ ; o ö s. É _ H ö 15 r 471 l ú r. o c c I < ' z t a- s ; ( Z 1 ci - f 'i' c a ,a._ rn°.n a`r°.,áo i _

417 25 35 25 37 _7 19 26 27 26 25 25 22 2? 22 22 tat

Jis 66.7 33.1 50.1 15 1171 13 1948 431 0.78 1.33 1460 0.2 3.3 1949 42 42 2 0 1 14 0 JAN FE3 70.1 35.2 51.6 11 1957 23 1945 316 ü.61 1.50 1963 T T 1966' 59 36 2 0 9 0 FER eAR 75.6 1.3 57.s 46 t155 21 1948 233 0.6a 1.21 1958 5.2 4.7 1964 47 79 7 1 0 4 0 414

ApR 65.4 47.2 6e,3 102 1965 29 1944 61 0.33 1.00 1952 0.0 0.0 38 22 1 10 0 0 APR rar ÿ4,0 54,6 7..1 112 t+5t .. 1170 11 8.36 0.67 1964 0.0 0.0 2 16 24 , 0 .AT 102.5 44 JVN 65.5 6..0 116 1970 1971 3 0.26 0.35 1963 9.1 0,0 27 17 1 29 0 0 O JUN

JJl 102.5 72.9 57.1 120 1964 55 1955 0 2.32 4.41 1953 0:0 0.0 46 29 5 31 6 0 0 JUL AU 100.1 70.6 65.4 115 1172 57 1956 3 2.05 1.64 1971 O. 3.0 59 35 5 30 1 0 0 AUG

SEP 95.2 65.2 61.7 113 1359 45 1965 0 1.23 4.75 1962 0.0 1.0 53 32 3 P e e 0 SEP OCT 66.6 52.7 71.7 112 1169 27 1171 22 0.71 2.45 1945 0.3 0.0 48 31 2 17 1 7 OCT

NCV 75.9 41.6 5t.s 46 1949 20 1356 158 0.70 1.55 1972 0.1 0.0 44 37 2 1 0 4 0 NOV OEC í1.5 I5.8 52.2 55 1350 17 1970 157 1.12 1.95 1957 r 1.3 1949 50 47 3 0 5 11 0 DEC

JUL FE3 rEa Sao r6AR 55.5 51.. 5s.6 120 1904 13 1943 1649 11.07 4.75 1962 0.4 4.7 1.964 45 It 26 271 1 41 0 TEAR

CLIMATE OF CORTARO 3 SW, \RIZOMA

Cortaro 3 SW lies At an elevation of 2270 feet -near the northern base of the ^acson Mountains, eleven miles northwest of Tucson. The Arizona- Sonora Desert Museum, which is located seven miles to the southwest, features the most dense saguaro stand in the world and afantastic display of desert plants and Arizona- Sonora animals. Brawley wash in the broad flat Avra Valley tics ten miles to die west while the normally dry Santa Cruz River follows a northwestward course only two miles to the cast. Numerous low desert hills are found in the area including the Roskruge Mountains to the west -southwest, the Silver Bell Moun- tains to the vest -ncrt °west and the Tortolita Mountains to the north. The greatest elevations are found on Mt. í,emnon in the Santa Catalina Mountains. which rises to a majestic 9157 feet,twenty -one miles to the northeast, on Spud Rock in the Rincon Mountains which ascends to 6590 feet, thirty -four miles to the east -northeast and on inspirational Mt. Wrightson in the Santa Rita Mountains, soaring to 9412 feet, forty -seven miles to the south -southeast.Nineteen miles to the southeast the historically famous San Xavier del Bac Mission contains magnificent works of art representative of the Gothic, Baroque, and Churrigueresque styles of Spain and Mexico. The Saguaro National Monument is found twenty -six miles to the east- southeast and boasts a wondrous variety of picturesque and beautiful desert growth. The sparse vegetation in the area basically consists of creosote bush and salt brush, although mesquite may Ue found along the Brawley Nash bottoms in the Avra Valley. Palo verde, cacti, and bur sage are prevalent in the Tucsonmountains. In the Rincon and Catalina Mountains chaparral and oak woodland yield to forests of yellow pine above 6500 feet.

Cortaro has a desert or semi -desert climate, receiving slightly more than eleven inches of precipitation in most years. Amounts have remained relatively constant over the years. the annual total having varied from about six inches in 1956 to about seventeen inches in 1967. The wettest period occurs during the warm season months and is associated with late afternoon or early evening thunderstorms that originate in the flow of warm.tropical air from the south, normally from the Gulf of Mexico. These storms are most intense over the mountainous regions to the east and are typically accompanied by very strong winds when they traverse the desert plain in a westerly direction. The most severe summer rains at Cortaro occur in conjunction with the infrequent passage over the state of dissipated tropical disturbances from the Pacific Ocean. One such stotf. on September 26,1962, dumped 4.75 inches on the town and flooded most of the low -lying sections. Drought conditions Are most prevalent in May when in Co out of every three years, no measurable precipitation occurs, Winter precipitation at Cortaro is less intense than the rains of summer, although it usually lasts for a considerably longer perlo.l. Cold season rains are associated with middle latitude storms that originate in the North Pacific Ocean and follow an easterly track across the continent. These storms normally pass too far to the north to produce more than strong winds and cloudy conditions. Occasionally, however, when they do follow a more southerly course and intensify off the southern California coast, a notable increase in precipitation occurs. Annual snowfall is entirely negligible.

Sur.+cr temperatures at Cortaro are extremely high, peaking well above 110 degrees in the first two weeks of July.while the relative h'.:.mtdities are low on the hottest days of the year and daytime heat is most intense for only a limited number of hours, air -conditioning systems are still vital during the summer months. The nights are reasonably comfortable, providing relief from the heat of the day.

In c,ntrast to the heat of summer, during the rest of the year at Cortaro. a mild. healthful climate dominates. Average daily temperatures in'the winter rarely dip below 50 degrees and daytime maxima often rise into the middle or upper seventies. The nights ara cool, with the temperature falling below the freezing point about forty days in an average year. ?ne thousands of tourists attracted to the general area of Cortaro are seldom disappointed by the relaxing climate that pre - vails. /vERAGE NJ'+Tr6T TEnPEPATURES 1F1 FOR C39T1Pp 3 S'a

TEAR JAN FE3 M19 APPIL NAY JUNE JULY AUG SEPT OCT NOV CEC ANNUAL YEA. 1945 54.31 61.31 7r.21 85.4 2.6 71.3 57.6 50.1 1945

1946 46.3 50.6 55.6 T1.0 73.6 66.2 57.4 84.t 11.4 65.1 53.. 54.0 67..8 1946 1947 4/.5 55.6 63.7 65.3 77.1 61.9 85. 81.9 !2.4 5..1 52.7 47.0 67.7 1947 19.6 .4. 49.7 51.2 56.6 74.2 04.5 10 %6 87.5 54.7 73.4 53.5 51.6 68.1 1948 1949 43.8 51.2 58. _3 58.6 74.1 54.9 15.9 91.9 81.1 47.2 53.9= 51.1 67.9 1149 1450 50.7 55.3 59.9 72.1 81.9 64.4 65.9 75.9 53.3 56.7 1950

1951 51.9 56.9 59.3 64.9 75.2 01.5 91.2 35.9 a2.5 72.2 50.1 51.3 69.1 1951 1952 45.5 52.3 64.7 73.1 33.0 35.7 55.3 33.7 75.1 55.3 1952 t953 3 59.5 59.21 65.3 69.2 53.0 87.4 36.3 82.5 ' 0 .3 61.1 47.4 50.3 1953 1954 52.5 61.11 53.5 73.3 76.3 83.'. 07.3 84.0 81.4 '1.3 61.5 51.1 59.8 1954 1955 46.1 .7.6 59.1 62.4 71.5 83.3 82.8 83.0 !3.5 71.5 5!.9 53.3 66.5 1955

1956 55. .5 58.5 64.4 76.6 05.1 85.5 64.0 '1.3 55.4 52.5 1956 1957 52.7 59.7 59.9 54.7 73.7 85.1 57.7 14.5 63.9 67.9 54.9 54.6 58.7 1957 1956 52.1 55.3 53.4 63.1 78.7 54.8 87.3 34.3 71.9 .8 57.6 54.2 63.4 1955 1959 52.7 51.5 53.1 73.5 74.3 87.8 S9.1 .3.4 51.5 71.0 58.5 52.5 59.4 1959 1960 47.4 .9.1 51.5 66.9 7..6 86.9 84.7 57.8 33.6 63.8 51.1 59.9 69.1 1950

1961 54.1 54.1 59.6 53.3 75.3 57.4 88.8 35.6 71.5 '0.0 55.1 50.9 59.2 1961 1962 49.9 95.7 54.6 71.2 73.5 82.1 87.6 89.2 01.1 70..5 62.7 55.2 69.6 1952 1963 40.5 59.1 59.7 84.4 55.1 7..4 5'.41 51.3 196S 1964 47 .5.8 55.3 63.4 74.1 52.7 59.8 83.7 78.41 55.5 52.2$ 1964 1905 53.21 91.97 56.31 46.2 70.81 73.7 88.9 67.07 /9.1 71.41 61.81 53.61 68.6 1965

1966 46.5 43.7 61.4 67.6 77.6 84.6 66.7 85.6 89.7 55.8 67.7 51.8 68.0 1966 1967 51.1 56.2 62.4 63.5 72.3 61.71 S6.7 86.0 31.6 71.5 62.2 47.4 68.5 1967 1968 51.3 58.1 57.9 63.0 73.9 !4.4 56.41 81.9 41.4 3/ 56.11 1968 1569 SI.6 52.7 54.6 70.5 73.4 83.71 66.91 69.41 34.2 59.3 59.5 56.5 69.4 1969 1970 50.9 58.3 57.11 52.3 75.9 85.9 90.8 61.51 77.91 55.8 59.9 52.5 58.6 1975

1971 51.. 53.5 61.7 65.6 69.1 `2.S 90.5 83.6 71.7 64.4 56.3 48.0 67.2 1972 1972 51.3 57.1 66.1 66.6 72.4 53.9 90.0 85.9 5..4 59.1 54.6 47.4 68.8 1972

TCT6L 7P.ECIPITITI3M 11NCK651 FOZ CORTARO 3 5M

YEAR JAN FE3 169 APRIL MAY JUNE JULY AUG - SEPT OCT NOV OEC ANNUAL. YEAR 1945 3.76 1.26 3.00 0.08 2.58 0.31 1.55 0.30 0.34 1945

1946 0.56 0.49 0.24 0.34 0.00 .0.00 1.63 4.56 3.42 0.58 1.58 0.59 13.69 1946 1947 0.11 0.39 0.10 T T 0.00 0.51 1.22 1.90 0.03 1.57 0.86 5.40 1947 1948 3.00 0.98 1.1,3 0.00 1.30 0.37 1.49 1.51 1.25 1.31 A.'3 7 1.23 44 1948 1949 1.41 1.00 0.37 1.23 0.00 0.00 3.69 0.77 0.92 1.63 0.24 6.86 '3.66 1949 1953 3.33 1.79 0.11 3.30 0.00 1.28 3.92 0.26 3.23 1.03 0.14 0.18 8.3E 1950

1351 1.24 1.13 1.17 2.12 T 0.00 1.31 1.77 n.47 2.09 1.22 0.64 11.71 1951 1952 0.67 0.15 2.93 1.47 0.02 0.44 3.24 3.05 9.23 0.00 2.57 0.70 15.50 1952 1951 0.23 0.92 3.71 0.04 0.00 0.00 5.69 0.50 0.00 0.30 0.10 0.15 9.34 1951 1954 0.99 0.62 2.42 3.10 0.22 0.47 2.65 1.53 2.91 7.04 0.00 0.17 12.52 1954 1955 2.1. 0.16 0.01 0.36 0.00 0.15 3.61 1.14 5.00 0.00 0.01 0.17 13.27 1955

1956 1.65 0.56 1.00 0.01 0.03 0.01 3.37 0.15 0.07 5.29 0.00 0.30 6.2' 1956 1957 1.53 1.06 1.29 3.10 1.37 0.91 1.09 3.18 0.00 1.45 0.53 0.99 16.71 1957 1955 T 2.16 2.55 1.04 0.00 0.28 3.63 2.32 0.60 0.27 1.32 0.00 11.47 195A 1954 0.30 3.32 0.30 1.01 3.03 0.20 2.57 3.55 T 1.52 0.23 2.55 11.76 1959 1960 1.00 3.54 0.24 0.30 0.00 T 0.94 0.81 1.34 3.49 0.02 0.78 7.16 1960

1961 1.16 2.03 3.29 0.00 0.00 0.25 1.60 3.44 0.37 0.54 0.75 2.19 10.82 1961 1962 0.91 3.52 3.45 1 0.00 0.70 0.99 1.17 5.15 0.52 0.40 1.02_ 12.91 1962 1963 1.03 2.24 9.52 0.62 0.00 0.35 0.63 4.38 3.25 0.34 1.1.1 0.00 12.62 1963 1964 0.30 1.00 3.47 0.43 0.00 0.00 0.00 1.92 1.79 1.16E 0.40 1.03 9.23 1964 1965 3.73 1.65 0.19 0.39 0.00 0.60 0.50 1.57 0.47 1.37 0.98 6.41 14.12 1965

1966 0.97 2.77 3.09 0.23 3.01 3.00 2.85 2.46 2.46 0.43 1.82 0.24 11.98 1966 1967 1.13 3.04 3.25 0.35 0.16 0.15 4.34 1.45 1.20 1.14 1.30 5.67 17.03 1967 1968 0.11 1.79 1.52 3.10 0.09 3.00 1.26 2.44 6.00 0.74 1.31 1.29 11.23 1969 1969 0.69 0.56 0.38 0.00 0.67 0.00 1.77 1.11 0.99 3.22 1.04 0.49 4.14 1969 1970 3.30 ..15E 1.01E 3.00 0.00 0.00 0.70 1.76 3.47 0.00 0.16 0.45 7.20 1970

1971 0.'1 0.66 3.13 0.47 0.03 0.60 0.94 9.82 0.72 1.58 0.66 2.39 18.47 1971 1972 0..4 0.33 0.33 3.00 0.11 0.53 1.00 2.17 0.50 4.50 2.19 0.55 12.11 1972

284 CLIMATOLOGICAL SUMMARY a 120NA S1N04A OESEdT r.7SCUm LATITUDE: 3215' ° 045 F04 PERIOD 1943 - 1971 EXTREMES FnP PÇPIDD 1941 - 1972 IONGITUOE 111- 10' ;415 ELEV. VII 2815

Estimated Mean number of days TemOenf_'e í'I' Frefptalim Totals (tootles) mean ' relative Temperatures humidity Mar. in. Weans E.::emes Snow, Sleet. Hail tpertenQ

. i

I 22 ç Áÿ áa: ° S _.- Ì = ^ _ q .__- ~ _ - ..n 3 I i ;,i 'c ó É ,2-, ( 5 I 4 2 2 a a_ I> A s 4- " 3 c >- 1 o.-á+°f-',' 2 P,'c i ó tal 15 15 17 10 17 17 15 la 15 12 11 11 11 !Aa

JAN 65.3 29.5 52.3 6 9 1971 13 1171 355 0.63 1.37 1963 T T 1962 60 42 3 0 0 6 0 JAN

F10 il.7 .2.4 56.6 9C íS63 2ö 1965 217 0.35 1.59 -1.165 0.3 5.0 1965 58 37 1 0 1 0 FER

T nAN 73.Z .5.J 5..1 '5 19E1 25 1971 201 0.62 0.73 1970 T 1954 46 31 3 I 0 1 0 MAR

.ii 32.7 50.2 6 1.2 112 1965 29 19.5 59 0.14 0.65 1463 T T 1953 17 23 1 6 0 8 0 APR nay 91.1 58.3 71.0 1.17 1.51 J6 1969 13 0.11 0.95 1944 0.0 0.0 '4 17 24 1 0 0 MA JUN 99.7 66.9 11.3 lib 0173 .8 1968 0 0.25 1.19 1150 T T 1952 27 08 29 0 1 0 JUN

Jul 100.. 71.7 67.1 11. 1910 60 1964 3 2.19 2.07 1946 T t 1954 .5 31 6 .10 0 it 0 JUL

AuL 96.6 72.6 85.6 111 1944 51 1954 0 1.6.1 2.20 1944 T T 1,850 5e 36 5 30 0 0 0 AU6 SCV 9o.1 09,4 62.6 109 115J 44 1966 0 1.29 1.95 1970 0.0 3.0 52 34 2' 0 0 0 SEP OCT 67.Z 59.6 73.4 101 1950 31 1971 17 0.69 2.40 1945 0.0 0.3 46 33 2 16 n 0 0 OCT NOY 74.6 43.2 61.4 91 1967 26 1953 142 0.70 1.40 1946 T T 1964 46 33 2 0 1 0 NOV JlC 67.2 .1.7 5..5 35 1970 20 1968 353 0.62 0.82 1371 T 5.0 1971 59 48 3 7 0 4 0 DEC

JUN JAN nCT 1PC rEAr 57.9 55.5 60.9 116 1377 13 1971 1355 9.52 2.40 1955 0.3 5.0 1971 57 1P 28 159 0 15 0 YELP

C1,LMATE OF ARIZONA SONORA DESERT MUSEUM, ARIZONA Arizona Sonora Desert museum lies at an elevation of 2815 feet on the western fringes of the Tucson Mountains, 12 miles west -northwest of Tucson. The combination of panoramic beauty, featuring the most dense saguaro stand in the world, and a multitudinous display of Arizona - Sonora animals and desert plants annually draws more than two hundred thousand visitors. To the west lies the broad, fiat Avra Valley which is permeated by an enormity of dry washes, emanating from the surrounding mountains. The normally drySantaCruz flows northwestward, li miles east of the museum. Elevations exceeding 8500 feet are found on Mt.Lem. -on :n the Santa Catalina Mountains, 29 miles to the northeast, on Spud Rock in the Rincon Mountains, 31 miles to the east and on awe- inspiring ht. Wrightson in the Santa Rita Mountains, 41 miles to the south -southeast. 1,ow desert hills such as the Roskruye and Silver 3eí1 Mountains are found to the west and northwest. Seventeen miles to the southeast stands the historically distinguished San Xavier del Sac Mission, possessing works of art whose sophisticated and folk traditions are links to the dothic, 3arotiue and Churrigueresque styles of Spain and Mexico. The Saguaro National Monument, 28 miles to the east- south- east, contains an astonishing variety of picturesque desert growth. Vegetation in the Tucson Mountains is dominated by palo verde, cacti and Surr sage. Jreosote bushis most common to the west of the Arizona Sonora Desert Museum in the Avra Valley, although mesquite and salt Seals are found in the Drawley Wash bottoms.,At intermediate elevations in the Catalina and Rincon Mountains ample quantities of chaparral and oak woodland exist, while forests of yellow pine are prevalent above 6500 feet. An essentially arid climate predominates at the Arizona Sonora Desert Museum, less than ten inches of precipitation falling in most years. :,mounts have fluctuated from less than two inches in 1968 to slightly more than seventeen inches in 1946. The wettest period occurs inthe summer months and is associated with an influx of moist, tropical air from the 'south, normally from the Oulf of Mexico. On the extremely infrequent occasions when weak tropical storms traverse Arizona from the southwest, significant rainfall may be recorded. Drought conditons are most harsh during the months of May and June, each of which typically receives below two tenths of an Inch of rain. Only small amounts of precipitation are measured in the winter months at the Arizona Sonora Desert Museum. The dominant pattern producing most of these rains consists of eastward moving systems that originate in the Pacific Ocean. when these disturbances follow a track sufficiently far south, the related rain showers usually cover a vide area and tend to be intermittent for several days. insignificant amounts of snowfall are received and the trace quantities that fall melt almost immediately.

During the summer months, temperatures at the Arizona Sonora Desert Museum quite often soar above the 100 degree mark. while both the average daytime and nighttime temperatures are slightly higher than those in Tucson, evenings still remain reasonably comfortable. The magnificence of the surrounding desert scenery is more than ample compensation for any discomfort encountered on hot days and fortunately, the most severe ;eat is limited to only a few hours.

During the rest of the year, the Arizona Sonora Desert Museum has one of the most mild, gentle climates In Arizona. Average temperatures in December and January rarely drop below 50 degrees and daytime readings well into the seventies are frequently recorded. Freezing temperatures are highly atypical of this desert region, being recorded on about fiteen days in an average year. A truly ideal climate accompanies the tens of thousands of inspired tourists that eagerly journey to the beautiful Arizona Sonora Desert Museum.

285 Av PAGE MCNiNLT1L49ERATURES 1F1 FJR ARIZONA SONORA DESERT iUSEU. rEAR JAN FES MAP APRIL MAT JJVE JULI AUG SEPT OCT 40V GEC ANNUAL TrA9 1941 73.4 61.8 51.1 1943 19 44 53.2 51.6 57.7 63.5 74.7g 41.4 37.4 50.1 71.5 51.2 53.2 68.1 1944 19.5 51.6 56.3 55.2 54.9 73.9 73.2e 55.6 84.2 52.1 72.1 54.4 1945

1946 51.3 54.. 61.6 72.0 72.8 A7.4 35.4 81.9 81.A 66.7 57.6 58.8 69.5 1945 1947 1941 1945 57.4 54.7 1948 1949 43.3 52.3 63.0 64.4 75.2s 84.7 45.7 55.3 51.4 55.9 54.5 53.8 69.3 1949 1950' 52.9 59.5 62.4/ ,2.. 74.2 53.5 53.2 85.51 80.5 79.9 57.44 62.1 72.1 1950

1951 53.2 56.2 61.1 55.9 75.3 52.61 55.4 55.81 85.44 74.5s 53.1 53.4 10.2 1951 1952 53.34 53.7 53.4 65.1: 15.8 04.1 57.21 85.7 84.8$ 79.5$ 57.7r 195? 1953 65.0: 71.31 84.5 85.31 87.01 71.5$ 57.74 1951 1354 60.6 63.31 69.4 75.51 81-.3 84.8 82.3 1954 1555 1955

1956 :956 1957 1957 1958 1958 1959 1959 1960 1.960

1961 1960 1962 53.2 57.3 56.6 72.5 73.9 52.4 58.11 0962 1963 .9.3 59.9 60.2 65.5 75.6 81.4 49.7 83.3 51.2 75.7 54.7 0961 196 62.8 73.4 82.8 54.61 52.6 74.6 56.7 53.9 1954 1965 54.2 51.7 67.1 74.3 1955

1966 52.4$ 65.2s 55.8 1966 1967 53.5 58.2 65.4 65.0 76.0 83.7s 55.6 48.4 84.7 76.3 65.5 49.n 11.3 1.367 1968 59.5s 59.9 64.6 73.6 54.5 58.2 84.9 82.6 75.4 59.5 52.4 1955 1969 56.2 53.9 56.8 65.5 74.7s 82.7 88.7 56.8 84.2 70.7 61.9 57.0 77.3 1969 1970 55.1 61.3 59.0 64.9 75.4 87.. 90.5 47.1 79.5 65.6 54.1 54.4 73.9 1970

1971 53.8 56.3 63.1 66.6 72.6 43.5 54.0 81.5 50.5 66.3 50.2 50.3 65.1 1971 1972 53.3 59.6 66.6 59.1 74.5 84.1 85.8 54.5 50.1 66.9 54.5 53.5 69.6 1977

TOTALPRECIPITATION (INCHES) FORARIZONA S0N09ADESERTMUSEUM

YEAR JAN FEB . +3R APRIL 7157 JUNE JULY AUG SEPT OCT NOV CEC ANNUAL YELP 1943 0.07 0.00 0.40 1963 1344 0.15 3.75 7.41 0.55 0.95 C.00 0.94 2.59 1.11 1.93 1.60 1.39 12.11 1444 1945 3.66 0.41 0.42 0.00 0.00 0.00 2.32 4.43 0.00 3.14 0.47 1945

1946 1.31 0.40 0.52 0.18 0.00 T 3.91 3.90 3.71 0.27 1.67 0.85 17.15 1945 1947 1447 1946 T 0.47 1944 1949 S.4J 0.20 3.13 0.22 1.00 0.47 1.33 0.41 0.55 0.57 0.22 0.44 6.54 1949 1950 0.17 1.12 0.21 0.00 0.11 2.07 3.75 0.54 0.19 3.00 0.33 s T 5.56 1950

1951 3.95 T 0.11 1.58 3.00 0.00 2.56 1.44 7.34 1.71 1.04 0.54 10.29 1951 1952 0.22 0.08 1.75 1.04 0.07 0.51 1.60 1.05 1.09 0.01 1.97 0.38 10.09 (952 1953 0.05E 1.11E 3.411 5.06 0.00 0.0C 2.95 0.62 0..00 0.03 0.03 0.06 S.CS 1951 1954 0.31 0.25 0.74 3.10 0.24 0.32 1.51 1.11 2.74E 1.04E 0.00 5.20E 9.80 1954 1955 1955

1956 1956 1457 1957 1958 1954 1959 1959 1960 1960

1961 1961 1962 1.15 0.53 0.39 T 3.30 0.31 1.47 1.462 1961 1.66 3.30 0.52 3.65 0.10 3.09 3.13 5.54 7.00 0.85 1.21E 0.00 10.65 1963 1964 0.15E 0.04E 0.59E 0.54 0.10 0.00 3.70 1.55 1.53E 1.89 0.93 1.03 1 4. 05 1964 1965 0.87 1.04 0.62 3.00 1465

1966 1.33 T 0.22 l96ß 1967 0.12 T 7.07 0.00 3.15 0.32 2.65 0.32 0.53 4.00 0.91 3.44 5.42 1967 1968 0.17E 0.30 3.37 3.39 3.00 1.17 0.52 0.00 0.00 C.03 0.15 0.22 1.15 1964 1969 ...72 1 .24 0.29 0.06 3.37 3.30 1.20 2.52 0.o0 0.15 1.98 0.69 4.22 1969 1970 0.30 0.00 2.21 0.17 0.00 0.13 1.87 1.24 5.19 0.52 0.16 0.35 11.84 1970

1971 0.30 C.75 3.30 0'.40 0.07 0.00 1.05 5.82 1.56 1.93 0.44 2.14 15.51 1971 1972 0.03 0.03 0.00 0.00 0.45 1.14 5.00 2.76 1.19 4.27 1.64 0.23 11.91 1577

286 CLIMATOLOGICAL SUMMARY T.JCSON .1:9P .:ELL14f. LIE? F198 UftTUOE: 32 174 15ÁN: F06 'E91J0 1949 -1970 'FYT,E+1E5 F10 0FOI00 1949 - 1972 LOfiCITUOE: 110 57' 6746 . LP/. tifT;- 2330

EstimateE Mean number of days nrerat;ro f' f. I Prec Citatmn Iota!s fineries) mean Tec.oeratures i ! refahve humidity Max. Min. Meanl Estiea:es Snow, $IBe!, flail (percent)

1 v _ t -' 1 - . o ö .z7 ITT s= = j o i, ó $ p ;= ó _ _ t 22 24 29 22 23 22 21 27 21 21 71 lA1

JL4 6b.e ,. 41.5 43 1451 9 1150 468 1.49 1.16 196n T 1.5 1951 61 41 3 t7 0 JAN Ffu 63.5 1..1 51.i 42 .i57 15 1972 366 0.72 1.21 1961 0.7 ?.5 1965 59 15 2 0 13 0 FE9 NsN 14.1 35.2 55.2 .. 1950 17 1355 247 0.75 ..SZ 1967 T 3.5 19E4 47 29 2. 1 6 0 YAR

s:R __. -.. 61.7 131 1965 36 1910 91 3.45 1.73 1152 T 1.5 1952 19 22 ? 5 0 1 0 AP,

+-T 41., 5t.2 71.1 119 1!55 31 1167 15 0.11 1.69 1167 T r 1954 29 16 1 70 7 0 MAT J,.r, i4.3 c.J.3 SJ.. 11. 1473 41 1171 O 1.29 2.48 1150 T T 1950 29 11 1 2Q J 0 0 JUN

JUL 113.I 70.6 55.5 111 1355 56 1962 0 2.47 2.20 1955 T T 1952 46 11 6 10 a O 0 JUL 6.:13 47.. 55.4 51.4 113 1972 52 1354 0 2.25 2.12 1951 r 7' 1952 59 36 5 3n 0 a 0 AuG S1P 96.5 62.3 71.3 139 1157 35 1365 0 1.31 2.92 1962 3.1 0.0 54 32 2 77 1 0 0 5E0 T CCt 67.1 49.8 54.5 t06 1455 25 1371 33 0.61 1.13 1151 T 1959 41 33 2 15 0 . 0 OCT r.OV 75.6 3S.4 57.3 90 1353' 19 1456 237 0.60 1.09 1952 1.2 4.0 1958 48 37 2 0 5 0 NOV ..__ ;7.7 32.3 52.7 55 1154 15 t954 451 1.16 1.94 1967 3.1 3.0 1971 61 47 3 0 4 17 O OFC

J'JN JAN SEP NOV rE G. S..2 .5.7 6b.5 ít4 1971. 9 1950 1955 11.13 2.92 1062 0.5 4.0 1954 48 32 31 156 0 66 0 YEAR

:v74A1.E`C.sfiLT TE40E1ATU4FS CFI FOR TUCSIN rT AMPgELL AVE EnoPOeM

TEA JA: FE? 15V APRIL MAY JUNE JULY AuG SEOT OCT NOY 4EC ANNUAL YEAR 44 55.1 64.3 69.9 80.0 52.9 51.4 50.3 63.9 59.6 47.2 1949 1954 4..4 53.5 57.7 55.5 68.5 78.9 82.2 82.7 75.0 73.7 59.7 53.6 56.7 1950

1951 .5.6 51.6 55.3 53.3 71.3 77.0 57.7 82.6 79.9 71.0 57.0 50.8 66.3 1951 1952 51 .9.3 51.4 63.9 73.7 30.7 73.7 43.5 80.1 71.1 54.6 48.4 65.9 1952 1953 51.. ..1.6 51.1 52.4 6.5.9 81.2 85.0 74.6 7`i.5 56.8 57.7 46.0 66.0 1951 195 ,..3 57.1 68.1 73.. 74.7 55.2 81.6 79.6 70.5 59.3 51.7 57.9 1154 1955 46.3 .7.;. 57.1 62.1 70.5 60.0 83.3 82.1 74.3 71.9 57.1 53.7 65.8 1955

t95ó 53.3 .7.5 57.7 61.2 73.3 '3.6 84.5 82.5 51.1 59.0 54.4 50.0 55.4 1956 1.457 53.3 59.. 53.0 52.5 59.. 3 3. 7 77.3 54.0 79.3 68.3 52.9 52.7 67.E 1957 t956 45.1 :3.5 52.3 61.9 75.6 83.4 06.6 84.5 80.5 71.4 56.0 51.3 67.6 1955 1454 5J.7 65.. 71.7 54.5 46.8 52.3 71,0 r,7.6 55.9 51.6 57.4 1959 1960 47.5 63.5 6..9 71.6 83.5 87.0 55.1 51.9 57.0 54.Z 47.1 56.8 1960

í'1b1 5:.0 57.1 64.3. 't.2 54.6 55.3 Si.. 77.5 5'.7 54.1 49.1 66.6 1961 t5í2 49.0 51.7 51.1 66.7 64.5 77.7 54.1 55.1 81.3 67.7 54.1 52.2 66.5 1962 1,63 .5.3 55.4 56.5 61.7 73.9 76.7 42.4 41.9 71.2 51.0 49.6 1963 196. .5.1 -5.. 53.J 61.1 59.3 73.4 85.37 82.7 76.4 69.5 53.3 50.2 64.2 1964 19.5 53.9 ñJ.- 68.3 75.1 85.0 74.2 77.1 69.7 60.6 52.1 65.2 1965

1460 .7.3 4511 51.6 64.9 74.2 51.0 55.5 64.5 79.G 67.0 59.1 49.7 56.7 1966 1367 51.3 63.11 60.7 53.5 7e.5 85.6 93.6 79.7 59.1 53.6 46.9 56.2 1167 196! 50.5 57.5 57.5 62.2 71.9 30.6 44.2 75.7 54.4 55.5 . 47.9 65.2 1960 1969 53.. 52.:í 51.2 64.9 73.0 78.9 65.8 86.9 40.5 55.9 57.6 51.5 57.1 1969 :471 55.0 54.7 59.3 72.4 11.1 55.9 e4.7 75.9 52.6 57.1 49.9 65.0 1970

1V71 .7.i 57.4 62.1 S5.6 79.3 57.9 52.3 75.4 64.5 55.2 47.11 65.1 1971 1972 45.- 53.3 63.. 63.8 73.3 50.3 85.4 81.1 76.1 67.4 51.6 47.4 65.7 1972

'5773 í0EC3PTT4t10N (1NCMESt FORr7C50N C47409ELL AVE Ex* FARM

5149 JAN F01 NAN APRIL 1SY JUNE JULY AUG SEPT OCT NOV EEC ANNUAL YEAR 1949 3.21 3.18 0.00 0.18 2.83 0.25 1.20 n.59 1.04 n.13 1949 1950 4.24 1.13 1.15 0.00 0.02 2.63 2.45 0.44 1.06 0.00 0.30 0.00 4.13 1950

1951 1.21 3.1" 0.20 1.97 0.33 0.00 1.75 4.31 0.37 1.86 1.22 0.71 11.43 1151 1952 0.23 0.15 2.33 2.39 3.34 0.11 1.94 1.45 0.12 3.00 2.51 0.61 11.84 1952 1953 C.35 0.79 3.81 . 0.02 t 0.00 3.02 0.69 0.00 T 0.06 0.14 5.58 1953 1954 0.53 1.57 1.71 0.02 3.23 3.93 2.02 1.43 2.65 3.06 8.09 0.11 10.54 1954 1355 1.31 3.16 T 1.22 0.43 5.57 2.79 0.05 1.41 T 0.29 11.85 1955

195. 1.15 0.31 9.01 0.41 0.00 2.15 1.29 0.72 0.57 0.10 0.07 0.13 5.63 1956 1,57 2.35 0.5. 1.27 0.24 0.74 5.17 1.67 7.33 0.15 7.54 0.53 0.81 13.24 1957 1456 T 1.33 2.51 1.13 0.33 0.34 2.54 1.23 0.18 3.92 1.25 0.30 12.01 1958 1559 3.12 3..3 3.13 7 1.00 1.03 3.53 4.11 T 0.44 1.26 2.53 12.10 1959 1365 3.31 .,.4. 1.11 0.23 2.32 1 2.59 1.32 3.53 0.61 0.35 0.72 9.70 1960

1961 1.02 1.:4 1.74 T 1.30 7 2.07 1.61 1.54 3.61 0.35 2.17 14.44 t9ót 1i,2 1.13 3.25 1.35 1 3.00 0.33 3.75 1.59 3.21 0.30 1.35 0.99 5.50 1962 :961 1.17 :.55 2.37 1.57 . t 2.98E 4.06 0.58 0.63 1.14 1.08 14.17 1463

1.51 . 146. 1.55 _.52 7.33 1 4.26 2.5 2.50 1.09 1.24 1.08 14.31 1145 19,5 1115 1.75 3.41 3.40 1 3.16 1.36 1.72 0.61 0.35 0.62' 5.77 14.11 1965

1960 1.56 2.31 0.01 0.26 0.01 0.37 2.49 1.91 3.13 2.67 0.34 0.20 13.10 1.966 1967 ..1b 3.04 3.36 1.55 0.70 3.07 3.07 1122 0.96 1.3> 0.33 4.27 13.02 l'í7 146. 1.21 ..55 .75 ...... '9 12. la..

287 CLIMATOLOGICAL SUMMARY tuCSON NURSL27 LATITUOE: 32 16' 1E1'45 FOR PF *TOC 1943 -1151 EYTPEYES r^P 'F'119 1141 -1151 LONCITL'CE:111 00' SoLS ELr;. Fr} 2285

Esama.ed Mean number a! "aPays Temperature t"F1 Ptec Mahon Totals (Inches)

. mean relative rec»e atures `riC y Sia1- 41,* h',eans Estrea:ez Snow. Sleet. Hai! ercenll

tt o .. ó S 1

I ög < rs;> 1" fr ::-'' ö=Dao= 1 _

IAi 4 1 Idi

JAN 3.51- 0..7 1149 2.3 0.0 .0AN EEO 3.71 9.14 1150 3.1 9.0 rE9 NAR 7.24 3.23 1149 1.3 0. YAP AP4 0..0 0.42 1951 3.3 1.3 3 APP MAI 3.00 1.1 0 MAY JJN 1.79 2.15 1950 2.1 1.7 JUN >,27 Jut 1.40 1150 3.n 0.0 8 JUL 1UG 1.42 1.51 04e-. n.7 0.3 6 Aur. SEP 0.51 3.76 1948 2.0 7.7 2 SEP OCT 0.31 1.30 1949 3.0 3.0 3 OCT NOY 0.30 1.0 0 NOV DEC 0.68 0.+6 1948 0.9 0.0 4 'DEC

J'J N YEAR 7.15 2.35 1150 0.0 37 YEA*

1CTALPRECIPTTAt;39t NCHES1 FORTU CSON NUPSE *,Y

TCAP JAN FEO MAR APRIL nay J'JNE JULY Au0 5r0T 117 NOV r,EC ANNUAL TEAR 1948 3.00 I.53 3.21 ..30 .33 0.71 1.11 3.27 0.87 1.40 0.00 0.96 1.31 1948 1949 1.45 0.13 3.37 0.26 0.00 ,. 0.00 1.99 3.32 0.57 0.53 0.30 0.94 6.56 1949 1950 0.14 ..53 0.20 0.00 0.30 3.07 3.58 0.33 0.25 0.00 6.09 0.14 1.4 1950

1951 0.74 3.36 0'.10 1.35 0.00 0.09 1.53 1.7o 0.34 1951

288 CLIMATOLOGICAL SUMMARY T1;.SO4 mnc,ETI,. :1'JS.+v,r:0:r LATITUDE: 32 15' ',FANSFO.I Rtz100 1941 - 197a FrieFMFS FOR RE)111 1914 - 1972 1CItwU0E: 11C 50' e9Oc ïf(.7: 2526

Estimated Mean number at Jays t tcpe. a:u: ei' nl Prec prtahon iot3ls ;Inches) sean reialive Temperatures humidity Mai. M'n. Vrms Eitremes Snow. Sleet. Nail r,ertntl

¡ _ E

I = _ I û -° - c - - ° c li. °° -=

! I > S. .°. c c ' c r c, ó o.- r..--Tt ,-, a o `-

t31 33 31 Is la 20 37 39 33 17 79 ?3 ?? 2? 22 lal

JaM 64.5 334 44.1 98 1953 12 1937 483 3.95 1.15 1115 1.3 S.0 1949 58 42 4 1 15 8 JIM 5t3 6S.1 35.1 51.7 11 1157 .. 1953 379 4.76 1.34 1958 1.1 3.0 1965 59 36 3 n 0 rEa

. max 12.. 55.5 44 1471 1S 1951 102 0.81 1.40 1167 r 1.0 1948 45 31 3 3 1 5 3 MAP avv S1.5 45.1 61.4 112 19.J 25 1938 .a8 0.43 1.30 1942 r 13 1944 3Q 5 1 1 0 3°° miY 'i0.9 52.3 7:., .19 1455 32 I467 ,24 3.14 1.01 1943 1.1 1.1 21 15 1 19 1 1 mlY

JJM 996 61.9 80.8 t:4 1973 4. t955 0 3.17 1.24 1918 r 1952 21 19 1 28 J e 0 JUN

JUL 100.6 71.5 76.1 11Z 1969 56 1918 3 1.95 2.73 1919 1.3 1.3 45 33 6 30 1 3 0 Pit 3J0 97.5 69.9 83.1 111 1962 56 1954 3 2.09 2.92 194n T T-1951 51 17 h 30 1 0 3 3U.

510 95.5 63.9 799 110 1945 40 1965 I 1.14 1.98 1949 t t 1141 53 31 1 75 8 0 1 SE° OCT 5b.4 51.7 69.1 1955 27 1471 36 0.72 1.79 1951 0.0 0.0 46 13 3 14 0 1 O 9,14 ,... 40.3 57.2 92 1934 19 1956 240 0.64 1.64 193t 0.1 1.0 47 17 2 0 5 0 NOV OEO 66.6 34.0 533 89 1454 14 1954 458 1.04 1.51 1957 T 4.3 1171 60 47 4 3 1 15 0 CEC

.eel'.'J9 J44 LUG Jam T2i1t e3.J 41.9 66.6 114 l'í71 12 1337 2331 10.85 2.92 1940 ... 5.1 1.41 47 32 3S 152 1 54 0 7c70.

CLIMATE OF TUCSON MAGNETIC OBSERVATORY, ARIZONA

The Tucson Magnetic Observatory is located at an elevation of 2526 feet, eight miles east -northeast of Tucson. It lies in a beautiful flac desert valley in southeastern Arizona that is encircled by a number of picturesque mountain ranges, a majestic setting indeed. Mt...canon in the Santa Catalina Mountains rises to over 9000 feet, fourteen miles to the north -northeast, Mt. Wrightson in the Santa Rita Mountains ascends to over 9400 feet, thirty -nine miles to the south and Spud Rock in the Rincon Moun- tains a:.proacnes 36J0 feet.'cigntcen miles to the east- southeast. The terrain to the west slopes downward irregularly for about twelve miles onto the flood plain of the Santa Cruz River and then rises some 2000 feet in six miles to the peaks of theTucson Mountains. The Observatory lies about one -half mile west of Pantano Wash and one mile south of the Rillito River. Both are normally dry and meet about two miles to the northwest. The Arizona- Sonora Desert Museum, a natural thriving community consisting of dense stands of saguaros interacting with desert animals and insects, is found in the Tucson Mountains While the very colorful Saguaro national Monument lies on the west slopes of the Rincor. Mountains. Nearly fourteen miles to the southwest the San Xavier del Bac Mission contains sophisticated works of art linking the Gothic, Baroque and Churrigueresque styles of Spain and Mexico. The dominant vegetation type in the undeveloped non -irrigated section near the Tucson Magnetic Observatory is creosote bush, with mesquite prevailing along the slopes of the Santa Catalina, Santa Rita and Rincon Mountains. At intermediate elevations in each of these ranges chaparral and oak woodland are quite common, giving way to forests dominated by yellowpine near the mountain crests. Almost half of the Observatory's average annual precipitation of slightly under eleven inches normally occurs during the monsoon- dominated months of July, August, and September. Most of the warm season rains are the result of thunderstorm activity associated with the influx of warm, moist air from the Gulf of Mexico into southeastern Arizona. Almost daily, cumulonimbus .,.i a,nt may be observed over the nearby mountains and by late afternoon or early evening thunderstorms often traverse the desert valley, accompanied by gusty winds. Rarely do the associated thundershowers last for more than thirty or forty minutes at a particular location. The heaviest summer precipitation often falls in conjunction with the occasional passege.,over Arizona of a si.jnilicantly weakened tropical storm system from the southwest.

Winter precipitation at the Tucson magnetic Observatory, less than one -half an inch of which typioally falls as snow, is generally longer -lasting and more widespread than the intense summer thundershowers.However, in both frequency of occurrence and :mount produced, cold season precipitation is rather difficult to predict, varying greatly from year to year. Eastward jour- neyer..: cyclonic storms, originating in the Pacific Ocean, are the principal systems bringing moisture into southern Arizona at this time of year. .:ace in a while these middle latitude storms will follow a more southerly track than usual and intensify of the .oast of southern Cali_fcrnia before entering the state. When these conditions exist precipitation amounts can be considerable. in 'Jece-ber 1565,a series of these storms deposited almost seven inches of rain on the Tucson basin. Runoff filled both Pantano wash ana the :illitoco overflowing, destroying several bridges.

The...cson Magnetic observatory has a warm summer climate, temperatures in mid -July normally fluctuating from the lower seventies- at -aunt to just over one hundred degrees in the afternoon hours. Readings above 110 degrees are sometimes recorded, especially in .ate dune and early July. However, it is not common for these severe temperatures to persist from day to day for mulethan a week. At ,.iç!:tt,.e residents of this region are frequently treated to brillant displays of lightning over the mountain peaks to the north and cast. A healthful, comfortable winter climate is usually found at the Tucson Magnetic Observatory. Average mid -winter temperatures never about fifty degrees, readings ranging from nighttime minima in the lower thirties to daytime maxima in the middle sixties. M ixima :nt.'.e tHmer eighties have been reported in January and February while at the opposite extreme, minima have never dropped below ten degrees.

289 AvE414EnNtr'Lr T29PE91r WES tF1 F09 t1X5O4 NAGNETiC 095ERVAT0IY rt AK JAN FFt' rtb't APRIL MAY JUNE JULY AUG 5'P1 "'r NOV CFC AN4U /L YEAR 1934 70.8 57.1 51.5 1914 1935 52.6 54.5 55.1 51.7 66.3 52.1 65.1 52.4 77.5 67.4 54.3 50.6 66.2 1935

1936 47.3 55.. 06.2 75.2 64.3 57'.4 11.0 77.1 57.6 51.1 46.7 57.1 1916 1917 39.7 5..1 61.6 71.7 10.3 55.6 65.6 11.4 '1.01 51.0 53.3 56.3 I937 1936 50.7 53.1 51.7 64.2 70.5 50.3 53.4 12.7 61.0 68.41 53.7 51.9 56.3 1516 1939 44.0 .3.6 57.i 65.6.1 'I.4 82.5 66.4 83.6/ 79.9 67.6 52.3 55.5 67.3 1939 1947 52.3 52.. 51.6 55.4 75.7 52.4 96.6 14.2 87.1 59.5 55.8 55.5 59.1 1940

19.1 51.2 55.J 55.7 54.6 71.4 76.6 55.4 63.3 77.6 55.8 59.3 50.7 56.1 1141 1942 51.6 43.6 53.17 61.6 73.6 80.1 68.8 84,4 50.0 57.7 65.6 52.4 65.+ 1942 1943 52.1 57.2 51.5 63.3 73.5 81.4 17.4 83.6 81.3 69.6 59.3 51.6 55.7 1943 19.4 .7. .9.9 54.2 50.9 71.5 79.3 16.2 85.9 7.4.0 71.2 54.9 50.5 55.0 1944 1345 49.3 51.6 51.5 62.1 71.6 77.7 84.9 65.2 50.t 70.1 55.1 49.4 56.1 1945

194E .7.3 53.2 56.3 59.1 71.6 14.3 15.8 53.5 62.1 64.2 51.5 51.2 56.7 1946 1947 41.4 55.4 51.3 63.7 75.3 10.5 17.9 83.1 51.7 56.5 53.3 47.4 67.1 1947 1940 49.6 53.3 51.2 66.1 73.1 92.2 55.8 85.3 57.4 72.5 52.7 50.7 57.1 1946 15.9 -3.3 49.4 56.5 65.5 71.1 81.7 54.9 33.4 82.2 55.9 62.6 50.1 55.4 1949 1550 48.6 55.3 55.1 67.2 69.6 79.1 12.2 13.1 .76.0 73.9 1,7.6 54.5 57.4 1950

1951 4,.9 ?1.7 55.6 53.3 71.9 77.4 85.9 51.6 511.5 73.1 56.4 49.6 55.4 1951 1952 4.3 9.5 5.3.7 61.3 73.6 83.3 54.4 64.6 61.9 72.6 54.2 45.0 55.7 1952 1953 S:.5 57.4 62.5 56.1 92.3 66.3 65.6 80.2 56.5 59.1 45.6 66.1 1951 íS54 53.3 59.1 56.3 66.1 73.5 80.5 35.8 82.5 61.1 71.2 51.6 51.6 50.3 1954 1455 5.0 46.7 56.. 61.3 61.5 79.4 53.3 81.4 79.0 71.8 55.11 52.5 45.2 1955 t956 53.1 46.1 56.. 61.6 13.1 14.3 54.5 52.2 51.76 57.9 55.14 49.61 65.3 1956 1957 '51.6 56. 56.3 60.64 56.1 63.4 67.8 84.14 79.31 67.1 51.91 51.6 66.7 1957 1956 47.5s 53.2 5 L11 61.61 76.24 13.3: 66.4 54.1 81.1 71.7 56.6 53.0 67.1 1956 1959 51.1 49.3 55.9 61.1 77.6 54.4 55.41 52.6 76.6 56.7 57.Z 51.1 56.9 1959 1960 45.3 .6.0 56.5 53.2 70.3 52.5 66.1 95.7 11.31 56.9 57.5 47.44 55.8 1960

1461 52.5 53.1 S7.. 64.. 71.. 64.5 55.6 63.9 7'.e 56.2 54.2 49.6 57.0 1951 1962 42.4 53.4 51.5 67.3 69.7 75.6 55.3 65.3 61.3' 56.1 66.1 52.7 67.0 1962 1461 .7.J 55.6 55.1, 61.2 74.6 77.61 87.6 32.7 62.1 72.0 57.38 50.0 67.0 1961 1464 44.54 45.1 5? 61.1 73.41 80.01 15.71 61.5 76.61 '1.0 53.3 50.4 54.4 1964 1465 51.1 51..1 51.0 62.7 67.9 75.3 56.0 54.4 77.1 '3.0 61.1 51.6 55.1 1165

1960 4c.. .6.3 57.1 53.6 71.9 61.0 55.5 64.1 p1.5 65.9 59.2 49.7 66.0 1956 1967 48.2 51.3 59.1 53.6 69.7 76.9 65.1 84.6 13.2 70.0 61.7 47.1 65.5 1967 t46a SG. 57.. 56.1 61.1 70.5 31.2 84.3 60.2 79.5 69.1 56.1 47.9 65.1 1968 1969 53.5 50.3 51.7 64.6 73.4 79.4 56.5 27.5 81.7 66.1 58..1 51.5 57.1 1969 1173 47.9 55.1 53.5 55.2 72.9 62.1 17,1 85.0 76.5 55.6 55.4 44.6 65.9 1970

1911 49.4 50.4 57.7 62.3 66.3 79.9 85.2 81.9 76.9 54.7 55.0 47.4 65.3 1171 1972 46.8 53.1 53.1 63.3 71.1 62.2 66.8 13.0 79.6 67.6 51.7 48.5 66.4 1972

TGTaIfwC1P31aT104 t14C1tE5FJt176S0N 1a0NET3C 085E0VATO7T

4116 JSt1 FEG .5651 APRIL NAY JUNE JULY 1176 SEPT OCT 40y OFC ANNUAL TEAR 193. 0.30 7.66 2.16 1914 1935 1.13 2.01 1.37 1' 0.13 0.00 2.11 3.73 1.00 T 2.13 0.74 14.56 1935

1935 1.15 1.7C 3.74 3.35 T 0.30 1.69 4.59 1.05 0.10 0.86 0.87 12.40 1936 1937 1.52 3.2: 3.37 3.03 G.25 0.15 2.49 2.76 0.58 0.24 0.35 0.87 16.31 1937 1931 3.51 1.72 3.77 0.23 0.01 1.39 0.56 1.65 0.43 1.01 0.11 1.06 7.37 2936 1939 3.17 1..5 3.5. 3.21 0.00 T 5.17 1.69 1.27 0.49 0.54 0.27 11.85 1939 1940 0.76 1.76 3.03 3.37 0.11 1..1 0.67 3.64 1.75 0.31 1.69 3.62 16.16 1940

1941 1.60 2.14 1.26 1.32 0.49 7 2.77 0.66 1.64 0.53 0.87 2.53 15.91 1941 1342 3.46 1.42 3.14 I.46 0.30 7 0.57 1.45 1.72 0.91 0.00 0.40 ".21 1942 2943 3.49 1.44 1.25 1.04 1.01 0.15 3.42 1.71 1.11 0.13 0.00 1.00 7.99 1941 1944 1.36 1.17 3.41 3.63 0.15 0.11 1.69 2.96 1.15 1.25 1.54 1.37 12.99 1944 1445 0.54 3.52 3.54 3.14 0.70 0.00 t.23 2.57 0.11 1.26 0.00 0.16 7.13 1945

1946 1.39 Z.II 0.51 1.11 9.30 T 2.94 3.63 2.40 0.52 0.76 0.50 13.59 1944 1947 0.10 1.74 0.21 r 7 0.25 0.61 2.13 1.68 0.49 0.53 0.19 5.50 1947 1948 T 1.33 0.67 3.00 0.30 0.02 1.59 1.17 1.12 0.78 0.02 1.15 1.11 1946 1949 3.25 5.41 1.34 T 0.01 1.50 0.54 3.96 0.23 0.21 0.56 13,10 1949 1450 0.25 1.25 3.25 T 0.15 1.47 2.17 0.15 0.51 1.05 0.00 T 6.15 1950

1951 1.52 0.21 0.23 1.64 0.14 0.00 1.16 2.53 0.36 2.15 1.27 0.91 12.00 1951 1952 0.13 1.17 2.34 1.19 9.42 0.56 1.90 3.67 0.11 3.00 2.71 0.63 14.04 195Z 7 T 1453 0.01 0.47 1.07 1 0.40 2.06 0.74 0.00 0.17 0.15 5.54 1953 1954 9.54 3.57 1.96 3.30 3.53 0.56 3.63 1.17 2.06 T T 3.07 11.36 1954 1955 1.47 0.24 3.13 ' T 4.15 0.45 4.77 2.16 0.07 0.25 0.04 0.43 10.61 1955

1956 1.1. 1.75 3.40 3.40 0.00 0.03 1.19 1.59 0.17 0.43 0.00 0.21 5.91 1956 1957 3.16 3.61 1.35 C.45 3.25 0.01 1.76 2.55 0.31 7.77 1.34 3.73 14.44 1957 1953 0.31 1.72 2.62 1.24 0.33 0.53 3.07 1.10 0.13 0.94 1.34 0.00 17.92 1956 1959 3.31 1..6 0.00 3.27 0.10 0.13 4.42 3.91 0.31 1.30 0.41 1.31 12.31 1959 1960 2.74 1.49 0.33 0.10 0.35 0.03 3.65 1.92E 0.13 5.51 0.1,6 0.63 9635 1960

1961 S.l6 3.34 0.41 T 3.35 0.00 2.82 1.92 0.85 0.51 0.56 2.54 11.19 1961 1962 1.51 1.17 1..5 3.13 9.10 T 2.52 1.11 2.41 1.20 0.21 0.81 9.71 1962 196J 1.15 2.12 0.80 1.45 0.34 0,30 1.86 2.02 1.04 1.06 0.97 0.14 11.63 196.3 1964 2.65 3.33 3.72 3.7. 0.33 0.00 1.74 4.00 2.29 1.11 1.05 1.12 13.41 1964 1965 7.69 0.69 9.17 9.47 7.36 0.03 1.15 2.11 3.60 0.35 1.31 6.99 14.59 1.965

1966 2.16 2.36 0.19 1.23 0.33 0.11 1.52 3.22 3.80 1.06 0.26 0.17 15.43 1966 1967 3.16 .:7 3..5 1.67 3.41 0.13 2.54 1.37 0.41 0.13 0.53 4.39 12.31 1967 1965 1.53 1.19 1.55 1.13 3.31 3.60 1.75 1.53 0.01 0.22 1.74 0.77 11.01 1966 1469 1.34. .7.4 3.32 1.11 3.26 3.03 2.68 1.71 0.42 0.91 1.45 0.89 1.44 1969, T 1976 7 3.33 2.31 1.2. 5.27 0.23 1.40 2.34 2.17 1.14 0.14 10.65 1970

1971 9.37 7.49 i 0.47 0.30 0.03 7.52 5.09 2.17 1.84 0.99 1.95 13.90 1911 1972 3.30 3.00 T 0.03 0..3 1..8 1.56 1.96 1.01 5.15 1.59 0.76 16.32 197?

290 CLIMATOLOGICAL SUMMARY 7UC.i2N UN14L1iI7T OF :al:Cri LATITUDE. 32 15' NFine FCP PF4I70 1941 - 1970 E479rmE5 roe 4.94107 1931 - 1972 1074GITUOL 110 57' EIEY. M 2444

Meannumber otdays I Estimated TrmT. nr : el'n Precipitationa on Totals(Inches) mean

¡ ' relative Temperaturcs humidity Max . Min. mom Extremes Snow, Sleet, Had (percenU

I Is _ _ - E. o E ó - óa° 4 °;e e E- s ä t ï Ë É > r,a4oo 2 lAl 33 20 30 25 25 28 22 21 27 22 22 ui

JAN 66.0 36.7 5t.. 90 1971 15 193? 395 0.83 1.00 1960 0.1 4.5 1949 60 4l I 0 0 9 0 JAN FCS o9.7 18.6 5..2 13 1957 10 1931 291 1.75 1.17 1963 0.2 3.8 1965 59 16 2 0 7 0rEB 1:4 74.5 .2.3 53.. 37 1472 22 1965 119 0.74 1.03 1954 T 0.7 194.4 45 28 3 1 C 2 0mi4 ar4 41.4 .... 65.1 104 1965 21 1945 54 0.45 1.10 1152 1 T 1967 17 21 2 7 5 . 8 A4 2n I:r 92.0 54.4 74.2 179 1150' 35 1967 in 3.14 0.11 1967 0.0 0.0 16 1 21 0 0 0.14Y JUN ,.O.Z 65.1 02.7 1:5 1950 48 1936 0 0.20 1.21 1954 0.0 0.0 24 15 t Z1 0 n 0 JUN

JUL 101.1 71.1 07.2 112 1150 54 1938 0 2.09 2.36 1950 0.0 0.0 44 30 6 I0 0 0 0 JUL aJv 90.A /t.b 85.2 (12 114.. 59 1162 0 2.06 2.10 1959 0.0 0.0 50 36 S In 0 0 0 AUG SCR 16.4 65.9 8t.2 112 1153 42 1965 0 1.15 2.34 1152 0,0 0.0 52 31 3 27 0 0 0 SEP OCT 77.1 54.0 70.6 104 1950 32 1971. 19 0.61 1.82 1972 0.0 0.0 48 33 2 16 0 0 0 OCT 40v 75.1 42.8 59.7 93 1967 23 1934 170 0.60 1.51 196A 0.0 0.0 47 38 2 0 2 0 40Y ..:- 61.4 17.5 52.5 05 1170 10 1954 365 1.11 1.97 1967 0.1 l.1 1941 60 47 4 0 3 7 0 OEC

JuN JAY SEo JAN 74.3 52.0 63.6 115 1960 15 1917 1493 10.73 2.14 1962 0.5 4.5 1.949 47 11 34 161 a )1 0 rEae

CLIMATE OF TUCSON, ARIZONA

Tucson lies at an elevation of about 2400 feet in a beautiful, saguaro -studded, desert valley in southeastern Arizona. The normally dry Santa Cruz River runs from south to north just west of town.Within ten to fifteen miles of Tucson the terrain is flat or gently rolling, with many dry washes. The valley floor, which rises gradually in elevation from the north and north - west to the south and southeast, is encircled by the Santa Catalina, the Tucson, and the Rincon Mountains.The highest peaks, rising sLo.'e 9000 feet, lie to the north and east at a distance of between 20 and 35 riles from Tucson. Tucson Mountain :ark, containing the well -known Arizona- Sonora Desert Museum, is located ten miles west of town. Nine miles to the south is the San Xavier del Sac mission, considered to be the most beautiful mission structure in the southwest. Some of the state's finest desert growth is found in the Saguaro National Monument, fifteen miles east and west of Tucson. Cresote bush is the most common type of vegetation in non -irrigated areas on the valley floor near Tucson. However, many different varieties of cactus may also be found. At higher elevations in the Catalina and Rincon Mountains, to the north and east of Tucson, creosote bush is replaced, first, by chaparral and oak woodland. and then, above 6500 feet, by yellow pine.

Although Tucson has a desert or semi- desert climate, the dryness and summer heat are not quite as extreme as they are further to the northwest. An average of more than ten inches of precipitation is recorded each year.Almost half of this falls during the summer. season, usually from showers and thundershowers originating in moist air that flows into Arizona from the Gulf of Mexico. Normally rainfall is most intense at Tucson in the late afternoon or early evening, but ocasionally a heavy downpour will hit the area in the middle of the night or even in the morning. It is probable that some of these storms, especially those affecting a large area, are associated with weak tropical disturbances moving northward from the Pacific Ocean and the Gulf of California.

- During most of the rest of the year Tucson receives very little precipitation. However, in winter a slight increase is noted when Pacific storms move far enough south in their journey across the country to affect Arizona. The precipitation associated with these disturbances usually falls in gentle, widespread, rain showers, which may continue intermittently for several days. Although an average of75 inches of snow falls annually at higher elevations in the Catalina Mountains, amounts are negli- çiole on the desert floor an the vicinity of Tucson. The heaviest snowfall reported in the city occurred - during an early season storm on December 8,1971. On this date 6.8 inches were recorded at the airport.

From early June to mid -September afternoon temperatures above 100 degrees are quite common at Tucson. Fortunately, the avast severe heat rarely lasts for longer thanacouple of hours before beinu dispelled either by darkness or by increasing cloudi- ness, associated with cumulus buildups to the east and south.Summer evenings are usually very pleasant, often being accompanied byabrilliant display of lightning over the nearby mountains.

Tucson is probably best known for its mild, dry winter climate, which attracts vacationists from all over the country. Early morning temperatures usually lie above the freezing point, and rarely drop low enough to damage the many crops grown in the area. The afternoons are pleasantly warm, with temperatures normally in the upper sixties or lower seventies. It isa rare day in winter that the temperature fails to reach fifty degrees.

The following table gives some information on the normal dates of first and last occurrences of certain critical minimum temperatures in the fall and spring, respectively, at Tucson.

Temperature Normal date of first Normal date of last (F) occurrence in fall occurrence in spring

32 Nov. 19 Mar. 19 28 Nov. 28 Feb. 16 24 Dec. 10 Jan. 28

291 IvfRAGE .+041IL7TFNPE,IItU9t5IFI FOR tuf.SJN uNiVEvSITY OF A'7170NA

7EAR JAN FER .AP 1P91L NAY J1149- JU:T aUT: SFPT 171 40V OFC 1440AL 7E05 1931 .9.3 53.6 57.1 67.2 71.. 51.5 16.6 02.2 11.5 55.5 54.0 4.. 67.7 1911 1972 .3.3 54.6 57.4 63.51 71.7 79.5 55.5 55.21 11.6 57.1 60.0 47.2 96.4 193' 1933 .7.7 47.5 57.5 511.6 67.1 52.4 11.4 55.9 11.6 72.0 59.4 52.2 55. 1911 1934 .9.4 56.4 61.9 59.0 71.4 79.5 5'7.6 61.5 79,6 71.5 55.7 52.1/ 59.1 1914 1935 52.1 55.0 55.1 0..7 57.6 12.0 dS.7 12.1 71.3 51.6 54.5 51.5 65.5 1915

1910 .8.8 53.2 59.1 66.9 75.1 1.3.5 56.6 53.1 77.5 61.6 59.9 50.9 67.8 1915 193/ 52 56.4 91.6 73.3 1.2 56.1 85.1 11.6 '1.0 59.. 54.1 47.1 1937 1538 52.4 5..2 57.5 0í.5 71.3 31.1 14.4 51.2 79.0 51.0 1911 1919 Sc.' .5.5 59.2 57.2 74. 32.5 97.2 14.5 79.4 57.5 52.2 '6.2 65.7 1939 1943 52.6 52.5 59.9 55.4 76.3 52.6 5b.'. 81.9 71.8 59.4 56.3 55.2 95.4 1940

1941 52.3 57.2 57.6 50.o 72.6 79.9 55.5 11.2 579.5 57.1 59.2 51.4 57 1941 1942 52.2 50.4 55.5 53.7 72.5 11.2 68.7 84.4 79.6 57.1 SA.S 51.2 57.2 0947 1943 51.1 55.9 59.2 57.6 73.6 51.2 96.1 52.5 71.7 51.6 55.7 51.7 59.1 1943 1944 4..6 51.0 56.6 63.3 73.2 50.4 37.6 87.5 79.8 71.6 54.7 50.4 57.1 1944 19.5 .9.: 52.5 55.3 6..7 7..0 75.6 17.0 94.9 71.4 05.8 55.4 49.2 66.5 1945

19.b 47.0 57.6 59.9 70.7 72.6 83.1 85.5 51.5 51.6 53.3 52.5 52.2 66.1 1949 19.7 .7.1 55.4 58.1 54.3 75.0 11.6 89.2 54.5 82.E 59.9 51.7 47.5 57.4 1947 19.8 J 51.1 5..1 66.1 75. 13.2 51.6 87.2 94.2 71.4 51.8 52.4 61.5 1941 1949 .3.8 50.9 55. 63.2 74.2 53.3 55.5 55.9 91.5 56.6 53.8 51.3 65.1 1949 1950 51.6 57.2 63.5 59.4 72.. 11.5 33.9 55.4 71.0 75.5 53.3 57.6 69.7 1950

1951 51.7 55.4 59.1 55.3 74.4 90.6 59.6 85.5 53.3 72. 1 51.7 47,1 59.1 1951 1552 51.6 52.5 53.5 56.1 77.0 53.6 67.0 87.0 33.9 75.9 55.1 50.9 69.4 1952 195J 54.5 57.5 51.2 65.6 69.4 94.0 64.0 57.5 92.6 '7.6 61.7 49.3 69.^ 1953 1954 53.7 67.3 53.5 77.9 76.4i 82.0 86.4 51.2 d1.7 71.9 51.4 52.4 69.9 195. 1955 .6.3 .3.7 53.9 63.4 71.2 61.2 63.6 67.1 83.9 73.5 59.4 55.1 67.0 1955

1556 56.4 49.5 67..1 65.1 76.2 36.3 35.8 54.5 14.2 72.9 'S.6 51.4 59.1 1956 1957 55.7 51. 67.9 66.0 '1.. 55.9 85.4 65.5 51.7 69.2 55.7 55.6 61.7 1957 1956 52.4 55.2 54.3 65.0 79.7 45. 88.0 15.0 511,3 72. 7 59.4 57.0 59.7 1.954 1959 55.7 53.7 50.3 71.1 74.1 16.1 57.9 82.6 60.57 71.1 61.2 SI.? 69.8 1954 1960 49.5 53.4 63.6 66.3 75.1 56.6 19.7 17.2 13.1/ 69.4 61.6 51.4 69.6 1960

1561 55.3 55.3 61.3 55.6 74.5 65.3 15.7 64.7 7 3. 1 59.6 55.7 51.9 61.: 1151 1962 51.., 56.9 55.6 13.51 73.1 61.3 56.5 67.1 17.7 70.7 51.5/ 54.5 69.4 1952 1163 57.7 55.5/ 6: 76.6 79.4 51.5i 53.2 92.0/ 72..1 51.1 53.1 66.7 1961 1964 40. .3.9 55.3' 53.6 72.3 11.71 51.5: 83.6 71.5 '2.5 55.7 52.11 56.7 115. 1965 53.6s 52.51 55.71 66.3 70.51 77.5 87.7 56.2 79.95 72.2$ 61.0 53.7 68.2 1965

1166 .9.2 50.5 57.6 75.5 93.7 87.6 65.4 79.8 51..6 91.4 50.4 61.3 1965 1357 .9.5 S..8t 62.35 52.It 72.2 21.2 66.2/ 95.1 11.5 72.2 51.4 55.4 69.1 195F 1955 54.5 61.1 61.5 55.. 76.0 15.2/ 57.5: 53.4 .1.7 72.2 41.7 51.3 61.7 1959 1959 55.. 54.6 55.6 59.2 75.75 82.5 19.1 89.7 54.4 59.1 51.51 55.3 70.5 1969 1470 52.2 59.7 5741 52.5 77.4 54.9 55.4 17.1 75.9 55.6 5 ?.5 54.1 59.1 1970

1971 52.5 55.3 62.4 65.4 71.9 53.5 69.4 62.. 19.4 55.. 51.5 59.1 51.' 1971 1972 53.4 55.9 67.5 55.9 75.6 63.6 89.7 85.3 81.0 70.5 55.4 52.5 70.3 1972

OCTALPRECIPITATION 11NCN5SI FORTUCSON uNIVF05117Or API2994

TEAR JAN 7E0 ,A9 AP916 `167 JUNE JULY AUG SEPT OCT NOV CFr lN11111L YEAO 1931 3.65 2.05 3.16 1.48 1.34 0.49 1.07 3.94 3.94 3.15 3.72 1.42 15.25 1911 1932 0.7. 1.27 0.40 0.12 7 0.15 2.58 1.51 0.23 1.62 0.31 2.11 13.94 1932 1933 1.13 0.24 1.20 3.03 0.03 0.10 1.60 2.23 1.52 1.92 11.47 0.35- 9.52 1911 1934 0.50 0.30 3.31 2.01 0.05 1.14 1.16 2.41 1.07 T 0.51 2.04 1.59 1974 1935 1.25 2.43 1.46 T 0.14 T 0.57 5.61 D.88 1.00 1.'9 1.24 15.77 1935

1936 1.96 1.12 3.55 3.37 1 0.06 2.82 3.13 1.51 0.14 1.11 0.85 12.74 1976

1937 1.62 C.23 0.63 0.01 0.25 T 2.06 1.29 1.4I 0.05 0.19 , 0.67 5.41 1917 1938 1.55 0.39 0..1 0.06 0.11 2.47 0.76 2.17 0.50 1.00 0.09 0.91 9.9 1911 1939 7.15 1.50 3.69 3.04 3.13 1 0.61 1.74 1.53 7.15 0.54 0.77 7,65 1919 19.0 3..5 1..7 3.05 0.21 4.52 1.14 0.84 2.54 2.72 1.13 1.62 7.12 14.75 1940

1941 1.64 2.11 1.01 3.95 0.61 T 1.46 3.40 1.45 7.75 0.11 2.12 15.52 1941 1942 0.52 1.65 3.44 1.37 0.00 T 0.59 1.11 1.56 1.47 T 0.37 9.35 1942 19.1 0..5 0.33 0.52 7 0.14 0.05 1.50 2.71 3.04 0.13 0.00 9.74 9.91 1941 1944 0.41 1.14 3.79 0.50 0.60 0.49 7.91 2.91 1.47 1.11 2.00 1.40 11.32 1944 135 3.65 0.41 3.62 0.06 1.03 0.00 1.22 2.95 0.12 1.42 0.00 0.16 7.51 1945

19.6 1.90 0.35 0.55 0.39 0.00 0.02 2.84 4.62 1.05 0.53 0.99 0.50 11.67 1945 1947 0.11 0.35 0.46 1 0.02 0.02 0.50 1.31 1.26 3.53 0.71 0.44 5.72 1947 1945 T 1..1 0.68 0300 4.03 1.46 1.03 0.99 3.91 0.55 T 1.19 5.51 1941 1949 1.4. 3.t7 0.45 0.41 3.01 0.02 1.65 0.61 0.49 7.63 0.12 1.05 7.74 1149 1950 0.2. 1.17 0.23 T 3.03 1.45 4.05 0.44 0.66 0.71 O T .SI 1950

1951 1.19 1.11 3.12 164 4. 1 0.3) 1.98 2.11 1.54 1.92 1.75 0.99 12.49 1951 1952 1.21 2.1 1.14 T C.22 1.11 1.45 0.11 1.30 2.51 0.52 10.6? 1952 1951 1.1. .32 0.33 C.25 0.02 1.19 3.96 0.22 0.13 7 0.05 1.15 5.47 1951 195. 1.57 1..3 1.55 '0.2 1.25 1..2 3.05 1..5 2.55 T 7.71 9.17 11.31 1954 1955 1.75 3.17 7.02 1 0.06 0.11 4.60 3.15 3.15 1.19 0.02 0.27 four01 1955

195b 0.99 0.76 0.011 0.37 T 1.38 1.49 1.72 0.11 1.24 7 0.15 5.82 1956 1957 2.15 0.5,8 1.01 1.20 0.76 0.21 2.54 1.54 0.72 2.49 0.42 0.71 13.35 1957 1958 T 1.51 2.39 1.96 3.35 0.53 2.22 1.1" 1.93 7.'1 1.22 1.00 12.63 1959 1959 .32 0.11 0.10 0.00 1.11 3.38 4.71 C.11 0.61 1.38 2.13 12.15 1959 1550 2.51 1.71 3.21 3.33 3.09 0.06 1.36 1.99 0.49 1.15 0.05 0.90 9.34 1960

1561 1.62 . 1.25 5.32 11.70 7.16 2.11 2.90 0.I' 1.57 4.5b 7.21 10.2' 1951 19o2 1.4 .17 2.34 0.30 0.00 0.00 2.14 1.07 3.14 1.21 7.14 0.99 10.17 1962 1963 1.17 1.73 0.60 0.50 2.31 0.31 7.68F 2.15 1.t0 3.19 1.21 0.09 1.51 1953 1164 1.31 T 1.35 3.43 0.73 3.10 1.10 t.f.. 1.99 1.45 1.25 1.77 t7..? 1154 1965 0.11 1.99 1.42 .... T 0.15 2.19 0.77 0.9 1.13 0.5 7.27 15.91 1965

1966 1.31 2.79 0.15 1.86 0.11 1.09 1.75 3.12 3.78 1.52 0.31 0.15 15.63 1965 1967 3.1. 0.32 0.57 0.65 0.74 0.29 0.51 0.55 1.02 1.26 0.70' 5.71 I5.'1 1967 1463 0..3 1.73 2.19 0.71 0.05 3.13 1.66 3.37 T 0.18 1.56 0.52 11.63 1951 1469 7.61 4.14 1.35 1.12 1.56 T 1.14 1.77 0.25 1.15 1.79 0.73 7.11 1959 1473 0.31 1.15 1.47 7.23 7.31 0.61 3.90 2.67 2.57 3.4. T 0.46 17.69 1970 292 CLIMATOLOGICAL SUMMARY 5:41N0 CANTON LATITUDE 32 19' .EANS PO.t PEQIOO 1941 - 1970 £tt.EMES rns .E.1 00 1141 - 1972 LONGITUDE: 110 49' 7155 acorn, 2640

Estimated Mean numoer ol days "rm,seratcre !'T? ' Prec pnalion Totals ¡Inches/ mean relative Tune atcres humidity Max. Min. %leans Extremes Soo., Steel, Hail IpercenU

( 1

v g e M. c É

< . I V c I c : - - ( e e ' cçç v.

3 E . É oe a j1 1a g ci ,.- f É E ( - I s. .ri. p .n.1o1

I . { , 141 33 :0 30 JZ 32 20 32 32 29 31 29 27 ?Z 22 27(A)

JAN 66.6 35.4 St.6 89 1950 15 1171 309 1.03 1.11'1965 0.2 1.7 1949 56 41 3 0 9 0 JAM rEá 59.6 16.7 5..1 33 1957 19 1355 331 0.76 1.11 1963 T 1.0 19.1 57 16 3 l ' 0 FEI st2 74.3 42.5 56.4 95 1956 23 1971 211 1.13 1.27 1970 0.1 2.0 1964 45 29 3 a 3 4 .8o AVE 83.3 49.5 66.4 134 1941 31 1945 56 3.47 ,.10 1^42 T 1967 36 21 2 6 0 0 0 Ar'a MAT 32.2 50.6 7..5 117 1953 37 1367 11 0.11 0.43 1357 0.3 0.0 25 15 1 At 0 0 0 sly JUN 100.6 65.7 53.1 115 1966 46 1355 0 0.21 2.11 1950 T T t955 27 t5 t 2. 5 0 0 JUN

JUL 102.0 72.1 87.4 114 1956 59 1945 0 2.07 2.66 1941 0.9 0.1 ' 44 29 7 30 0 3 0 JUL 8u0 49.1 70.6 65.0 113 1162 56 1954 3 2.17 3.22 1971 t 1 1954 59 16 T In 0 0 0 AUG Ste 97.0 66.0 61.5 112 1345 39 1345 0 1.14 1.78 1.62 0.1 0.3 54 3 3 27 0 1 0 Srn OCI 57,4 55.0 71.2 104 1955 24 1371 19 0.82 1.61 1951 r 1 1951 45 34 3 15 0 4 0 OCT NJ,/ 75.7 47.7 59.7 42 1947 24 1946 263 0.67 1.86 1965 r r 1964 45 36 2 0 2 0 NOv 7lC o3.2 71.1 53.1 69 1354 16 1954 366 1.20 1.91 1957 T 3.3 1971 59 46 4 3 0 6 0 AEC

JUN JAN AUG OEC ',EA,/ 54.7 57.7 66.4 115 1166 15 1971 1526 11.85 J.22 1171 0.2 1.3 1971. 46 31 39 159 0 27 7 7F10

CLIMATE OF 5AUINO CANYON, ARIZONA

Sabino Canyon lies at an elevation of 2640 feet about eleven miles east -northeast of Tucson in southern Arizona. It is a very popular recreational area for Tucsonans, featuring one of the prettiest and most photogenic streams in Arizona. plenty of cottonwood. mesquite, and palo verde trees for shade, steep saguaro -studded canyon walls. and a number of easy trails. The canyon has a general north -south orientation, extending upward into the Santa Catalina Mountains which rise to over 9000 feet on Mt. Lenmon. To the northeast of these mountains is found the north -westward flowing San Pedro River, merging with the westward flowing Gila River approximately forty -five miles north of Sabino Canyon.Thirteen miles to the southwest the normally dry Santa Cruz River follows a northwestward course. ultimately emptying into the Gila River just north of the Sierra Estrella Mountains near Phoenix. Elevations in excess of 6000 feet are also found in the Rincon Mountains fifteen miles to the southeast and in the Santa Rita mountains forty miles to the south. The terrain within twenty -five miles of Sabino Canyon to the west and south is essentially flat, with gently rolling desert hills prevailing. Twenty miles to the west -southwest the Tucson Mountains rise to 4677 feet. The well -known Arizona- Sonora Desert Museum is located in the Tucson Mountains, ten miles west of Tucson.Eighteen miles southwest of Sabino Canyon stands the historically famous San Xavier del Bac Mission and eight miles to the southeast is the western extremity of the magnificent Saguaro National Monument. The vegetation to the southwest in the non -irrigated sections near Tucson is dominated by creosote bush while to the northeast in the valley of the San Pedro River, mesquite and creosote are quite prevalent. :n the Catalinas and Rincons, to the north and southeast respectively, chapparal and oak woodland are common, yielding to forests of yellow pine at elevations above 6500 feet.

Sabino Canyon has a semi -desert climate. averaging just under twelve inches of precipitation a year. Almost 50 percent of this normally falls during the monsoon months of July, August, and September in association with thunderstorms that develop in the flow cf moist, tropical air from the Gulf of Mexico. most of the warm season rains at Sabino Canyon occur in the late after - noons or early evenings, although nighttime and early morning showers are not unknown.Some of the heavier late summer rains at Sabino Canyon probably develop in currents of moist air that enter southern Arizona from weakened tropical distuxtances centered off the Gulf of California or in the Pacific Ocean.

Only small amounts of precipitation are measured during the rest of the year at Sabino Canyon, with a slight secondary maximum normally occuring during the winter. At this time storms originating in the Pacific Ocean may follow a track sufficiently far tauth in their ;:urnev across the continent to affect southern Arizona. Typically, they produce gentle, widespread precipitation, host of which falls as rain. The precipitation may continue intermittently for a few days. At higher elevations in the neighboring mountains over six feet of snow may fall during the wetter winters. Sabino Canyon has warm summers, temperatures on an average mid -July day fluctuating from the lower seventies at right to just over the 100 degrees during the hottest part of the day. Fortunately, relative humidities are low when intense daytira heating occurs and the extreme heat seldom lasts for more than a few hours.During the warm season beautiful displays of lightning are often seen over the Catalinas and Rincons itn the early evening.

The winters are extremely pleasant at Sabino Canyon. Mild temperatures and dry weather are the general rule. Minima below 15 degrees have never been reported and the maximum daily temperature always surpasses the freezing point.While the normal mid- winter temperature variation extends from the upper thirties to the upper sixties, maxima in the upper eighties have occurred during warm winter periods.

293 AY E.1GE ,ONrhLTTE'PE91TURFS tFtFOR SA9I90CANYON

TEAR JAN Fin 4A4 APRIL v4T JU4E JULY AUG SEPT ^.^T 40Y OEC ANNUAL YSAR 1941 56.4 14.7 79.5 57.3 61.1 51.0 1941 1942 53.4 51.6 56.7 6...2 13.2 62.6 59.5 05.6 51.7 59.9 61.1 54.6 58.5 1942 19.3 54.: 55.9 61.3 69.4 75.1 12.S 15.2 54..7 11.9 71.1 61.7 52.4 711.1 0941 15..4 49.3 57.6 55.5 62.0 72.6 79.7 57.1 65.1 79.7 72.6 56.9 52.7 46.9 1144 1945 51.1 54.1 55.0 61.6 7..1 79.. 36.8 91.5 77.6 56.0 59.6 51.1 66.3 1945

194o 9.3 53.6 bl.. 72.2 75.2 56.4 17.4 35.0 11.1 66.8 55.6 69.2 1946 77.5 54.5 19.7 49.7 5.1.4 63.. 56.6 52.1 59.4 71.6 1 54.7 49.4 68.9 1147 1948 52.6 52.2 5..6 63.. 75.4 53.5 51.. 54.2 55.6 '7.8 54.9 52.9 68.6 1943 1949 44.7 50.8 59.3 66.1 73.9 53.9 15.9 64.7 54.0 91, 65.17 52.2 53.4 1949 1950 51.9 58.2 61.2 70.2 73.4 92.5 14.1 95.1 79.4 77.5 61.7 58.1 72.. 1950

1951 51.5 54.9 55.7 55.5 74.3 11.3 13.6 15.7 T1.5 72.5 59.8 52.5 59.0 1951 1952 52.3 51.5 53.2 65.7 76.5 33.9 15.7 85.2 54.7 76 56.7 51.0 68.7 1952 1953 54.1 52.5 62.7 55.7 69.5 44.5 67.9 57.4 11.6 72.1 52.2 49.5 69.7 1951 1954 54.1 61.0 59.5 71.2 75.2 73.2 57.7 31.5 S2.7 62.7 55.1 1954 1955 .7.5 49.8 57.7 54.5 72.4 52.4 54.. !1... .5 ,..3 54.7 55.7 68.. 1955

1956 56.4 49.8 60.5 65.3 76.5 66.8 56.2 51.1 14.6 '3.9 59.6 53.0 69.4 1956 1957 5..5 67.5 59.3 64.5 77.7 35.6 39.2 35.7 12.9 59.2 55.3 54.9 69.2 1957 1951 51.6 55.9 54.4 64.4 79.3 55.8 58.3 55.3 51.5 '2.6 59.2 56.5 59.6 1958 1959 55.0 53.0 1.1.7 70.. 7..1 57.2 13.3 53.3 50.3 73.4 51.5 51.2 69.5 1959 19b0 .8.2 .1.0 62.4 57.2 74.1 86.1 36.2 86.8 53.2 59.1 61.1 50.6 58.6 1961 l9bl 54.7 55.1 53.1 67.5 74.5 66.5 57.0 84.8 79.0 73.Z 56.2 52.3 59.7 1961 1962 51.3 56.0 5..2 73.5 72.5 91.3 86.1 87.6 52.9 71.5 61.8 55.0 59.2 1962 1963 .9.9 58.2 59.1 64.4 77.1 40.7 86.6 71.4 - 53.5 73.6 50.3 53.7 69.3 1963 1964 46.1 48.5 55.3 64.0 73.3 52.3 57.7 53.7 77.9 72.5 55.1 53.1 65.8 1964 1965 53.9 52.2 56.3 65.5 71.1 79.4 67.7 65.0 75.9 72.9 61.0 53.3 68.3 2965

1966 48.7 48.9 60.6 67.0 77.3 53.8 54.1 85.0 60.3 70.0 62.6 57.2 66.8 1956 1967 52.5 57.2 61.2 64.0 73.3 81.5 85.9 85.3 51.1 '1.9 63.2 49.4 69.0 1967 1968 53.3 59.3 59.0 64.3 7..1 84.6 55.6 11.5 51.3 72.1 51.3 50.9 63.7 1965 1969 56.3 53.7 55.. 67.9 75.6 82.0 57.5 57.4 52.9 55.4 69.2 54.2 69.3 1959 :970 51.3 55.1 56.7 62., 76.5 54.2 18.9 55.9 71.1 66.4 61.5 53.5 68.6 1970

197: 52.2 53.3 51.5 71.9 62.2 15.1 51.1 75.5 5..2 55.3 47.9 56.5 1971 1972 55.9 56.3 66.1 56.7 73.5 81.8 87.1 12.6 79.3 56.3 51.6 50.5 67.6 1972

7074472ECIPITATIGN t!9CNE51 FORSABINO CANYON

11 44 J4N FEU nAR A9R11 MAY JUNE JULY JUG SEPT O-. T 90v CEC ANNUAL YELP 1941 4.22 1.15 2.17 ..64 0.94 2.99 1941 29.2 3.56 1.31 7.15 1.75 0.70 C.04 0.91 1.27 1.49 0.65 0.47 6.59 1947 1943 2.58 1.41 1.56 0.03 0.25 0.19 0.21 2.44 1.34 7.25 0.00 1.04 5.37 1943 1944 3.67 1.06 1.76 7.7u 0.44 0.35 1.25 3.93 1.77 1.00 1.51 1.59 15.6' 1944 1945 0.34 2.13 J.44 1.14 3.30 7.30 7.24 2.56 1.33 2.15 0.00 0.28 10.52 1945

1946 2.51 0.17 0.62 0.06 0.01 7 1.61 3.79 1.59 3.15 0.64 0.66 12.50 1946 19.7 2.07 3.12 125 T 0.34 0.30 J.17 3.77 0.70 7.68 7.63 0.33 6.36 1947 1948 T 1.15 0.90 7.70 0.00 0.04 1.01 2.09 1.19 1.11 T 1.72 7.83 1948 1949 2.01 7.19 0.45 3.4. 1.11 0.07 2.25 2.84 1.17 1.49 0.14 0.94 12.03 1949 1950 0.46 1.29 0.32 2.04 2.37 2.51 2.37 0..46 5.01 7 7 9.51 1950

1951 1.50 0.21 7.42 2.41 0.32 T 2.35 1.90 0.44 2.06 1.63 1.13 14.07 1951 1952 1.29 3.23 2.71 1.22 G.I4 7.23 1.77 2.49 3.65 0.00 7.39 0.56 12.66 1952 1953 0.10 1.12 1.11 7.32 7.13 0.37 7.37 1.54 0.00 T 0.16 0.17' 7.59 1353 1954 1.12 3.39 2.51 T 1.34 7.48 3.75 3..5 2.52 0.15 0.0n 3.09 14.89 1954 1955 1.59 0.19 .... T 3.06 0.43 4.79 2.44 3.01 0.38 T 9.27_ 10.18 1955

1956 1.05 0.53 1.22 0.36 T 3.12 2.52 1.53 0.11 0.55 0.00 0.12 7.01 1956 1957 3.45 0.75 1.60 0.26 0.56 0.02 0.97 2.30 3.12 3.69 1.11 0.71 15.54 0.357 2958 1 2.15 1.79 1.33 0.33 0.50 3.23 1.05 3.50 1.39 1.16 0.00 I4.66 1955 1959 7.65 0.14 0.00 1 2.90 5.04 0.42 1.75 6.37 2.75 14.05 1959 1960 3.221 0.53 1.35 3.74 0.75 T 7.96 2.03 1.74 7.67 0.19 7.56 9.16 1960

1961 t..1 0.56 0.32 0.00 7 1.58 2.19 0.53 0.64 0.65 Z.53 10.51 1961 1952 1.27 1.31 1.60 T 0.03 2.27 1.39 1.57 1.66 0.19 3.41 0.92 9.6^ 1962 1963 1.. 2.59 9.67 3.51 7 0.08 2.40 2.26 0.57 0.61 1.10 0.09 12.32 1963 1964 0.51 1 1.92 1.23 0.00 T 2.21 1.10 5.35 1.57 0.85 1.50 14.96 1964 1965 1.30 1.17 3.49 7.80 0.06 3.34 0.72 2.08 0.93 3.06 1.21 7.55 15.22 1965

1966 1.66 2.59 0.31 0.3J 0.01 0.10 1.30 3.33 3.40 0.59 0.40 0.29 14.33 1966 1967 0.15 0.05 0.49 0.75 0.59 0.08 4.10 1.16 1.59 9.75 0.62 4.41 14.97 1967 1968 1.51 1.16 1.75 0:81 3.22 0.37 1.54 2.69 0.03 0.52 2.05 1.11 12.79 1965 1959 1.44 0.54 3.40 0.09 0.41 0.00 2.26 2.76 0.43 7.33 1.62 1.15 11.24 1969 1970 T 3.19 2.23 0.31 1 0.28 2.31 7.58 2.47 0.56 0.71 0.40 11.31 1970

1971 0.29 3.75 T 0.36 T T 0.60 7.87 2.31 1.95 0.93 2.15 17.71 1971 1972 T 0.20 0.01 7.03 0.32 1.57 3.96 2.17 1.55 5.24 1.33 0..57 16.95 1972

294 CLIMATOLOGICAL SUMMARY PALISAÜE RAN,FR ;t LATITUDE, 22 25' MEINS 1 ^.t Ptt3O 1963 - 3470 CY!REr'S FOP 'aaICO t755 -1972 LONGITUDE. 110- 43' 6207 ELEY. (r1.x 7945

Mean number cl days Tempenl.. e -,' F¡ Precipitation Totals lInches) Estimated mean reiati7e Tempe alures humidity Mu. Means E3:temes Snow, Sleet, HaI Min. I (percent)

1 I

< i

E I _ E °

I i tt i m 2 >. S c s ó é ? ñ ... :=1o^<ó4 u I i

III 6 6 5 6 6 5 6 (51

JaN 43.1 24.7 34,1 05 1171 - 5 1371 945 1.93 2.40 1964 14.1 34.0 1966 64 6' 3 0 t 24 0 J49 F19 .-.6 2..9 1-..1 65 147: 4 1965 146 2.44 2.44 1455 18.4 54.0 1965 56 50 4 0 2 25 0 FEI RAR 47.3 25.7 17.1 72 11/2 - 6 1371 157 2.12 1.19 1170 55.5 31.0 1971 59 54 4 0 2 26 O 9A9

APR 56.1 3:.1 41.9 76 t1ó5 á t470 627 1.56 1.70 1945 5.5 14.0 1165 51 41 2 0 3 14 0 AP9

MAT 66.7 .1.6 51.7 52 1463 23 1.961 147 0.42 3.96 1147 1.7 4.1 1969 41 31 1 0 4 0 MAY

JI+N 14.4 41.7 51.1 31 :374 33 1969' 141 4.37 0.75 1172 3.3 7.4 15 29 1 4 1 0 JUN

Jul 75.5 52.7 64.1 1/ 1972' 37 1368 60 4.75 1.93 1167 1.0 0.0 59 57 10 0 1 3 0 JUL AuG 73.0 50.3 61.7 35 t37? 40 1969 107 3.96 2.32 1369 0.0 3.0 , 74 50 4 0 U 9 0 6Ur: 4.24 SLP 81.1 .5.E 57.: 13 1977 :E 1971 231 3.75 19'0 0.3 1.0 65 53 5 . 0 1 SE'

;:t 61.5 .11.0 44.. 75 1)7' t6 :972 4h4 1.52 2..7 177? 2.1 11.1 1971 5F 45 ( ^ J 7 9 nCT Nov 52.7 '31.5 41.4 71 t171 1-171' Atli 2.73 2.10 1159 3.1 13.0 19'2 55 51 1 17 0 NOV

OtC 44.3 27.5 33.4 `3 1177 -31 1165 957 5.23 2.5t 14A5 13.3 19.1 1965 55 52 7 v 4 'S 05C

JJN M59 1173 53 tLsd 573.3 16.5 4:.4 41 . 7. - 6 t311 6273 21.x9 1.76 91.7 59.3 11/5 5q e 9 145 YEAa

M:NTH TE "çli:'Jì;; IFI =3LISS0E PAN15E2 j131109 rEAR JAN FEI MIS SPEIL pise JUNE Jute 1UG SEPT O ^.T NOV OFC 3INIJAL YEAR 1165 37.6 ..3 16.6 44.3 51.4 :1.4 á5.i 64.2 57.9 53.4 44.6 14.6 45.4 1965

1166 33.3 J-1.4 41.0 56,7 62.9 66.1 62.0 51.0 50.5 44.9 5.3 45.5 1946 1967 35.3 73.3 4343 .3.1 52, 59.9 61.7 60.9 55.2 51.5 1957 116E 17.7 36.7 41.4 54.1 63.3 62.5 5..4 56.0 52.1 11.0 12.1 47.2 195E 1969 3..7 3?.. 73.3 47.0 53.0 59.5 63.1 63.1 57.6 46.9 17.5 31.3 45.E 1969 1970 33.1 37.1 33.5 79.1 54.3 62.4 64.2 61.1 54.7 43.8 41.1 34.4 46. 1974

1971 35.1 37.3 43.2 45.9 51.1 61.4 66.7 61.7 59.0 43.6 41.7 32.5 44.4 1971 1972 31.4 44.01 49.'. 49.6 55.7 62.4 66.5 61.7 54.4 50.5/ 37.1í 35.5' 51.6 1972

TOTALPRECIPI`111JN tINCHESI FOR VALISSOE RANGER STSTION

TLAR J19 FEI MAR APRIL MAY JUNE JULY 5U, SEPT OCT NOV arc- ANNUAL TES? 5965 3.10 1.71 2.16 2.33 T 0.10 5.56 2.81 0.20 7.30 5.52 12.64 17.93 1945

1966 3.44 5.44 0.36 0.05 0.01 1.60 4.03 7.64 7.36 7.66 1.34 1.75E" 33.93 1966 1567 3.52 0.15 3.73 1.11 1.03 0.13 5.01 1.59 4.60 1.65 1.16 5.40E 25.45 1967 196E 2.35 3.15E 3.19 1.11 0.22 0.04 7.47 3.06 1.25 0.41 2.54 1.90E 25.09 196E 1969 2.77 1.65 1.47 3.21 1.12 0.00 5.14 4.50 1.14 0.35 5.07 2.51 20.11 1966 1973 r 4.65 4.75 0.56 0.09 0.35 4.46 3.05 4.56 7.13 0.12 1.95 25.04 1970

1971 0.64 2.22 0.72 3.30 0.33 4.23 7.39 5.15 4.62 1.08 4.74 10.79 1971 1972 0.00 0.00 t 0.30 3.51 2.79 2.47 4.26 3.27 3.44 1.20 3.40 76.74 1972

295 CLIMATOLOGICAL SUMMARY MOUNT LLMMCh INN L51lTUOE: 12' 27' .FANS F0ì PE °I00 199G -1953 EnTREMëS FOR REnI0n 1350 - t96.1 LONGITUDE 110. 45' 5732 ELEV. (FT.e 7790

Mean number al days 'eau,ature i"F? Prec pltation Totals (Inches) Estimated mean re!atrve Tempe Mures humidity Mu. ;ìn. Means Extremes Snow, Sieet.Hati I ,percenU

I E - E i ° V o ^>^;ñ; _e'. ^+ - ff ° ó ñ 'v è3 -E É 1 3 s = 1 .. t c r eli i É < É > ó _ v._,+ .°..-. o:=1,.o < tit 13 ta .0 1.1 1C 10 10 4 1^ 10 9 10 13 10 la (At

4 JAN 41.4 27.9 35.2 65 1962 - 1960 566 2.31 2.36 1452 t 1.7 23.7 1954 54 57 1 3 2 26 JAN FE3 .3.2 22.5 35.4 65 13630 - 7 :353 529 1.55 4.at 1153 1.6 15.9 1961 55 57 2 7 2 25 FED MAR 52.7 25.1 39.5 59 1956 - 1 1962 733 2'..4 4.90 1.354 19.3 31.3 1957 57 50 3 e 1 25 MAR APR 60.5 32.2 45.4 7. 1959 14 1956 552 0.97 2.10 1153 5.0 25.5 1951 5n 37 2 9 14 0 509

MAY 55.5 11.1 53.3 36 1351 23 1751 364 9.29 2.76 1954 T 1.1 1951 41 11 1 0 0 5 0 MAT JUN 77.4 -7.1 52.3 11 1363 33 1461 117 ,, .34 -.31 1952 T T 1951 13 27 2 0 0 0 JUN

JUL 76.5 51.5 64.0 39 1350 39 1360 46 5.79 3.00 1953 t T 1154 60 55 10 0 1 0 S JUL AU/: 74.2 50.9 62.6 87 t353 44 1955 51 5.47 3.00 1151_. , .1 1.5 t954 73 59 11 1 1 0 AUC SEP 13.3 47.6 60.6 87 1359 33 1361 131 Z.00 2.60 954 t T 19521 63 46 3 0 0 0 SE° OC: 66. 40.5 53.5 79 1950 20 1961 179 1.57 3.51 1151 1.9 20.3 1961 54 44 2 0 0 4 0 nCT

NOV 56.3 31.6 45.0 71 1462 4/953 6l0 1.50 3.15 1951 7.1 38.0 1952 54 46 2 0 15 0 NOR

OTC .4.6 24.7 37.2 63 1953 1 1954 879 1.99 2.53 1961 11.7 65.0 1461 66 53 4 1 l 2' 0 OEC

JJN FE3 MAR DEC

YEAi. 62.3 35.4 49.7 91 1360 - 7 1963 5650 26.77 4.90 t154 57.5 ' 65.7 1961 57 47 45 9 144 TEAR

AvEaAc.EMONrnLTTEMPERATURES IFI F09 MOUNTLEMMON INN

TEAR JAN 7E3 MAR APRIL MAY JUNE JULY AUC 5 °RT 3CT Nov Q C ANNUAL 755' 195: 55.21 52.9 61.3 63.9 59.4 59.5 50.0 44.9 1955

1951 35.5 35.4 39.2 .3.7 53.. 60.6 57.5 61.0 63.". 52.7 41.9 34.9 49.3 1951 1952 36.0 34.61 31.5 .3.4 55.6 52.3 64.1 63.1 62.7 59.2 37.6 33.5 .A.S 1952 1953 41.: 35.3 49.5 44.8 47.1 53.6 63.3 6..3s 63.5 51.9 45.1 13.6 49.5 1953 1954 37.ós 41.7 35.5 50.31 54.3 60.S 64.3 54.6 60.1 54.5 45.9 I1.5t 55.3 1954 1955 2ó.5t 32.11 40.0 60.ít 60.7 54.7 44.n 40.31 1955

1956 43.41 45.21 45.3 58.1 67..1 17.1 1956 1957 1957 1956 51.6 41.1 43.4 1955 1959 41.1 17.9 42.5 52.3 55.1 63.5 64.5 61.3 51.6 53.5 49.2 18.5 51.7 1959 1560 29.5 30.9 43.1 44.5 51.7 64.3 65.0 61.5 59.6 45.9 .1.6 15.5 LA.) 1950

1961 37.. .2.1 47.3 51.1 61.6 64.5 62.2 56.2 45.3 45.1 13.95 1961 1962 37.5 I..9 31.1 45.2 53.71 55.5 61.9 61.9 59:5 55.4 53.6 15.8 45.9 196' 1963 33.1 .1.3 47.3 52.9 1963

70TAL Pacc:PrrArt3N (INCHES/ FORNOUN? LEMMONINN

YEAR JAN FED MAR APRIL MAY JUNE JUL" 4U7 SEPT OCT NOV OFC ANNUAL YEA 1950 1.87 7.97 2.95 0.36 3.00 3.30 T 1951

1951 3.32 1.13 1.95 4.26 0.45 0.30 5.38 0.55 4.92 4.25 5.41 1951 1952 4..6 0.36 6.15 2.30 T 1.30 4.61 7.36 1.90 0.00 4.71 1.95 35.10 1952 1953 3.15 1.30 3.44 3.0G 0.67 3.40 10.88 0.30 1.11 1.10 1.45 1.20 71.51 1951 1954 ..30 1.33 3.55 T 1.25 3.03 7.57 4.73 4.35 0.23 0.00 7 49.17 1954 1955 1.30 J.65 3.13 11.71 3.10 0.47 0.05 1.04 1955

1956 C.í2 3..1 0.33 1.94 1.91 0.60 1454 1957 1957 1958 3.37 3.00 1959 1959 3.23 T T 3.03 0.91 6.28 10.54 0.10 5.65 3.22 1954 1960 4.35 3.95 3.23 3.0a 0.52 0.30 2.61 0.0CF 1.64 1.51 0.59 0.76 1963

5561 3.23 2.67 C.15 1.30 0.50 3.40 3.94 3.94 1.02 0.60 10.31 1951 1962 4.59 1.65 5 T 9.30 3.30 3.62 2.17 5.73 1.05E 2.70 3.33 21.24 1952 3963 4.31 3.55 2.13 0.00 1963

296 CLIMATOLOGICAL SUMMARY SINUARITA LATITUDE DI'58' .F :NSE04 PF0I03 1156 -1473 EYt6EMES Fnp PF6COn 1156 - t977 LONútTUDE 110 58' 7401 1.1EY. 1íT1. 2 6 9 0

Estimated Mean number of days ter-xn:re l'Fl Pree Mahon Tcta's (Inches; mean relative Tempe attues tumidity Mat. Min. `.:cans :+t:cmei Snow, Sleet. Hail ;percent)

i Ì ( =

+l:a:e - i I _ S g S < { , c o î - c r. < 1.. É r C _ > ó _ a. ó, e,-. o ,-.0 1 Se A_

1a1 1) 15 tl 15 15 15 14 15 11 15 I4/

JAN 67.1 11.3 44.1 51 1471 10 1172 485 1.66 3,15 1466 0.1 3.0 54 35 2 0 1 23 0 JAN 94 FE3 7t.3 ." 53.4 1957 :5 2972 332 1.51 1.37 1966 0.3 4.3 1965 51 32 - 1 1 11 3 FEI y44 75.2 3'.6 56.5 95 217: 15 1965 261 7.58 6.15 1151 0.1 4.5 1954 45 26 2 t 1 5 C MA*

3P4 d.3 .;.5 61.1 173 1761 Z3 1971 n1 2.25 0.56 1955 3.3 1.3 11 20 t 7 1 1 1 AP6 NAT 13.: 41.3 PI.1 11; 11S3 St 1171' l' 3.37 3.53 1957 1.0 2.3 10 17 22 0 0 NAY

JUN 111.1 c1.6 .1.1 1t3 1166 24 1371 0 1.29 0.71 1957 0.3 0.3 29 15 t 29 0 1 0 JUN

43 JUt. 131.3 68.4 64.9 112 196u 1467 1 T.66 3.10 1971 0.0 0:-0 45 31 5 11 1 0 0 JUL AUG 95.6 66.1 32.5 tll t9655 S1 1967 3 2.03 1.10 1971 0.0 1.7 50 31 5 31 0 0 0 Au; SFP 96.1 61.2 71.2 112 1457 34 1955 1 t.25 2.21 1977 0.1 3.0 54 35 ? 27 0 3 3 SEP .1GI 58.2 47.. 57.1 115 1963 29 1970 32 0.63 1.13 1960 0.0 0.3 44 14 1 14 1 1 2 OCT 1431( 74.5 3.4 57.3 19 1461 ld 1959 221 0.58 1.30 1465 0.4 6.1 1958 46 40 2 0 0 5 0 N0T 3EG 57.7 34.0 ,1.4 35 1970 .. 1960 431 1.33 1.94 1057 T r 1965 57 46 1 0 0 14 0 OEC

JJN JAN JUL 90V rEA. 14.1 48.3 66.5 :IS 1966 13 11.'2 1110 10.16 3.41 1970 1.3 6.0 1955 47 31 25 151 1 Sn 0 TEAP

.JNhqr17M0E

1966 47.1 49.4 54.4 66.68 74.98 80.48 84.18 50.68 65.08 1966 1967 51.38 65.08 77.01 53.58 51.08 77.1 56.3 50.3 46. 1967 1963 49.4 56.8 57.5 64.1 72.3 13.t 81.5 31.4 77.6 71.78 58.9 52.1 67.4 1968 1569 82. 53.3 5..3 ó6.T 74.1 60.2 15.9 57.0 50.8 55.0 53.2 55.1 66.4 1969 1970 5G.7 56.0 55.. 53.2 73.. 30.2 55.0 85.3 75.9 55.08 1976

:971 51.68 55. 3t 51.18 77.6$ 15.38 75.18 53.98 1471 1172 1. 3.38 51.61 71.76 79.68 13..58 1972

.GTAL P?E.:IPi11114 1:4:.MEGI co., SAMUA91T1 x144 JAN TER MA4 APRIL NAY JUNE JULY AUG SEPT !1r:7 NOV OEC ANNUAL YEAR 1.356 9.30 C.10 T 0.17 3.56 0.79 0.29 3.42 C.30 1956 1517 1.if 3..7 1.61 0.31 0.60 3.83 1.95 2.39 1,31 1.76 0.56 0.40 11.:7 1957 1555 1.11 3.79 1.92 0.56 0.33 1.32 3.13 1.15 1.32 0.16 0.93 0.00 11.55 1958 1959 3.03 2.03 0.03 1.10 2.31 1.67 0.09 1.27 1.85 1.79 5.02 1959

1900 1.21 4..3 3.15 0.00 0.30 0.30 1.18 - 2.57 2.06 1.26 0.11E 1.20E 10.17 1960

1961 4.12 0. 7.3t 3.30 3.30 0.79 2.34 7. 50 M.60 1.43 0.30 1.52 10.33 1961 1962 1.26 3.03 3.63 3.00 0.03 0.08 0.97 1.94 1.17 1.14 n. 30 1.18 7.60 1962 1963 1.51 3.14 1.52E 0.56 0.30 0.00 1.73 3.39 0.49 0.66E 1. 75 3.00 9.60 1963 1964 4.05 7.59 2.55 3.03 3.16 4.91 3.19 5.14 0.15 0.75 0.25 16.54 1964 1965 2.59 2.12 3.20 3.20 0.33 0.35 2.01 0.27 1.12 1.03 0.43 4.16 12.15 1965

1966 1.31 2.01 35 0.25 3.35 0.23 3.60 2.88 1.90 0.60 0.00 0.08 13.38 1966 1967 0.37 6.35 3.73E . 3.54E 0.33 1.38 2.70 1.22 0.55 0.44 0.22 4.50E 12.07 1967 1968 0.6, 1.15 I:lt 3.37 0.03 3.90 1.53 2.2g 1.23 1.36 t.63 0.51 10.14 1966 1969 0.75E .39 2.16 3. J.16 3.33 1.64 3.50 1.65 0.00 0.63 1.00 11.61 1969 1973 ..JO ..47 3.35 0.70 0.00 1.00 5.88 1.18 2.73 0.20 n.00 0.65 11.89 1970

1971 0.00 3.55 0.33 3.41 3.00 0.03 1.51 4.19 3.70 1.11 0.11 7.09 15.37 1971 ;972 3.37 1..3 0.30 0.16 1.30 2.31 0.67 1972

291 CLIMATOLOGICAL SUMMARY I.,,.J.. u.. .1dPC43 L;tif`JCE: 32' 07' 1595 F04 PE =130 1946 -.970 EYTa£"£S E00 CE9105 1941 - 1977 ::ti;I3uoE: 110' 56' 8620 ESE7. (iC} 2584

Mean number of days -' : empef _:J: e! F¡ ' PRCiO:: ah0n fonts, ;InCheS) Estimated mean reiative Teme atures hum dity S1Ja. Min. S:nnl Ec'remes I Snow, Sleet. Hal Der en')

i 1

i i v b E T. E __ 1 _ I i ç c ( o o - _ e_-., i _ _ Er - _ f n ñz ait° = ' 1 d S v i i - `3 ( 7. i i_ i i .s E ( . *_ i.s c > a r É É ó .., o ó S

( _ _

til 21 23 21 2S 25 27 23 75 23 2S 23 23 22 22 22 lall

51 JA. 6..1 37.7 51.7 57 1951 16 1949 414 2.75 1.95 1960 0.4 4.7 1.144 41 1 0 0 7 : JAN 71(.0 67.2 :9.4 51.J 12 1157 20 1955 325 7.64. 1.25 1956 0.3 3.4 1965 59 17 2 0 < Q cE9 ,4R 71.4 .3.1 57.5 4? 1150 21 1965 212 2.63 1.19 1952 7.4 5.7 1964 45 30 2 5 2 0 NaR ..a 31.1 4ù.4 _5.5 45 1465 34 /4675 67 0.34 0.74 1452 T 1.0 1456 16 22 2 4 9 1 0 41,0 59.7 78 MAY 57.7 71.7 1:7 1+5.S 1950 12 0.13 0.50 1167 0.0 0.9 28 16 11 :1 0 3 laY til :17^.' 47 1955 0 74 75 JJ. 16. 57.1 82.3 3.2$ 1.27 :954 7.0 3.1 15 1 . 4 0 JUN

JUL 11.4 71.7 .,.. Ill 1451 63 1960' 0 2.60 3.91 t955 T r 11424 45 32 7 29 0 2 0 JUL 7 AJv 95.1 71..8 54.3 1:5 1451 51 1956 3 2.25 2.43 1961 r 1955 59 15 6 28 9 0 0 AO; 4. ;EP 14.0 67.1 31.7 t07 115;' 1965 0 1.29 2.55 t9ó4 r T 1952' 51 15 3 24 G n 0 SEP 71.0 r 041 55.0 56,7 1:1 1455 26 1971 26 0.63 1.75 1972 1 1950 47 34 2 10 . 0 0 0G7

'106 73.0 45.2 51.1 11 115. 24 1958 191 1.55 1.57 1665 2.1 6.4 1958 47 59 2 7 7 1 o NOV

1EC 65.. 15.9 52.2 5: 1954 16 195. 397 0.95 1.22 1967 0.2 6.5 1971 59 49 3 0 7 S 0 GEC

JUN JA4 JUL GEC YLAk 72.0 5:.: 61.1 111 1977 10 1949 :561 .1.91 1.93 1954 1.5 6.1 1971 47 11 33 141 9 20 0 YEAR

y347.45T14-L91TUtE5 !£1 FOR tUCSOtI 950a1?vORT

iCeA rE, A> .Pal M1Y JU'I£ JULY 12G 5E^T G,T %CV nEG ANNUAL TEaR 1548 75.1 33.4 66.3 15.2' 52.6 '1.1 51. 6 51.2 67.5 1948 14-4 .J.J 67.. 73.4 53.2 85.1 14.7 52.1 56.4 54.1 50.9 67.3 1449 :SSO 50.. 54.2 71.6 81.5 52.1 '3.3 76. 8 51.0 56.9 59.4 1950

1951 5C.3 57.7 5% .4,4 74.3 80.5 58.a 44.9 83.2 72.5 54.5 51.5 65.1 1951 1952 51.7 61.5 í2.7 65.: 75.3 53.4 56.0 55.1 51.3 75.4 56.4 59.1 65.2 1952 1953 5;.4 52.2 6:-.5 55.2 65.9 54.1 56.8 56.4 12.9 75.0 61.6 44.6 55.5 1953 1954 53.5 J.3 5'4.1 71.5 75.9 81.1 16.5 33.4 52.9 74.2 62.7 53.3 70.5 1954 1455 4b./ .3.5 59.6 6... 71.5 52.3 14.6 51.8 11.2 74.3 55.5 55.5 67.5 1955

1955 50.1 48.7 00.2 54.2 75.5 56.2 35.4 84.0 44.3 70.2 57.8 57.5 55.5 :456 1957 53.5 01.. 54.6 54.2 71.2 65.3 55.1 54.2 51..3 67.9 54.1 54.9 59.0 1957 1456 51.4 55.5 5-.2 64.5 79.1 54.9 56.5 a..5 82.5. 71.9 57.8 55.6 3e.1 1958 1959 53.5 51.5 Si.2 69.1 72.5 e5. 16.6 41.8 80.2 69.7 54.5 51.4 58.2 1959 1966 46.3 .7.. 61.7 65.7 71.9 53.5 15.3 54.2 51.7 67.3 53.2 49.1 67.0 1960

1961 52.5 51. 51.2 66.2 72.9 54.7 56.1 81.4 .77.1 54.4 54.4 50.5 67.2 1961 1962 49.0 54.7 53.3 70.1 71.7 50.3 54.3 87.f 81.3 70.6 61.5 54.0 63.2 1962 1961 ,e.J .5 57.7 64.0 77.3 51.5 87.6 57.3 62.4 73.2 59.3 52.7 65.6 1963 196. 47.6 .7.7 54.8 63.2 71.2 52.0 86.2 11.6 76.3 47.1 55.2 52.4 56.8 1964 1965 51.6 51.. 55.1 64.5 70.1 77.6 85.0 414.1 76.5 '1.4 67.6 52:1 67.0 1965

1966 47.7 47.. 63.1 66.8 76.1 62.4 55.3 42.9 71.1 04.1 51.1 52.4 67.5 1966 .407 51.. 55.ó 62.1 62.1 71.4 17.7 45.4 14.6 80.7 71.6 52.3 b 's 68.1 1967 .464 9.. 55.7 63.2 71.1 81.5 44.4 41.1 50.7 71.7 51.3 50.6 65.1 1966 t904 55.5 SJ.1 5:.3 66.6 74.9 1Q.' 54.1 16.1 11.2 65.5 55.6 52.4 65.0 1969 1470 50.0 57.0 55.4 61.1 75.2 53.4 87.2 14.8 75.4 65.1 69.1 51.4 57.3 1970

td 7 t Sí.5 2.1 59.1 52.8 69.1 51.Z 57.5 41.3 79.1 54.2 56.4 47.1 66.7 1971 1'72 .C.- 55.5 65.2 05.3 72.3 11.6 36.5 .2.9 73.6 66.5 53.9 49.0 57.1 197?

1[145 4''7,'.'S133'+ 11':::51 1J= T5J, 5N 9j0 114P07T

Yr 1: JA'; r.-, Aa .4'015 aY AMC /'JtY 3ilf. 5r0T 1ST NOV r'r[ ANNUAL YEAR 1Q4i t .. 5.27 r 0.07 C.16 3.02 1.25 l.:l 7.56 0.06 0.93 9.31 194.5 :'e.5 5.15 _... t:.1 -I ;.J1 7.21 0.52 1.42 1.92 9.61 0.52 0.17' 0.14 7.56 1040 :555 ..lè ...... _ 1 J.71 1.24 1.72 9.45 1.15 T r 0.27 0.70 1950

i . . . . 5 1 1 . . - . . - . 5.56 C..11 T 1.44 2.44 0.34 1.71 1.27 C.99 ..'^ :051

t 1.45 2. t.5t 2.32 0.10 1.75 1.n6 0.49 0.10 t.90 0.73 17.55 1952 _ 155 5.15 1.15 3.51 . 0a t 1.13 2.57 0.46 0.09 T 0.15 0.12 S.J. 1951 1454 2.73 7.': 5.51 ...... :7 1.46 2.03 2.50 3.05 0.0Z 6.06 7.56 '11.61 1454

1+55 1.89 4.:1 7.:1 , ..Jl 0.31 5.10 7,43 0.75 0.12 T 0.13 15.46 1955

1955, 1.13 .... 0.70 0.31 T 0.16 2.77 1.12 0.17 3.27 t 0.22 7.04 1956 1457 2.37 .15 5.93 1.10 .11 0.17 1.25 1.97 T 7.52 0.55 1.9 11.56 :957 1,51 1.tS 5.12 ..5 0.22 1.51 5.20 0.51 3.21 1.21 1.79 9.00 12.63 195 145', 0.11 J .38 t 1 .dt 1.31 T 1.92 2.7. 7 5.70 1.29 1.97 9.99 1959 , :541 ,... 5.4. ..25 5.:0 l.;a 9.25 0.73 2.19 1.10 3.71 0.07 0.9I 5.74 1950

1555 1.9í . ..41 1 5.90 1.26 1.51 4.2' 0.51 3.65 3.44 1.57 12.59 1361

1562 1.34 :.Si 5.75 . 4.;:7 0.?5 1.31 1,46 7.55 1.72 7.41 0.93 5.55 1952 1401 .A0 ,... !.:14 ... r T 1.66 2.46 1.45 0.60 1.25 0.01 9.47 1961 1964 .1. .15 . .67 7.JL 0.01 4.42 3.90 5.11 1.11 0.67 0.41 17.43 t 4964 11,5 7..5 0.54 1,27 3.23 T 0.9t 2.13 1.12 0.52 1.07 1.77 5.C2 51.51 1965'

1460 ../. 2.'5 C.19 4.12 0.11 0.02 2.57 3.11 3.53 7.12 O.b6 0.19 14.41 1956 1167 3.:2 7.4t, 5.29 0.62 0.42 2.72 2.00 1.35 1.93 0.44 3.44 12.93 1457 1966 1.15 1.37 1.71 1.62 T 0.51 1.97 1.12 r 0.09 1.56 ;.32 5.14 1955

29b APPENDIX B

299 191 ,,y,t.,,

Stochastic Process

If X(t) is the output from a stochastic process, the usual case, especially in hydrology, is a single time series of the process. That is, only one sample function is available from a process. Repeated samples are not available as is often the case for random variables. Therefore, the problem is much more complex and requires more assumptions or knowledge of the physical system.While this concept is elementary and obvious, it is quite often unsaid or overlooked. For stochastic processes the limit laws are of primary importance. The degree of uncertainty relative to random variables and stochastic processes is shown in the attached sketch (Figure 2). While this sketch is not all inclusive of the differences between random variables and stochastic processes, it does serve to illustrate the primary differences for hydrologic time series. It is obviously a simplification of the concepts of random variables and stochastic processes.

THUNDERSTOR`1 RAINFALL MODEL

Many assumptions and simplifications are involved in developing a model of a physical process. This is certainly true in modeling thunderstorm rainfall. The physical processes causing a thunderstorm at a certain time and place are very complex, as are the processes determining depths, duration, and areal extent of the thunderstorm rainfall. Thus, many assumptions and simplifications are necessary to make model solutions practical.

A stochastic air -mass thunderstorm rainfall model for generating runoff -producing rainfall based upon certain assumptions and simplification has been proposed (Osborn, Lane, and Kagan, 1971). This model (CELTH -5) is developed in two parts. The first part, or routine, determines whether a storm will occur, and if so, the time of occurrence. The second part generates runoff -producing rainfall through addition of individual synthetic storm cells.

More recently, CELTH -6, a model for generating total storm rainfall has been suggested. In CELTH -6, total storm rainfall is generated by adding random amounts of nonrunoff producing rainfall, as determined by a negative exponential distribution, to each runoff - producing rainfall cell generated by CELTH -5. In this paper, the assumptions and simplifications incorporated in the runoff -producing rainfall model are examined, since they are possible causes of uncertainty in the stochastic output. The assumptions and simplifications are listed and discussed as follows:

1. All runoff -producing storms for small (100- square -mile and less) watersheds in southeastern Arizona result from air -mass thunderstorms. These thunderstorms are the runoff "design" storms for small watersheds. Moist air for air -mass thunderstorms generally comes from the Gulf of Mexico.

300 2. Frontal activity is not importantin runoff design in southeastern. Arizona, although tropical storms off Baja California may move moist Pacific air into Arizona, particularly in September (Sellers, 1960). In southeastern Arizona (Walnut Gulch) storms occurring from "Pacific" air are still considered air -mass for small watershed design.

3. Storm probability of occurrence is based on 12 years of Walnut Gulch data. The process is assumed stationary, and the 12 -year record is assumed to adequately represent a longer record.

4. There is no persistence between events. That is, there is no allowance for a causal relation resulting in wet -wet, dry -dry, and so on. However, there is seasonal persistence, as indicate by changing probabilities for thunderstorm occurrence during the season (May 15 -Oct. 15). There is a much greater chance of occurrence on a day in late July, for example, than in June or early July, and this is included in the model.

5. Storm starting time is normally distributed about a mean of 1700 hours with a standard deviation of 3.5 hours (determined from Walnut Gulch data), corresponding to the late afternoon occurrences due to diurnal heating.

6. No two storms can occur within less than 3 hours; two or more storms can occur in one day. there is a 1/5 chance of two storms occurring on the same day, 1/25 chance of three occurring, and so on. The fractions for multiple occurrence are multiplied times the regular probabilities. For example, ifthe model indicates the chance of a storm occuring before 2100 hours is 0.4, there would be a.08 probability of a second storm occurring on the same day.

7. Thunderstorms are assumed to be made up of three or more circular cells.

8. Lndividual cell center depth varies according to a negative exponential distribution.

9. Cells have a fixed diameter at near zero rainfall (.01 inch).

10. Cell depth -area relationship is linear from the center out to a radius ofJT (the radius for an area of one square mile). At this radius the depth is 85 of center depth. From this "isuliyet" down to .01 the relationship is logarithmic.

11. Cells within each thunderstorm develop sequentially both in title and direction, although they may occur almost simultaneously. Individual cells are temporally contiguous.

2.6 -

301 12. The model generates runoff -producing rainfall (0.5 in /hr or greater) continuously at any point, and this rainfall can be adequately described by depth, duration, and centroid.

13. The first thunderstorm cell can be centered anywhere in a specified field. Its location is random as determined by a uniform distribution.

14. The preferred direction of the second cell in respect to the first cell is random as determined with a uniform distribution.

15. The distance between successive cells is determined independently by a triangular distribution roughly representing a gamma distribution. The triangular distribution was chosen for simplicity by trial and error, because a more sophisticated distribution was not believed to be justified due to the difficulty of precisely defining limits of individual cells.

16. The third cell movement direction is determined by a truncated normal distribution about the direction established between the second and first cell. Direction of movement of successive cells is determined similarly.

17. The number of cells in a storm is determined by a Poisson distribution, truncated with a 3 -cell minimum as suggested by Petterssen (1957) and by observations of Walnut Gulch data. The value used in the distribution is such that very few storms contain more than 6 or 7 cells.

MODEL VALIDITY

In order to test the validity of the storm rainfall model and thus determine whether the assumptions and simplifications incorporated are reasonable, itis necessary to compare observed with simulated rainfall characteristics. Also, since the objective in simulating thunderstorm rainfall is to obtain peak discharge predictions through a deterministic functional relation of rainfall and runoff, model validity can be tested by comparing observed peak discharge rates with chose obtained with the rainfall- runoff functional relation and simulated rainfall. In this paper both types of comparisons are made. The functional relation used to obtain peak discharge for a given simulated thunderstorm rainfall is one previously developed for the Walnut Gulch watershed.

In addition to testing validity of assumptions and simplifications in the rainfall model, a sensitivity analysis was done to evaluate the uncertainty in values of rainfall model parameters.

2.6 - 5

302 APPENDIX C

303 fT?it V ; V Table 1.- -Period of record for streamflow- gaging stations included in the statistical u:maries- Continued 3

Period of record Gaging station

Page muter

CGLORA05 R15711 BASF:- Continued OILS RIVER B.AS7',- Continued Santa Cru:River-Continued Tanaue Verde Creek -Continued 09484560 Cieneca Creek near Pantano 248 09484590 Davidson Canyon Mash near l'ail 250

09484600 Pantano Wash near Vail 252 1 09485000 Rincon Creek near Tucson 254 09386000 Rillito Creek near Tucson 257 09486300 Canada del Oro near Tucson 262 09386500 Santa Cruz River at Cortaro 264 09496800 Altar Mash near Three Points 268 09188500 Santa Rosa Wash near Vaiva Vo, near Sells 270 09489000 Santa Cruz River near Laveen 272 09489070 North Fork of East Fork Black River near Alpine 276 09489100 Black River near Maverick 278 09489200 Cacheta Creek at Maverick 290 09189499 Black River above Willow Creek diversion, near Point of Pines 82 09389700 Big Bonito Creek near Fort :Apache 84 9949U500 Black River near Fort Apache 86 09490800 .North Fork 'White River near Greer 88 09491000 North Fork White River near 'nary 90 09492400 East Fork White River near Fort :Apache 92 09304000 White River near Fort :Apache 94 Salt River: 09494300 Cortito Creek above Corduroy Creek, near Show Lou 296 09494500 Corduroy Creek above Forestdale Creek, near Show Lou 208 09495500 Forestdale Creek near Show Low :n5 09496000 Corduroy Creek near vouch, near Show Low 302 09496500 Carrizo Creek near Show low 305 Unnamed tributary: 09496600 Cibecue No.1, tributary to Carrizo Creek, near Show low 307 09496700 Cibecue No. tributary to Carrico Creek, nearShow Las 309 09497500 Salt River near Cnrosotile 311 09497800 Cibecue Creek near Chrysotile 315 09497900 (Terry Creek near Young 317 09497930 Cherry Creek near Globe 319 09498500 Salt River near Roosevelt 321 00198800 Tonto Creek near Gisela 326

I 09498970 Rye Creek near Gisela 325 1 ' 09499000 Tonto Creek above Can Creek, near Roosevelt 330 Big Chino Wash (head of Verde River): 09502800 Williamson Valley Wash near Paulden 334 Verde River: 09503000 Granite Creek near Prescott 336 09503700 Verde River near Paulden 338 09504000 Verde River near Clarkdale 345 09504500 Oak Creek near Cornvhlle 342 09505200 'net Seaver Creek near Rimrock 34o 09505250 ied Tank Draw near Riasrock 339 Shy Beaver Creek: 09505300 Rattlesnake Canyon near Rdaurock 350 09505550 Dry Beaver Creek near Ranrock 352 09505800 West Clear Creek near Cara Verde 354 09507600 Fist Verde River near Pine 356 09507'00 Webber Creek above West Fork 'Webber Creek, near Pine 358 09507980 East Verde River near Childs 360 09503300- Wet Bottom Creek near Childs 362 09508500 Verde River below Tangle Creek, above :horseshoe Dam 364 09510070 West Fork Sycamore Creek above McFarland

I I Canyon, near Sunflower 164 09110080 West Pork Svcatore Creek near Sunflower 3-0 09510100 East Fork Sycamore Creek near Sunflower 09510150 Sycamore Creek near Sunflower Mesquite Mash: 09510180 Rock Creek near Sunflower 09510200 Sycamore Creek near Fort 'cuowell 3 -3 09512100 Indian Send Wash at Scottsdale 350 09512200 Salt River tributary in South sbsantain Park, at Phoenix 332 i,., 09512400 Cave Creek at Phoenix 384 09512.500 Agua Fria River near :Mayer 386 09512800 Agua Fria River near Rock Springs 390 09513790 New River near Rock Springs 592 09515800 New River at New River 594 09513835 New River at Bell Road, near Peoria 396

I 09513860 Skunk Creek near Phoenix 398 09515300 ilassayampa River at Box damsite, near Wickenburg 355 09517500 Centennial Wash near Arlington 3n3 I i,< 09518000 Gila River above diversions, at Gillespie Jam 405 09520170 Rio Come: near Ajo 409 SULPI11R SPRING '01.117f WHITCsAT DRAW' BASIN Whitewater Draw: I 09537200 Leslie Creek near 'deal 111 09537500 Whitewater Draw near Douglas 413

304 Table 2.-- Flood- frequency data fOr selectedstreamfloi- gaging stations--Contlnues

DRATNAGE FLUOQ MAGNITUDE.TN CUBIC FEE PER CURD. AGEA 13 FON INUTCAtEONECUNRENCF 7NT 0 L. T TEARS 3TLTION (IN SUU /RE NUMBER STATION NAM[ PFRTUO OF NECONO MILOS) U7 OS OIO 72SE By 0100

09444500 SAN FRANCISCO NEVER AT 1691.1905 07. 2766.00 7230 17600 20000 45900 63240 69100 CLIFTON. ARIL. 1911 -75

09445300 MILLON CR NO POINT OF PINES NR 1995 -67 102.00 629 1530 2330 3670 4670 6256 MORENCI. ARIZ.

09446000 MILLON CR NR 0000LE CINCLE 1941- 67.1973 149.00 1090 3220 5630 9980 14300 19500 RANCH NR MORENCI, ARIZ.

09446500 EAGLE CR NR 0000LE CIRCLE 1944 -67.1973 377.70 2500 6330 10000 16200 21040 20400 RANCH NR MURENCI. ARIZ.

04447000 EAGLE CR ABV PUMPING PLANT NR 1932,1944 -75 613.00 2330 0200 10100 16700 22600 30100 MORENCl. ARIZ.

09444500 GILA R AT HEAD OF SAFFURU 1914475' 7696.00 9100 20900 31600 49500 66400 86000 VALLEY NR SOLOMON. ART2.

09456000 SAN SIMON RIVER NR SAN 0100N, 1923.1931 -41 814.00 2670 4660 6200 0290 9950 11700 ARIZ.

09401000 SAN SIMON RIVER NR 004.000N, 1931 -75 2192.00 4640 7030 9950 12700 19900 17100 ARIZ.

09406500 GILA RIVER LT CALVA. ARIZ. 1930 -75 11470.00 6000 13000 22100 37000 54400 76400

09000300 SAN CALLUS RIVER NEAR PERIO0T. 1916.1930 -75 1027.00 7220 15400 22500 33400 A2100 53000 ARIZ.

09670500 SAN PEDRO RIVER AT PALUMINAS, 1930 -33.1933 -40. 741.00 6390 10100 12000 16300 19000 21800 ARIZ. 1950 -73

0997/000 SAN REDRO RIVER AT C000LEGTON 1916 -75 1219.00 0950 12900 17900 20000 39100 43900 ARIZ.

09472000 SAN PEDRO RIVER NEAR 14260913 -77 2930.00 7750 15200 21400 30900 39000 40100 REDINRTON, ARIZ.

09472300 SAN PEDRO RIVEN NR MAMMOTH, 1926,1431 -40 3610.00 10100 29300 39200 52000 .65600 75300 ARIZ.

09473000 ARAVAIPA CREEK NEAR M4MMOTH, 1914 -21.1631 -11. 541.00 9900 9530 13200 14400 22700 27400 0012. 1966 -75

04474000 GILA R AT KELVIN. ARIZ. 3091,1906.1907, 16011.00 19100 46000 70500 120600 173600 2.4900 19(2 -00

09474000 GILA R AT KELVIN. ARIZ. 1929 -75 5125.00 7020 15000 21000 33100 44900 50700 DRAINAGE AREA BL COOLIDGE DAN

09//0500 QUEEN CR AT NMI7LON 0/05ITE NR 1417-20.1440-59 194.00 9050 10600 17000 27900 38100 S0100 SUPERIOR. ARIZ.

09400000 SANTA CRUZ RIVER NEAR LOCNIEL, 1949 -75 02.20 1530 2760 3710 5020 6060 7190 ARIZ.

09480500 SANTA CRUZ RIVER NEAR NOGALES. 1430 -75 533.00 4100 7140 9400 12700 15400 10200 ARIZ.

01111000 SON011 CREEK NEAR PATAGONIA. 1930 -72 204.00 2110 5320 7920 10400 12000 15400 ARIZ.

04482000 SANTA CRUZ RIVER AT 1940- 47,1452 -75 1062.00 4210 0020 11000 15200 10600 22200 V CONTINENTAL ARIZ.

09462400 AIRPORT 0404 AT TUCSON. ARIZ. 1966 -75 15.20 320 572 764 1030 1240 1470

09402500 SANTA CRUZ RIVER AT TUCSON. 1915 -75 2222.00 5160 6700 11300 14000 171Ú0 20309 ARIZ.

09903100 TANQUE VERDE CREEK NEAR 1960 -75 43.00 1100 L20G 3010 9150 5000 0000 TUCSON, ARIZ.

04909000 RABINO CREEK MEAR TUCSON, 1433 -13 35.00 1030 2390 3650 5670 7090 9500 ARIZ.

09909200 BEAR CREER NEAR TUCSON. ARI!. 1900 -71 I4.30 264 700 1140 1490 2590 3420

09989600 PANTANO NASH NEAR VAIL. ARIZ. 1950`73 457.00 4330 10000 17000 27300 36600 47600

04405000 RENCOR CREER NEAR TUCSON, 1952 -75 60.80 106) 2900 5010 0550 12000 16100 ARIZ.

09100000 RILLITO CREEK NEAR TUCSON. 1919 -73 592.00 9400 9130 12300 14700 20200 23400 ARIZ.

305 Table 2.-- Flood- frequency data for selected streamflow- gag1n9 stations -- Continued 14 uRAINAGE FLOOD MAGNITUDE, IN CUBIC FEET PER SECOND. AREA FON INDICATED NECUMRENCF INTERVAL. IN YEARS STATION (IN SAUARE huLBER STATION NAME PELILLO OF NECORO 1LES) 02 05 010 025 050 0100

09986300 CANADA DEL ORO NEAR TUCSON, 1966 -75 250.00 2010 5410 0670 19400 20400 27100 ARIZ.

09066500 SANTA CRUZ RIVER AT CORTARO. 1990 -47,1950 475 3503.00 6140 12700 15000 19900 22600 25400 ARIZ.

0/060600 ALTAR RASH NEAR THREE P0)005. 1966 475 463.00 5310 10100 10100 19900 20400 10100 ARIZ.

09404500 SANTA ROSA MASO NO VA /VA VO. 1955 -75 1702.00 1050 4490 0000 14700 21600 30000 ARIZ.

09089000 SANTA CRUZ RIVER NEAR LADEEN, 1940 -46,1940 -75 6541.06 1030 2690 4300 7290 9900 13300 ARIZ.

09469070 NORTH FORK OF EAST FORK BLACK 1946 -75 36.10 216 603 1000 1690 2360 3150 RIVER NR ALPINE. ARIZ.

09469100 SLATS RIVER NEAR MAVE0ICK. 1963 -15 315.00 1450 3050 4520 6690 6560 10600 ARIZ.

09069200 PACMETA CREEK NEAR MAVERICK. 1956 -75 14.60 101 162 244 330 399 472 ARIZ.

09469499 SLACK R ASV NILLON CR DIV NO 1954 475 560.00 1990 4350 0440 9640 12000 15600 POINT OF PINES, ARIZ.

59469700 BIG BONITO CREEK NR FORT 1956 -75 119.00 611 1150 1570 2140 2600 3200 APACHE, ARIZ.

09490500 BLACK RIVER NEAR FORT APACHE, 1950 -75 1232.00 9050 12300 19600 31000 43000 56100 ARIO.

09490600 NORTH FORK WAITE RIVER NEAR 1906 -75 39.00 196 291 354 433 492 551 GREER. ARIZ.

09491000 NORTH FORK NMITE RIVER NEAR 1966.1946 -75 66.00 390 643 906 1210 1460 1720 MCNARY. ARIZ.

09492400 EAST FORK 60411E RIVER NR FORT 1956 -75 36.00 241 776 471 593 665 776 APACHE, ARIZ.

09494000 ',MITE ROVER NEAR FURT APACHE, 1950 -75 032.00 3270 5300 6630 6610 10300 11900 ARIZ.

09494300 CARRIZO CR ABV CORDUROY CR NR 1554 -66 225.00 1960 3670 5440 7730 9650 11700 MN LOH, ARIZ.

09496000 COR0060r CREEK NEAR MOUTH. 1952 -75 203.00 1020 3610 7350 14500 22200 32300 NEAR SHON LOn. ARIZ.

09096500 CARRIZO CREER NEAR !HON LON, 1952 -75 439.00 2640 7320 11400 19200 26100 14200 ARIZ.

09496600 CIBECUE 1 TRIO TO CARRIZO CR 1956 -70 .10 45 96 140 206 263 327 NR OHO, LON, ARIZ.

09496700 CIBECUE 2 IRIS TO CARRIZO CR 1956 -70 .06 42 71 93 122 146 170 NR SMOK LON. ARIZ.

09497500 SALT RIVER NEAR CHRC500ILE, 1916,1925 -75 2049.00 9170 21000 32300 51100 60700 59700 ARIZ.

04497600 COSECUE CREEK NEAR C0030TTLE, 1959 -75 P95.00 3630 6920 9560 15300 16500 19000 ARIZ.

09497900 CHERRY CREEK NEAR YOUNG, ARIZ. 1063 -75 62.10 1340 3220 4930 7640 10100 12400

09497900 CHERRY CREEK NEAR GLOBE. ARIZ. 1966 -75 200.00 1970 4300 6360 9530 12300 15300

09496500 SALT RIVER NEAR N000EVELT. 1916,1925 -75 4306.00 12400 31600 51500 66500 121000 164000 ARIZ.

09494600 TONTO CREEK NEAR GISELA. ARIZ. 1965 -75 430.00 6920 21600 33500 52900 70500 90700

00490070 RYE CREEK NEAR GISELA. ARIZ. 1963,1966 475 122.00 2040 0390 9540 29600 19000 23900

/949900/ TONTO CREEK AOOVE GUN CO, NO 1901 -75 675.00 9600 21600 32700 49900 65000 62200 ROOSEVELT. ARIZ.

09502000 ',ILLIAMSUN VALLEY RAS MR 1065 -75 255.00 735 1750 2720 0340 5830 1590 PAULOEN, ARIZ.

09503000 GRANITE CREEK NR PRESCOTT, 1933 -47,1963.1066 39.60 715 1660 ' 2560 4050 5396 6076 ARIZ.

306 229 GILA RIVER BASIN

09482000 SANTA CRUZ RIVER AT CONTI.N'ENTAL, A2

LOCATION. --Lat 31 °51'12', long 1I0S8'40 ",in NE4NE4 sec.23, T.IS S., R.13 E. (unsurveyed), Pima County, Hydrologic Chit 15050301, in Spanish land grant of San Ignacio de la Canoa, near left bank on downstream side of pier of highway bridge at Continental.

.AINAGE AREA. --1,062 mil (4,305 km2), of which 395 mil (1,023 km =)is in Mexico.

NATER ANNUAL PEAK OATS GAGF HEIGHT OF CODE ANNUAL MAx DATE AATFM TOTAL VOLUME, YEAR DISCM,CFS ANNUAL PEAK,FT GAGE MT.FI YEA,: ACNE -FI

1940 12100 08-14-40 8.85 1941 2050 1941 3670 08-09-41 5.4 1442 3560 1942 2700 07-28-42 4.95 1943 10100 1943 4000 08-01-43 5.55 1944 4070 1944 4440 08-12-44 5.80 1945 17660 1945 7820 06-04-45 7.25 1946 12400 1946 4120 09-09-46 5.94 NM 6.00 07-27-46 1452 3260 1947 5330 10-01-46 6.40 1953 7970 1952 1820 08-15-52 4.20 1954 17800 1953 4910 07-17-53 6.20 1957 44200 1954 14600 08-05-54 30:10 1957 1010 1955 17500 08-19-55 11.34 1957 1220 1956 3090 07-29-56 4.0 1957 14200 1957 1690 08-21-57 3.62 1954 5970 1958 5620 08-05-58 5.83 1960 14100 1959 3900 08-17-59 5.43 1961 7850 1970 3740 01-12-60 5.70 1962 7230 1961 4820 08-23-61 5.80 1963 13700 1962 2480 01-25-62 4.80 1964 29800 1963 4220 08-06-63 5.65 1965 184 1964 14000 09-10-64 10.13 1966 64400 1965 370 09-12-65 6.15 1467 3490 1966 5990 12-23-75 9.34 1966 42100 1967 3730 07-27-67 8.81 1969 2970 1968 18000 12-20-67 15.3 197u 3640 1969 1680 08-05-69 5.79 1971 126U0 1970 3720 07-20-70 7.80 1972 1450 1971 3270 08-20-71 7.30 1973 112un 1972 3290 07-14-72 8.72 1974 4510 1973 2130 03-14-73 7.20 1975 446n 1974 3450 09-03-74 8.10 1975 3350 09-01-75 8.15

NM Not maximum gage height for water year. GILA RIVER BASIN 229

09482000 SANTA CRUZ RIVER AT CONTINENTAL, AZ-- CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 CNARBE IM CUBIC FEET PER SECOND .N

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 2627 2829 303132 3334 YEAR NUMBER OF OATS IN CLASS

1941 337 1 1 1 1 3 4 1 1 6 1 1 1 1 1 2 1 1 1942 339 2 3 2 1 2 1 2 4 2 3 3 1

1943 317 1 1 5 1 4 5 3 1 2 4 3 8 5 2 1 1 1

1944 348 2 3 1 1 3 1 2 1 1 2 1

1945 330 3 1 1 2 2 1 5 1 1 6 3 2 1 4 1 1

1946 311 11 3 3 1 1 3 3 1 2 3 4 1 4 3 3 2 2 1 1 1 1952 329 3 1 2 1 1 3 1 1 2 1 3 3 2 4 1 3 3 1 1

1953 330 2 3 1 2 1 3 1 2 1 2 3 1 1 1 1 1 3 2 1 2 1

1954 306 3 1 2 2 1 1 4 2 1 2 4 5 1 3 3 1 6 2 2 6 1 2 2 1 1 1955 320 2 1 2 1 1 1 1 1 1 2 1 3 1 1 1 1 2 3 4 5 3 3 1 2 1

1956 355 1 2 1 1 3 1 1 1 1957 338 1 1 1 1 2 1 5. 2 1 2 3 2 1

1958 318 1 2 1 2 5 3 2 1 2 2 1 2 2 1 4 3 3 4 1 1 2 1 1 1959 319 1 1 1 1 2 2 4 2 1 5 4 4 3 2 2 1 3 4 1 1 1

1960 322 1 2 L 1 3 4 1 4 2 t 1 2 4 3 3 1 2 1 2 2 2 1

1961 319 1 2 3 S 3 2 3 1 1 4 2 1 5 3 1 3 1 2 2 1 1962 346 1 1 2 1 1 3 2 2 1 1 1 1 1 1

1963 319 1 1 2 2 2 2 1 2 4 2 4 2 2 4 3 3 2 2 1 1 3 1964 323 2 1 1 2 2 1 1 4 3 3 1 6 1 3 4 1 3 2 1 1 1965 354 1 1 1 2 1 3 1 1

1966 288 1 2 3 1 1 2 2 1 4 3 4 5 5 4 6 3 6 2 3 2 6 l 3 4 2 1 1967 330 1 1 1 1 1 5 1 4 5 4 2 2 2 3 1 I 1968 318 2 1 2 1 3 2 3 2 6 1 2 3 5 1 2 1 1 1 2 3 2 1 1 1969 323 2 1 5 2 4 3 3 5 2 3 1 3 1 2 2 1 1970 318 3 3 4 3 t 2 1 2 4 4 1 1 3 1 1 1 1 2 1 3 1 2 1 1

1971 309 1 2 1 2 L 2 3 3 3 2 3 2 1 3 S 3 4 2 2 1 2 1 1 1 1 1972 344 1 1 2 1 2 1 1 3 2 2 2 1 2 1

1973 346 1 1 1 1 2 1 1 1 1 2 1 1 2 3 1974 342 0 2 1 1 1 1 2 2 I 3 2 2 2 1 1975 340 I 1 1 1 2 1 1 3 2 3 3 3 1 2

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 9638 10957 100.0 12 5.5 33 773 7.1 24 300 30 148 1.3 0.10 28 1119 10.2 13 7.7 60 740 6.8 25 420 33 118 1.0 0.20 17 1091 10.0 14 11.0 47 680 6.2 26 590 30 85 .7 3 0.30 19 1074 9.8 15 15.0 57 633 5.8 27 820 19 55 .5 4 0.40 14 1055 9.6 16 21.0 47 576 5.3 28 1100 16 36 .3 S 0.50 21 1041 9.5 17 29.0 52 529 4.8 29 1600 7 20 1 6 0.70 15 1020 9.3 18 41.0 65 477 4.4 30 2200 6 13 .1 7 1.00 57 1005 9.2 19 57.0 53 412 3.8 31 3100 3 7 8 1.40 23 948 8.7 20 79.0 59 359 3.3 32 V400 2 4 9 2.00 53 925 8.4 21 110.0 55 305 2.7 33 6100 2 2 10 2.80 40 872 8.0 22 150.0 64 245 2.2 34 11 3.90 59 832 7.6 23 220.0 33 181 1.7

308 230 GILA RIVER BASIN

09482000 SANTA CRUZ RIVER AT CONTINENTAL, AZ-- CONTINUED

LOWEST NFAN VAIUFANnoANaTN, FUR TnFFUIIn4T146NU°8FNUFCUNSECIIiTVEDAYSIN YEARENUTNGSEPTEMNER30 [NARGF,IN CURIC FEET PEASECDND

YEAR 1 3 7 14 30 60 90 17u 163

1941 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.0625

1942 0.00 2 0.88 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 1 1943 0.00 3 0.00 3 0.00 S 9.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 2 1944 0.00 4 0.00 a 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 3 1945 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4

1946 0.00 b 0.00 6 0.00 b 9.00 6 0.00 6 0.00 6 0.00 6 0.00 b 0.00 5 1952 0.00 7 0.00 7 0.U0 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6 1953 0.00 e 0.00 8 0.00 6 0.00 8 0.00 B 0.00 8 0.00 6 0.00 B 0.00 7 1954 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 1.1930 1955 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.00 8

1956 0.00 11 0.00 11 0.00 11 0.0011 0.00 11 0.00 11 0.0011 0.00 11 0.00 9 1957 0.0012 0.0012 0.u012 0.0012 0.0012 0.0012 0.0012 0.0012 0.0010 1958 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0011 1959 0.0814 0.0014 0.0014 0.0014 0.0014 0.0014 0.0014 0.0014 0.0012 1960 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0n15 0.0015 0.0013

1961 0.0016 0.0016 0.0016 0.0016 0.0016 0.0016 0.0016 0.0016 0.0014 1962 0.00 17 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.00 17 0.1926 1963 0.0018 0.0016 0.0018 0.0016 0.0016 0.0018 0.0016 0.00i8 0.0015 1964 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.0016 1965 0.0070 0.0020 0.0020 0.0020 8.00?0 0.0020 0.0020 0.0070 0.0017

1966 0.00?1 0.0021 0.0021 0.0021 0.0021 0.00?1 0.0021 0.00?1 10.0031 1967 0.0022 0.0022 0.00?2 0.00?2 0.0022 0.0022 0.0022 0.0022 0.0016 1968 0.00?3 0.0023 0.00?3 0.0023 0.0073 0.0023 0.0023 0.0023 0.6529 1969 0.0074 0.0024 0.00?4 0.00?4 0.0024 0.0024 0.0024 0.00?4 0.0019 1970 0.0025 0.00?5 0.0025 0.00?5 0.0025 0.0025 0.0025 0.0025 0.0924

1971 0.00Pb 0.0026 0.0076 0.0076 0.0026 0.00Pb 0.0026 0.0026 0.0020 1972 0.0027 0.0027 0.80?7 0.00?7 0.00?7 0.0027 0.0027 0.0077 0.0021 1913 0.0028 0.0028 0.0028 0.00Pb 0.0026 0.0028 0.0028 0.0026 0.1126 1974 0.0029 0.0029 0.0029 0.0079 0.0079 0.0079 0.0029 0.0029 0.0022 1975 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0023

309 GILA RIVER BASIN 131

09482000SANTA CRUZ RIVER AT CONTINE`TAL, AZ-- CONTINUED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE OAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 t20 183 1941 363.0 24 161.0 25 71.0 27 35.0 27 28.0 26 15.027 10.027 7.5 27 4.927 1942 474.0 22 234.0 22 116.0 21 69.0 21 41.0 23 25.023 20.022 15.0 22 9.822 1943 861.0 17 454.0 15 274.0 14 160.0 14 137.0 13 81.013 57.013 43.0 13 28.013 1944 528.0 21 296.0 18 195.0 17 129.0 16 65.0 17 34.020 23.020 17.0 20 11.020 1945 1330.0 10 754.0 10 500.0 8 406.0 6 247.0 6 133.0 6 90.0 6 68.0 6 44.0 6

1946 1150.0 12 606.0 13 327.0 13 221.0 12 145.0 12 92.011 65.011 49.0 11 32.011 1952 311.0 26 135.0 26 79.0 25 49.0 26 34.0 2S 22.025 16.025 12.0 25 7.725 1953 1090.0 13 853.0 8 401.0 9 201.0 13 117.0 14 59.014 39.014 29.0 14 19.014 1954 4290.0 4 1690.0 5 1200.0 4 168.0 510.0 3 294.0 4 208.0 4 157.0 4 103.8 4 1955 3500.0 5 2080.0 4 1440.0 3 936.0 2 786.0 1 414.0 1 276.0 1 207.0 1 136.0 1

1956 227.0 28 84.0 28 37.0 28 21.0 28 17.0 28 8.529 5.729 4.2 29 2.829 1951 110.0 29 48.0 29 31.0 29 19.0 29 16.0 29 10.028 6.828 5.1 28 3.428 1958 1410.0 9 722.0 11 330.0'12 274.0 9 192.0 9 112.0 8 80.0 7 60.0 7 39.0 7 1959 878.0 16 400.0 17 266.0 15 146.0 15 83.0 15 47.016 31.017 23.0 17 15.017 1960 2500.0 6 1320.0 6 761.0 6 368.0 7 199.0 7 100.010 66.010 54.0 10 33.018

1961 931.0 15 422.0 16 182.0 18 100.0 18 69.0 16 47.017 32.016 24.0 16 16.015 1962 1300.0 11 539.0 14 232.0 16 108.0 17 54.0 19 49.015 33.015 25.0 15 16.016 1963 972.0 14 655.0 12 366.0 11 248.0 11 191.0 10 114.0 7 77.0 8 58.0 8 38.0 8 1964 6110.0 2 2510.0 3 1190.0 5 570.0 5 423.0 5 248.0 5 166.0 5 124.0 5 81.0 5 1965 32.0 30 18.0 30 9.2 30 4.6 30 2.3 30 1.530 1.130 0.8 30 8.530

1966 5190.0 3 2960.0 2 1470.0 2 852.0 3 436.0 4 295.0 3 216.0 3 182.0 3 166.6 3 1967 650.0 18 253.0 21 110.0 23 65.0 22 46.0 22 26.022 19.023 14.0 23 9.423 1968 9800.0 1 5370.0 1 2760.0 1 1360.0 1 681.0 2 341.0 2 234.0 .2 175.0 2 115.0 ;2 1969 341.0 2S 133.0 27 75.0 26 55.0 24 38.0 24 24.024 17.024 22.0 24 8.124 1970 545.0 20 269.0 20 116.0 22 61.0 23 49.0 20 30.021 20.021 15.0 21 10.021

1971 1430.0 8 765.0 9 369.0 10 301.0 8 199.0 8 106.0 9 71.0 9 53.0 9 35.0 4 1912 284.0 27 169.0 24 100.0 24 51.0 25 27.0 27 15.026 10.026 7.6 26 5.026 1973 1470.0 7 1060.0 7 548.0 7 256.0 10 181.0 11 90.012 60.012 45.0 12 31.022 1974 579.0 19 283.0 19 151.0 19 80.0 19 62.0 18 37.018 25.019 19.0 19 t2.019 1975 404.0 23 197.0 23 121.0 20 78.0 20 49.0'21 35.019 28.018 21.0 18 14.018

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL NAY JUNE JULY AUG SEPT BY ROWS (NEAN.VARIANCESTANOARD DEVIATION.SKEWNESSCOEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE 1.98 0.15 37.5 8.82 8.88 4.97 0.00 0.00 0.30 33.7 94.6 20.6 21.3 0.64 19670 1280 1500 516 0.00 0.00 0.85 2081 24660 2634 4.62 0.80 140 35.8 38.7 22.7 0.00 0.04 0.92 45.6 157 S]4 2.77 5.48 3.94 4.91 4.97 5.29 5.48 3.38 2.94 2.94 5.01 2.33 5.39 3.74 .05 4.36 4.57 5.48 + 3.06 1.35 1.63 2.44 0.93 0.07 17.6 4.13 .16 2.33 0.00 0.00 0.14 ]5.8 45.2 9.65

DISCHARGE. IN CUBIC FEET PER SECOND STATISTICS ON NORMAL ANNUAL MEANSIALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORK 18.0 477 21.8 1.97 1.21 -0.150

***.. Skewness and coefficient of variation could not be computed owing to a zero -value month.

310 232 GILA RIVER BASIN

09482400AIRPORT WASH AT TUCSON, AZ

LOCATION. --lat 32 °09'09 ", long 110 °58'52 ", in Nn.SE4 sec.2, T.15 S., R.13 E., Pima County, Hydrologic Unit 15050301, 25 ft (7.6 m) upstream from Santa Clara Avenue, 0.7 mi (1.1 km) upstream from mouth, 4.3 mi (6.9 km) downstream from confluence of North and South Forks, and 4.9 mi (7.9 km) south of city hall in Tucson.

DRAINAGE AREA. --23.0 mi' (59.6 km2).

WATER ANNUAL PEAK DATE GAGE HEIGHT OFnATER TOTAL VOLUME, YEAR OISCH,CFS ANNUAL PEAK.FT YEAR ACRE -FT

1966 322 09 -11-66 4.25 1966 333 1967 106 07 -17 -67 3.66 1967 58 1968 385 08 -20 -68 4.39 1948 173 1969 118 08 -28 -69 3.71 1949 97 1970 823 07 -20 -70 4.14 1970 811 1971 549 10 02 -70 3.44 1971 718 1972 310 07 -16 -72 3.67 1972 252 1973 159 10 -19 -72 2.88 197S 272 1974 689 07 -07 -74 2.41 1974 417 1975 377 07 -12 -75 2.01 1975 198

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 2829 303132 3334 YEAR NUMBER OF DAYS IN CLASS 1966 333 4 2 1 2 1 3 1 2 1 4 1 1 2 1 1 1 1967 348 1 2 2 3 2 1 3 1 1 1 1968 347 1 2 1 5 1 3 1 2 1 1 1 1969 347 2 3 1 3 1 1 2 3 1 1 1970 348 1 1 1 1 1 1 2 2 1 1 1 1 1 1 1

1971 340 1 1 1 2 1 2 1 2 3 2 1 1 1 1 1 3 1 1972 343 2 1 1 1 1 1 1 1 1 2 7 2 3 1 1973 340 3 1 1 1 1 1 1 5 1 3 1 1 3 1 1 1974 343 2 1 1 1 2 1 1 3 1 2 3 1 1 1 1 1975 354 1 1 1 1 2 1 1 2 1

^' IS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERCY CLASS VALUE TOTAL ACCUM PERLT 0.00 3443 3652 100.0 12 0.5 18 161 4.4 24 17 6 .24 .6 0.01 2 209 5.7 13 0.7 9 143 3.9 25 22 3 18 .4 2 0.02 0 207 5.7 14 1.0 11 134 3.7 26 30 15 .4 3 0.03 0 207 5.7 15 1.3 13 123 3.4 27 40 5 11 .3 4 0.04 2 207 5.7 16 1.7 13 110 3.0 28 53 1 6 .1 5 0.05 0 205 5.6 17 2.3 7 97 2.7 29 70 3 5 .1 6 0.07 0 205 5.6 18 3.0 14 90 2.5 30 93 2 7 0.09 1 205 5.6 19 4.0 11 76 2.1 31 120 2 2 8 0.30 15 204 5.6 20 5.3 19 65 1.8 32 9 0.20 13 189 5.2 21 7.1 9 46 1.3 33 10 0.30 6 176 4.8 22 9.5 7 37 1.0 34 II 0.40 9 170 4.7 23 13.0 6 30 0.8

311 GITA RIVER BASIN 233

09482400 AIRPORT WASH AT TUCSON, AZ-- CONTINUED

LUMEST MFAN VALUE A::DRAMKEhnFUR TMF FuLLneTNG NUM6ER OF CUNSFCIITTVFHAYS INYEAREhUINGSEPTFMBERV9 DISCHARGE,IN CuRIC FEET PFRSECOnn MEAN

YEAR 1 3 7 14 NO 6U 40 1?0 103 1 1 1966 0.00 0.00 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 u.07 11 0.00 2 0.00 2 1967 0.00 2 u.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 1 1968 0.00 3 u.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.01 ò 0.01 9 1969 0.00 4 0.00 4 0.00 4 0.00 M 0.00 4 0.00 4 0.00 4 0.01 9 O.U1 7 1910 0.00 5 0.00 5 0.00 5 u.00 5 0.00 5 0.00 5 0.80 5 0.01 10 O.U1 ö

1911 0.00 b 0.00 b 0.00 6 0.00 b 0.00 b 0.00 b 0.00 6 0.00 3 0.00 2 1972 0.00 1 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 4 0.00 3 1973 0.00 ö 0.00 ö 0.00 8 0.00 ö 0.00 8 0.00 b 0.00 8 0.u2 il 0.04 10 1974 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 5 0.90 4 1975 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.00 6 0.00 5

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE.IN CUBIC FEET PER SECONO MEAN

YEAR 1 3 7 15 30 60 90 120 183 1966 32.0 7 14.0 7 6.0 7 3.3 5 2.8 5 2.2 4 1.4 4 1.1 4 0.7 4 1967 15.0 9 5.0 9 2.2 9 1.3 9 0.710 0.410 0.310 0.210 0.2 10 1968 44.0 5 15.06 6.3 6 3.0 6 1.5 8 0.8 8 0.5 8 0.4 8 0.3 8 1969 12.010 4.110 1.810 0.910 0.7 9 0.5 9 0.4 9 0.3 9 0.2 9 1970 170.0 1 97.0 1 42.0 1 20.0 1 10.0 1 6.7 1 4.5 1 3.4 1 2.2 1

1971 71.0 4 32.0 3 20.0 2 9.6 3 7.5 2 4.3 2 2.9 2 2.2 2 1.5 2 1972 26.0 8 11.0 8 4.9 8 2.7 8 2.5 6 1.6 6 1.1 6 0.8 6 0.5 6 1973 74.0 3 31.0 4 13.0 4 6.7 4 3.5 4 1.9 5 1.3 5 1.0 5 0.7 S 1974 124.0 2 45.02 19.0 3 9.7 2 6.2 3 3.2 3 2.3 3 1.7 3 1.1 3 1975 39.0 6 15.0 5 6.4 5 3.0 7 1.5 7 1.0 7 0.7 7 0.5 7 0.4 7 DISCHARGE, IN CUBIC FEET PER SECOND STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS (MEAN,VARIANCE,STANDARD DEVIATION.SKEWNESS,COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 0.73 0.15 0.25 0.00 0.06 0.04 0.03 0.00 0.02 2.49 0.99 0.68 1.76 0.06 0.15 0.00 0.02 0.00 0.01 0.00 0.00 9.26 0.82 0.80 1.33 0.24 0.39 0.01 0.13 0.06 0.08 0.01 0.06 3.04 0.91 0.89 1.74 1.50 1.19 3.16 2.73 1.61 2.88 3.16 3.13 1.55 0.99 2.16 1.82 1.59 1.55 3.16 2.33 1.69 2.33 3.16 2.94 1.22 0.91 1.32 13.4 2.73 4.64 0.03 1.05 0.67 0.60 0.08 0.37 45.7 18.3 12.4

DISCHARGE. IN CUBIC FEET PER SECOND STATISTICS ON NORMAL ANNUAL MEANSIALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 0.46 0.12 0.35 1.10 0.76 0.197

312 234 GI1A RIVER BASIN

09482500 SANTA CRUZ RIVER AT TUCSCM, AZ

LACATICN. --Iat 32 °13'16 ", long 110 °58'52 ", in NERNE4 sec.1S, T.14 S., R.13 E., Pima County, Hydrologic Unit 15050301, on downstream side of center pier of Congress Street Bridge in Tucson.

.RAINAGE AREA. --2,222 mi= (5,755 lame), of which 395 mil (1,023 1481)is in Mexico, adjusted for 15.2 mi' (39.4 km2) of Tucson Arroyo drainage area contributing to this station effective July 1956.

HATER ANNUAL PEAK GATE HIGHEST GAGE HEIGHT OF CODE MATER TUTAL VOLUME, TEAR DISCM,CFS SINCE ANNUAL PEAK,FT YEAH ACNE -FT

1915 15000 12 -23 -14 1905 1906 27000 1916 5000 01 -20 -16 1915 81000 1917 7500 09 -08 -17 1916 37340 1918 4900 08 -07 -18 1917 28400 1919 4700 08 -02 -19 1918 4930 1920 1950 08 -09 -20 1919 27500 1921 4000 08 -01 -21 1920 7920 1922 2000 07 -20 -22 1921 32100 1923 1900 08 -17 -23 1922 10800 1924 2050 11 -17 -23 1923 15700 1925 3400 09 -18 -25 1924 3700 1926 11400 09 -28 -26 1925 6940 1927 1950 09 -07 -27 1926 20200 1928 1600 08 -01 -28 1927 3140 1929 10400 09 -24 -29 1928 2920 1930 1770 08 -07 -30 1929 24300 1931 9200 08 -10 -31 1930 8080 1932 4200 07 -30 -32 1931 37300 1933 6100 08 -21 -33 1932 14700 1934 6000 08 -23 -34 1933 7100 1935 10300 09 -01 -35 1934 7570 1936 5400 07 -26 -36 1935 70400 1937 3280 07 -10 -37 1936 8770 1938 9000 08 -05 -38 1937 8260 1939 8000 08 -03 -39 1938 7620 1940 11300 08 -14 -40 1939 24400 1941 2490 08 -14 -41 1940 13500 1942 1670 08 -09 -42 1941 4990 1943 4510 08 -02 -43 1942 3060 1944 6530 08 -16 -44 1943 11100 1945 10800 08 -10 -45 1944 9760 1946 4260 08 -04 -46 1945 20700 1947 2960 10 -01 -46 1946 14900 1948 3860 08 -16 -48 1947 6510 1949 3800 08 -08 -49 1948 8650 1950 9490 07 -30 -50 1949 10500 1951 5020 08 -02 -51 1950 28900 1952 3820 08 -16 -52 1951 7230 1953 5900 07 -15 -53 1952 6050 1954 9570 07 -24 -54 1953 9710 1955 10900 08 -03 -55 1954 36000 1956 2610 07 -29 -56 1955 50200 1957 3050 08 -31 -57 1956 1290 1958 6350 07 -29 -58 9.85 1957 2230 1959 4420 08 -20 -59 9.15 1958 17700 1960 6140 08 -10 -60 10.24 1959 6870 1961 16600 08 -23 -61 15.60 1960 13000 1962 4980 09 -26 -62 7.90 1961 16300 1963 4670 08 -26 -63 12.82 1962 8250 1964 13000 09 -10 -64 18.05 1963 16200 1965 1190 07 -16 -65 8.49 1964 38100 1966 5500 08 -19 -66 12.30 1965 936 1967 5860 07 -17 -67 12.17 1966 43160 1968 16100 12 -20 -67 17.24 1967 5890 1969 8710 08 -06 -69 13.92 1968 38200 1970 8530 07 -20 -70 13.81 1969 5200 1971 8000 08 -17 -71 NM 1970 8680 1972 3470 07 -15 -72 1C.03 1971 11800 1973 4710 10 -19 -72 10.86 1972 5230 1974 7930 07 -08 -74 13.44 1973 13200 1975 2480 07 -12 -75 9.55 1974 7790 1975 5800 N4 Not maxima gage height for water year. GIL.i RIVER B.SI\ 235

094825005:.\7A CUZ RIVER AT TUCSON, AZ-CO\7I\LED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECOND MEAN

CLASS o 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 272829)031323334 YEAR NUMBER OF DAYS IN CLASS 1915 247 1 3 1 3 2 1 1 8 24 8 8 10 9 11 4 9 3 1 3 1 1 2 1 1 2

1916 299 2 1 7 1 1 14 3 3 2 2 3 7 7 6 1 1 1 2 2 1 1917 321 3 3 1 3 1 3 2 3 4 4 2 4 3 1 3 2 1 1 1918 348 4 3 1 1 1 1 2 1 1 1 1 1919 324 2 2 1 1 1 1 4 1 4 3 3 2 5 3 2 5 1 1920 274 1 4 12 14 5 10 16 3 4 7 6 2 2 3 1 1 1

1921 309 1 1 1 7 2 2 1 2 3 2 1 4 I 3 2 8 7 3 3 2 1922 299 4 2 1 3 10 9 11 2 1 4 2 1 1 3 3 3 2 1923 314 5 7 2 3 2 2 3 2 3 3 2 2 4 4 2 3 2 1 1924 294 4 1 18 16 21 3 2 1 2 1 1 1 1925 335 2 1 2 2 1 1 2 3 1 I 1 3 2

1926 299 26 9 4 1 3 3 2 3 2 1 1 2 1 1 1 1 I 1927 295 3 10 6 17 10 4 1 6 4 6 1 1 1 1928 348 _ 2 3 4 3 1 2 1 1 1 1929 326 5 3 1 3 1 1 2 1 2 1 5 2 3 1 2 1 1 1930 320 3 2 1 4 2 3 3 2 5 3 3 5 2 1 3 3

1931 291 11 5 1 2 1 2 4 2 4 5 3 4 4 3 S 6 I 3 2 1 1 1932 331 3 2 3 2 1 2 1 2 2 3 3 3 4 1 2 1 1933 339 4 2 2 1 1 1 1 1 2 2 1 1 1 1 2 1 2 3 2 1 1934 314 13 Z 1 3 2 2 8 1 4 4 1 3 1 1935 307 6 2 4 3 7 5 1 2 1 4 4 1 2 4 4 2 1 2 1 1 1

1936 279 27 21 6 8 2 1 2 2 1 1 6 1 1 1 S 1 1 1937 320 e 2- 4 1 3 2 3 4 2 1 4 3 3 1 1 2 1 1938 322 16 5 1 2 2 3 2 1 1 1 3 1 1 1 1 1 1 1939 315 2 2 4 3 3 2 2 1 4 3 1 1 4 3 2 3 3 1 2 :2 2 1 1940 318 15 1 1 3 2 4 2 4 1 3 3 2 3 1 1 1

1941 320 7 5 1 1 4 3 3 2 2 2 2 2 3 3 5 1942 305 27 4 1 3 2 2 3 1 3 6 2 3 1 1 1 1943 309 5 1 2 1 2 5 1 2 4 3 6 4 6 5 4 3 1 1 1944 340 3 2 1 2 3 1 3 1 2 2 2 1 1 1 1 1945 324 2 2 2 2 1 2 4 4 3 2 1 4 3 1 1 2 1 1 2 1

1946 300 3 2 2 1 6 4 4 4 7 2 5 5 4 3 3 3 2 1 1947 328 6 1 1 1 1 1 1 4 2 2 2 4 3 2 2 2 1 1 1948 330 4 1 3 1 2 2 5 3 2 2 2 3 1 1 1949 312 2 2 1 2 7 6 2 3 1 1 2 2 3 2 2 1 2 2 2 2 1 2 2 1 1950 318 1 2 1 5 2 1 2 1 4 3 2 1 3 3 1 4 2 1 1 1 3 1

1951 328 2 1 I 5 3 1 3 1 1 3 4 1 3 2 1 2 1 1 1 1952 316 3 3 2 1 1 2 3 2 3 3 1 3 3 2 2 3 3 2 4 1 1 2 1953 330 2 1 1 2 3 2 3 2 1 1 2 2 1 5 1 1 1 2 2 1954 289 3 3 1 5 1 3 1 6 2 3 3 1 3 2 3 4 2 4 6 2 5 '2 2 3 5 1 1955 315 2 1 3 2 2 1 2 1 1 1 2 1 2 1 3 4 2 5 1 5 4 1 2 1

1956 349 1 3 1 1 1 2 2 2 1 1 1 1 1957 319 6 5 4 1 1 1 2 1 2 1 5 1 2 1 3 5 3 1 1 1950 292 5 5 2 3 2 2 3 1 4 5 2 4 2 3 3 1 1 4 3 6 1 3 3 3 1 1 1959 318 2 3 4 1 2 1 3 2 1 1 6 7 1 2 3 2 1 4 1 1960 313 3 2 2 2 3 2 2 2 2 5 4 1 1 2 2 1 3 2 3 2 2 2 2 1

1961 324 1 2 2 2 4 2 2 2 4 3 2 1 4 2 1 3 1 2 1 1962 335 2 2 2 1 1 I 1 4 1 1 1 2 1 2 1 1 1 1 2 1 1 1%3 312 1 3 1 1 1 1 1 4 3 2 1 4 2 2 2 5 1 4 2 5 1 I 2 2 I _4 1944 311 1 3 1 1 4 1 3 3 1 2 2 2 1 4 6 3 4 1 5 1 1 1 1945 331 2 2 2 1 2 3 3 3 3 3 1 2 2 2 2 1

1966 289 1 2 2 3 2 3 1 2 1 3 3 2 3 4 7 2 5 2 9 3 4 3 5:2 1 1 1967 330 1 1 1 2 2 3 1 1 1 3 2 1 2 2 6 1 2 1 1 1 1960 295 3 2 1 4 1 4 7 4 4 4 1 3 5 3 2 3 2 2 3 2 1 2 1 1 1 1 1969 339 1 1 2 3 2 1 2 1 2 2 1 3 3 1 1 1910 299 20 4 1 2 2 3 2 6 2 3 3 2 2 2 2 1 3 '2 2 I 1

19T1 323 5 7 1 1 9 3 5 4 3 1 2 1

1972 320 5 4 1 2 2 2 4 1 4 2 1 "3 1 1 3 1 I 2 1 3 1 . 1 1973 318 3 1 3 3 1 1 1 3 3 2 1 6 2 1 4 1 2 1 2 3 1 2 1974 271 5 13 12 17 6 4 1 1 3 1 2 5 1 I 4 1 1 1 1 1975 315 3 3 2 2 1 3 1 2 2 2 5 1 1 1 1 1 2 2 2 7 2 1 2 1 236 GILA RIVER BASI4

09182500 SANTA CRUZ MIR AT TUCSON, A2--CQ\TI\UED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 -- Continued SCMARGE. IN CUBIC FEET PER SECOND AN

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 19155 22280 100.0 12 6.2 118 1949 8.7 24 380 92 300 1.3 1 0.10 87 3125 14.0 13 8.7 153 1831 8.2 25 540 58 208 .9 2 0.20 57 3038 13.6 14 12.0 140 1678 7.5 26 760 62 150 .6 3 0.30 37 2981 13.4 15 11.0 155 1538 6.9 27 1100 38 88 .3 4 0.40 62 2944 13.2 16 24.0 164 1383 6.2 28 1500 17 50 .2 5 0.60 33 2882 12.9 17 34.0 129 1219 5.5 29 2100 15 33 .1 6 0.80 278 2849 12.8 18 49.0 131 1090 4.9 30 3000 7 18 7 1.10 30 2571 11.5 19 68.0 131 959 4.3 31 4200 6 11 8 1.60 154 2541 11.4 20 96.0 150 828 3.7 32 6000 3 5 9 2.20 118 2387 10.7 21 140.0 129 678 3.0 33 8400 2 2 10 3.10 115 2269 10.2 22 190.0 135 549 2.5 34 11 4.40 205 2154 9.7 23 270.0 114 414 1.9

315 GITA RIVER BASIN 237

09482500 SANTA CRU_ RIVER AT TUCSON, Ai-CONTINU :D

Ll1NE5T MF4N VALU 46f1 44ei5Tuf FUR TMF FUI Lf1nTrJf. NUwtlFW UF CIINSFCIITTVE 4415IM 1E4NENOTNOSERTEM4ER10 nI4CM446F.Im ConicFUT WFKSECp6n 461

YEAR 1 3 7 14 30 60 40 120 143

1906 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.04 I 1915 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.5261 1.8056

1916 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 2 8.5061 1917 0.00 4 0.04 4 0.00 4 0.00 4 0.00 4 4 0.00 a 0.00 3 0.00 2 1918 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 O.On 5 0.00 5 0.00 4 0.1339 1919 0.00 b 0.00 b 0.00 b 0.00 b 0.un 6 0.UOu.un b 0.00 6 0.00 5 0.00 3 1920 0.00 7 0,00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.0453 1.1053

1921 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 6 0.00 4 1922 0.00 9 0.00 9 0.00 9 0.00 q 0.00 q 0.00 9 0.00 9 0.00 7 0.925! 1923 0.001u u.0010 0.00IO 0.0010 0.0010 0.0010 0.0010 0.00 8 0.00 5 1924 0.00Il 0.0011 0.0011 0.0011 0.00II 0.0011 0.2162 1.1462 1.1054 1925 0,00t2 0.00l2 0.0012 0.0012 0.0012 0.0012 0.00 11 0.00 9 0.00 6

1926 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0012 0.2559 0.2646 1927 0.0014 0.0014 0.0014 0.0014 0.0014 0.0014 0.0013 0.0010 0.0324 1928 0.0015 - 0.0015 0,0015 0.0015 0.0015 0.0015 0,0014 0.00II 0.1440 1929 0.00lb 0.00lb 0.00lb 0.0016 0.0016 0.0016 0.0015 0.0012 0.00 7 1930 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.00lb 0.0013 3.7059

1931 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.02S6 0.0349 13.0063 1932 0.0019 0.0019 0.0019 0.0019 0.0019 U.0019 0.0011 0.0014 5.9060 1933 0.0020 0.0020 0.9020 0.0020 0.0020 O.On20 0.0018 0.0015 0.07'22 1914 0.0021 0.0021 0.0021 0.0021 0.0021 0.00?I 0,0019 0.00Ib 0.10 34 1935 0.0022 0.0022 0.0022 0.0022 0.0022 0.0022 0.0020 0.0017 1.0052

1916 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 0.0021 0.0018 0.4648 1917 0.0024 0.0024 0.90 211 0.0024 U.0024 0.0024 0.0022 0.0019 0,0116 1938 0.0025 0.0025 0.0025 0.0025 0.0025 0.0025 0.0023 0.0020 0.0628 1919 0.002b 0.00Pb 0.0026 0.0026 0.0026 0.0026 0.0024 0.0021 0.0117 1940 0.0027 0.0027 0.0027 0.0077 0.0027 0.0427 0.0025 0.0022 0.79SO

1941 0.0028 0.0028 0.0028 0.0028 0.0028 0.0028 0.1861 0.1456 1.9057 1942 0.0029 0.0429 0.0029 0.0029 0.0029 0.0029 0.2263 0.1857 0.2544 1943 0.00lu 0.0030 0.0410 0.0010 0.0030 0.0030 0.0026 0.0023 0.1035 1944 0.0011 0.0011 0.0011 p,0011 0.0031 0.0031 0.0027 0.0024 0.00 8 1945 0.0032 0.0032 0.0032 O.0012 0.0032 0.0012 0.0028 0.0145 0.0116

1946 0.0013 0.0033 0.0033 0.0033 0.0033 0.0033 0.0029 0.0025 0.1441 1947 0.0014 0.0034 0.0014 0.0014 0.0014 0.00la 0.0030 0.0146 0.1136 1948 0.0015 0.0015 0.0015 0.0035 0.0035 0.0035 0.0031 0.0026 0.0119 949 0.00Ab 0.0016 0.0036 0.0016 0.0036 0.0036 0.0032 0.0077 0.1137 950 0,0017 0.0037 0.0017 0.0037 0.0037 0.0037 0.0033 0.0028 0.00 9

1951 0,0018 0.0018 0.0038 9.00lb 0.0018 0.0038 0.0034 0.0029 0.0010 1952 0.0019 0.0019 0.0039 0.0019 0.0039 0.0039 0.0035 0.0030 0.0425 1953 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0036 0.0031 0.0120 1954 0.0041 0.0041 0.0041 0.0041 0.0041 0.0041 0.0037 0.0147 0.5049 1955 0.0042 0.0042 0.00a2 0.0042 0.0042 0.0042 0.0038 0.0032 0.0011

1956 0.0043 0.0043 0.0043 0.0043 0.0043 0.0043 0.0019 0.0033 0.0012 1947 0.0044 0.0044 0.0044 0.0044 0.0044 0.0044 O.On40 0.0350 0.0426 1958 0.0045 0.0045 0.0045 0.0045 0.0045 0.0045 0.0860 0.2?5e 0,2545 1959 0.0046 0.0046 0.0046 0.0046 0.0446 0.0046 0.0041 0.00l4 0.0013 - 1960 0.0047 0.0047 0.0047 0.0047 0.0047 0.0047 0.0042 0.0035 0.0933

1961 0.0048 0.0048 0.0048 0.0044 0.0048 0.0048 0.0043 0.0036 0.0323 1962 0.0049 0.0049 0.0049 0.0049 0.0049 0.0049 0.0044 0.0037 0.2143 1963 0.0050 0.0050 0.0050 0.0050 0.0050 0.00SO O,p458 0.0351 0.1442 1964 0.0051 0.0051 0.0051 0,00S1 0.0051 0.0051 0.0045 0.0352 0.0427 1965 0.0052 0.0052 0.0052 0.0052 0.0052 0.0052 0.0046 0.0148 0.0432

1966 0.0053 0.0953 0.0053 0.0053 0.0053 0.0053 0.0047 0.0038 12.0062 1967 0,0054 0.0054 0.0054 0.0054 0.8054 0.0054 0.0048 0.00Ng 0.0014 1968 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0049 0.1055 2.9058 1969 0.0056 0.0056 0.0056 0.0056 0.0056 0.0056 0.04SO 0.0040 0.0729 1970 0.0057 0.0057 0.0057 0.0057 0.0057 0,0163 0.0257 0.4960 0.3547

1971 0.0058 0.0058 0.0058 0.0056 0.0458 0.0557 0.0051 0.0041 0.0015 1972 0,0059 0.0059 0.0059 0,0059 0.0059 0.0058 0.0052 0.0042 0.1338

1973 0.0060 0.0060 " 0.0060 0.0060 0.0060 0.0059 0.0053 1.1963 1.1945 1974 0.0061 0.0061 0.0561 0.0061 0.0061 0.0060 0.0054 0.0143 0.0430 1975 0.00A2 0.0062 0.00h2 0.0062 0.0062 0.0061 0.0155 0.0144 0.0221

316 238 GILA RIVER BASIN

09482500 SANTA CRUZ RIVER AT TUCSON, A --CCNEINUED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1915 8510.0 1 6970.0 1 3830.0 1 1850.0 1 937.0 1 629.0 1 444.0 1 335.0 1 221.0 1

1916 4000.0 9 2830.0 4 1550.0 3 832.0 5 422.0 8 211.011 141.012 106.012 70.0 12 1917 2710.017 1090.018 669.018 415.016 273.016 216.0 9 158.0 9 119.0 9 78.0 9 1918 1490.028 762.026 327.032 153.040 77.044 41.048 27.051 21.047 14.0 47 1919 2750.015 1390.016 631.019 457.015 372.010 212.010 153.010 115.0 10 75.0 10 1920 550.051 285.054 154.052 118.046 64.040 39.0SO 28.047 21.048 14.0 48

1921 2080.021 946.021 759.015 537.014 434.0 7 262.0 6 179.0 7 135.0 7 88.0 7 1922 630.049 337.052 229.044 183.032 129.029 86.025 58.027 44.027 29.028 1923 900.044 597.035 441.023 278.020 208.020 132.020 88.020 66.020 43.0 20 1924 830.047 338.051 149.054 71.056 38.057 25.055 17.055 13.055 9.4 55 1925 460.055 365.047 178.050 86.052 65.047 55.043 39.041 29.041 19.0 43

1926 6150.0 4 3000.0 3 1290.0 5 619.0 7 312.013 162.017 109.016 82.016 54.0 15 1927 378.057 135.059 74.058 38.059 27.059 20.058 14.058 11.058 7.1 58 1928 700.048 353.049 153.053 73.054 43.055 23.056 16.056 02.056 7.9 56 1929 4710.0 5 1850.010 792.014 374.018 217.019 192.014 136.014 102.014 67.0 13 1930 539.092 360.048 210.046 111.047 77.045 54.044 37.044 28.044 22.0 36

1931 3460.012 2260.0 6 1280.0 6 770.0 6 454.0 5 257.0 7 181.0 6 137.0 6 90.0 6 1932 1330.031 706.028 357.028 233.027 I20.031 82.027 55.028 41.028 27.029 1933 880.045 564.038 242.043 152.041 91.041 59.040 39.042 29.042 19.0 44 1934 1060.040 475.041 311.033 171.035 110.037 60.039 41.038 31.038 20.040 1935 4620.0 6 1880.0 4 873.011 562.012 297.015 164.015 110.015 82.015 54.0 16

1936 1500.027 623.031 268.039 148.042 118.033 66.034 44.035 33.036 22.0 37 1937 905.042 394.045 287.036 164.036 97.039 64.035 46.034 35.034 23.0 35 1938 1910.022 736.027 331.030 202.030 117.034 62.036 42.037 31.037 21.0 38 1939 2420.018 1450.015 1070.0 9 601.011 350.011 202.012 137.013 103.013 67.0 14 1940 4270.0 8 1560.013 692.017 334.019 194.022 106.022 74.023 55.023 36.0 23

1941 252.060 141.058 99.057 71.055 47.054 33.054 23.053 17.053 11.0 53 1942 536.053 228.055 113.055 68.057 38.056 21.057 16.057 12.057 7.9 57 1943 1120.038 565.037 282.038 155.039 119.032 78.030 61.025 46.025 30.0 26 1944 2740.016 937.022 444.022 257.024 130.028 81.028 55.029 41.029 27.0 30 1945 3820.010 1470.014 753.016 549.013 316.012 162.016 108.017 81.017 53.0 17

1946 1340.030 623.032 300.035 219.028 150.024 104.023 77.022 58.022 38.022 1947 1140.035 389.046 167.051 78.053 48.053 34.053 23.054 17.054 11.0 54 1948 1130.036 396.044 254.040 215.029 132.027 67.033 48.032 36.032 24.0 33 1949 1190.034 618.033 364.026 177.034 111.036 85.026 58.026 44.026 29.0 27 1950 3120.013 2170.0 7 1220.0 8 833.0 4 453.0 6 240.0 8 162.0 8 121.0 8 80.0 8

1951 1730.023 767.025 363.027 197.031 113.035 60.037 40.039 30.039 20.0 41 1952 495.054 345.050 204.046 98.049 63.049 40.049 28.048 21.049 14.0 49 1953 1070.039 957.028 530.021 268.023 158.023 79.029 53.030 40.030 26.0 31 1954 2390.019 1220.017 868.012 603.0 9 479.0 4 269.0 5 192.0 5 150.0 5 99.0 5 1955 3010.014 1650.012 1340.0 4 863.0 3 721.0 2 420.0 2 280.0 2 210.0 2 138.0 2

1956 286.059 95.060 41.060 21.060 19.060 10.060 6.960 5.260 3.4 60 1957 356.058 170.057 73.059 54.058 33.058 19.059 12.059 9.359 6.1 59 1958 1720.024 703.029 304.034 272.022 231.017 138.018 97.018 73.018 48.0 18 1959 554.050 313.053 244.042 158.037 87.042 57.041 38.043 29.043 19.0 42 1960 2180.020 1060.018 568.020 277.021 146.025 73.031 49.031 37.031 24.0 32

1961 4570.0 7 1810.011 816.013 391.017 202.021 126.021 85.021 64.021 42.0 21 1962 1320.032 493.040 213.045 100.048 51.052 43.046 28.049 21.050 14.0 50 1963 1580.026 845.024 386.025 242.026 230.018 135.019 90.019 68.019 44.0 19 1964 6400.0 3 2750.0 5 1250.0 7 601.010 414.0 9 307.0 3 208.0 3 156.0 3 102.7 3 1965 121.061 58.061 26.061 13.061 7.461 6.961 4.761 3.561 2.3 61

1966 3680.011 2150.08 976.010 604.0 8 308.014 200.013 149.0 11 112.011 73.0 11 1967 1600.025 549.039 329.031 157.038 94.040 46.045 33.045 25.045 16.0 45 1968 7750.0 2 4790.0 2 2400.0 2 1180.0 2 593.0 3 298.0 203.0 4 153.0 101.0 4 1969 1120.037 442.043 209.047 123.044 71.046 42.047 28.050 21.051 14.0 51 1970 1020.041 586.036 251.041 120.045 90.043 68.0 32. 47.033 35.033 23.0 34

1971 900.043 700.030 344.029 246.025 144.026 96.024 65.024 48.024 32.0 25 1972 858.046 457.042 196.049 94.050 63.050 35.052 26.052 20.052 13.3 52 1973 1410.029 849.033 387.024 181.033 '121.030 60.038 40.040 30.040 35.0 24 1974 1300.033 604.034 283.037 143.043 98.038 56.042 43.036 33.035 21.0 29 1975 432.056 193.056 108.056 93.051 52.05k 37.051 31.046 23.046 15.0 46

317 GILA RIVER BASIN 239

09482500 SANTA CRUZ RIVER AT TUCSON, AZ- -CONTINUED

DISCHARGE, IN CUBIC FEET PER SECOND STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

12 OCT NOV UEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT 9 47 BY ROWS (MEAN,vARIANCE.STANDARD DEVIATION,SKEWNESS,COEFF. OF VARIATION,PERCENTAGE OF AVERAGE VALUE) 10 3.57 5.62 30.7 14.8 10.8 3.52 0.10 0.07 1.37 52.9 102 34.6 48 146 752 18770 3267 1461 164 0.08 0.11 20.2 5356 13880 3928 12.1 27.4 137 57.2 38.2 13.5 0.29 0.33 4.49 73.2 118 62.7 7 5.81 7.39 5.33 5.56 4.05 4.97 3.99 5.96 4.27 3.07 2.55 3.23 28 3.38 4.88 4.46 3.86 3.53 3.85 2.95 4.65 3.29 1.38 1.15 1.81 20 1.37 2.16 11.8 5.69 4.16 1.35 0.04 0.03 0.53 20.3 39.2 13.3 55 43

15 58 56 13 DISCHARGE, IN CUBIC FEET PER SECOND 36 STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS) 6 29 MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 44 22.0 398 20.0 2.04 0.91 0.030 40 16

37 35 38 14 23

53 57 26 30 17

22 54 33 27 8

41 49 31 5 2

60 59 18 42 32

21 50 19 3 61

11 45

51 34

25 e2 24 39 46

318 240 GIL1 RIVER BASIN

09483100 TANQUE VERDE CREEK NEAR TUCSON, AZ

LOCATION. --Lat 32 °14'48 ", long 110 °40'46 ", in NE,ANWW sec.2, T.14 S., R.16 E., Pima County, on right bank 4.4 mi ('.1 km)east of Tanque Verde School, 7.4 mi (11.9 km) upstream from Aqua Caliente Wash, 7.8 mi (12.b ion) northwest of Spud Rock, and 17.5 mi (28.2 km) east of City Hall in Tucson.

DRAINAGE AREA.- -43.0 mil (111.4 km2).

MATER ANNUAL PEAK DATE GAGE HEIGHT OF nATFH TOTAL VULUME. TEAR DISCM,CFS ANNUAL PEAK,FT YEAR ACRE -FT

1960 789 u1-11-60 2.83 960 8810 1961 1260 09-08-61 2.85 961 1900 1962 925 12-16-61 2.99 962 6450 19b3 154u 02-11-63 3.50 963 3460 1964 2630 09-10-64 4.86 964 5180 1965 828 09-04-65 3.21 965 3260 1966 2760 12-22-65 4.93 968 230u0 1967 1260 07-16-67 3.71 967 766 1968 3080 12-20-67 5.14 960 11380 1969 278 01-15-69 2.37 989 1690 1970 1060 03-02-70 3.50 97u 3850 1971 2350 08-21-71 4.64 971 3370 1972 1190 07-16-72 3.64 974 3600 1973 2120 10-19-72 4.38 973 16400 1974 804 07-08-74 3.18 974 2540 1975 210 - - 2.19

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE INCUBIC FEET PER SECOND MEAN

CLASS 0 I 2 3 4 5 6 "7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 262728293031323334 YEAR NUMBER OF DAYSIN CLASS 1960 166 1 4 10 7 11 3 8 8 5 11 2 2 9 9 10 16 16 13 11 4 11 5 9 3 5 4 3

1961 23610 11 30 3 1 5 4 2 5 5 1 3 7 3 5 4 4 5 5 4 4 4 2 2

1962 123 5 5 11 2 10 84 1 3 7 5 9 12 7 12 27 30 30 27 7 4 6 3 2 1 1 2 1 1963 163 3 4 7 2-6 3 69 7 11 11 17 14 15 12 8 20 12 10 8 3 3 2 1 1 1 1 1 1964 241 7 4 7 6 4 5 13 6 13 8 3 5 3 3 3 4 2 4 5 4 2 4 3 1 3 2 1 S 132 30 IT 11 21 14 6 8 16 11 25 20 19 7 8 5 6 4 2 2 1

1>66 159 12 9 5 9 3 5 5 7 6 13 2 11 22 15 19 13 11 8 8 6 5 4 2 2 1967 207 89 20 4 10 4 5 4 4 2 6 1 3 3 1 1 1 1966 133. 23 12 7 10 4 7 11 5 7 5 21 32 23 19 15 6 7 8 1 2 2 3 1 2 1969 183 32 15 6 4 6 3 20 19 13 23 14 7 8 S 2 2 1 1 1 1970 142 82 16 7 12 8 11 17 7 10 9 9 S 6 7 2 1 2 3 3 2

1971 282 25 3 1 3 1 4 2 2 2 1 3 8 2 5 3 5 3 3 2 3 2 1972 118 S2 19 22 17 11 13 10 12 11 14 12 11 13 7 7 5 5 6 1 1973 93. 23 5 6 6 5 5 11 13 23 17 16 25 20 37 11 6 10 10 8 5 2 3 1 2 2 1974 226 70 '9 3 14 2 5 3 3 2 1 5 1 3 2 2 4 1 2 1 1 1

CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 2604 5479 100.0 12 1.2 125 1644 30.0 24 78 44 139 2.5 1 0.01 26 2875 52.5 13 1.8 132 1519 27.7 25 110 33 95 1.7 2 0.02 28 2849 52.0 14 2.5 124 1367 25.3 26 160 21 62 1.1 3 0.03 65 2821 51.5 15 3.5 133 1263 23.1 27 220 22 41 .7 4 0.05 20 2756 50.3 16 4.9 189 1130 20.6 28 310 7 19 .3 5 0.07 32 2736 49.9 17 7.0 184 941 17.2 29 440 4 I2 .2 6 0.10 462 2704 49.4 18 9.9 153 757 13.8 30 620 6 8 .1 7 0.20 173 2242 40.9 19 14.0 170 604 11.0 31 880 2 2 a 0.30 96 2069 37.8 20 20.0 90 434 7.9 32 9 0.40 143 1973 36.0 21 28.0 80 344 6.3 33 10 0.60 100 1830 33.4 22 39.0 67 264. 4.8 34 11 0.90 86 I730 31.6 23 56.0 58 197 3.6

319 GIL1 RI \ER BASIN 241

09483100 EACUE VERDE CREEK NEAR TUCSON, AZ-CONTINUED

LUNtST MFAN VALUEANDRANKTNf. FUOTHF FUtLn.T.rf. NUM6FM UF fUN5FCIITTVF 0AY5IN YEARENDINGSEDTFMBER 30 DISCMARGE,IN CURIC FEET PFR5ECnN0 MEAN

10 YEAR 1 3 7 14 60 90 120 163 1960 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 .14 5

1961 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 .31 6 1962 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.0613 0.2712 .6010 1963 0.00 4 0.00 4 0.00 4 U.00 4 0.00 4 0.00 4 0.00 3 0.41 13 .8011 1964 0.00 5 u.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4 0.00 3 .09 3 1965 0.00 6 U.00 6 0.00 6 U.00 b U.00 6 0.00 b 0.00 5 0.01 7 .19 9

1966 0.00 7 0.01 7 0.00 7 0.00 7 0.00 7 0.00 7 0.04 I1 1.1914 .1014

1967 0.00 0 0.00 8 0.00 8 0.00 8 0.00 8 0.00 b 0.00 6 0.00 4 .00 1 1968 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.3615 1.9015 .8012 1969 0.00 10 0.00 10 0.0010 0.0010 0.0010 0.0010 0.0210 0.09 9 .62 7 1970 0.00 11 0.00 11 0.00 11 0.0011 0.00 11 0.00 11 0.0512 0.2610 .7015

7971 0.0012 0.0012 0.0012 0.0012 0.0012 0.0012 0.00 7 0.00 5 .01 2. 1972 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.00 8 0.01 6 .14 4 1973 0.00t4 0.0014 0.0014 0.0014 0.00ta 0.01 15 0.0614 0.2711 .8013 1974 0.00IS 0.0015 0.0015 0.0075 0.0015 0.0014 0.00 9 0.03 6 .92 6

HIGHEST MEAN VALUE ANO RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECONO MEAN

YEAR 1 3 7 15 30 60 90 120 1960 300.0 7 241.0 6 208.0 4 139.0 3 106.0 3 65.0 3 46.0 36.0 4 4

1961 92.015 50.015 38.013 24.014 20.013 15.013 9.913 7.413 E3 1962 453.0 5 296.0 5 158.0 6 92.0 6 50.0 6 40.0 6 30.0 5 26.0 S 1::4.1111 5 1963 518.0 304.0 154.0 7 79,0 7 42.0 8 25.0 8 19.0 8 34.0 8 9.5 7 1964 422.0 6 186.0 7 159.0 5 123.0 5 68.0 5 43.0 5 29.0 6 21.0 6 14.0 6 1965 122.012 57.012 52.011 31.012 24.011 19.0 9 15.0 9 12.0 9 8.4 9

1966 890.0 1 657.0 1 362.0 1 341.0 1 213.0 1 124.0 1 107.0 1 86.0 1 57.0 .1 1967 102.014 62.013 28.015 16.015 12.015 6.115 4.115 3.115 2.015 1968 851.0 2 464.0 3 238.0 3 124.0 4 80.0 4 58.0 4 53.0 3 44.0 3 30.0 3 1969 122.013 61.014 30.014 24.013 14.014 9.614 8.014 6.514 4.314 1970 250.0 8 141.0 9 69.0 9 60.0 9 32.0 9 11.010 11.012 8.511 7.811

1971 189.010 170.0 8 109.0 8 77.0 8 49.0 7 28.0 7 19.0 7 14.0 7 9.38 1972 140.011 83.011 43.012 35.010 20.012 16.011 15.010 12.010 7.810 1973 748.0 3 530.0 2 269.0 2 149.0 2 142.0 2 91.0 .2 65.0 2 51.0 2 43.02 1974 226.0 9 110.010 62.010 32.011 31.010 16.012 11.011 8.112 S.322

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS tALL DAYS/

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS (MEAN,VARIANCE.STANOARD DEVIATION.SKEWNESS,COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 4.56 2.05 24.7 14.8 21.2 15.0 3.45 0.31 0.05 3.17 8.24. 9.82 392 142 - 11.8 2639 587 939 688 27.3 0.80 0.04 23.4 148 11.9 3.44 51.4 24.2 30.6 26.2 5.23 0.90 0.21 4.84 22.2 18.8. 3.11 1.89 3.11 2.85 1.27 2.79 2.05 3.67 3.87 1.88 2.46 2.67 2.61 1.68 2.08 1.64 1.45 1.74 1.51 2.93 3.86 1.53 1.47 1.95 4.25 1.91 23.1 13.8 19.8 14.0 3.22 0.29 0.05 2.95 7.69 8.97

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORK 8.90 73.1 8.55 1.78 0.96 -0.460

320 24Z GILA RIVER BASIN

09484000SABINO CREEK NEAR TUCSON, AZ

LOCATION. --Lat 32 °19'01 ", long 110 °48'36 ", in SE4NE4 sec.9, T.13 S., R.15 E., Pima County, on right bank 0.5 mi (0.8 km)north of Coronado National Forest boundary and 12 mi (19.3 km) northeast of City Hall in Tucson.

,GAINAGE AREA. --35.5 mil (91.9 km2).

HATER AN -YUAL PEAR DATE CUOES GAGE HEIGHT OFAArgo TOTAL VOLUME, YEAR DISCH,CFS ANNUAL PEAR,FT YEAS ACHE -FT

1933 510 09-10-33 4.73 1933 5160 1934 472 09-22-34 4.59 1904 904 1935 540 02-06-35 4.85 1935 11400 1936 500 01-29-36 4.69 1910 4330 1937 2020 02-07-37 6.51 1917 4510 1938 3200 03-03-38 7.13 1918 4490 1939 385 08-06-39 3.96 1919 2150 1940 904 02-23-40 4.98 1940 2600 1941 3190 12-30-40 7.13 1941 ?1000 1942 449 09-30-42 4.34 1942 4090 1943 567 03-05-43 4.56 1943 3050 1944 175 07-08-44 3.31 1944 3340 1945 916 07-30-45 5.15 1945 0430 1946 2000 08-23-46 6.30 1946 3460 1947 227 12-26-46 3.41 1947 1070 1908 380 08-06-48 4.06 1948 1560 1949 1430 08-08-49 5.78 1949 9480 1950 2280 07-07-50 6.50 1990 1670 1951 750 08-02-51 5.11 1951 2740 1952 1640 01-13-52 6.25 1952 14000 1953 861 07-16-53 5.31 1951 5630 1954 5110 03-23-54 8.43 1954 12700 1955 2000 08-03-55 6.55 1955 7790 1956 55 08-11-56 2.33 1996 377 1957 2030 01-09-57 6.65 1957 8210 1958 1500 03-22-58 5.85 1958 15000 1959 4240 07-26-59 7.85 1959 4190 1960 3600 12-24-59 5.95 1960 15500 1961 910 08-30-b1 5.25 1961 1690 1962 1010 09-26-42 5.44 1962 11600 1963 2070 00-15-63 6.54 1963 5950 1964 1310 09-13-64 5.82 1964 5110 1965 244 02-07-65 4.24 1965 7000 1966 6400 08-10-66 9.65 1966 14900 1967 788 07-17-67 5.67 1967 2070 1968 2340 12-19-67 7.30 1968 19100 1969 310 01-14-69 4.99 1969 5490 1970 7730 09-06-70 10.21 1970 9850 1971 660 08-10-71 5.52 1971 3100 1972 1710 10-01-71 6.87 1972 6420 1973 2750 10-19-72 7.68 1973 75400 1974 117 07-20-74 4.78 1974 1400 GILL RIVER BASIN 243

09484000 SABINO CREEK NEAR TUCSON, A2-- CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECONO MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 27 18 19 20 21 22 23 24 25 26 27 2829 30 3132 3334 YEAp NUMBER OF DAYS IN CLASS 1433 14 13 10 34 30 9 19 14 17 6 11 14 15 12 15 22 18 24 18 30 12 3 1 j934 37 31102 37 23 20 12 15 7 14 6 8 8 7 14 10 2 4 2 2 1 3 1 4 9 16 8 14 17 24 19 17 22 24 7 6 3 1 1935 14 33 20 7 13 15 4 12 14 19 16

1936 41 14 10 4 26 11 6 11 12 7 23 10 27 33 8 13 23 21 19 16 8 6 9 5 2 1 1 j937 36 44 11 24 22 6 7 3 8 S 23 10 11 11 8 6 7 8 13 39 14 21 14 4 4 2 2 1 1 1938 38 78 32 39 20 8 8 8 4 7 16 7 13 13 12 9 11 8 4 7 8 S 5 1 1 1 1 1 1939 24 40 18 18 S2 6 3 e 7 30 26 19 15 16 15 8 17 19 19 15 5 1 2 1 1 1440 13 27 29 1S 14 9 3 !1 29 25 39 22 23 24 28 16 11 7 S 3 6 2 2 1 2 1

1441 16 15 9 21 15 6 3 6 8 10 12 15 14 16 10 13 13 29 26 23 27 16 14 18 2 4 2 1 t 1942 36 23 12 6 11 6 8 7 6 10 6 9 8 12 14 15 25 29 32 38 20 14 8 S 2 2 1 1443 66 16 58 11 16 9 4 34 10 7 4 11 19 26 21 12 8 9 6 2 3 5 3 1 1 1 1944 7 13 10 21 80 3S 14 8 8 10 S 7 30 14 19 24 13 15 20 16 7 7 2 1 1945 38 16 48 4 5 4 4 7 5 5 3 11 15 10 14 20 31 21 30 29 23 11 5 3 1

1946 45 25 S 13 14 23 9 10 6 10 5 16 16 9 30 40 32 14 14 12 8 5 3 1 1441 75 23 7 10 16 7 2 2 19 13 28 20 44 35 23 13 9 6 5 2 2 :2 1 1 1448 44 13 t2 17 22 23 6 28 3o 43 14 20 17 13 10 13 18 12 3 2 2 2 1 1 1949 6 15 12 5 3 65 18 11 4 12 4 12 9 12 9 7 12 28 34 30 19 9 14 2 3 1 1 2 1956 18 1S 31 46 24 19 21 11 6 10 16 27 34 44 11 9 4 3 3 6 5 1 1

1951 46 7511 27 11 3 4 14 .3 4 13 14 13 14 13 30 5 6 4 .5 2 1 2 1952 32 35 15 4 4 -4 .3 e S -0 3 6 12 17 19 22 23 15 28 23 26 20 14 8 6 1 1 3 1. 1953 96 28 .2 3 3 9 5 T 4 10 10 22 26 27 29 17 22 8 11 10 S 2 5 1 2 1 1454 26 7 2 3 4 2 7 9 8 13 17 10 15 20 e 6 7 lo 6 8 S 4 1 2 1 1 1 1 1435 1443 25 21 24 37 13 11 11 15 6 12 13 17 27 23 16 8 5 3 5 11 4 7 3

1956 89110 22 18 10 21 AI 16 8 6 S 11 13 8 14 8 5 2 1057 123 37 1 5 4 2 8 3 4 6 12 9 9 6 11 9 17 13 25 24 10 7 6 4 4 2 1 1458 43 11 5 2 2 1 1 8 3 6 6 13 25 23 16 19 32 24 22 24 15 13 19 16 9 1 2 1 1 1951 61 IT 5 2 6 3 9 29 18 23 29 28 35 23 20 11 8 6 9 6 6 1 2 2 3 3 1941 42 32 13 10 10 9 12 8 3 7 5 9 22 11 11 18 18 13 20 16 14 23 15 12 5 2 2 1 2 I

1161 121 53 38 3 3 1 2 16 10 7 14 15 23 8 11 7 7 6 5 '7 2 2 3 1 1962 93 15 8 2 6 2 1 9 4 3 S 21 17 9 10 5 3 15 32 21 37 27 5 3 1 1 1143 44 25 9 7 6 5 12 18 20 10 7 10 8 21 I7 41 21 21 21 14 8 9 6 1 3 1 1964 78 15 9 3 8 I 45 23 15 19 14 12 12 16 18 17 13 8 8 6 7 5 2 1 2 2

1965 73 14 10 .2 15 2 20 17 33 27 18 15 18 13 24 35 16 11 1 1

1966 73 30 9 21 3 4 5 7 9 e 15 1 1 8 24 24 -36 26 29 22 51 4 1 1 2 1 1967 60 2 2 1 1 5 1 4 5 4 33 26 S0 47 32 23 15 13 10 15 5 3 4 1 2 1 1948 40 1 1 4 22 S 13 18 2 10 -4 7 8 13 12 18 13 25 27 3 17 51 28 15 10 6 1 2 1969 74 7 S 4 1 3 1 10 3 1 12 8 11 19 21 24 18 37 36 33 11 8 2 3 1 MO 49 7 8 7 11 16 1 4 3 3 2 2 26 41 29 32 32 21 17 13 11 10 10 4 1 1 2 1 1

MI 67 2 3 6 13 11 3 22 12 26 49 27 37 15 12 12 10 6 2 7 5 3 8 2 3 1 1 1972 105 3 4 3 2 3 ,6 7 3 9 S 10 42 32 14 23 21 13 12 19 6 9 4 -4 4 2 1 1973 29 1 2 1 I7 1 3 2 5 4 10 15 8 49 43 26 26 22 19 20 24 15 11 1 2 3 2 1974 164 1 3 S 8 S 2 12 5 3 15 19 21 22 23 11 6 13 9 6 5 1

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT 0 0.00 2291 15340 100.0 12 0.8 662 7589 49.5 24 72 183 443 2.8 1 0.01 968 13049 85.1 13 1.2 779 6927 45.2 25 100 124 250 1.6 2 0.02 729 12081 78.8 14 1.8 710 6148 40.1 26 150 55 126 .8 3 0.03 437 11352 74.0 15 2.6 650 5438 35.4 27 220 24 71 .4 4 0.04 557 10915 71.2 16 3.7 716 4788 31.2 28 320 22 47 .3 S 0.06 462 10358 67.5 17 5.4 655 4072 26.5 29 460 11 25 .1 6 0.09 48 9896 64.5 18 7.8 559 3417 22.3 30 660 8 14 7 0.10 385 9848 64.2 19 11.0 646 2858 18.6 31 960 3 6 8 0.20 927 9463 61.7 20 16.0 580 2212 14.4 32 1400 1 3 1 0.30 348 8936 58.3 21 24.0 149 1632 10.6 33 2000 2 2 18 0.40 580 8588 56.0 22 34.0 452 1183 7.7 34 11 0.60 419 9008 52.2 23 49.0 298 731 4.8 244 G/ LA RIVER BASIN

09484000 SABINO CREEK NEAR TUCSON, A2 -- CONTINUED

1 L19E5T 8E49 UALUF aun4AN4T8.FUa TMF FUI Ln..TN.NUwBFW UFfUNSEC1'TTrF11Ar5INrEAWf:9U1N.8EPTEM0E430 nISCMARGF,IN CUBIf. FEFT VFH SFcnNn NEAN

40 rEA9 1 3 7 14 10 hu 120 183 1933 0.01 41 0.01 41 0.01 01 0.01 18 0.0441 0.3739 0.7310 1.00 20 3.2073

1914 0.00 1 0.04 1 0.04 1 0.00 1 0.00 1 0.V0 1 0.01 7 0.03 6 0.27 3 1935 0.00 2 0.00 2 0.04 2 0.04 2 0.3135 0.1737 1.0434 2.40 13 8.1016

1936 0.00 3 0.00 3 u.04 3 0.00 3 4.04 2 0.00 2 0.0h19 1.30 29 3.0022 1417 0.00 4 0.00 4 U.U4 4 U.00 a 0.00 3 0,00 3 0.0?13 0.35 17 2.2018 1918 0.00 S 0.00 5 0.04 5 0.00 5 0.00 4 0.0171 0.01 8 0.02 4 2.7020 1919 0.00 6 u.00 6 0.00 6 0.00 b 0.00 5 U.0110 0.1223 0.74 73 2.9021 1940 0.00 7 0.00 7 0.00 7 0.00 7 0.0116 0.0435 0.44?9 0.93 25 1.4014

1941 0.01 42 0.01 42 0.01 42 0.01 39 0.0117 0.38Ou 3.5041 0.90 42 7.9035 1942 0.00 B 0.04 8 0.00 8 0.04 8 0.00 6 0.00 4 0.0516 0.42 20 4.2026

1943 3.04 9 0.00 9 0.00 9 0.00 9 0.00 7 0.00 5 0.00 1 0.22 11 1.8016 1940 0.00 10 0.00 IU 0.04 10 0.01 40 0.0118 0.0011 0.0517 0.32 16 4.4027 1945 0.00 11 0.00 11 0.L8 11 0.04 10 0.04 8 0.0122 0.7912 4.00 38 6.2432

1946 0.00 12 0.00 12 0.00 12 0.00 11 0.00 9 0.00 b 0.0314 0.6? 22 2.6019 1947 0.00 13 0.00 13 0.04 13 0.00 12 0.0010 0.00 7 0.00 2 0.01 1 0.11 2 1948 0.04 14 0.00 14 0.04 14 0.04 13 4.0011 0.04 8 0.0518 0.26 13 1.6015 1949 0.00 15 0.00 15 0.04 15 0.01 41 0.0119 0.0414 1.4037 4.80 41 7.7034 1950 0.00 lb 0.00 16 0.00 16 0.00 14 0.0140 0.0228 0.0971 0.41 19 1.3012

1951 0.00 17 0.00 17 0.00 17 0.00 15 0.00 2 0.0123 0.01 9 0.02 5 0.00 I 1952 0.00 18 0.00 18 0.00 18 U.00 16 0.00 3 0.1918 1.5018 2.80 34 8.7037 1953 0.00 19 0.00 19 0.00 19 0.00 17 0.00 4 0.01 74 0.2375 1.70 32 4.0024 1954 0.00 ?U 0.00 20 0.04 20 0.00 18 0.00 5 0,00 9 0.01 10 0.01 2 13.0040 1995 0.00 71 0.00 71 0.00 21 0.00 19 0.04 6 0.01 25 0.0315 0.27 14 2.00 17

1996 0.00 22 0.04 22 0.00 22 0.00 70 0.00 7 0.0010 0.00 3 0.02 3 0.37 4 1957 0.00 23 u.00 23 0.00 23 0.00 21 0.04 8 0.00 11 0.00 4 0.93 26 5.1428 1958 0.00 24 0.00 24 0.09 20 0.04 72 0.00 9 0.0432 1.8039 3.20 36 12.0039 1959 0.00 25 0.00 25 0.00 25 0.00 23 0.0070 0.0012 0.01 11 0.09 8 0.46 6 1960 0.00 Pb 0.00 Pb 0.00 Pb 0.00 74 0.0021 0.0013 0.3228 0.56 21 1.4013

1961 0.00 77 U.00 77 0.00 77 0.00 75 0.0022 0.0014 0.00 5 0.0h 7 0.46 7 1962 0.00 98 0.00 78 0.00 78 0.00 26 0.0023 0.0?29 0.2426 0.22 12 5.7031 1963 0.00 29 0.00 29 0.00 79 0.00 27 0.0024 0.0126 0.1424 1.30 30 5.4029 1964 0.00 10 0.00 30 0.00 10 0.00 78 0.0025 0.01 27 0.3027 0.29 15 0.83 9 1965 0.00 31 0.00 31 0.00 11 0.04 29 0.0076 0.0015 0.0820 0.93 77 5.5430

1966 0.00 32 0.00 32 0.04 32 0.00 30 0.0077 0.1036 1.1935 4.10 39 70.0042 1967 0.00 33 0.00 33 0.00 33 0.00 11 0.0028 0.0016 0.7431 0.91 24 0.91 11 1968 0.00 14 0.00 34 0.00 34 0.00 32 0.0029 0.4441 2.5040 4.20 40 8.9038 1949 0.00 35 v.00 35 0.00 15 0.00 33 0.0030 0.0017 1.303b 2.80 35 4.0025 1970 0.00 36 0.00 lb 0.00 36 0.00 34 0.0031 0.0733 0.8333 1.50 31 6.3033

1971 0.04 17 0.00 37 0.04 37 0.00 35 0.0032 0.0018 0.01 12 0.15 10 0.45 5 1972 0.00 18 0.00 18 0.00 38 0.04 36 0.00 33 0.0019 0.1422 0.13 9 0.a9 8 1973 0.00 39 0.00 39 0.00 39 0.01 42 0.04 42 1.5042 4.9042 4.00 37 14.0041 1974 0.00 40 0.00 40 0.00 40 0.00 17 0.00 14 0.0070 0.00 6 0.39 18 0.8610

323 GILA RITIER BASIN 24

09484000 SABIN° CREEK NEAR TUCSON, AZ-- CONTINUED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENOING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

143 YEAR 1 3 7 15 30 60 90. 120 183 3.2023 1933 99.035 58.035 43.032 38.030 33.027 28.021 22.021 18.022 13.021 0.27 3 1934 64.039 42.031 19.040 10.040 6.040 5.340 4.040 3.041 2.041 8.1036 1935 383.014 304.011 180.011 109.012 72.012 57.0 8 46.0 7 31.0 9 25.010

3.0022 1936 183.026 110.027 61.028 43.027 38.023 23.026 17.025 14.025 9.725 2.2018 1937 655.010 345.010 175.012 124.0 8 78.010 56.0 9 43.010 34.010 23.0 11 2.7020 1938 670.0 9 436.0 7 211.0 8 110.011 57.016 29.019 20.024 15.024 11.024 2.9021 1939 108.033 69.033 39.034 24.036 13.038 8.437 6.136 5.336 4.835 1.40t4 1940 436.012 190.017 93.022 46.024 28.028 16.031 11.031 8.432 6.4 '1

7.9015 1941 803.0 S 542.0 5 290.0 5 182.0 6 124.0 6 14.0 5 87.0 2 76.0 2 54.0 2 0.2026 1942 265.021 154.022 102.020 61.022 39.021 32.017 32.015 28.015 23.012 1.8016 1943 395.013 226.015 127.018 69.019 37.024 20.028 14.028 11.028 7.029 4.4027 1944 84.038 44.038 32.037 24.037 23.033 18.029 14.029 11.029 8.326 32 6.20 1945 142.032 87.030 ' 48.031 36.031 28.029 24.024 22.022 19.021 14.018

2.6019 1946 215.023 110.028 63.026 42.028 25.030 16.030 12.030 8.730 5.933 0.11 2 1947 61.040 38.040 19.041 10.041 6.041 4.141 3.641 3.240 2.340 1.6015 1948 97.036 48.037 38.036 25.035 14.037 7.138 4.939 3.639 3.937 7.7034 1949 357.017 189.0I8 140.014 80.016 67.013 42.014 36.013 32.012 22.0I3 1.3012 1950 175.029 80.031 39.03S 22.038 15.036 8.836 5.937 4.437 3.638

0.0A 1 1951 176.028 104.029 50.030 26.032 25.031 14.032 9.634 7.233 6.132 8.7037 1952 460.011 231.014 197.0 9 117.0 9 83.0 9 48.012 44.0 8 42.0 8 35.0 7 4.0024 1953 179.027 122.025 62.027 40.029 25.032 13.033 9.932 9.731 8.127 40 13.00 1954 2010.0 2 1130.0 1 522.0 1 251.0 2 127.0 5 64.0 7 43.011 33.011 31.0 8 2.00 17 1955 246.022 173.019 I30.015 95.013 74.011 41.015 28.018 21.018 14.019

0.37 4 1956 10.042 1.142 4.942 4.842 3.342 2.04? 1.442 1.042 0.942 5.1028 1957 869.0 4 388.0 9 185.010 94.014 66.014 44.013 36.014 28.013 18.015 12.0039 1958 158.0 7 420.0 8 277.0 6 185.0 4 :29.0 4 87.0 4 63.0 6 48.0 6 37.0 6 0.46 6 1959 211.024 148.0a3 71.025 43.025 36.025 23.025 16.026 12.026 7.730 1.4013 1960 754.0 8 484.0 6 274.0 7 168.0 7 147.0 2 95.0 2 72.0 5 57.0 5 42.0 5

0.46 7 1961 90.037 57.036 28.038 26.033 20.034 12.034 8.135 6.035 4.236 5.7031 1962 267.019 157.021 98.021 76.017 59.0IS 54.011 44.0 9 42.0 7 31.0 9 5.4079 1963 266.020 212.016 128.017 81.015 49.0 17 29.020 22.023 17.023 12.023 0.83 9 1964 284.018 232.013 129.016 74.018 41.019 31.018 26.019 19.019 13.022 5.5030 1965 104.034 64.034 55.029 43.026 36.026 33.016 30.017 26.016 18.016 20.0002 1966 1570.0 3 966.0 2 491.0 2 357.0 1 240.0 1 138.0 1 117.0 1 105.0 1 72.0 1 4_4111 1967 152.031 74.032 41.033 26.034 17.035 12.035 9.633 7.234 5.334 38 1968 380.015 293.002 172.013 112.010 88.0 8 81.0 6 76.0 3 69.0 3 49.0 4 25 1969 206.025 128.024 75.023 56.023 39.020 26.023 22.020 19.020 14.020 `6.4033 1970 2130.0 1 877.0 3 434.0 3 208.0 3 107.0 7 55.010 37.012 28.014 22.014

0.45 5 1971 170.030 115.026 13.024 64.021 38.022 22.027 16.027 12.027 1.928 0.49 6 1972 374.016 160.020 106.019 65.020 44.018 27.022 31.016 25.017 17.017 41 14.00 1973 776.0 6 579.0 4 333.0 4 182.0 5 141.0 3 100.0 i 76.0 4 62.0 4 52.0 3 0.8610 1974 41.041 31.041 19.039 15.039 10.039 5.535 5.038 3.738 2.539

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEAN$ (ALL DAYS)

OCT NOV DEC JAN FEE, MARCH APRIL MAY JUNE JULI AUG SEPT

BY ROWSIMEAN,VARIANCE,STANDARODEVIATION,SKEwNESS,COEFF. JF VARIATION.PERCENTAGE OFAvERAGE VALLE) 5.09 3.43 16.6 16.1 20.9 26.4 9.78 1.85 0.33 5.36 12.0 9.07 212 34.8 1426 551 727 944 169 11.9 0.90 57.6 183 472 14.5 5.90 37.8 23.5 27.0 30.7 13.0 3.45 0.95 7.59 13.5 21.7 4.57 2.56 4.11 1.97 1.40 1.56 1.93 3.05 3.87 1.69 2.36 3.82 2.86 1.72 2.28 1.46 1.29 1.16 1.33 1.87 2.65 1.42 1.13 2.39 4.01 2.71 13.1 12.7 16.5 20.8 7.70 1.45 0.26 4.22 9.45 7.15

DISCHARGE. IN CUBIC FEET PER SECOND STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEwNESS COEFF. OF VARIATIUN SERIAL CORR 10.5 96.0 9.60 1.91 0.93 -0.233

324 246 GILA RISER BASIN

09484200 BEAR CREEK NEAR TUCSON, AZ

LOCATION. --Lat 32 °18'22 ", long 110 °48'03 ", in NU% sec.1S, T.1.3 S., R.1S E., Pima County, on left bank 0.8 mi (1.3 lan)upstream from mouth and 1S mi (Z4 km) northeast of City Hall in Tucson.

DRAINAGE AREA.- -16.3 mie (42.2 km2).

PATER ANNUAL PEAR OATG GAGE HEIGHT OF ATF,< TUTAL VULUME, YEAR OISCs.CFS ANNUAL PEAN,FT EA' ACRE -FT

1960 575 01-11-60 2.30 960 s210 1961 53 09-12-61 1.27 461 49 1462 225 12-16-61 1.96 962 4400 1963 357 02-11-63 2.17 0.5 2130 1964 433 09-13-64 2.38 964 2080 1945 192 02-07-65 1.90 965 3135 1966 1150 12-22-65 4.90 966 11400 1967 13 09-25-67 1.46 967 2e6 1968 621 12-20-67 3.3b 968 6184 1969 214 01-15-49 2.40 069 1420 1970 670 09-06-70 3.60 970 2420 1971 495 06-19-71 3.16 971 182 1972 247 10-01-71 2.33 972 1760 1973 818 10-19-72 3.35 973 4480 1974 57 01-09-74 1.31 974 371

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 2829 303132 3334 YEAR NUMBER OF DAYS IN CLASS 1960 129 40 7 8 5 15 16 3 5 6 8 20 9 2 9 7 5 7 14 19 6 4 12 4 1 '2 2 1

1961 255 11 5 15 22 29 6 8 6 2 1 2 1 1 1 1962 167 6 6 32 7 4 4 2 1 1 2 4 2 4 7 11 14 15 16 22 21 10 5 1 1 1963 65 4124 40 27 17 12 16 5 4 9 21 16 17 9 9 7 2 5 8 S 2 1 1 1 1 1964 165 2244 7 9 7 7 10 5 6 6 13 10 15 9 5 3 4 1 4 4 3 2 3 2 1965 140 7 22 20 14 12 19 4 6 14 16 13 15 15 18 14 8 6 1 1

1966 134 1 11 9 9 3 3 17 16 14 9 6 9 9 19 19 10 18 23 8 3 2 2 1 2 1967 126 47 27 54 42 27 24 11 3 1 1 2 1968 140 23 13 13 1 12 13 6 5 10 14 21 11 18 23 10 13 6 6 1 2 1 '9 140 35 18 14 18 4 17 25 26 24 18 10 7 1 4 2 1 1 3 148 22 13 29 36 27 17 11 6 11 9 6 2 4 3 12 4 1 1 1 1 1

1971 316 16 6 3 4 2 3 3 2 2 1 3 1 1 2 1972 212 14 14 9 9 7 14 22 11 8 4 13 6 .3 3 5 4 4 2 2 1973 77 3 8 10 10 4 7 11 7 6 29 18 18 24 21 18 16 17 15 9 16 6 T 2 1 2 2 1 1974 191 8 3 24 33 20 17 13 6 3 3 12 2 7 8 S 1 2 1

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 2411 5479 100.0 12 0.9 145 1641 30.0 24 43 59 130 2.3 1 0.01 128 3068 56.0 13 1.2 206 1496 27.3 2S 60 33 71 1.2 2 0.02 92 2940 53.7 14 1.7 135 1290 23.5 26 83 13 38 .6 3 0.03 134 2848 52.0 15 2.4 143 1155 21.1 27 110 10 25 .4 4 0.05 0 2714 49.5 16 3.3 135 1012 18.5 28 160 4 15 .2 S 0.06 113 2714 49.5 17 -4.5 125 877 16.0 29 220 5 11 .2 6 0.09 0 2601 47.5 18 6.3 108 752 13.7 30 300 4 6 .1 7 0.10 275 2601 47.5 19 8.6 89 644 11.8 31 410 2 2 8 0.20 190 2326 42.5 20 12.0 116 555 10.1 32 9 0.30 210 2136 39.0 21 16.0 147 439 8.0 33 10 0.50 115 1926 35.2 22 23.0 83 292 5.3 34 11 0.70 110 1751 32.0 23 31.0 79 209 3.8

325 CIL1 RIVER BASIN 247 09484200 BEAR CREEK NEAR TUCSON, AZ-CONTINUED

LUIEST MFAN VALUFANO9ANKIN0 FUR TIFFULLITwiNGNUM9FRUFf.UNSFCUiIVFnAY$ INYEARENUTNG SEP7FM4ERlu 'ISCMARGF,IN f.UAIC FEET PERSECnNO =N

YEAR 1 3 7 14 10 6U 90 i?0 SA3

0.00 1 1960 0.00 1 U.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.01 4

1961 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.01 3 1962 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.62 8 1963 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.01 11 0.01 9 1.10f0 1964 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4 0.00 4 0.05 5 1965 0.00 6 0.00 b 0.00 6 0.00 6 0.00 6 0.00 b 0.00 5 0.00 5 1.3012

1966 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.0213 0.1713 3.2015 1967 0.00 8 0.00 8 0.00 ö 0.00 ö 0.00 8 0.00 ö U.01IV 0.11 12 0.10 b 1968 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 b 0.4214 1.1011 1969 0.0010 0.0010 0.0010 0.00 11) 0.0010 0.0010 0.01 12 0.07 11 0.60 9 1970 0.00 11 0.0011 0.00 II 0.00 11 0.00 il 0.00 11 0.00 7 0.0610 1.6013

1971 0.0012 0.0012 0.0012 . 0.0012 0.0012 u.0012 0.00 8 0.00 b 0.00 1 1972 0.0013 0.0013 0.0013 U.0013 0.0013 0.0013 0.00 9 0.00 7 0.00 2 1973 0.0014 0.0014 0.0014 0.0014 0.0014 0.1115 0.5915 0.4515 2.140 14 1974 0.0015 -0.0015 0.0015 0.0015 0.0015 0.0014 0.0010 0.03 8 0.14 7

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE OATS IN YEAR ENDING SEPTEMBER 30 DISCHARGE.IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1960 316.0 3 225.0 3 138.0 2 92.0 2 66.0 2 44.0 3 31.0 3 25.0 3 17.0 3

1961 23.013 10.014 4.914 2.414 1.214 0.615 0.415 0.315 0.215 1962 129.0 8 78.0 8 50.0 8 39.0 6 29.0 5 26.0 5 21.0 5 20.0 5 13.0 5 1963 153.0 6 110.0 6 69.0 6 43.0 5 24.0 6 14.0 8 9.7 8 7.3 9 4.8 9 1964 106.0 9 82.0 7 64.0 7 36.0 7 20.0 7 15.0 6 11.0 7 8.3 7 5.7 7 1965 97.010 48.011 30.011 24.010 19.0 8 15.0 7 14.0 6 13.0 6 8.4 6

1966 468.0 1 321.0 1 176.0 1 142.0 1 99.0 1 56.0 1 51.0 1 43.0 1 29.0 1 1967 5.615 3.515 2.215 1.415 1.115 0.714 0.814 0.714 0.514 1968 265.05 154.0 5 87.0 -4 58.0 4 38.0 4 35.0 4 30.0 4 25.0 4 16.0 4 1969 142.0 7 68.0 9 34.010 22.011 13.011 7.811 6.310 5.010 3.411 1970 361.0 2 163.0 4 76.0 S 36.0 8 18.0 9 9.3 9 6.211 4.811 4.010

1971 16.014 13.013 7.8I3 4.413 3.013 1.513 1.013 0.813 0.513 1972 80.011 56.018 44.0 9 25.0 9 15.010 8.110 9.0 9 7.4 8 4.9 8 173 314.0 4 228.0 2 130.0 3 74.0 3 63.0 3 44.0 2 31.0 2 26.0 2 21.0 2 74 28.012 18.012 9.512 6.612 3.912 2.112 1.412 1.112 0.712

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT 4OV OEC JAN FEB MARCH APRIL NAY JUNE JULY AUG SEPT BY ROWS (MEAN.VARIANCE.STANDARD DEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 3.15 1.03 12.7 10.2 12.4 8.82 2.07 0.22 0.00 0.66 1.80 3.63

55.0 - 2.02 533 223 233 138 12.3 0.45 0.00 4.14 5.88 45.2 7.41 1.42 23.1 14.9 15.3 11.7 3.50 0.67 0.01 2.03 2.42 6.72 2.94 1.10 2.89 2.43 0.91 1.63 2.36 3.83 3.85 3.66 1.24 1.96 2.35 1.38 1.82 1.46 1.23 1.33 1.69 3.10 3.66 3.09 1.35 1.85 5.56 1.82 22.4 18.0 21.8 15.6 3.66 0.38 0.00 1.16 3.18 6.41

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 4.69 21.7 4.65 1.19 0.99 -0.452

326 248 GILA RIVER BASIN

094845o0 CIE \EGA CREEK NEAR PANTANO, AZ

LOCATION. --Lat 31 °59'04 ", long 11U °35'57 ", in NW-2 sec.l, T.17 5., R.17 E., Pima County, on do%nstream end of first pier from right abutment of bridge on Interstate Highway 10, and 1.2 mi (1.9 An) southeast of Pantano.

DRAINAGE AREA. --289 mil (749 km2).

NATEK ANNUAL PEAK DATE GAGE MEIGMT OF nAT9 TOTAL VOLUME. YEAR DISCm.CFS ANNUAL PEAK,FT YCA4 ACNE -FT

1968 1870 07-26-68 4.06 190.4 645 1969 990 07-22-69 3.40 197U 1790 1970 1770 07-20-10 3.98 1971 2760 1471 2240 08-03-71 4.51 1972 1140 1972 1930 09-13-72 4.46 1473 730 1973 678 02-22-73 4.10 1474 4540 1974 2570 07-14-74 5.05 1975 393 1975 1590 U9-02-75 4.40

DURATION TABLE OF DAILY VALUES FOR YEAR ENOIN6 SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 303132 3334 YEAR NUMBER OF OAFS IN CLASS 1969 346 1 1 3 1 1 3 3 1 4 1 1970 340 1 1 1 1 2 2 1 2 2 1 2 1 1 1 3 3

1971 332 1 1 1 1 2 4 2 3 2 1 1 1 4 2 6 1 1972 338 .2 1 2 2 6 2 1 2 2 1 1 1 2 1 1 1 1973 346 1 1 3 1 1 2 2 2 2 1 1 1 1 1974 344 2 1 1 2 1 1 1 2 1 2 3 1 2 1 1975 352 1 1 1 1 1 1 1 1 2 1 2

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUN PERCT 0 0.00 2398 2556 100.0 12 0.8 14 131 5.1 24 38 7 47 1.8 1 0.01 1 158 6.2 13 1.2 7 117 4.6 25 52 10 40 1.5 2 0.02 2 157 6.1 14 1.6 11 110 4.3 26 71 8 30 1.1 3 0.03 0 155 6.1 1S 2.2 6 99 3.9 27 97 9 22 .8 4 0.04 3 155 6.1 16 3.0 7 93 3.6 28 130 6 13 .5 5 0.06 1 152 5.9 17 4.1 7 86 3.4 29 180 4 7 .2 6 0.09 0 151 5.9 18 5.6 5 T9 3.1 30 250 2 3 .1 7 0.10 3 151 5.9 19 7.7 11 74 2.9 31 350 1 1 8 0.20 5 148 5.8 20 11.0 4 63 2.5 32 9 0.30 2 143 5.6 21 15.0 4 59 2.3 33 10 0.40 4 141 5.5 22 20.0 3 55 2.2 34 11 0.60 6 137 5.4 23 27.0 S 52 2.0

LOWEST MEAN VALUE ANORANKTNR FOR THE FOLLONtNG NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 14 30 60 90 120 143

1969 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1. 1970 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2

1971 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 1972 0.00 4 0.00 a 0.09 a 0.00 4 0,00 a 0.00 a 0.00 A 0.00 4 0.00 9 1973 0.00 5 0.00 5 O,On 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.59 7 1979 0.00 6 0.00 6 0.00 b 5.00 b 0.00 b 0.00 6 0.00 6 0.00 6 0.00 5 1975 0.00 7 0.00 7 0,00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6

327 GILA RIVER BASIN 249

09484560CIaTGA CREEK NEAR PANTANO, AZ-- CONTINUED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS INYEAR ENDING SEPTEMBER30 DISCHARGEIN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1969 53.0 7 32.0 7 21.0 7 13.0 7 8.1 6 5.1 5 3.4 5 2.5 5 1.7 6 1970 166.0 5 79.0 3 56.0 3 29.0 3 19.0 3 14.0 3 10.0 3 7.5 3 4.9 3

1971 238.0 2 135.0 2 92.0 1 60.0 2 40.0 2 22.0 2 15.0 2 12.0 2 7.6 2 1972 213.0 3 77.0 50.0 4 25.0 4 13.0 4 8.6 4 5.7 4 4.3 4 2.8 4 1973 200.0 4 74.0 5 32.0 5 15.0 5 8.8 5 4.4 6 2.9 6 2.2 6 2.0 S 1974 486.0 1 212.0 1 91.0 2 81.0 1 60.0 1 31.0 1 25.0 1 19.0 1 12.0 1 1975 95.0 6 56.0 6 26.0 6 13.0 6 6.4 7 3.3 7 2.2 7 1.6 7 1.1 7

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS LALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS (MEAN.VARIANCE,STANDARD DEVIATIONSKEWNESS.COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 0.31 0.00 0.00 0.00 1.13 0.17 0.00 0.00 0.32 11.3 9.16 5.55 0.5 0.00 0.00 0.00 9.00 0.22 0.00 0.00 0.83 319 I70 29.1 0.73 0.00 0.00 0.01 3.00 0.47 0.00 0.00 0.91 17.9 13.1 5.40 2.60 2.65 2.65 2.65 2.83 2.83 2.45 2.07 0.50 2.40 2.65 2.65 2.65 2.83 4444 2.83 1.58 1.42 0.97 1.09 0.00 0.00 0.01 4.06 0.59 V.00 0.00 1.16 40.5 32.8 19.8

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 2.35 4.16 2.04 1.33 0.87 -0.584

Skewness and coefficient of variation could not be computed owing to a zero-value month.

328 250 GILA RIVER BASIN

09484590 DAVIDSON CANYON WASH NEAR VAIL, AZ

LOCATION.- -Lat 31 °59'37 ", long 11U °38'40 ", in SASE4 sec.31, T.10 S., R.17 E., Pima County, on right bank 0.3 mi (0.5 km)upstream from Interstate Highway 10, 2.0 mi (3.2 km) upstream from mouth, and 5.5 mi (8.8 km) southeast of Vail.

DRAINAGE .AREA. --50.5 mil (130.8 km2).

WATER ANNUAL PEAK DATE GAGt HEIGHT OF nA1Fk TUTAL VOLUME, YEAR DISCH,CFS ANNUAL PtAK,FT `'EAR ACREFT

1968 3040 07 -26 -68 5.14 191,4 470 1969 587 08 -05 -69 3.60 1974 1040 1970 6860 07 -20 -70 7.95 1971 A35 1971 1490 08 -10 -71 3.73 1972 756 1972 1320 09 -07 -72 3.61 197y 0 1973 28 10 -19 -72 2.22 1974 754 1974 1460 09 -21 -74 4.0 1975 ?U8 1975 708 07 -08 -75 3.20

DURATION TABLE -OFDAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

CLASS 0 I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 11 18 19 20 21 22 23 24 25 26 27 2829 3o3132 3334 YEAR NUMBER OF DAYS IN CLASS 1969 49 1 1 1 5 4 10 10 36 12 78 106 21 15 11 3 1 1 1970 342 2 2 3 1 1 2 3 1 2 1 1 2 1 1

1971 233 11 5 5 4 15 12 4 34 12 13 2 1 1 1 2 1 1 1 3 1 1 2 1972 331 2 2 2 1 3 1 S 5 5 3 1 2 1 1 1 1973 362 1 2 1974 344 1 2 1 3 1 1 1 1 1 1 2 2 3 1 1975 359 1 1 1 1 2

CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT 0 0.00 2020 2556 100.0 12 0.5 81 284 11.1 24 16 2 27 1.0 1 0.01 14 536 21.0 13 0.7 108 203 7.9 25 21 25 .9 2 0.02 8 522 20.4 14 0.9 22 95 3.7 26 28 5 21 .8 3 0.03 12 514 20.1 15 1.2 I7 73 2.9 27 38 4 16 .6 4 0.04 7 502 19.6 16 1.6 12 56 2.2 28 50 6 12 .4 S 0.05 23 49S 19.4 17 2.2 4 44 1.7 29 66 3 6 .2 6 0.07 19 472 18.5 18 2.9 2 40 1.6 30 88 2 3 .1

7 0.09 10 453 17:7 19 3.9 1 38 1.5 31 120 1 1 8 0.10 57 443 17.3 20 5.1 4 37 1.4 32 9 0.20 31 386 15.1 21 6.8 3 33 1.3 33 10 0.30 54 355 13.9 22 9.1 1 30 1.2 34 11 0.40 17 301 11.8 23 12.0 2 29 1.1

LOWEST MEAN VALUEANDRANKTNRFORTHF. FOLLnwtNGNUMBFROFCONSECUTIVEDAYSIN YEARENDINGSEPTEMPER34 DISCHARGE,IN CUBIC FEET PERSECOND MEAN

90 YEAR 1 3 7 14 SO 60 170 183 1969 0.00 1 0.00 1 0.00 1 0.00 1 0.01 7 0.26 7 0.33 7 0.38 7 0.41 7 1970 0.00 2 0.00 2 0.00 2 0.00 2 0.00 1 0.00 1 0.00 l 0.00 1 0.00 1

1971 0.00 3 0.00 3 0.00 3 0.00 3 0.00 2 0.04 2 0.00 2 0.00 2 0.04 6 1972 0.00 4 0.00 4 0.00 4 0.00 4 0.00 3 0.00 3 0.04 3 0.00 3 0.00 2 1973 0.00 5 0.00 5 0.00 5 0.00 5 0.00 a 0.00 4 0.00 4 0.00 a 0.00 3 1974 0.00 6 0.00 6 0.00 6 0.00 6 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4 1975 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6 0.00 b 0.00 6 0.00 6 0.00 5

329 GILV RIVER BASIN 251

09483590 DAVIDSON CANYON WASH NEAR VAIL, AZ--CONTINUED

HIGHEST MEAN VALUE ANO RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYSIN YEARENDINGSEPTEMBER30 OISCHARBE.IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1969 22.0 6 7.8 6 4.3 6 2.2 6 1.4 6 1.2 6 1.0 6 1.0 5 0.9 4 1970 231.0 1 112.0 1 48.0 1 23.0 1 18.0 1 8.8 1 5.8 1 4.4 1 2.9 1

1971 70.0 4 53.0 2 23.0 2 19.0 2 12.0 2 6.8 2 4.5 2 3.4 2 2.3 2 1972 117.0 2 40.0 17.0 4 8.0 4 4.0 4 2.0 4 1.3 4 1.0 4 0.7 5 1973 0.2 7 0.1 7 0.0 7 0.0 7 0.0 7 0.0 7 0:0 7 0.0 7 0.0 7 1974 75.0 3 45.0 3 20.0 3 9.4 3 8.0 3 4.9 3 4.2 3 3.2 3 2.1 3 1975 49.0 5 16.0 5 7.0 5 3.3 5 1.7 5 1.5 5 1.2 5 0.9 6 0.6 6

DISCHAPGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT

BYROWS(MEAN.VARIANCE.STANOARD DEVIATION.SKEWNESS.COEFF.OF VARIATION.PERCENTA6E OFAVERAGE VALUE) 0.10 0.14 0.23 0.11 0.18 0.20 0.15 0.11 0.07 2.48 3.40 2.06 0.07 0.13 0.26 0.08 0.10 0.10 0.06 0.04 0.02 15.5 15.9 7.68 0.27 0.36 0.51 0.28 0.31 0.31 0.24 0.20 0.13 3.93 3.99 2.77 2.65 2.65 2.49 2.64 1.46 1.30 1.31 1.45 1.57 1.86 1.22 1.71 2.61 2.65 2.21 2.55 1.77 1.57 1.61 1.78 1.88 1.58 1.17 1.34 1.11 1.47 2.49 1.17 1.90 2.17 1.58 1.23 0.75 26.9 36.8 22.4

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 0.70 0.28 0.53 0.11 0.75 -0.000

330 252 GILA RIVER BASIN

09484600 PANTANO WASH NEAR VAIL, AZ

LOCATION. --Lat 32 °02'09 ", long 110 °40'37 ", in SW SEi sec.14, T.16 S., R.16 E., Pima County, on right bank 60 ft (1S m) upstream from dam, 2.2 mi (3.5 km) southeast of Vail, 2.4 mi (3.9 km) southwest of Pistol Hill, and 20 mi (32 km) southeast of City Hallin Tucson.

DRAI.NAGE AREA.- -457 mil (1,184 km:).

EATER ANNUAL PEAK DATE GAGE HEIGRT GF r;4TF.9 TOTAL VOLUME. YEAR 015C6,CFS 4,4NUAL PEAK,FT YtAR ACRE -FT

1958 3h000 08-11-58 24.00 1964 4060 1959 9310 06-17-59 9.6U 1941 5P40 1940 7304 08-09-60 8.30 1942 4000 1961 52110 06-25-61 6.87 1963 7540 1462 1500 09-26-62 3.65 1964 434u0 1943 9700 08-25-63 10.90 1965 2460 1964 9960 09-10-64 11.06 1966 4710 1965 5680 09-12-45 8.23 1967 6180 1966 7410 08-13-66 9.25 1468 662n 1967 7680 08-18-67 9.54 1464 1660 1968 2640 12-20-67 5.46 1970 3660 1969 857 08-6969 3.40 1971 6680 1970 6650 07-20-70 8.95 1972 11;60 1971 8700 08-19-71 10.34 1973 2930 1972 1460 09-07-72 4.65 1474 2500 1973 371 10-04-72 3.10 1974 1780 07-20-74 7.05 1975 1700 09-02-75 6.70

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 35 262726293031323334 YEAR NUMBER OF DAYS IN CLASS 1960 57 167 49 34 16 10 1 4 2 1 2 12 4 2 1 2 1 1

1961 54 116107 50 2 3 1 1 5 1 4 1 4 3 2 1 1 3 1 5 1962 2 90 140 84 28 4 2 2 3 2 1 3 1 1 1 1 1963 47200 52 25 6 2 4 3 2 2 1 1 3 1 S 5 2 2 1 1 1964 2 2 3 50 150102 5 13 4 4 3 3 1 4 4 2 2 2 1 4 2 1 1 1 1965 2 15 16 21 50 47 95 76 26 7 1 1 1 2 1 I 1 1 1

1966 6 20 18 33 32 29 43 34 59 19 5 6 5 4 13 6 6 3 6 4 2 4 3 2 1 1 1 1967 1 1 S 12 25 94 79 82 21 10 6 7 2 4 2 3 1 1 3 1 2 1 1 1 1968 7 14 19 61 69 47 57 37 17 3 8 1 1 6 5 3 3 1 3 1 1 1 I 1969 4 17 36 40 23 44 48 88 50 1 1 2 1 1 1 1 1 1 1

1910 1 1 20 27134 82 48 16 6 1 2 2 2 1 2 1 1 2 1 1 2 1 1 I.

1971 19 8 16 20 35 24 65 37 50 41 4 5 6 7 3 5 1 1 1 3 1 3 3 2 2 1 2 1972 3 20 31 68 25 73 80 47 1 2 1 4 2 2 1 1 1 3 1 1973 17 27 15 25 22 14 22 32 47 42 33 12 9 7 6 6 6 7 5 4 1 4 1 1 1974 20206 56 22 11 13 7 4 1 2 1 2 1 1 2 6 2 3 1

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 56 5479 100.0 12 3.7 127 600 11.6 24 100 26 79 1.4 1 0.10 241 5423 99.0 13 4.9 60 473 8.6 25 140 la 53 .9 2 0.20 97 5182 94.6 14 6.4 46 413 7.5 26 180 15 35 .6 3 0.30 107 5085 92.8 15 8.5 48 365 6.7 27 240 6 20 .3 4 0.40 161 4978 90.9 16 11.0 27 317 5.8 28 310 4 14 .2 5 0.50 162 4817 87.9 17 15.0 42 290 5.3 29 410 3 10 .1 6 0.70 467 4655 85.0 18 20.0 41 248 4.5 30 550 4 7 .1 7 0.90 770 4188 76.4 19 26.0 36 207 3.6 31 120 1 3 8 1.20 1053 3418 62.4 20 34.0 20 171 3.1 32 950 2 2 9 1.60 896 2365 43.2 21 45.0 33 151 2.8 33 10 2.10 539 1469 26.8 22 59.0 21 118 2.2 34 11 2.80 330 930 17.0 23 78.0 18 97 1.8

331 GILA RIVER BASIN 253 09434600 PANTANO WASH NEAR VAIL, AZ -- CONTINUED

PANFTyf, tU44E9T MOAN VALUFANn FUP TMF FULLOwTnn NUM4F4 UF CUNSFCNITVF04YS INYEA4 ENUTNf,SEPTFMMER3u nISCMARGF,IN CU9ICFEETPOWSFCnNn MEAN

3 7 14 10 60 YEAR 1 96 1Pu 193 12 1960 0.90 14 0.9014 0.90 0.90 11 1.00IV 1.1912 1.40 12 1.50 11 2.2012

1.00 15 1.0015 1.00 15 13 I1 1961 1.00 1.00 1.10 9 1.19 8 1.30 7 1.50 6 0.80 13 4.8713 0.9013 12 10 1962 0.91 1.1012 1.19 1,19 9 1.30 8 1.70 9 10 8 1963 0.70 12 0.7712 0.79 0.79 9 0.86 0.91 8 0.91 b 0.91 5 0.96 4 0.40 10 0.47 9 1.00 14 1.1014 13 11 1964 1.10 1.19 1.30 10 1.4010 1.50 7 1965 0.30 8 0.40 8 0.40 8 0.40 7 0.91 9 1.40 13 1.0 13 1.7012 1.4010

1966 0.20 4 0.20 4 0.24 4 0.26 4 0.31 4 0.64 5 1.30 11 1.7013 7.0015 1947 0.40 9 0.57 10 0.89 11 1.3015 1.5015 1.60 15 1.80 15 1.8014 2.3013 1968 0.60 11 0.60 11 0.61 9 0.8?10 1.1914 1.50 14 1.60 14 2.2015 3.1014 1969 0.20 5 0.20 5 0.24 5 0.39 6 0.46 5 0.53 4 0.91 5 1.30 9 1.8011 1970 0.30 6 0.30 6 0.31 b 0.36 5 0.61 6 0.42 7 0.86 4 11.87 3 0.4A 3

0.00 1 1 0.00 1 ,2 1971 0.00 0.00 l 0.14 0.24 2 0.41 2 0.71 2 0.83 2 1972 0.30 7 0.30 7 0.39 7 0.46 8 0.64 7 0.74 b 0.74 3 0.95 6 1.19 5 2 1973 0.00 2 0.00 2 0.00 2 0,00 0.15 3 0.31 3 1.00 7 0.80 4 1.70 8

0.00 3 _ 0.00 3 0.00 3 0.00 3 i 1 1974 0.05 0.10 0.10 I O.10 i 0.10 1

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1960 337.0 8 196.0 8 89.0 7 46.0 9 27.010 15.011 10.011 8.111 5.911

1961 220.011 169.01 89.0 8 71.0 7 51.0 6 35.0 5 24.0 6 18.0 6 13.0 6 1962 158.012 56.013 24.014 13.014 9.114 6.314 5.413 4.313 3.313 1963 898.0 3 396.0 3 234.0 3 148.0 3 95.0 3 58.0 2 39.0 2 30.0 2 20.0 2

1964 2230.0 1 818.0 1 379.0 1 205.0 1 106.0 1 66.0 1 48.0 1 36.0 1 24.0 1 1965 297.0 9 100.011 44.012 21.012 17.012 9.412 7.812 6.212 4.712

1966 550.0 6 381.0 4 178.0 4 94.0 4 53.0 4 38.0 4 30.0 4 23.0 4 16.0 4 1967 490.0 7 203.0 7 162.0 6 90.0 5 52.0 5 33.0 6 26.0 5 20.0 5 14.0 5 1968 952.0 1 355.0 5 173.0 5 86.0 6 45.0 8 25.0 7 18.0 7 15.0 7 11.0 7 1969 74.015 31.015 17.015 10.015 6.715 4.915 3.515 2.815 2.515 1970 568.0 5 204.0 6 88.0 9 58.0 8 46.0 7 25.0 8 18.0 8 14.0 8 9.3 8

1971 603.0 4 500.0 2 275.0 2 153.0 2 96.0 2 53.0 3 37.0 3 27.0 3 18.0 3 1972 140.014 52.014 27.013 17.013 9.313 7.113 4.914 3.914 3.014 1973 146.013 83.012 51.010 29.011 25.011 18.0 9 13.010 9.810 7.0 9 1974 245.010 104.010 46.011 40.010 27.0 9 16.010 14.0 9 10.0 9 6.810

DISCHARGE, IN CUBIC FEET PER SECOND STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS (MEAN.VARIANCE.STANOARD DEVIATION.SKEWNESS.COEFF. OF VARIATIONsPERCENTAGE OF AVERAGE VALUE) 2.36 1.4 7.82 2.99 4.84 3.06 1.80 1.22 1.08 14.0 27.2 14.0 4.34 0.58 253 16.8 80.5 18. 1.34 0.22 0.38 179 877 613 2.08 0.76 15.9 4.09 8.97 4.28 1.16 0.47 0.62 13.4 29.6 24.8 1.19 0.31 2.41 3.47 3.31 3.34 1.79 -0.73 0.65 1.41 1.36 3.72 0.86 0.53 2.03 1.37 1.85 1.40 0.6 0.38 0.57 0.96 1.09 1.77 2.89 1.77 9.56 3.65 5.91 3.7 2.20 1.49 1.32 17.1 33.2 17.1

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 6.70 14.2 3.77 0.49 0.56 -0.111

332 254 GIL1 RIVER BASIN

09485000RINCON CREEK NEAR TUCSON, AZ

LOCATION. --Lat 32 °07'46 ", long 110 °37'32 ", in NW1/4NE1/4 sec.17, T.15 S., R.17 E., Pima County, on left bank 0.2 mi (0.3 km)north of Sentinel Butte, 9 mi (14.5 km) upstream from mouth, and 22 mi (35.4 km) southeast of City Hall in Tucson.

DRAINAGE AREA.- -44.8 mil (116.0 km2).

HATER ANNUAL PEAK DATE GAGE HEIGHT OF CODE ANNUAL MAX DATE WATEN TOTAL VOLUME, YEAR DISCH,CFS ANNUAL PEAK,FT GAGE MT.FT YEAR ACRE -FT

1953 194 07-30-53 3.78 1993 591 1954 2160 08-19-54 6.50 1954 4770 1955 8250 08-03-55 9.90 1955 4760 1956 150 07-20-56 4.35 1956 52 1957 3570 01-09-57 7.37 1957 5410 1958 492 03-22-58 5.46 NM 5.60 06-24-58 1958 4160 1959 5220 10-21-58 8.50 1999 2230 1960 747 01-12-60 5.69 196U 5680 1961 2600 08-22-61 6.92 1961 764 1962 227 01-24-62 4.36 1962 4930 1963 3420 08-25-63 7.47 1963 4370 1964 948 09-23-64 5.30 1964 1240 1965 311 08-18-65 4.68 1965 966 1966 3100 12-22-65 7.25 1966 17600 1967 157 08-13-67 3.90 1967 73 1968 1860 02-12-68 6.26 1968 6600 1969 548 09-06-69 4.88 1949 988 1970 1200 08-01-70 5.67 1970 1600 1971 9660 08-19-71 10.50 1971 4970 1972 360 07-16-72 4.55 1972 2600 1973 1440 10-19-72 5.89 1973 11400 1974 664 08-01-74 4.94 1974 260 1975 340 09-02-75 4.63

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER30 DISCMAwGE.Iv CUBIC FEET PER SECOND REAR

CL455 c 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 262728293031 323334 YEAR NUMBER OF DAYS IN CLASS

1953 296 20 13 2 5 2 1 2 5 1 1 2 4 2 3 3 3

1954 290 12 8 5 5 1 1 3 3 4 1 5 2 1 8 2 2 1 1 2 2 1

1955 29S 7 3 8 2 4 5 1 2 1 3 3 2 4 2 6 4 5 1 2 3 2

1956 259 89 21 1 2 1 1 1 957 208 12 7 5 17 16 10 13 10 11 8 8 6 5 6 6 5 2 3 1 4 1 1 .956 153 19 28 33 23 9 7 8 12 11 5 2 2 5 8 14 12 7 3 2 1 1

1959 161 73 25 6 15 12 2 5 4 6 4 5 5 5 4 4 1 1 4 2 1 1960 204 15 15 3 3 e 4 5 12 7 4 5 9 14 18 14 5 5 8 5 1 1 1

1961 316 9 5 3 4 1 2 1 4 2 5 3 2 1 4 2 1 1962 191 16 10 6 14 1 1 2 1 7 6 11 35 25 17 15 3 2 2

1963 213 1' 14 2 16 8 6 7 6 12 11 8 7 9 9 9 3 7 1 1 4 1 1 1964 322 3 3 4 2 2 4 2 4 3 1 2 3 3 1 3 1965 137 71 18 8 15 4 11 13 20 15 18 21 5 6 3

1966 114 13 18 9 9 8 9 16 8 6 7 8 8 12 4 15 24 34 18 16 3 2 2 1 1 1967 289 25 4 26 18 1 1 1 1968 139 1 3 14 13 13 16 12 6 6 6 7 12 31 28 17 14 6 8 6 2 3 1 1 1 1969 238 1 1 1 1 2 6 5 6 8 5 23 21 10 10 11 6 3 3 3 1 1970 172 7 18 32 36 13 12 7 9 20 5 2 4 4 4 2 3 4 4 3 1 1 1 1

1971 286 3 2 2 1 1 1 4 19 7 1 1 1 1 12 7 4 1 3 2 3 1 1 1 1972 155 2 1 3 2 3 14 7 18 24 8 12 21 22 7 10 9 6 11 5 11 11 2 1 1 1973 89 4 4 6 2 3 17 3 3 11 16 26 35 11 13 17 12 14 19 12 10 7 5 11 1 6 2 3 1 1 1 1974 305 4 2 4 2 2 21 8 1 1 3 2 1 1 1 1 1 1

NM Not maximau gage height for water year.

333 GI1A RIVER BASIN 255 09485000 RINCCN CREEK NEAR TUCSON, AZ-- CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30-Continued DISCHARGE.I!. CUBIC FEET PER SECOND MEAN

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT o 0.00 4848 8035 100.0 12 1.2 176 1677 20.9 24 77 40 105 1.3 1 0.01 11 3187 39,7 13 1.7 172 1501 18.7 25 110 24 65 .8 2 4.02 18 3176 39.5 14 2.4 130 1329 16.5 26 150 15 41 .5 3 0.03 34 3158 39.3 15 3.5 131 1199 14.9 27 220 12 26 .3 4 0.05 42 3124 38.9 16 4.9 145 1068 13.3 28 310 7 14 .1 5 0,07 45 3082 38.4 17 6.9 125 923 11.5 29 430 1 7 6 0.10 470 3037 37.8 18 9.7 158 798 9.9 30 610 5 6 1 0.20 246 2567 31.9 19 14.0 149 640 8.0 31 860 1 1 8 0.30 159 2321 26.9 20 19.0 129 491 6.1 32 9 0.40 226 2162 26.9 21 27.0 111 362 4.5 33 10 0.60 142 1936 24.1 22 39.0 82 251 3.1 34 11 0.90 117 1794 22.3 23 54.0 64 169 2.1

LOWEST MEAN VALUE AND RANKING FORTHE FOLLOWING NUMBEROFCONSECUTIVE DAYSIN YEARENDINGSEPTEMBER30 DISCHARGE,IN CURIO FEET PER SECOND MEAN

YEAR 1 3 7 14 30 60 90 120 163

1953 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.6012 1954 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 2.1018 1955 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 1

1956 0.00 a 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 a 0.00 a 0.00 2 1957 0.00 5 0.005' 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.0717 1.5016 1958 0.00 6 0.00 6 0.00 6 0.00 b 0.00 6 0.00 6 0.0719 0.7121 3.7020 1959 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6 0.01 12 0.04 8 1960 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 7 0.00 5 0.08 9

1961 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 8 0.00 6 0.00 3 1962 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.00 9 0.00 7 0.6613 1963 0.00 11 0.00 11 0.0011 0.00 11 0.0011 0.0011 0.0010 0.0614 a.0021 1964 0.0012 0.00t2 0.0012 0.0012 0.0012 0.0012 0.00 11 0.00 8 0.00 a 1965 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0012 0.0715 0.8715

1966 0.0014 0.0014 0.0014 0.0014 0.0014 0.00ta 0.3621 0.6420 0.4022 1967 0.0015 0.0015 0.0015 0.0015 0.0415 0.0015 0.0013 0.00 9 0.00 5 1968 0.0016 0.0016 0.0016 0.0016 0.0016 0.00ib 0.1720 0.9922 1.7017 1969 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.0014 0.1018 0.5611 1970 0.0018 0.0016 0.0018 0.0018 0.0016 0.0122 0.0518 0.0716 0.8314

1971 0.0019 0.0019 0.0019 0.0019 0.0019 0.0018 0.0015 0.0010 0.00 6 1972 0.0020 0.0020 0.0020 0.0020 0.0020 0.0019 0.0117 0.0513 0.1610 1973 0.0021 0.0021 0.0021 0.0021 0.0021 0.0020 0.4522 0.3719 3.5019 1974 0.0022 0.0022 0.0022 0.0022 0.0022 0.0021 0.0016 0.0011 0.04 7

334 256 GILA RIVER BASIN

09485000 RINCGN CREEK NEAR TUCSON, AZ-- CONTINUED

MIGHEsT MEAN VALLE ANO RANKING FORTHE FOLLOWING NUMBEROF CONSECUTIVEDAYSIN YEAR ENDINGSEPTEMBER30 DISCHARGE.I. CUBICFEET PER SECONO vEAN

Y.-01 1 3 7 15 30 60 90 120 183 1953 32.019 27.0lb 21.017 12.018 6.319 3.219 2.119 1.619 1.619 1954 398.0 6 235.0 6 115.0 7 56.0 9 30.010 17.0 11 11.012 8.412 7.611 1955 392.G 7 185.0 8 106.0 8 91.0 71.0 3 40.0 6 27.0 6 20.0 6 13.0 6

1956 7.522 2.822 1.322 0.722 0.422 0.322 0.221 0.221 0.121 1957 754.0 3 329.0 4 154.0 5 72.0 7 44.0 8 22.010 15.010 12.010 7.810 1958 249.010 146.0 10 105.0 9 71.0 8 47.0 7 29.0 7 19.0 7 15.0 8 11.0 8 1959 225.012 97.012 74.012 41.011 23.013 12.013 7.913 5.913 3.914 1960 269.0 9 190.0 7 125.0 6 94.0 3 64.0 4 42.0 3 31.0 4 24.0 4 16.0 4

1961 138.013 65.014 31.016 17.016 11.016 6.416 4.318 3.218 2.118 1968 104.014 68.013 46.013 33.015 25.011 23.0 9 19.0 8 19.0 7 12.0 7 1963 248.1 11 136.0 11 77.011 54.010 39.0 9 24.0 8 16.0 9 12.0 9 8.5 9 1964 102.015 57.016 45.015 35.014 19.015 10.015 6.915 5.215 3.415 1965 17.020 13.020 13.0.19 8.919 6.818 5.517 4.517 3.816 2.516

1966 977.0 1 590.0 1 297.0 1 209.0 1 150.0 1 91.0 1 82.0 1 68.0 1 45.0 1 1957 13..)21 4.321 1.921 0.921 0.621 0.321 0.222 0.222 0.122 1968 684.0 4 331.0 3 176.0 3 89.0 5 50.0 6 41.0 4 32.0 3 26.0 3 17.0 3 1969 76.017 36.017 17.018 13.017 7.417 5.318 4.616 3.617 2.317 1970 276.0 8 159.0 9 80.010 38.012 20.014 11.014 7.114 5.414 4.113

1971 634.0 5 324.0 5 161.0 4 81.0 6 59.0 5 41.0 5 27.0 5 21.0 5 14.0 5 1972 77.016 60.015 47.014 35.013 23.012 14.012 13.0 11 10.011 7.012 1973 8! -8.0 2 550.0 2 278.0 2 141.0 2 124.0 2 79.0 2 55.0 2 42.0 2 32.0 2 1974 50.018 20.019 10.020 4.720 2.420 1.220 0.820 0.620 0.420

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS ALL DAYS)

GCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS(MEAN.VARIANCE,STANDARDOEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTAGE OFAVERAGE VALUE) 2.09 0.59 9.48 8.25 11.6 10.4 2.38 0.16 0.08 1.09 12.1 5.29 32.4 1.38 783 266 509 329 22.1 0.18 0.10 7.31 310 110 5.69 1.17 28.0 16.3 22.6 18.1 4.70 0.42 0.32 2.70 17.6 10.5 3.05 2.11 4.15 2.39 2.15 2.60 2.55 3.93 4.55 4.04 1.66 2.66 2.72 2.00 2.95 1.98 1.94 1.75 1.98 2.60 3.78 2.47 1.46 1.99 3.30 0.92 14.9 13.0 18.3 16.3 3.75 0.26 0.13 1.72 19.0 8.32

DISCHARGE, IN CUBIC FEET PER SECOND STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 5.28 33.2 5.76 2.08 1.09 -0.445

335 GILA RIVER BASIN 2S7

09486000 RILLITO CREEK NEAR TUCSON, AZ

LOCATION. --Lat 32 °17'41 ", long 110 °59'00 ",in SI.SE: sec.14, T.13 S., R.13 E., on right bank 600 ft (183 m) downstream from Pima Canyon, 1,880 ft (549 m) downstream from bridge on U.S. Highway 89, 4.8 mi (7.7 km) upstream from mouth, and 5.4 mi (8.7 km) north of City Hall in Tucson.

DRAINAGE AREA. --918 mi' (2,378 km2). At former site (sta 09485850), 892 mi' (2,310 km2).

RATER ANNUAL PEAR GATE CUUES GAGE HEIGHT OF RA1FH TOTAL VOLUME, TEAR UISCH,CFS ArvNUAL PEAR,FT TEAK ACHE -FT

1915 17000 12-23-14 1914 8910 1916 7620 01-19-16 191b 52300 1917 10000 08-11-17 191/ 9770 1918 5300 03-01-18 1918 12600 1919 9250 07-27-19 1919 37200 1920 7600 02-21-20 1970 26000 1921 16000 07-31-21 1921 42900 1922 3250 08-09-22 1972 3030 1923 5000 08-26-23 1973 0670 1924 1980 .12-26-23 1474 5760 1925 3500 09-17-25 1975 4720 1926 1750 09-27-26 1926 1140 1927 2200 09-12-27 1927 4500 1928 4500 08-01-28 1976 1960 1929 24000 09-23-29 1929 76400 1930 4600 08-08-30 1930 10600 1931 7200 08-10-31 1931 12900 1932 7200 07-29-32 193d 14900 1933 4400 09-10-33 1433 1650 1934 3000 07-17-34 1934 2100 1935 13400 08-31-35 1935 18300 1936 4500 08-17-36 1936 3600 1937 2980 08-17-37 1937 4450 1938 3000 03-04-38 1930 2500 1939 9710 08-03-39 1939 6480 1940 13200 08-13-40 1940 8350 1941 9900 12-31-40 1941 29900 1952 1600 09-14-42 1942 5170 1943 3650 08-15-53 1943 2600 1944 4100 06-09-45 1944 3190 1945 7000 08-10-45 1945 3890 1946 4160 08-.31-46 1946 3040 1947 7660 08-15-47 1947 4120 1948 779 09-2b-48 1946 960 1949 1640 09-15-49 1949 2920 1950 9490 07-30-50 1950 7260 1951 9500 07-25-51 1451 4140 1952 1630 11-11-51 1952 6160 1953 5470 07-1e-53 1953 1740 1955 7680 07-24-54 1954 13000 1955 8070 07-21-55 1995 12300 1956 2050 07-29-56 6.30 1996 315 1957 9500 01-09-57 7.14 1957 4220 1958 8930 08-12-58 9.64 1958 11300 1959 7710 08-17-59 8.86 1999 5250 1960 3610 01-12-60 6.98 1960 13500 1961 4140 07-22-61 7.36 1961 2720 1962 2690 09-26-62 6.48 1962 4360 1963 7640 08-26-63 9.20 1983 5730 1964 9420 09-10-64 8.58 1964 9500 1965 754 09-12-65 5.20 1965 1030 1966 12400 12-22-65 10.36 1966 53300 1967 3100 08-19-e7 Es 6.84 1967 1490 1968 7740 02-12-68 5.44 1974 445 1969 2220 08-05-69 7.00 1970 555 1970 7000 09-06-70 1971 9290 08-20-71 8.49 1972 1620 08-12-72 6.35 1973 5160 10-20-72 b.2 1974 1440 08-02-74 6.94 1975 2270 07-16-75

ES Discharge estimated from another site.

336 258 GILA AMR BASIN

09486000 RILLITO CREEK NEAR TUCSON, A2-- CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 2829 303132 33 34 YEAR NUMBER OF DAYS IN CLASS

1914 331 1 2 1 6 1 1 3 4 5 2 3 1 1 1 2

1916 272 1 1 2 2 1 10 5 3 5 4 11 7 9 7 5 9 6 1 3 1 1

1917 333 1 1 1 1 3 2 2 3 2 4 3 2 1 2 1 1 2 343 1918 2 2 3 3 l 1 1 1 1 1 1 1 1 2 1

1919 276 5 6 2 8 2 2 21 18 2 4 2 3 1 2 2 2 4 2 1

1920 267 7 2 2 9 3 8 6 9 8 14 14 5 7 4 1

1921 328 2 1 3 6 2 4 4 2 S I 2 1 3 1 1922 341 1 1 7 1 4 1 3 2 2 2 1923 329 3 3 1 4 1 2 4 2 5 2 I 2 2 1924 333 1 2 5 1 3 4 5 2 2 3 3 2 1925 342 2 2 1 1 1 1 2 3 2 1 3 2 2

1926 338 3 5 3 1 3 4 3 1 2 1 1

1927 309 3 1 1 11 3 4 6 8 8 5 2 2 1 1

1928 352 1 3 3 2 1 1 1 1 1

1929 331 3 2 1 2 1 6 3 2 1 6 2 2 1 1 1 .4 1930 330 3 3 1 4 2 2 1 2 2 1 3 2 1

1931 321 2 4 2 3 6 3 3 1 6 1 3 3 1 1 2 2 1 1932 286 6 8 3 4 3 5 6 8 9 9 7 6 1 2 2 1 1933 320 10 5 S 9 1 10 2 1 1 1

1934 338 8 2 1 2 3 1 2 2 3 1 1 1

1935 312 10 4 2 9 5 1 3 2 2 5 2 1 3 2 1 1

1936 338 4 4 3 3 3 1 2 1 2 I 3 1

1937 331 S 1 3 6 4 2 2 2 1 5 1 1 1

1938 344 3 4 4 3 1 1 1

1939 385 2 2 1 2 3 2 1 3 1 1 1 1 1940 346 4 2 1 2 3 1 1 2 1 1 1 1

1941 286 9 A 6 2 2 4 3 12 6 7 7 4 4 5 3 I 1942 332 4 2 1 2 3 3 2 8 2 3 1 1 1 1943 3A3 2 3 1 1 2 3 3 2 2 1 2

1944 342 6 1 5 2 2 1 1 1 1 1 I 1 1

1945 318 9 3 2 9 4 4 4 5 2 2 2 1

1946 339 2 1 3 2 3 4 1 3 2 2 2 1 1947 348 1 3 3 1 1 2 1 1 1 1 1 1 1948 347 1 1 1 1 3 3 4 2 2 1 333 3 1 1 5 1 1 1949 4 3 3 1 . 2 3 2 1 1

1950 343 1 1 3 2 3 2 1 2 1 1 1

1951 346 1 2 1 2 1 2 2 4 1 1 2 1952 321 1 1 2 5 5 6 3 5 7 2 2 4 1 1 1953 349 1 3 1 1 l 1 1 1 1 1 2 1 1

1954 328 1 3 1 3 6 5 6 1 4 4 2 1 1955 329 2 1 1 1 1 3 1 6 2 4 6 2 2

1956 357 2 3 1 1 1 1

1957 342 1 1 3 2 3 4 1 5 1 1 1 1958 301 1 1 3 1 2 S 2 2 3 6 2 10 7 8 5 1 3 2 1959 336 1 1 3 4 1 1 I 9 3 2 2 1

1960 322 1 2 1 1 2 2 2 6 5 6 6 1 1 2 2 2 1 1

1961 348 1 1 1 1 1 2 2 1 1 2 1 I 2 1962 323 2 1 2 2 4 3 3 7 3 2 1 1 1 2

1963 339 2 1 1 1 1 1 4 5 5 1 2 1 1 1964 337 1 1 1 1 2 3 1 1 4 2 4 3 1 1 1 1 1 1965 327 1 1 2 1 2 5 3 5 3 7 4

1966 284 2 1 1 2 5 2 11 4 11 7 7 7 8 4 2 1 2

1967 356 2 1 2 1 1 1 1 1974 357 1 1 2 2 1 1 1975 357 1 2 2 2 1

CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE -TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERLT 0 0.00 18126 20088 100.0 12 1.6 97 1748 8.7 24 300 81 219 1.0 1 0.01 1 1962 9.8 13 2.5 71 1651 8.2 25 470 59 13B .6 2 0.02 0 1961 9.8 14 3.9 178 1580 7.9 26 720 30 79 .3 3 0.03 0 1961 9.8 15 6.1 99 1402 7.0 27 1100 22 49 .2 0.05 0 1961 9.8 16 9.4 108 1303 6.5 28 1700 14 27 .1 5 0.07 0 1961 9.8 17 14.0 184 1195 5.9 29 2600 10 13 6 0.10 15 1961 9.8 18 22.0 162 1011 5.0 30 4100 3 3 7 0.20 14 1946 9.7 19 34.0 183 849 4.2 31 6300 e 0.30 8 1932 9.6 20 53.0 135 666 3.3 32 9700 9 0.40 26 1924 9.6 21 82.0 132 531 2.6 33 15000 10 0.70 140 1898 9.4 22 130.0 103 399 2.0 34 11 1.10 10 1758 8.8 23 200.0 77 296 1.5

337 GILA RIVER BASIN 259

09486000 RILLIlO CREEK NEAR TUCSON, A2-- CONTINUED

LUVEST MEAN VALUFANn4ANKTNF.. FUR TMFFUtLOFTNG. 4UM4F4 OF GUNsrC"TTVFOAYS INYEAHENDING.SEPTFMIEP30 015CIIA4GF,IN G,uRIC FEFT IFASFCnNO MEIN

04 YEAR 1 i 7 14 30 60 120 1e3

1 1 0.00 1 0.00 1 0.01 34 14 1914 0.04 1 0.00 1 0.00 0.00 1 0.00 2.30 1916 0.00 2 O.00 2 0.On 2 O.On 2 0.00 2 0.01 2 0.00 2 2.8055 15.0054 3 3 1917 O.On 3 0.00 3 0.00 0.un 0.00 3 0.00 3 0.00 3 0.00 1 3.3042 1918 0.00 4 U.00 4 0.0n 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 2 13.0052 1919 0.00 5 U.UO 5 0.00 5 0.00 5 0.00 5 0.00 5 0.1154 0.26co 3.5043 1920 0.00 b 0.00 6 0.04 b 0.00 b 0.00 6 0.00 6 0.00 5 0.50S3 7.1047

1921 0.00 7 0.00 7 0.00 7 0.00 1 0.00 7 0.00 7 0.00 6 0.00 3 0.00 1 1922 0.00 8 0.00 8 0.00 8 0.00 8 0.0n 8 0.00 8 U.00 7 0.00 4 0.2425 1923 0.00 9 0.00 9 0.00 4 0.00 9 0.00 9 0.00 9 0.00 8 0.00 5 0.00 2 1924 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.00 9 0.00 6 0.4417 1925 0.00 11 0.00 ti 0.0011 0.0011 0.00 11 0.0011 0.0010 0.00 7 0.00 3

192b 0.0012 0.0012 0.00t2 0.0012 0.0012 0.0012 0.0011 0.01 40 0.5830 1927 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0012 0.1648 3.6044 1928 0.0014 0.0014 0.0014 0.0014 0.0014 0.00ta 0.0013 0.00 8 0.00 4 1929 0.001S 0.0015 0.0015 0.0015 0.0015 0.0015 0.0014 0.00 9 0.00 5 1930 0.00lb 0.00lb 0.00lb 0.0016 0.00ib 0.0016 0.00IS 0.0010 9.20aq

1931 0.0017 0.0017 0.0n 17 0.0017 O.Un17 0.00t7 0.00lb 0.0011 15.0053 1932 0.0018 0.0018 0.0018 0.00lb 0.011 ib 0.0018 0.0017 U.3051 10.0050 1933 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.00lb 0.0141 0.5129 1934 0.0020 0.0020 0.0020 0.0070 0.0020 0.0020 0.0419 0.0012 0.00 6 1935 0.0071 0.0021 0.0071 0.0021 0.0021 0.0071 0.OnPO 0.0013 4.0085

1936 0.0022 0.0022 0.0022 0.0022 O.Un22 0.0022 0.0021 0.0014 3.1041 1937 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 0.0012 0.0142 2.8040 1938 0.0024 0.0024 0.0024 0.0024 0.4024 0.0024 0.0023 0.0015 1.7037 1939 0.0025 0.0025 0.0075 0.0025 0.0025 0.un25 o.on14 0.00tb 0.00 7 1940 0.00Pb 0.0026 0.0026 0.00Pb 0.00lb 0.0026 0.0025 0.0243 0.7114

1941 0.0027 0.0027 0.0027 0.0027 0.0027 0.0027 0.0026 0.0444 7.3048 1942 0.0028 0.0028 0.00Ro 0.0028 0.0028 0.0028 0.0021 0.0017 0.6433 1943 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0018 0.011 18 1.7038 1944 0.0030 0.0030 0.0030 0.0010 0.0030 0.0030 0.0079 0.0019 0.00 8 1945 0.00tl 0.0031 0.0031 0.0031 0.0031 0.0031 0.0030 0.1849 1.0036

1946 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 0.0031 0.0010 0.00 9 1947 0.0033 0.0033 0.0033 O.Un33 0.0033 0.0033 0.0032 0.0071 0.0010 1948 0.0014 0.0034 0.0014 0.0034 0.0034 0.0034 0.0033 0.0022 0.00 11 1949 0.0035 0.0035 0.0035 0.0015 0.01135 0.0035 0.0034 0.0073 0.0312 1950 0.0036 0.0036 0.0036 0.0036 0.00lb 0.0036 0.0035 0.0024 0.0012

1951 0.0037 0.0037 0.0037 0.0037 0.0037 0.0037 0.0036 0.0025 4.0013 1952 0.0038 0.0038 0.0038 0.0038 0.0n18 0.0038 0.1153 0.4452 0.6632 1953 0.0039 0.0039 0.0079 0.0039 0.0039 0.0039 0.0017 0.0026 0.0413 1954 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0038 0.0077 17.0055 1955 0.00al 0.0041 0.00at 0.0041 0.00at 0.0041 0.0019 0.0078 0.0014

1956 0.0042 0.0042 0.0042 0.0042 0.0042 0.0042 0.0040 0.0079 0.0124 1957 0.0043 0.0043 0.0043 0.0043 0.0043 0.0043 0.0041 0.0545 0.5078 1958 0.0044 0.0044 0.0044 0.0044 0.0044 0.0044 0.4455 1.3054 11.0051 1959 0.0045 0.0045 0.0045 0.0045 0.0045 0.0045 u.0042 0.0030 0.0015 1960 0.0046 0.0046 0.0046 0.0046 0.0046 0.0046 0.0043 0.0031 0.00lb

1961 0.0047 0.0047 0.0047 0.0047 0.0047 0.0047 0.0044 0.0032 0.0017 1962 0.0048 0.0048 0.01148 0.00as 0.0048 0.00ab 0.0n45 0.1347 0.3826 1963 0.0049 0.0049 0.0044 0.0049 0.0049 0.0049 0.0046 0.0033 0.6531 1964 0.0050 0.0050 0.0050 0.0050 0.0050 0.0050 0.0047 0.00t4 0.0018 1965 0.0051 0.0051 0.01c1 0.0051 0.0051 0.0051 0.0152 0.1146 0.8935

1966 0.0052 0.0052 0.0052 0.0052 0.0052 0.0052 0.0048 0.0015 5.0046 1967 0.0053 0.0053 0.0053 0.0053 0.0053 0.0053 0.0049 0.0036 0.0019 1974 0.0054 0.0054 0.0054 0.0054 0.0054 0.0454 0.0050 0.0077 0.0070 1975 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0051 0.0038 0.0021

338 260 GILA RIVER BASIN

09486000 RILLITO CREEK NEAR TUCSON, AC-- COtiTINUED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1914 1250.020 424.027 183.027 92.031 88.022 47.023 45.016 34.016 22.020 1916 4900.0 2 3720.0 2 1830.0 2 1240.0 1 655.0 2 349.0 2 240.0 2 180.0 2 118.0 2 1917 1410.017 536.020 295.020 160.020 126.013 68.012 48.013 36.014 24.0l8 1918 2130.0I3 866.013 397.014 261.010 131.012 65.013 67.011 52.0 9 35.010 1919 2790.0 6 1880.0 5 1140.0 5 828.0 4 517.0 4 293.0 4 198.0 4 148.0 4 101.0 4 1920 2450.0 8 1120.010 563.0 9 349.0 8 196.0 9 135.0 7 110.0 7 90.0 7 66.0 7

1921 4920.0 1 4010.0 1 2250.0 1 1090.0 2 675.0 1 354.0 1 238.0 3 179.0 3 117.0 .3 1922 310.047 112.047 86.041 63.037 32.039 21.039 16.038 12.038 7.738 1923 500.035 257.035 136.032 96.029 70.025 56.020 37.022 28.022 18.023 1924 830.028 597.017 306.019 172.018 88.023 47.024 31.024 23.024 16.025 1925 437.041 272.034 135.033 78.032 67.026 39.026 26.026 20.026 13.027

1926 451.040 151.044 65.045 32.046 16.049 8.649 6.549 4.949 5.244 1927 487.038 190.040 90.040 50.043 41.036 23.037 17.037 13.035 8.435 1928 200.050 87.050 51.049 25.049 19.046 11.047 7.248 5.448 3.549 1929 4640.0 3 2790.0 3 1210.0 4 571.0 5 304.0 S 217.0 5 150.0 5 113.0 5 74.0 6 1930 1040.024 -. 539.019 237.022 123.023 100.020 57.018 41.017 30.019 29.016

1931 1180.023 771.015 399.013 200.017 105.019 54.021 36.023 27.023 32.013 1932 1420.016 554.018 257.021 159.021 115.015 61.016 47.014 46.012 30.014 1933 333.044 112.048 48.050 22.050 13.050 6.850 4.752 3.552 2.352 1934 320.045 107.049 58.047 29.047 16.047 13.046 10.044 7.645 5.045 1935 2360.0 9 1470.0 7 650.0 8 393.0 7 200.0 8 105.0 8 70.0 9 52.010 36.0 8

1936 490.037 190.041 84.042 72.034 40.037 20.040 14.040 10.040 7.340 1937 748.030 417.028 180.028 102.028 51.031 29.029 19.030 14.031 9.931 1938 783.029 314.031 135.034 63.038 32.038 16.042 11.041 8.142 6.941 1939 1890.015 774.014 346.0'16 167.019 89.021 57.019 39.020 29.020 19.022 1940 2270.0I2 1170.0 9 505.011 238.013 120.014 64.034 45.015 34.015 22.019

1941 3990.0 4 1880.0 6 841.0 6 440.0 6 243.0 6 151.0 6 143.0 6 113.0 6 75.0 5 1942 226.049 122.046 53.048 25.048 16.048 10.048 10.045 7.546 4.947 1943 274.048 139.045 60.046 45.044 29.042 17.041 11.042 8.441 6.442 1944 560.034 348.038 152.031 78.033 50.032 26.033 18.033 13.036 8.834 1945 1230.021 434.026 191.026 104.027 57.029 29.030 19.031 14.032 10.030

1946 497.036 194.038 83.043 67.035 42.035 24.035 17.034 12.037 8.237 1947 888.026 303.032 177.029 127.022 63.028 33.028 22.029 16.029 11.028 1948 88.054 34.054 23.053 14.052 11.051 6.352 5.350 4.050 2.650 1949 316.046 167.043 93.039 43.045 31.040 15.043 10.046 7.744 5.046 1950 2010.014 686.016 315.018 207.015 109.017 61.015 41.018 31.017 20.021

1951 667.031 349.029 163.030 122.024 67.027 35.027 23.028 17.028 11.029 1952 485.039 242.036 129.035 64.036 44.034 22.038 25.02T 19.027 17.024 1953 426.043 231.037 119.037 57.039 29.043 15.044 9.747 7.347 4.848 1954 2320.010 1050.011 462.012 216.014 108.018 54.022 37.021 28.021 33.022 1955 914.025 436.024 381.015 243.012 169.010 103.010 69.010 52.011 34.011

1956 110.053 37.053 16.055 8.654 4.555 2.355 1.555 1.155 0.855 1957 1310.018 464.0a3 199.025 93.030 50.033 25.034 17.035 13.033 8.336 1958 863.027 476.022 316.017 203.016 111.016 58.017 39.019 30.018 29.015 1959 1210.022 435.025 232.023 118.025 77.024 43.025 29.025 22.025 14.026 1960 2300.011 1200.0 8 653.0 7 325.0 9 206.0 7 105.0 9 73.0 8 55.0 8 36.0 9

1961 428.042 185.042 81.044 55.041 30.041 23.036 15.039 11.039 7.539 1962 601.032 284.033 122.036 57.040 28.044 27.031 18.032 15.030 9.632 1963 1290.019 510.021 222.024 104.026 52.030 26.032 17.036 13.034 8.933 1964 2650.0 7 917.012 525.010 259.011 134.011 77.011 53.012 40.013 26.017 1965 48.055 29.055 17.054 8.355 8.052 5.553 3.853 3.053 2.153

1966 3520.0 5 2670.0 4 1390.0 3 927.0 3 585.0 3 295.0 3 260.0 1 203.0 1 133.0 1 1967 578.033 193.039 104.038 52.042 26.045 15.045 11.043 8.043 5.243 1974 174.051 70.051 30.051 16.051 7.953 6.751 4.751 3.651 2.351 1975 147.092 49.052 23.052 12.053 6.254 3.454 2.354 1.754 1.154

339 GILA RIVER B.ISIN 261

09486000 RILLITO CREEK NEAR TUCSON, .2-- CONTINUED

DISCHARGE. IN CUBIC FEET PER SECOND STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

FEB MARCH APRIL MAY JUNE JULY AUG SEPT OCT NOV DEC JAN 183 22.0 20 BY ROWS (MEAN.VARIANCE.STANOARO DEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 18.0 2 0.72 2.47 48.6 25.1 27.7 17.2 0.76 1.26 0.59 31.9 37.9 16.1 2049 ?4.0 18 2.78 68.0 57950 8678 5378 1340 5.76 86.3 3.88 7661 2342 48.4 45.3 35.0 10 1.67 8.25 241 93.2 73.3 36.6 2.40 9.29 1.97 87.5 7.42 4.64 2.40 5.20 )1.0 4 2.87 3.88 6.55 5.22 4.29 2.57 3.53 3.83 7.38 3.34 2.TS 1.28 2.80 i6.0 7 2.31 3.34 4.95 3.71 2.65 2.12 3.18 18.0 7.68 0.34 1.17 23.1 12.0 13.2 8.19 0.36 0.60 0.28 15.2 :7.0 -3 7.7 38 8.0 23 IN CUBIC FEET PER SECOND .6.0 25 DISCHARGE. .3.0 27 STATISTICSON NORMAL ANNUAL MEANS(ALL DAYS) 5.2 44 MEAN VARIANCE STANDARDDEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 8.4 35 17.0 2.27 1.25 0.072 3.5 49 13.6 288 4.0 6 9.0 16

:2.0 13 0.0 14 2.3 92 5.0 45 6.0 8

7.3 40 9.9 31 5.9 41 9.0 22 2.0 19

1.0 S ..9 47 í.4 42 3.8 34 3.0 30

3.2 37 .0 28 .6 50 .0 46 .0

.0 er .0 24 .8 48 .0 22 .0 11

. 8 55 .3 36 .0 15 .0 26 . 0 9

.5 39 .6 32 .9 33 .0 17 .1 53

.0 1 .2 43 .3 51 .1 54

340 262 GILV RIVER BASIN

09486300 CANADA DEL ORO NEAR TUCSON,AZ

LOCATION. --tat 32 °22'27 ", long 111 °U0'31 ", in S1 Nkz sec.22, T.12 S., R.13 E., Pima County, Hydrologic Unit 1505U3û1, on right bank at upstream side of Overton Road, 4.7 mi (7.0 km) upstream from mouth,and10.5 mi (16.9 km) north of City Hall in Tucson.

DRAINAGE AREA.- -250 mil (648 km2).

RIa1HR1S.-- Records poor. Lago del Oro -- capacity 9,40U acre -ft (11.0 hm2)- -16 mi (26 km) upstream, has contained no storage since May 4, 1971, as gates were opened by court order; however, peak flows are regulated while passing through the lake.

4ATER ANNUAL PEAK DATE GAGE .+EIGHT OF 4A¡FK TOTAL VOLUME, YEAR U1SCH,LFS ANNUAL PEAK,FT YEAR ACNE-F1

1966 2290 12 -22 -65 4.53 19h7 91 1967 652 06-55 -67 3.76 1966 5460 1968 13900 12 -20-67 7.65 19h9 44 1969 454 07 -22 -69 3.51 197u 10u0 1970 1930 04-18 -70 4.37 1971 1830 1971 4200 08 -17 -71 5.20 197d 113 1972 728 08 -12 -72 4.17 1973 133 1973 3750 10 -19 -72 3.85 1974 857 197a 7700 07 -20.74 5.80 I97y 4? 1975 454 09 -04 -75 3.50

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 1 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 36 31 32 33 34 YEAR NUMBER OF DAYS IN CLASS 1967 361 1 1 2

1968 358 1 1 1 2 1 1 1 1969 363 1 1

1970 356 3 1 2 1 1 1

1971 348 2 1 1 1 1 3 1 2 I 1 1 1 1

1972 357 3 1 1 1 1 1 1

1973 356 3 1 1 1 1 1 1

1974 355 1 1 1 1 1 1 1 1 1 1 1975 361 1 1 1 1

SS VALUE TOTL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0.00 321 3287 100.0 12 1.0 2 51 1.6 24 57 2 12 .3 1 0.01 72 2.2 13 1.5 0 49 1.5 25 79 2 10 .3 2 0.02 71 2.2 14 2.0 4 49 1.5 26 110 2 8 .2 3 0.03 71 2.2 15 2.8 4 45 1.4 27 150 1 6 .1 4 0.05 71 2.2 16 4.0 4 41 1.2 28 220 2 5 .1 5 0.07 71 2.2 17 5.5 37 1.1 29 300 2 3

6 0.10 71 2.2 18 7.7 2 33 1.0 30 420 1 7 0.20 61 1.9 19 11.0 5 31 0.9 31 590 1 1 8 0.30 61 1.9 20 15.0 7 26 0.8 32 9 0.40 57 1.7 21 21.0 4 19 0.6 33 10 0.50 55 1.7 22 29.0 3 15 0.5 34 11 0.80 53 1.6 23 41.0 0 12 0.4

341 GILA RIVER BASIY 263 09486300 CANADA DEL ORO NEAR TUCSON, A2-- CO\TINUED

LUWEgT MFAN VAIUFANO4A4TNf. FUQ TnFFp(LnoT,rG MU°BFR UF CUNSFCIITTVF nAY5IN YEARENOTN.SEOTEMREQ10 nISCMARGF.IN CUpIf FEFT PERSFCnhn MEAN

YEAR i 3 7 t4 z0 AO Qu 120 183 {q67 1 0.00 0.00 1 0.00 1 0.00 1 0.On 1 0.00 1 0.00 1 0.00 1 0.00 1 t968 0.00 2 u.un 2 0.U0 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.0a10 jq6q 0.00 3 U.00 3 0.00 3 u.On 3 u.Un 3 O.UO 3 0.00 3 0.00 3 0.00 2 iq70 0.00 4 0.00 0 0.1.0 a u.On a 0.00 a 0.00 4 0.00 a 0.00 4 0.00 3

1971 0.00 5 0.00 5 0.06 5 0.00 S 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4 1472 0.00 b 0.00 b 0.00 b 0.00 b 0.00 b 0.00 b U.00 6 0.00 6 0.00 5 1973 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6 1974 0.00 d 0.00 8 0.00 8 0.00 b 0.00 6 0.00 8 0.00 8 0.00 d 0.00 7 1975 0.00 9 0.00 9 0.00 9 0.00 9 U.00 9 0.00 9 0.00 9 0.00 9 0.00 8

HIGHEST MEAN VALUE AND NANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND PEAN -

YEAR 1 3 7 15 30 60 90 120 183 1967 19.0 8 6.3 8 2.7 8 1.3 8 0.9 7 0.6 7 0.5 7 0.4 7 0i3 7 1968 2400.0 1 873.0 1 390.0 1 182.0 1 91.0 1 46.0 1 30.0 1 23.0 1 15.0 1 1969 22.0 7 1.3 7 3.1 7 1.5 7 0.7 8 0.4 8 0.2 8 0.2 8 0.1 8 1970 348.0 3 116.0 4 58.0 4 27.0 4 17.0 3 8.4 3 5.6 3 4.2 3 2.8 3

1971 290.0 4 161.0 2 95.0 2 58.0 2 31.0 2 15.0 2 10.0 2 7.7 2 5.0 2 1972 24.0 5 8.0 5 4.6 5 2.6 5 2.1 5 1.1 5 0.7 5 0.6 S 0.4 5 1973 24.0 6 8.0 6 4:6 6 2.6 6 2.1 6 1.1 6 0.7 6 0.6 6 0.4 6 1974 375.0 2 136.0 3 59.0 3 28.0 3 14.0 4 7.2 4.8 4 3.6 4 2.4 4 1975 11.0 9 3.7 9 1.6 9 0.7 9 0.4 9 0.4 9 0.2 9 0.2 9 0.1 9

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT ß'0V DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY SOWS (MEAN.VARIANCE.STANOARO DEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 0.00 0.00 12.9 0.00 0.02 0.00 0.00 0.00 0.00 1.48 3.72 1.88 0.00 0.00 861 0.00 0.01 0.00 0.00 0.00 0.00 17.4 84.7 17.5 0.00 0.00 29.3 0.00 0.08 0.00 0.00 0.00 0.00 4.17 9.20 4.18 2.36 3.16 3.16 3.14 3.10 2.97 2.28 3.16 3.16 .- 2.82 2.48 2.22 0.00 0.00 64.4 0.00 0.12 0.00 0.00 0.00 0.00 7.39 18.6 9.43

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 1.69 5.64 2.38 1.94 1.42 -0.387

. * * ** Skewness and coefficient of variation could not be computed owing to a zero -value month.

342 GILA RIVER BASIN 264 09486500 SANTA CRUZ RIVER AT CORTARO, AZ

LOCATION.- -Lat 32 °21'04 ", long 111 °05'38 ", in NW's'W3t sec.35, T.12 S., R.12 E., Pima County, Hydrologic Unit 15050302, on downstream side of right bridge pier U.5 mi (0.8 km) southwest of Cortaro, 2.6 mi (4.2 km) downstream from Canada del Oro, and 3.7 mi (6.0km) downstream from Rillito Creek.

DRAINAGE AREA.- -3,503 mil (9,073 km2), of which 395 mie (1,023 km2) is in Mexico.

RATER ANNUAL PEAK DATE GAGE NEIGET OF CORE ANNUAL .MAX DATE nATEK TOTAL VuLUME, YEAR DISCH,CFS ANNUAL PEAK,FT GAGE IT.FT YEAH ACNE -FT

1940 17000 08 -14 -40 1940 20100 1941 7800 12 -31 -40 1941 24500 1942 1550 08 -09 -42 1942 5770 1943 5500 09 -24 -43 1943 17F00 1944 56S0 08 -16 -44 1944 14300 1945 14000 08 -10 -45 1945 24100 1946 4440 08 -04 -46 1946 16400 1947 7500 08 -15 -47 1951 11500 1950 12900 07 -30 -10 9.1 1952 15700 1951 6820 07 -25 -51 6.50 1953 1u900 1952 6100 08 -10 -52 6.2 1954 53100 1953 10800 07 -14 -53 8.10 1955 6740n 1954 9150 07 -24 -54 7.53 1956 1580 1955 16600 08 -03 -55 9.90 1957 4810 1956 3150 07 -29 -56 5.00 1958 70500 1957 4400 09 -01 -57 5.69 1959 13700 1958 7890 08 -12 -58 7.03 190.0 22P00 1959 8000 08 -20 -59 6.70 NM 6.73 08 -17 -59 1961 17100 1960 6420 08 -11 -60 6.12 1962 12700 1961 14700 08 -23 -61 9.00 1963 20540 1962 11200 09 -26 -62 9.22 1964 18740 1963 7240 08 -26 -63 7.10 1965 2270 1964 15900 09 -10 -64 9.29 1966 13500 1965 2710 07 -16 -65 3.83 1967 d3V0 1966 16800 12 -22 -65 8.60 1968 53140 1967 5740 07 -17 -67 9,04 NM 9.13 07 -11 -67 1969 5140 1968 15800 12 -21 -67 12.17 1970 26500 1969 8400 08 -06 -69 11.64 1971 45600 1970 11200 07 -20 -70 12.65 1972 73400 1971 9100 08 -20 -71 12.70 1973 45800 1972 7050 08 -12 -72 11.35 .1974 43100 1973 9000 10 -19 -72 12.10 1975 43700 1974 11700 07 -08 -74 13.02 1975 5200 07 -12 -75 10.35

NM Not maxima gage height for water year.

343 GILA RIVER BASIN 265

09486500 SANTA CRUZ RIVER AT CORTARO, AZ--CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER30 DISCHARGE.IN CUBIC FEET PER SECOND MEAN

20 21 22 23 24 25 262728293031323334 0 1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17 19 CLASS DAYS IN CLASS YEAR 7 1 2 1 1940 317 4 7 1 3 2 4 5 5 1 1 3 2

1941 304 5 1 1 1 7 1 2 4 2 5 3 7 2 2 6 3 4 1 1 2 2 3 1 5 1 1 1942 314 3 1 1 1 13 3 2 2 2 1 2 4 6 4 5 3 2 3 1 2 1 1943 307 4 3 1 3 3 2 3 2 2 2 2 1 3 1 2 1 1 1944 334 2 2 1 1 2 1 4 1 2 3 1 1 2 4 3 4 3 3 2 1 1 1 2 1 1945 315 9 6 1 2 1 3 1 2 4 1946 305 3 6 1 3 1 2 4 5 3 5 4 3 7 2 3 1 2 1 3 1 2 1 2 1 1951 228 7 7 3 10 12 15 18 15 7 9 3 3 1 4 4 6 2 1 9 4 2 5 4 3 1 1952 22913 12 5 13 4 13 19 8 3 3 2 1 3 1 1 2 6 2 2 1 1 1953 324 3 2 1 2 1 2 1 2 3 2 3 5 2 2 4 6 5 4 2 3 6 4 1 5 2 1954 297 1 1 2 2 1 2 5 3 1 2 1 1 4 1 3 1 3 4 1 5 3 2 1955 305 1 1 2 1 2 2 2 1- 3 1 1 1 5 1 2 2 5

2 2 1956 347 1 1 1 1 1 2 1 2 2 1 1 1 1957 334 _ 3 1 1 1 1 3 3 2 2 4 3 1 2 1 1 1 1 4 4 4 5 3 8 3 9 3 3 7 2 5 6 2 2 1 1 1958 274 4 1 2 2 2 1 4 1 2 4 3 3 5 1 3 1 5 1 2 1 1959 318 1 1 2 1 1 2 3 2 2 3 1 2 4 2 1 3 3 2 2 1 2 2 1 1 1960 322 1 2 1 3 1 2 1 2 4

5 4 1 1 2 1 1 1 1961 330 1 1 2 2 1 1 2 3 1 2 2 1 1 1 2 1 1 1962 340 1 1 1 1 1 2 1 1 3 1 1 1 4 4 2 3 4 5 4 1 3 1 1 1 1963 316 1 3 3 3 2 4 3 1 4 4 3 6 2 3 1 5 2 1 1964 316 1 1 1 2 3 3 5 1 1 1 2 2 1 1 1965 334 1 1 1 2 1 1 3 3 1 1 1 2 5 2

4 6 4 4 4 1 2 1 1 1 1966 300 2 2 1 2 2 1 2 1 3 2 2 3 1 5 2 6 3 1 1 1 1 1967 330 2 1 1 3 2 1 1 1 2 1 1 2 2 2 2 3 1 2 1 1 1 1 1 1968 315 1 1 3 2 3 2 1 2 3 7 4 5 4 2 4 1 1 1969 333 1 1 1 1 1 1 3 2 2 3 3 3 2 2 5 2 1 2 1970 12 3 2 3 18 13 3 10 23 26 40 36 35 33 32 36 18 4 2 3 2 1

5 3 3 1 1971 1 1 1 12 2 11 35 44 63 109 46 15 3 1 3 2 2 1 1 1972 11 1 1 5 2 7 15 19 37 107 116 14 12 6 6 1 2 25 4 4 3 2 3 1 3 1 3 1 1 1973 55 1 1 5 8 5 17 23 21 21 43 50 29 35 48 5 4 3 1 3 1 1 1 1 1974 1 2 3 57 232 2 7 3 2 1975 10 175 124 36 2 5 1

PCRCT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM 0 0.00 8170 11688 100.0 12 6.2 111 2769 23.7 24 380 56 2I3 1.8 25 540 44 157 1.3 I 0.10 43 3518 30.1 13 8.7 131 2658 22.7 2 0.20 38 3475 29.7 14 12.0 205 2527 21.6 26 760 40 113 .9 3 0.30 25 3437 29.4 15 17.0 298 2322 19.9 27 1100 23 73 .6 4 0.40 59 3412 29.2 16 24.0 377 2024 17.3 28 1500 24 50 .4 5 0.60 32 3353 28.7 17 35.0 646 1647 14.1 29 2100 12 26 .2 6 0.80 98 3321 28.4 18 49.0 338 1001 8.6 30 3000 S 14 .I 7 1.10 61 3223 27.6 19 69.0 135 663 5.7 31 4300 4 9 8 1.60 95 3162 27.1 20 97.0 107 528 4.5 32 6000 4 5 9 2.20 65 3067 26.2 21 140.0 53 421 3.6 33 8500 1 1 10 3.10 93 3002 25.7 22 190.0 61 368 3.1 34 11 4.40 140 2909 24.9 23 270.0 74 287 2.5

344 266 GIIA RIVER BASIN

09486S00SANTA CRUZ RIVER AT CORTARO, AZ-- COMTIMIED

1VwE3T HFAN VALUE ANO 44NKTNf. rug TwF FU1_LMA1N, NUm8FM UF [UNSfC1iTTVF MAYS 1N YEAw MING 1EPTFMRE4 30 '5C944GF,Iv CUR1C FEET err/ 5E060 N

oQ YEAR 1 S 7 14 3U 60 120 143

1940 0.00 1 0.00 0.00 1 0.00 1 0.00 1 0.00 1 0.06 1 0.38 24 2.00 19

1901 0.00 2 U.00 2 0.00 2 0.011 2 0.U6 2 0.00 2 0.04 ?4 0.15 ?2 14.00 Pb 1942 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.20 26 0.2? ?3 1.30 17

1943 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 U.u4 4 0.00 2 u.on 1 1.10 to 1944 0.00 5 U.00 S 0.00 5 0.00 5 0.00 5 0.00 5 0.00 3 0.00 2 0.00 1 1945 0.00 o 0.00 6 0.00 b 0.04 b 0.00 b 0.00 6 0.00 9 0.04 21 0.03 6

1946 0.00 7 0.00 1 0.00 7 0.00 7 0.04 7 0.00 7 0.00 5 0.00 3 0.00 2 1951 0.00 4 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 6 0.00 4 0.03 7 1952 0.00 4 0.00 9 0.00 9 0.00 9 0.00 9 0.02 ?6 0.10 25 1.40 25 5.40 21 1953 0.00 tU 0.00 10 0.00 10 0.00 10 0.00 10 0.00 9 0.00 7 0.00 5 0.03 8 1954 u.00 11 0.00 I1 0.00 11 0.00 II 0.00 11 0.00 10 0.00 8 0.00 6 17.00 27 1955 0.00 12 0.00 12 0.00 12 0.00 12 0.00 12 0.00 11 0.00 9 0.00 7 0.03 9

1956 0.00 13 0.00 13 0.00 13 0.00 13 0.00 13 0.00 12 0.00 10 0.00 8 0.30 13 1957 0.00 14 u.00 14 0.00 14 ú.00 14 0.00 14 0.00 13 0.00 11 0.00 9 0.25 12 1958 0.00 15 u.00 15 0.00 15 0.00 15 0.00 15 0.00 14 0.04 ?2 1.90 ?6 11.00 24 1959 0.00 16 0.00 16 0.00 t6 0.00 16 O.Un 16 0.00 15 0.00 12 0.00 10 0.00 3 1960 0.00 17 0.00 t7 0.04 17 0.00 17 0.00 17 0.00 16 0.00 13 0.00 11 0.03 10

1961 0.00 10 0.00 18 0.10 18 0.00 18 0.00 18 0.00 17 0.00 14 0.00 12 0.67 15 1962 0.00 19 0.00 19 0.00 19 0.04 19 0.00 19 0.00 18 0.00 15 0.00 13 0.48 14 1963 0.00 ?0 0.00 20 0.00 7o 0.00 20 0.00 20 0.00 19 0.04 23 0.03 20 5.10 20 1964 0.00 ?1 0.00 21 0.00 21 0.00 21 0.00 21 0.00 20 0.00 16 0.00 14 0.07 11 1965 0.00 ?2 0.00 22 0.00 22 0.00 22 0.00 22 0.00 21 0.00 17 0.00 15 1.40 18

1966 0.00 23 0.00 23 0.00 23 0.00 23 0.00 23 0.00 22 0.00 18 0.00 16 13.00 25 1967 0.00 14 0.00 74 0.00 24 0.00 24 0.00 24 0.00 23 0.04 19 0.00 17 0.02 5 1968 0.00 25 0.00 25 0.00 25 0.00 25 0.00 25 0.00 24 0.00 20 0.00 le 7.70 23 1969 0.00 Pb 0.00 26 0.00 26 0.00 26 0.00 26 0.04 25 0.00 21 0.00 19 0.00 4 1970 0.00 27 0.00 27 0.36 18 2.40 28 3.50 28 5.40 27 6.30 27 6.30 27 6.90 22

1971 0.00 ?8 0.00 28 5.60 10 9.10 30 12.00 10 14.00 30 20.00 30 26.00 30 28.00 30 1972 0.00 29 0.00 29 1.09 29 7.10 29 11.00 29 13.00 29 16.00 29 18.00 29 22.00 29 1973 0.00 10 0.00 30 0.00 27 0.00 27 0.94 27 7.60 28 8.00 28 11.00 28 21.00 28 1974 10.00 31 13.00 31 10.00 11 24.00 11 29.00 11 15.00 11 17.00 11 18.00 31 19.00 11 1975 30.00 13 32.00 33 13.00 13 35.00 13 17.00 13 39.00 33 39.00 33 41.00 33 46.00 33

345 GIL4 RIVER &ASIN 267

09386500 SANTA CRU: RIVER AT CORTARO, A_--G11TI\L'E'J

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND NEAR

43 YEAR 1 3 7 15 30 60 90 120 163 .0019 1940 7490.0 3 2650.0 4 1150.0 6 542.0 8 296.o 9 157.0 9 108.0 10 82.010 54.012

.0026 1941 4000.0 8 1730.011 758.012 382.013 202.015 122.018 95.015 77.013 50.015 .30 17 1942 447.030 210.030 107.030 58.030 32.030 22.030 17.029 12.030 8.330 .1016 1943 1150.024 867.020 381.022 244.022 175.019 132.015 96.014 72.016 47.017 .00 1 1944 2800.012 955.017 455.019 371.014 200.017 120.020 80.020 60.020 39.022 .03 6 1945 5210.0 6 1910.0 7 965.0 8 677.0 6 385.0 6 196.0 7 131.0 7 98.0 8 64.010

.00 2 1946 1820.020 731.023 352.023 240.023 173.021 123.017 90.017 57.017 44.018 .03 7 1951 1860.016 888.018 420.021 307.015 174.020 95.023 64.023 48.024 32.024 .4021 1952 761.028 569.025 304.025 148.026 90.027 55.027 37.027 28.027 23.026 .03 B 1953 1430.023 1400.012 867.0 9 428.011 239.012 121.019 80.021 60.021 40.020 .0027 1954 2370.013 1740.010 1350.0 5 804.0 618.0 4 351.0 4 254.0 4 198.0 136.0 4 .03 q 1955 3990.0 9 2050.0 5 1700.0 3 1160.0 3 950.0 1 563.0 1 376.0 1 282.0 1 185.0 1

.3013 1956 326.031 119.031 54.031 26.032 24.031 14.031 9.231 6.931 4.531 .2512 1957 819.027 279.029 120.029 78.029 47.029 26.029 17.030 13.029 8.629 .0024 1958 1660.022 662.024 311.024 294.017 202.016 125.016 88.019 66.019 53.013 .00 3 1959 1840.019 849.021 532.014 288.018 182.018 114.021 76.022 57.022 37.023 .0310 1960 4300.0 7 2010.0 6 1060.0 7 498.0 9 285.010 143.011 100.013 75.015 49.016

.6715 1961 5380.0 5 1890.0 8 855.010 431.010 223.013 134.014 89.018 67.018 44.019 .4814 1962 2990.011 1110.014 477.018 223.024 115.026 59.026 40.026 30.026 20.027 .1020 1963 1800.021 883.019 437.020 295.016 263.011 154.010 103.012 77.014 51.014 .0711 1964 6900.0 4 2690.0 3 1370.0 4 705.0 5 394.0 5 312.0 5 214.0 5 161.0 5 105.0 5 .4018 1965 201.032 111.032 54.032 33.031 18.032 11.032 7.432 5.532 4.232

.0025 1966 8460.0 2 5730.0 2 2710.0 2 1660.0 1 878.0 2 457.0 2 353.0 2 264.0 2 173.0 2 02 5 1967 2090.015 744,022 -507.016 245.021 130.024 67.025 45.025 34.025 23.025 7023 1968 8760.0 1 5880.0 1 2890.0 1 1420.0 2 711.0 3 381.0 3 277.0 3 208.0 3 139.0 3 00 4 1969 1110.025 439.027 232.028 131.027 73.028 47.028 32.028 24.028 16.028 9022 1970 1850.017 1050.015 505.017 261.020 159.022 137.013 106.011 82.011 56.011

0030 1971 2240.014 1240.013 709.013 569.0 7 359.0 7 218.0 6 160.0 6 129.0 6 98.0 7 0029 1972 1060.026 511.026 233.027 128.028 115.025 74.024 60.024 51.023 39.021 0028 1973 3330.010 1780.0 9 761.011 421.012 323.0 8 173.0 8 121.0 8 93.0 9 103.0 6 0011 1974 1840.0 18 1000.016 518.015 282.019 222.014 141.012 116.0 9 98.0 7 80.0 8 0033 1975 649.029 298.028 245.026 198.025 131.023 102.022 92.016 80.012 66.0 9

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AU8 SEPT BY ROWS(MEAN.VARIANCE.STANDARO DEVIATION.SKEWNESS.COEFF. OF VARIATION.P£RCENTABE OF AVERAGE VALUE) 16.1 7.22 62.6 18.7 21.7 19.1 5.25 5.00 7.18 74.1 136 45.6 1796 182 35820 2017 2124 1391 170 147 195 7292 26490 4684 42.4 13.5 189 44.9 46.1 37.3 13.1 12.1 14.0 85.4 163 68.4 4.81 2.67 3.70 4.42 2.89 2.91 2.78 2.60 1.78 2.09 3.09 3.32 2.63 1.87 3.03 2.40 2.12 1.96 2.49 2.42 1.94 1.15 1.19 1.50 3.84 1.72 14.9 4.47 5.18 4.55 1.25 1.19 1.71 17.7 32.6 10.9

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 35.2 745 27.3 1.20 0.78 -0.139

346 APPENDIX D

347 fr

Ranking of Total Dissolved Solids Loading by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Total Dissolved Solids (TDS) (lbs /ac /yr) Watershed

More than 100 134 N4 123 N9 122 N2 121 Nil 120 E7, N7 114 N8, N12 111 A4 110 E4, N17 108 E5, N3, N10 107 E3 105 N6

100 or Less

100 E1 99 E10, Hil 97 Kl, N13, N15 95 E8, 02 94 C2, E7 93 M3, 01 92 Cl, C4, Ml, N14 91 B1, B2, B4, B5, B6, 05, 06 90 C3, C5, C6, J3 89 B3, M2 88 C7, F2, G1, I2 87 C8, E1 + 2, H2, H4, 14, 16,15,14+ 5 86 Fl, H6, N16 85 C9, I1, J4, N5, 03 84 E2 83 H10, I3 82 Al, C10, E9, J1 81 H7, L2, L5 80 D1, K2, L4 79 H9, L3 78 H3, H8 77 H5 74 H1 69 L1

348 e Ranking of Suspended Sediment Loading by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Suspended Sediment (ibs /ac /yr) Watershed

More than 900 1013 E-3 997 N-11 992 E-1 990 E-5 989 E-11 982 0-2 973 E-10, H-11, N-10 957 N-17 955 N-9 947 B-1 946 B-4 943 0-1 940 0-5 939 B-3 937 8-5 934 8-6, E-1 + 2 929 E-4 923 0-6 918 E-2, 0-3 915 N-16 911 A-1 909 G-1, N-13 908 E-9

750 to 900 900 J-3 898 F-2 891 A-4, N-12 886 D-1 881 N-14 878 N-4 873 B-2 863 C-2 862 N-8 861 N-2 860 C-3 859 C-9 855 H-10 835 E-7 831 N-7

349 Tab4e--3---1_LIGnrat i.n ued )

Suspended Sediment (lbs /ac /yr) Watershed

750 to 900 ( Con' t)

818 C-5 814 C-10, E-8 813 C-1, K-1 812 C-8 796 C-4 794 H-8 793 N-15 789 N-3 788 H-5 780 C-6 776 H-3 768 J-1 755 F-1 753 M-3

600 to 750

740 H-7 729 I-1 720 N-6 705 H-6 703 M-1 696 C-7 676 K-2 665 N-1 663 M-2 641 I-6 637 H-9 619 L-5, N-5 610 L-4 607 H-1, H-2 603 L-2

Less than 600 588 L-3 512 L-1 488 H-4 442 J-5 376 I-3 363 I-5 337 (I-4 + I-5) 317 I-2 266 I=4

350 Tàb e-3 - Ranking of Organic Loading (as Indicated by CO2) by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Chemical Oxygen Demand (COD) (lbs /ac /yr) Watershed

More than 300

317 E3, H11 314 El, E5 311 El0 308 N9 307 Nil 306 02 305 El + 2 304 81, B3, 84 303 E2 302 Al 301 E9

250 to 300

300 B5, B6, H10, N3 299 N12, 03 298 E4 296 E11, N13 295 D1, H5, N8 294 C3, M3 293 H3 292 C4, F2, N4, N14 291 H8 290 C9, E7, N7, N16 289 M1 288 E8 287 82, C2, C10, M2, N15 283 N5, N17 282 L2, 15 280 Ji, N2 279 L3 278 05 276 C5, L4 272 N6 268 C8 267 K1, K2 265 H7 261 N1 260 Li 259 C7 256 Cl, 01 253 C6

351 Tâtrl e1-8-( Cö ñ tinued-___

Chemical Oxygen Demand (COD) (lbs /ac /yr) Watershed

Less than 250

248 H1 244 Fl 236 I1 232 H9 231 H6 221 A4 216 N10 209 I6 208 H2 161 H4 137 J4 119 I3 110 I5 101 I4 + I5 90 12 76 14 a e- Ranking of Nutrient Loading (Nitrate) by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Nitrate (NO3).

(1bs /ac /yr).. Watershed

More than 2.00

3.41 I2 2.80 I4 2.74 C7 2.64 N6 2.63 C7 2.51 Cl 2.48 N1 2.34 H4 2.23 N5 2.22 Li 2.12 H6 2.11 A4 2.10 H1, I4 + I5, L3 2.06 L2 2.04 N4 2.02 I6

1.G1 to 2.00

2.00 L4 1.99 M2 1.98 L5, M1 1.89 N7 1.87 I1 1.85 C8 1.84 I5 1.81 M3 1.79 N2 1.78 -N3 1.73 E4 1.72 E8 1.64 H2 1.63 - N15 1.62 C5 1.61 C4 1.60 N8 1.58 K2 1.57 H7 1.56 F1 1.54 E7, E11 1.53 H9

353 1.9jCo Hued)

Nitrate (NO3)

(1bs /ac /yr) Watershed

1.01 to 2.00 (Can't)

1.47 C2 1.43 N12 1.39 J4 1.38 82 1.32 Kl 1.28 N9 1.22 J1 1.17 C3, N11 1.15 H3, N10 1.08 N17 1.07 H5 1.01 H8 1.00 N13

Less. than 1.00

.93 H11 .92 C10 .89 E5, H10 .88 N14 .84 C9 .81 E10 .78 J3 .73 F2 .72 G1 .71 E3 .70 01 .68 B5 .66 I3 .60 B6 .58 E1 .57 B4 .55 06 .53 N16 .52 81, B3, 02 .51 05 .47 03 .46 E1 + 2 .43 El .42 Al .41 E9

354 T-aM e -lO Ranking of Nutrient Loading (Phosphate) by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Phosphate (PO4)

(ls /ac /yr) Watershed

.16 I2, I3, N10

.15 Fl, I1, I4, I5, I4 + 5, J4, 01, 05

.14 Al, B1, B3, D1, E2 + 1, E9, F2, G1, H4, H6, I6, N16, 02, 03, 06

.13 B2, B4, B5, B6, Cl, C2, C3, El, H1, H7, H9, H10,

H11, N13, N14 .

.12 C5, C6, C8, C9, E3, E5, E10, H1, H3, H5, H8, J3, N11, N17

.11 C4, C10, E4, E7, E8, E11, Ji, K1, N8, N9, N12, N15

.10 A4, C7, K2, M3, N2, N4, N7

.09 L1, L2, L3, L4, L5, Ml, M2, N1, N3, N5, N6

355 - Tab-i-é 3:i1í Ranking of Bacterial Loading (as Indicated by Fecal Coliform) by Watershed within and Contiguous to the Urban Window, Pima Country, Arizona

Fecal Coliform (FC) (Counts /100 ml _ 1012) Watershed

More than .300

.415 L1 .381 L3 .376 L2 .368 N5 .364 L4 .362 L5 .344 M2 .318 M1 .306 N1 .301 K2

.200 to .300

.296 N6 .283 M3 .282 H1, N3 .264 C7 .258 N7 .240 E7 .238 N15

.237 ' J1 .236 N4 .231 E8, H3 .230 A4 .228 C4 .219 N8 .217 H5 .216 N2 .213 N12 .211 Kl .210 H8, N17 .202 H9

.100 to .200 .200 N10 .194 C10, H7 .189 N9 .183 C5 .182 H2 .179 E4, H4

356 -atil e 3.1 -11 Rued)

Fecal Coliform (FC) (Counts /100 ml = 1012) Watershed

.100 to .200 (Con't)

.172 H10 .164 C3 .162 I4, I6 .160 C6, 01

. 159 C2 .158 C8 .156 E11, I2 . i56 C9 .155 E5 .154 N14 .151 H11 .149 B2, I4 + 5, J3 .147 E10, H6

.145 I5 .139 N13 .138 N11 .135 Cl

. 129 B6 .127 .126 Il .125 B5, E3 .121 F1 .119 B4 .118 N16, 05 .117 G1 .114 B3, I3 .113 Bl .112 F2 .110 D1, 02 .108 El, 06 .104 03 .103 El + 2 .102 Al, E2 .100 E9

.357 APPENDIX E

358 { r : t;t.t..I :. 417-g

GENERAL CONCEPTS AND PROCEDURES Each watershed area or water source in the area of study was evaluated in its present environmental condition, and the general physiographic and hydrologic condition of each source area was noted. A fairly detailed study of the land use types contained within the specific watershed area was also made through analyses of topographic maps and aerial photographs. These land use types reflect fairly uniform hydrologic groups which have similar infiltration capacities and runoff hydrographs. The numerical values for the water quantity section were determined, where possible, from actual field data collected over many years by the U.S. Geological Survey and the Water Resources Research Center. Water quantity data were estimated by transposing known data to similar areas when actual field data were not available. With the actual and estimated runoff volumes and peak flows, statistical frequency analyses were made for specific watershed areas and hydrologic groups. The authors have conser- vatively estimated the storm runoff volumes, and have slightly overestimated peak flows for design purposes for each frequency level. At locations which have flowing water, such as, San Xavier Rock and Material's Company and the Congress Street Storm Sewer, a water sample was taken for detailed water quality analyses. At the majority of the water sources, however, mean water quality values were estimated through the transposition of water quality data from similar urban and desert watersheds, which have been sampled for the past eight years by personnel from the Water Resources Research Center. Lastly, possible uses of the water in the development of the Santa Cruz Riverpark are discussed for each Water Source. The locations of all Water Sources are shown in the map at the beginning of the report, and the detailed discussion of Water Source Locations No.. I through 25 presented below in approximate downstream order. WATER SOURCES WATER SOURCE NO. I- 1iughes Wash I. I)ccription of the Area a. Overview The drainage area of Hughes Wash is located in alluvial valley fill in the central part of the "Tucson Basin. General slope of the land is to the west- northwest at about AO Feet per ruile, and ridges on the watershed at-e nearly parallel to stream channels. Average elevation is 2600 feet above mean sea level. Ihc vegetation can be described as desert growth with the creosote bush probably ranking first in population. Near sites of surface runoff, mesquite density ranges From moderate to heavy and commonly is accorn- panic(' bs good grass coverage. In addition, cholla, ocotillo and barrel cactus ate nurnetol cactus are tutnerous.

359 b.Drainage area = 9.0 square miles to Interstate I -19. c.Watershed composition by land use types. Desert area = 8.7 square miles or 96.7 percent. -Composed of grassland, desert brush and a large cacti population. Paved area = square miles or 2.2 percent. -Composed of paved surface area, and large root amts associated with commercial or industrial facilities. Denuded, or bare area = 0.1 square miles or 1.1 percent. -Composed of low -density vegetative cover, and bare soil. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, I year -30 Winter, I year- 10 Summer,2 year -100 Winter, 2 year- 30 Summer,IO year -300 Winter,l0 year- 60 Summer, 25 year -390 Winter,25 year -190 Summer, 50 year -550 Winter,50 year -250 Summer, 100 year -730 1Vinter, 100 year -320 b.Peak flows for given frequencies in cubic feet per second. 2 year- 600 50 year -1500 10 year-I000 100 year -1900 25 year -1300

3. Mean Water Qualities from Watershed Area* Summer Winter Units Storms Storms a. Total dissolved solids = mg /1 210 200 b. Suspended solids = mg/ I 6,000 2,700 c.Chemical oxygen demand = mg /1 400 190 cf. Temperature = °C 24 12 e. pH = 8.7 7.9 f.Bacterial density = (1) Total coliforms = # /100 ml 25x 104 80x 10' (2) Fecal coliforms = #/100 ml 30 x 10' 40 x 10= (3) Fecal streptococci = # /100 ml lOx 104 12 x 10' *Assuming transposition of waterquality datafrom Atterbury Water- shed (desert).

4. Possible Water Uses :A large meander on the Santa Cruz River, 1500 feet north of LOS Reales Road, is perhaps the best location for a storage basin within the river channel in the Linear Pak. The Santa Cruz River bed can be straightened, then protected by rip -rap material, permitting the meander to function as a recharge pit and storage basin. The site could store flood %eater flows from the Santa Cruz River as well as desert and urban storm runoff. The straightening of the stream channel will also prevent further erosional cutting on the west sicle of the meander. San Xavier Rock & Materials Company would be willing to build the detention basin and the proposed channel for rights to the gravel. Specific details regarding recharge from a storage basin are discussed in an earlier section of this report. WATER ER SOURCE NO. 2 -San Xavier Rock `Materials Company Nash 1. Description of the area a. Overview The watershed encompassing this wash is located in alluvial valley fill in the central part of the Tucson Basin. General slope of the land is to the west - northwest at about 40 feet per mile. Average elevation is 2600 feet above mean sea level and vegetation can be described as desert growth. Throughout most of the watershed, the larger washes have well defined

360 channels. The smaller washes consist of a large number of small rivulet extending over a wide region. Upstream erosion, redeposition of sedi ment, and heavy growth of vegetation have been accompanied by partis choking of the principal washes. Plo&dwaters spread out in certain section of the watershed. Storm runoff front a small portion of the "Tucson Airpot drains into the main wash producing increased surface flows. Hughes Aircraft Company plant located within the watershed area is pre sently discharging industrial processingNvatersinto a waste ditch. Thi ditch conveys the effluent approximately one -half mile to a pond fror which the water is dissipated by evaporation and seepage. DeCook ( 197C made intermittent measurements of the combined industrial effluent (lo, between 1966 -1969 and found an average discharge of approximately 30 acre -feet per year. Chemical analysis of the industrial effluent is suir marized in Table 4, and the water quality data indicates that this salvage able water cannot be used in its present state. However, according to Ec ward C. Spaulding, Plant Supervisor, (Oral communication, 1976) a ne' reverse osmosis treatment plant will be completed by March, 1977. How ever, properly treated industrial effluent of this kind may possibly be use for recreational and aesthetic purposes.

l.d,lr (,nn, al Ch.u.uter and Comru ta Trace Metals in Ilulusu,al MM.,' at Ilughn :\ìrrrafl Company PL.". 11k{ì0 197411.

Chcmi, al C.»utimenls .Conte n:¢ìon (myi IY Calcium 75 Magnesium 10 Sodium ,40 Chloride 2í Sulfate 133 Birarbonate 173 B.,n n, 0.20 Fluoride I.2 Potassium 2ß pi l 8.0 Nitrate as \1 h 5.1, Phosphate as l'o. 34 Silica ISioa Total t)issulsed Solids 535 Trace Steal

Iton 0.11i Manganese O.0 Chromium. 1.85 .,Lrl 0.25 Copper 0.082 Zinc 0.112 Lead 1.10 Cadmium 0.01 C,,I.,It 0.13 Sonnuhun O.72

{,wage of fanusasamples take,, at various fluor rates during normal olmr. lon, July -Se neuther. 19116. - 1o,.,i. h, mum.,. (1t sample.,,ulvrr,l I, Sia,r1Iral,hI).pann,rmshowed hexavalrm chromium 0.178 mg /1.

b.Drainage area = 1.7 square miles to Interestate I -19. c.Watershed composition by land use types. Desert area = 0.7 square miles or 41.2 percent. -Composed of grassland, desert brush and cacti. Urban ara = 0.4 square miles or 23.5 percent -Composed of single and multi-family units on land parce smaller than one acre including rooftops, paved and not paved rights -of -way, anti vegetative cover. Suburban area = 0.1 square miles or 5.9 percent. -Composed of single family units on land parcels greater tha one acre, including rooftops, paved and non -paved rights -o way, and vegetative cover. Paved area = 0.2 square utiles or 11.3 percent. -Composed of paved surface area, and large roof areas assi ciate(i with commercial or industrial facilities. Denuded, or bare area = 0.3 square miles or 17.6 percent. -Composed of low- density vegetative cover and bare soil.

361 2.Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year - 20 Winter, 1 year- 10 Summer, 2 year- 40 Winter, 2 year- 30 Summer,10 year -100 Winter,10 year- 80 Summer,25 year -130 Winter,25 year -100 Summer,50 year -180 Winter,50 year -140 Summer, 100 year -230 Winter, 100 year -170 b. Peak flows for given frequenciesin cubic feet per second. 2 year- 400 50 year -1200 10 year- S00 I00 year -1400 25 year -1000 3.Mean Water Qualities from WatershedAreas* Summer Winter Units Storms Storms a.Total dissolved solids = mg /1 220 160 b. Suspended solids = mg/1 1,500 900 c.Chemical oxygen demand = mg/1 300 130 d. Temperature = °C 24 12 e.ph = - 8.7 7.8 f.Bacterial density = (1) Total coliforms = #1 100 ml 80 x 104 20 x 103 (2) Fecal coliforms = #/ I00 ml 30 x 104 40 x 102 (3) Fecal streptococci = #/100 ml 50 x 103 10 x 102 *Assuming transposition of water quality data from Atterbury Watershed (desert). Supplemental water samples were taken at various locations on the property owned by San Xavier Rock & Materials Company for a detailed chemical analysis. Sediment -laden tv'ater discharging at approximately one cubic foot per second from the gravel -washing operation into the dry channel of the Santa Cruz River was also sampled. As the gravel- washing effluent proceeded downstream, an additional seater samplewastaken. The water quality analysis for each water source sampled is summarized in "Fable 5.

Table 5. water Quality Anahscs From yariutó raxatlolb at.the Sail Xavier Kock Sr Materials (: i:, sa,npling Downstream

II.5 nuir IhlUn Chemical East wr,u 1Lmping I/ivhat grlrom .uran,fron, C,nstimrnts Units Pond Pnnd N'rIi (:rasci l'laut t'ale,n,.i K..ul pH - 8.2 7.5 8.5 8.0 8.5 kaa-trical Cunductrsilv m,nh,ycm 0.79 0.78 1.00 0.7`t 0.80 Temixin0re C: 15.1 19.3 14.4 21.1 24.2

Tut Mullis JO.' 1 7 (1.4 1250 Suspended Solids mgii 13 28 3 Iti,82(I Volatile Stop. S,duls mgtl 8 10 3 MO Cr D "WI 49 :12 4 2:19 3I (:a" "g:l 72 81 85 8; 75 ttIg mgt i 13 13 10 15 13 11.1311 lai d0.>s /C;,( :Us) "gil 231 25ti :11li 278 2411 ..\a' mgll 1 H 112 2142 112 114 (:1h.h,%I 0 II 5 II It nctt..ign 228 274 1'2'! - 21", Chigt1 33 21 ,p1 -94 '" K' nigtl 8 4 1:1 10 II 8:11..-N ,ng71 1111 I4 0.1 11 11 3 Kield.dd-N mg!! 0.4 0 0.8 0 n 5

Nth-A+N( s-S 514/ I 2.2 +1 2-8 2.7 '1o,.dCoMlm s '118ni

4.Possible Water Uses The effluent from the gavel -washing operations presently flows for several miles along the Santa Cruz River; and with minor bank landscaping, this natural stretch of the river can be even more scenic than it is at present.. A potential also exists for using thetwosmall settling lakes for landscaping or other water -related activities. WATER SOURCE NO. 3-Mission Manor Area 1.Description of the Area a. Overview The watershed of the \fission Manor area is located near the southern city boundary of Tucson, Arizona. General slope of the land is to the west - northwest at about 40 feet per mile with an average elevation of 2550 feet above mean sea level. The watershed has a (yell- defined channel passing through and collecting storm runoff from the soil -vegetation surfaces, paved and non -paved streets and building roofs. Storm runoff from portions of the Tucson International Airport, a surrounding urbanized area, and a large desert area is drained by the channel. The urban area includes single and multiple family dwellings, several types of rooting materials, paved and unpaved areas, and lawns and gardens subject to fertilization and chemical pest control. The small developed portion of the watershed has a considerable influence on the runoff volumes, flow rates, and peak arrival times. In addition, pattern of street arrangements will affect the drainage performance. This watershed has a composite type of street pattern which produces a complex storm runoff hydrograph. b. Drainage area = 1.9 square miles to Interstate 1 -19. c.Watershed composition by land use types. Desert area = 1.0 square miles or 52.6 percent. -Composed of grassland, desert brush and cacti. Urban area = 0.6 square miles or 31.6 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square mile or 5.3 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights-of-way, and vegetative cover. Paved area = 0.1 square mile or 5.3 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 0.1 square mile or 5.2 percent. -Composed of low -density vegetative cover and bare soil. 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, 1 year- 20 .Winter, 1 year- 10 Summer, 2 year- 50 Winter, 2 year- 40 Summer,10 year-110 Winter,10 year- 90 Summer, 25 year -150 Winter,25 year-110 Summer, 50 year -210 Winter, 50 year -160 Sumner, 100 year -260 Winter. 100 year -180 b. Peak flows for given frequenciesin cubic feet per second. 2 year -450 50 year-1150 10 year -750 100 year -1400 25 year -950 3.\1catt Water Qualities from WatershedArea* Summer \\'inter Units Storms Storms a.Total dissolved solids = mg /1 220 160 h.Suspended solids = urg!I 1,700 500 c.Chemical oxygen demand = ntgi I 3:6) 150 d.Temperature = °C 26 14 C.ph = - 7.-1 7.1 f.Bacterial density _ (1) Total conforms = #1100 tnl 90 x 10' 50 x 10" (2) Fecal conforms = #1100 ruf 40 x I(N 20 x 10" (3) Fecal streptococci = #1100 ml 35 x 103 90 xI U= *Assuming transposition of \vate! quality data from Arcadia Watershed (Urban).

363 4. Possible Water lises The desert and urban storm runoff from the small drainages that make up this water source can be diverted into broad- based, grassed terraces to create a greenbelt area along a development area with potential between I -19 Freeway and the Santa Cruz River. \i'ATER SOURCE NO. 4-Airport Wash I.Description of the .Area a. Overview The watershed contributing to Airport Wash is located in alluvial valley fill in the central part of the Tucson Basin. General slope of the land is to the west- northwest at about 45 feet per mile and ridges on the watershed are parallel to the stream channels. Average elevation is 2700 feet above mean sea level. The vegetation can be described as desert growth with the creosote bush probably ranking first in population. Near sites of surface runoff the mesquite density ranges from moderate to heavy and, commonly, is accompanied by good grass coverage. In addition, cholla, ocotillo, and barrel cactus are numerous. Throughout most of the watershed, drainage diverts into two main branches of Airport Wash. Only in a few locations do these washes have tyell defined channels. In most parts, the washes consist of a large number of small rivulets extending over a wide region. Upstream erosion, redeposition of sediment, and heavy growth of vegetation have been accompanied by partial choking of the principal drainageway above the University of .Arizona Environmental Modification Facility. Floodwaters spread out and cross Country Club Road in a 600- foot -wide Overflow section, then are concentrated in the flood channel below. The channel extends on through the Tucson International Airport, through an area being developed for industry, and finally through several residential subdivisions before empty - ing into the Santa Cruz River. The Tucson Airport .Authority has improved and maintained the channel through the airport area; it has been estimated that the existing channel can carry peak flows of 10 -year recurrence through this area. The remain - der of the main channel has been progressively improved and maintained by the City of Tucson: however, the increasing encroachment of urbanization along both sides of the wash increases the probable damage that would result from any overflow. b. Drainage area = 23.5 square miles to Interstate I -19. c.Watershed composition by land use types. Desert area = 21.5 square miles or 91.5 percent. -Composed of grassland, desert brush and a large cacti population. Urban :area = 0.9 square miles or 3.8 percent. -Composed of single and multi-family units on land parcels smaller than one acre including rooftops, payed anal non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square mile or 0.4 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of- way, and vegetative cover. Paved area = 0.3 square miles or 1.3 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 0.7 square miles or 3.0 percent. -Composed of low -density vegetative cover and bane soil. 2. Quantities of Water a.Water volumes for given frequencies in acre- feet." Summer, I year - 70 Winter. I year - 20 Sutnnter. 2 scar- 200 \'inter. 2 year- 120 Summer,10 year- 630 Winter,10 year- 530 Summer,25 year - 760 Winter,25 year- 570 Summer,50 year-1150 Winter,50 year- 830 Summer, 100 year -I1G0 Winter,I00ycar-1030

364 *The extension of Country Club Road to the south into the Interna- tional Airport causes ponding of storm runoff above the road. Since we believe this condition to be only temporary, the volumes presented are corrected to what we believe they would be with unimpeded flow. b. Peak flows for given frequencies in cubic feet per second. 2 year- 650 50 year -2400 10 year -1500 100 year -2800 25 year -2000 3.Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a. Total dissolved solids = mg /1 180 .150 b. Suspended solids = mg /1 3,500 2,000 c.Chemical oxygen demand = mg /1 200 150 d. Temperature = °C 25 13 e. pH = - 8.5 - 7.7 f.Bacterial density = ( 1 )Total coli forms = #1100 ml 40 x 104 80 x 102 (2) Fecal coliforms = #/100 ml 16 x 104 30 x 102 (3) Fecal streptococci = #/100 ml 20 x 104 14 x 10" *Assuming transposition of water quality data from Atterbury Watershed (desert). 4. Possible Water Uses Desert and urban runoff possibly could be diverted from Airport Wash for storage in a detention basin between the I -19 Freeway and the Santa Cruz River. To facilitate diversion, a collapsible rubber dam could he located in the narrow portion of the wash downstream of the Freeway, provided backwater effects would not be a problem. Collected water could be used in the vicinity of the detention basin for maintenance of vegetation on the banks of the Santa Cruz River. Surplus water in the basin could be used for artificial groundwater recharge. WATER SOURCE NO. 5 -Rodeo Wash 1. Description of the Area a. Overview The watershed of Rodeo Wash is located in the southern portion of the city of Tucson, Arizona. General slope of the land is to the west -northwest at about 40 feet per mile with an average elevation of 2600 feet above mean sea level. The watershed has a well- defined channel passing through and collecting runoff from the soil -vegetation surfaces, paved and non -paved streets and rooftops. Storm runoff water from the county fairgrounds, a surrounding urbanized area, and a large desert region is drained by the channel. The urban area includes single and multiple family dwellings, several types of roofing materials, paved and unpaved areas and lawns. The desert vegetation is composed of creosote bush, native grasses and cacti. The small developed portion of the watershed has a considerable influence on the runoff volumes, flow rates, and peak arrival times In addition. the pattern of the street arrangement will affect the drainage performance. In the upper reaches of the watershed, heavy growth of vegetation and debris have caused a partial choking of the principal channel. b. -Drainage area = 6.1 square miles to Interstate 1 -19. c.Watershed composition by land use types. Desert area = 4.5 square miles or 73.8 percent. -Composed of grassland, desert brush ;mcl cacti. Urban area = 1.0 square miles or 16.4 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.2 square miles or 3.3 percent. -Composed of single fancily units on land parcels greater than one acre, including rooftops. paved and non -paved rights -of- way, and vegetative cover.

365 Paved area = 0. I square mile or 1.6 percent. -Composed of paved surface area, and large roof areas associated frith commercial or industrial facilities. Denuded, or bare area = 0.2 square mile or 1.6 percent. -Composed of low- density vegetative cover and bare soil. Parks or grassed areas = 0.2 square miles or 3.3 percent. -Composed of high density vegetative cover with essentially no exposed soil areas. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 40 Winter, 1 year- 20 Summer,2 year -110 Winter, 2 year- 60 Summer,I O year -260 Winter,10 year -170 Summer,25 year -360 Winter,25 year -230 Summer,50 year -500 Winter,50 year -330 Summer, 100 year -660 1Vintcr, 100 year -400 b.Peak flows for given frequencies in cubic feet per second. 2 year - 600 50 year-1800 10 year -1 200 100 year -2200 25 year -1500 3.Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg /1 200 190 b. Suspended solids = mg/ 1 800 500 c.Chemical oxygen demand = mg /I 300 150 d. Temperature = °C 28 16 e. pH = 7.3 7.0 f.Bacterial density (1) Total coliforms= #/100 ml 15 104 12x 104 (2) Fecal coliforms = # /100m1 10x 104 40x 103 (3) Fecal streptococci = # /100 ml 60 x 103 35 x 103 *Assuming transposition of water quality data from High School Watershed (urban). 4.Possible Water Uses Desert and urban storm runoff could be diverted into broad based, grassed terraces, or a possible holding pond on a potential golf course site which could be developed along the banks of the Santa Cruz River, north of Ajo Road. The golf course site can provide a valuable demonstration of water conservation, control and treatment systems which can be used, such as, flood runoff storage, settling, grass filtration, grass -soil filtration, and chlorination. Possible uses can also be demonstrated, such as, landscape irrigation. water- related landscaping, fishing and boating, and swimming. Specific details regarding the above methods of control, treatment, and use are discussed at the beginning of this report. Serious consideration should be given at this point to the use of treated sewage effluent that has been chlorinated for maintenance of the golf course and park areas when storm runoff is not available. The effluent should be managed so that nutrient removal by grasses is an integral part of the plan. Direct recharge of secondary sewage effluent in the Santa Cruz River channel should not be permitted unless the treated effluent meets the required EPA 1983 Waste Treatment Standards (best practical technology) for this practice. Further, any wastewater recharge operation should include a comprehensive ground -water monitoring program. WATER SOURCE NO. 6- julian Wash including Tucson Diversion Canal 1.Description of the Area a. Overview The watershed associated with this wash is located in the south- central portion of the city. General slope of the land is to the west -northwest at about 40 feet per mile sith an average elevation of 2600 feet above mean

366 influence on the runoff volumes, flow rates and peak arrival times. In addition, pattern of street arrangements and the Ajo Detention Basin will affect the drainage performance. The complexity of the watershed drainage pattern probably produces complex storm -runoff hydrographs. The following hydraulic information regarding the Julian Wash and the Tucson Diversion Channel System is from the U.S. Corps of Engineers, 1963. Drainage Design Area Discharges Stream or Channel Location (sq. miles) (cfs) Tucson Diversion Detention -Basin 17.8 15,300 Channel Inlet "Tucson Diversion Detention -Basin 17.8 9,300 Channel Outlet Julian Wash Tucson Diversion 28.0 12,000 Channel Tucson Diversion Downstream from 45.8 17,000 Channel Julian Wash Confluence For Standard Project Storm Required basin capacity = 1,800, acre feet Approximate basin area = 110 acres Maximum depth = 17 feet The Irvington Road Power Plant of the Tucsonas and Electric Company is presently discharging both cooling tower effluent and sanitary wastes into the City sewer system. Engineers at the plant have indicated that the cooling tower effluent could be easily directed to another discharge point, so that this water would be available for other uses such as landscape irrigation, water- related activities, etc. The cooling effluent is presently derived from four cooling tower units. The rate of outflow ranges approximately from 300 to 600 gallons per minute, and the yearly cooling effluent flow in 1974 was 809 .acre feet. However, due to new generation facilities and more recycling of water, Dr. Charles McCauley, Senior Assistant Engineer of the Environmental Ser- vices Section, indicates that cooling water effluent flow will be maintained at approximately 350 acre feet per year (Oral Communication, 1976). The chemical concentration of the cooling water will also be such higher. The cooling water is supplied by pumping from wells, of ,which six are about 1,000 feet deep and the fifthis 2,500 feet deep. The results of chemical analyses of waters from all these wells, as sampled in 1962, are illustrated in Table 6. The water from the wells is pumped to a surge tank for temporary storage, whence it supplies makeup water to the towers. This composite water becomes concentrated about five times during its use in the cooling process. In addition, sulfuric acid is added to neutralize the alkalinity of the incoming well water, chlorine is added for algae control, and hexa- metaphosphates are added to prevent scale formation and in- hibit corrosion. The chemical character of the effluent, sampled in Sep- tember 1967 from the main discharge line from the tower complex and April, 1974 is also illustrated in Table 6. b. Drainage area = 46.0 square miles to Interstate I -19. c. Watershed composition by land use types. Desert area = 32.5 square miles or 70.6 percent. -Composed of grassland, desert brush and cacti. Urban area = 2.5 square miles or 5/1 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non -paved rights -of -way, and vegetative cover. Suburban area = U.S square miles or 1.7 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and vegetative cover.

367 Paved area = 4.0 square miles or 8.7 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 6.0 square miles or 13.0 percent. -Composed of low -density vegetative cover and bare soil. Park or grassed areas = 0.2 square miles or 0.6 percent. -Composed of high density vegetative cover with essentially no exposed soil areas. 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, 1 year- 250 Winter, 1 year- 100 Summer, 2 year 750 Winter, 2 year - 400 Summer,10 year -1900 Winter,10 year-1100 Summer,25 year -2550 Winter,25 year -1500 Summer,50 year -3550 Winter,50 year -2200 Summer, 100 year -4650 Winter, 100 year -2700 b. Peak flows for given frequencies in cubic feet per second. 2 year -1500 50 year -4800 10 year -3000 100 year -5800 25 year -3300 3. Mean Water Qualities from Watershed Area* Summer Winter Units Storms Storms a. Total dissolved solids = mg /1 210 220 b. Suspended solids = mg /l 900 500 c.Chemical oxygen demand = mg/ 1 280 120 d. Temperature = °C 28 16 e. pH = 7.3 7.0 f.Bacterial density = (1) Total coliforms = # /100 ml 15 x 104 12 x 104 (2) Fecal coliforms = #/1001111 10 x 10° 40 x 103 (3) Fecal streptococci = #/100 ml 60 x 103 35 x 103 *Assuming transposition of waterquality data from High School Watershed (urban).

Table 6. Chenikul Character of Winer from Wells and C,wsbng Power Effluent at Irvington koud stream Electric Generating Plant

(.,o eu,,atom (mg II Input Water Er fluent Effluent (Composite From (fCa on pi one Frira, (Composite Fron Four In.hndin, Firm Coaling Poor Cooling Wells) rowers) To rsl 1967 Sept.. 19(( April. 1976 Chen/col Canso/went Calciu m 36 161 2(141 )lagncsium 6 71 Sodium 79 °i0 Chloride 22 116 911 Sulfate 145 1,167 1,37 Bicarbonate 21ì 20 33 l en,peram,e. C 3ti 33 [biro. 0.1s Q63 Fluoride 1.6 7.1 pll 8.2 7.s 7- .6 Nilraue as Nth 1.0 6.0 Ph, sph: to aas PO, 0.55 3.147 riaasstom 2.5 12.1 Silica (Silk) 1s 59 IMI Tout dissolved n ;PIS 338 l.,rlh1ev , (AMI

1n,r.1fn,.f 0 0.13 0L'0 0.IM1'2 I1019 chr, nI .m u lkl-1 U(All sielel 0 0 (.;upScr 001° 0 0',4 I.in IIIMIM Eefi1

ul i.1IM.j II

Cadmium 11 IIlM11 Cbu 0 St n.uu ol 1 76; 5uM - l'culprrauur ranged l,un, 3t/m55C,asapanullumEtonufwelidepth.

Des 1 l'l,'UI C NS.(ndo,ScuhrA,stantEngoeer.ftheEnsrnnmenultienwes5enam.Tucw,nGaskElervnG, d h+IC.,.unonua..u,. ;9711)

369 4. Possible Water Uses Desert and urban storm water from Julian Wash can be stored in a detention basin between-the I -19 Freeway and the Santa Cruz River. The water could provide a water hazard for a golf course or a lake for a potential recreational area. All excess water can be discharged into the Santa Cruz River for recharge purposes. Serious consideration should be given at this point to the use of treated sewage effluent that has been chlorinated for maintenance of the golf course and park areas when storm runoff is not available. The effluent should be managed so that nutrient removal by grasses is an integral part of the plan. Direct recharge of secondary sewage effluent in the Santa Cruz River channel should not be permitted unless the treated effluent meets the required EPA 1983 Waste Treatment Standards (best practical technology) for this practice. Further, any wastewater recharge operation should include a comprehensive ground -water monitoring program. \ VATER SOURCE NO. 7-Robles Pass Wash 1.Description of the Area a. Overview The watershed of Robles Pass Wash is located near the western boundary of the city limits and within the eastern foothills of Tucson Mountain Range. General slope of the land is to the east at about 200 feet per mile with an average elevation of 2650 above mean sea level. The watershed has a defined channel with small rivulets extending over a small region. Sur- face drainage is rapid from the steep hills, and moderate from the gently sloping foothills and valley. Slopes range front 0 to 3 percent in the alluvial valley bottom, to greater than 45 percent on the rock slopes of the foothills. In the lower reaches of the watershed, the channel has a heavy growth of riparian vegetation producing an areal spreading of floodwaters. A wide variety of trees, shrubs, grasses and cacti cover the watershed. The foothills and ridges of the watershed are the result of Paleocene volcanic activity. The hills are flanked by alluvial and colluvial fans, terrace deposits and flood -plain alluvium. The common sediments are.caliche, metallic dendrites and alluvium. Rock outcrops and shallow soils with a clayey horizon ( Argids) over bedrock composes the major portion of soil association in the watershed. The Argids soils produce large runoff events when the soil -moisture regime has been satisfied and the soil infiltration capacity has been exceeded by rainfall. The gravelly alluvial terraces and coarse alluvial deposits in the streambeds have a high permeability and low runoff potential. The composite soil association and geology in the watershed produces a complex drainage environment, whereby low seasonal and annual runoff volumes are associated with long periods of non - runoff. Peak flows are relatively small with return periods of less than five years. However, as the rainfall intensity increases over the infiltration capacity, the peak flows become exceedingly large. itis obvious that any structural design should account for the skewed frequency distribution of these peak flows.

b.Drainage area = 1_9 square tuiles to Mission Road. c.Watershed composition by land use types. Desert area = 1.7 square miles or 89.5 percent. -Composed of grassland, desert brush and tt large cacti population. Urban area = 0.1 square mile or 5.3 percent. -Composed of single and multi -fancily units on land parcels smaller than one acre including rooftops, payed and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square utiles or 5.2 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of way, and vegetative cover.

369 2.Quantities of Water a.Water volumes for given frequencies in acre -feet. Sumter,1 year- 10 Winter, 1 year- 5 Summer, 2 year- 20 Winter, 2 year -10 Summer,10 year- 40 Winter,10 year -20 Summer,25 year- 70 Winter,25 year -40 Summer,50 year -100 Winter,50 year -70 Summer, l00 year -120 Winter, 100 year -S0 b.Peak flows for given frequencies in cubic feet per second. 2 year- 200 50 year -1900 10 year -1200 100 year -2300 25 year-1700 3. Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg/1 180 150 b. Suspended solids = mg /1 3500 2000 c.Chemical oxygen demand = mg /1 200 125 d. Temperature = °C 24 12 e. pH = - 8.0 7.5 f.Bacterial density' = (1) Total coliforms = #1100 ml 50 x 104 70 x 102 (2) Fecal coliforms = #1100 ml 20 x 104 40 x 10= (3) Fecal streptococci = # /100 1111 12 x 104 12 x 10" *Assuming transposition of tyater quality data from Atterbury Watershed (desert). 4.Possible Water Uses Desert and urban storm runoff should be allowed to flow and recharge along the west branch of the Santa Cruz River, This storm water could also be diverted into a natural storage basin, approximately one river mile downstream from Ajo Road, between the two branches of the Santa Cruz River. The potential storage basin is presently being used as sanitary landfill and. therefore, the site must have debris removed before any storm runoff water can be stored. If the basin cannot be completely cleared, then care must be taken, as by lining the basin with plastic, to prevent leaching of harmful landfill constituents into the ground water. Specific details regarding recharge in the river channel are discussed earlier in this report. WATER SOURCE NO. 8 -Big Wash 1.Description of the Area a. Overview The watershed for this source is located near the western boundary of the cite limits and within the foothills and mountain range of the 'Tucson Mountains. General slope of the land is to the east -southeast at about 220 feet per mile with an average elevation of 2750 feet above mean sea level. The watershed has a defined channel with small rivulets extending over a small region. Surface drainage is rapid from the steep, relatively impermeable hills, and moderate runoff occurs from the gently sloping foothills and valley. Slopes range from 0 to 3 percent in the alluvial valley bottom, to greater than 45 percent our the rock slopes of the foothills. In the lower reaches of the watershed, the channel has a heavy growth of riparian vegetation producing .weal spreading of tloodwaters.A wide variety of trees, shrubs, grasses, and cacti cover the watershed. Rock outcrops and shallow soils with a clayey horizon or caliche (.4rgids) oycr bedrock composes the major portion of soil association in the watershed. The composite soil association and geology in the watershed produces a complex drainage environment, whereby lots seasonal and annual runoff volumes are associated with long non -runoff periods. How- ever. as the potential rainfall intensity increases over the infiltration capacity. the potential peak flows become exceedingly large. It is obvious that any structural design should account for the skewed frequency distribution of beak flows.

370 b. Drainage area = square miles to Mission Road. c.Watershed composition by land use types. Desert area = 2.6 square miles or 92.9 percent. -Composed of grassland, desert brush and a large cacti population. Urban area = 0.1 square [Hiles or 3.6 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square mile or 3.5 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and'vegetative cover. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 10 Winter, I year- 5 Summer, 2 year- 20 Winter, 2 year- 10 Sumner,IO year- 60 Winter,IO year- 50 Summer,25 year -100 Winter,25 year - 60 Summer,50 rear -130 Winter,50 year- 90 Summer, 100 year-170 Winter, 100 year-110 b. Peak flows for given frequenciesin cubic feet per second. 2year- 300 50 year -2800 10 year -1800 100 year -3200 25 year -2500 3.dean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg/1 190 160 b. Suspended solids = mg /1 3000 2000 c.Chemical oxygen demand = tug/ I I50 100 d. Temperature = °C 24 12 e. pH = - 8.0 7.4 f.Bacterial density = (1) Total coliforms = #/ I 00 ml 50 x 10' 50 x102 (2) Fecal coliforms = #1100 ml 30 x 102 (3) Fecal streptococci = #1100 ml I O x 104 I O x 102 *Assuming transposition of water quality data from Atterbury Waterbury (desert). 4. Possible Water Uses Besicles using the storm runoff produces( from Water Source No. 8 as previously recommended for runoff from Water Source No 7, consideration should be given to possibly using this water source for maintaining vegetation l%itl1in the Santa Cruz Riverpark and for diverting part of this storm runoff to Kennedy Lake.

WATER SOURCE NO. 9

1.Description of the Area a. Overview The watershed of this water source is located near the western city boundary of "Tucson, Arizona and \vithin the foothills and mountain range of the Tucson Mountains. General slope of the land is to the cast at about 90 feet per mile with an average elevation of 2550 feet above [Wean sea level. The watershed has a defined channel with small rivulets extending over a small region. Surface drainage is rapid from the steep, relatively impermeable hills and moderate runoff occurs from the gently sloping foothills and valley. Slopes range from U to 3 percent in the alluvial valley bottom, to greater than 45 percent on the rock slopes of the foothills. In the lower reaches of the watershed, the channel has a moderate growth of riparian vegetation producing areal spreading of floodwaters. A wide variety of trees, shrubs, grasses and cacti cover the watershed. Rock outcrop and shallow soils with a clayey horizon or caliche (Argil) over bedrocks .composes the major portion of soil association in the watershed. The composite soil association and geology in the watershed produces a complex drainage environment, whereby low seasonal and annual runoff volujes are associated with long non- runoff periods. However, as the potential rainfall intensity increases over the infiltration capacity, the potential peak flows become exceedingly large. It is obvious that any structural design should account for the skewed frequency distribution of peak flows.

b. Drainage area = 1.1 square mile to Mission Road. c.Watershed composition by land use types. Desert area = 0.8 square miles or 72.7 percent. -Composed of grassland, desert brush and large cacti population. Urban area = 0.1 square miles or 9.1 percent -Composed of single and multi- family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.2 square miles or 18.2 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and vegetative cover. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, i year- 19 Winter, 1 year- 5 Summer, 2 year- 20 Winter, 2 year -15 Summer,10 year- 30 Winter,10 year -25 Summer, 25 year- 60 Winter, 25 year -40 Summer, 50 year- 80 Winter, 50 year -60 Summer, 100 year -100 Winter, 100 year -70 b. Peak flows for given frequenciesin cubic feet per second. 2 year- 100 50 year -1 200 10 year- 700 100 year -1400 25 year -1000 3.Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg /1 190. 160 b. Suspended solids = mg /1 3000 2000 c.Chemical oxygen demand = mg /1 150 0100 d. Temperature = °C 24 12 e. pH = - 7.9 7.4 f. Bacterial density = (1) Total conforms = #1100 ml 50 x 10' 50 x 102 (2) Fecal Coliforms = # 1100 ml 10 x 10i5 30 x 102 (3)Fecal streptococci = #/100 ml 10 x 10" 10 x 102 *Assuming transposition of water quality data from Atterbury Watershed (desert). 4.Possible Water Uses Storm runoff volumes that can be expected on an annual basis from this source are relatively small and, hence, flood control is probably not feasi- hlc. \v:\ TER SOURCE NO. 10- Extended Cholla \1'ash 1. Description of the Area a. Overview The watershed of this water source is located near the western boundary of the city limits and within the foothills and mountain range of the Tucson Mountains. General slope of the lanci is to the east at about 100 feet per mile with an average elevation of 2600 feet above mean sea level. The b. Drainage area = 1.2 square miles to Mission Road. c.Watershed composition by land use types. Desert area = 0.9 square miles or 75.0 percent. -Composed of grassland, desert brush and a large cacti population. Urban area = 0.1 square miles or 8.3 percent. -Composed of single and multi -family units on land parcels smaller than one acre including roof tops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square miles or 8.3 percent. -Composed of single family un;is on lanci parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and vegetative cover. Paved area = 0.1 square miles or 8.4 percent. -Composed of paved surface area, and large roof areas associ ated with commercial or industrial facilities. 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, 1 year- 10 Winter, 1 year- 5 Summer, 2 year - 20 Winter, 2 year -15 Summer,10 year - 40 Winter,10 year -30 Summer. 25 year- 60 %Vinter,25 year -50 Summer, 50 year- 90 Winter, 50 year -70 Summer, 100 year-110 Winter, 100 year -85 b. Peak flows for given frequencies in cubic feet per second. 3. Mean Water Qualities from Watershed Area* Summer Winter Units Storms Storms a.Total dissolved solids = mg/ 1 190 160 b. Suspended solids = mg /1 3000 2000 c.Chemical oxygen demand = mg /1 150 100 d. Temperature = °C 25 13 e. ph= - 7.9 7.5 f.Bacterial density = (1) Total coliforms = #/100 ml 50 x 104 50 x 102 (2) Fecal coliforms = #1100 ml 10 x 104 30 x 102 (3) Fecal streptococci = #/100 ml l0 x 104 10 x 102 *Assuming transposition of water quality data from Atterbury Watershed (desert). 4. Possible Water Uses Although storm runoff volumes from this source me relatively small, consideration should be given to using this water source for irrigating a pros- pective park in the area and possible for maintaining a water -related recreation facility in the park. WATER SOURCE NO. 11-01d Julian Wash a.Overview The watershed of Old Julian Wash is located in the central business district of Tucson, Arizona. General slope of the land is to the north-northwest at about 70 feet per mile with an average elevation of 2400 feet above the mean sea level. The watershed has a «ell defined channel passing through and collecting runoff from the soil -vegetation surfaces, paved and non - paved streets and building roofs. Storm runoff water from in urbanized area is also drained by the channel. The urban area includes single and multiple family dwellings. several types of rooting materials, paved and unpaved areas, and lawns. The developed area of the watershed has a primary influence on runoff volumes, flow depths auul peak arrival tintes. Pattern of the streets arrangements will affect the drainage performance. A major channel problem in certain reaches is the large quantity of debris clinging the channel, thereby reducing channel capacity and increasing flood hazard in the surrounding urban areas. Overall, the watershed has a composite type of

373 urban water flow pattern which produces a complex storm runoff hydrograph. b. Drainage area = 1.0 square miles to the Santa Cruz River. c.Watershed composition by land use types. Desert area = 0.2 square miles or 20.0 percent. -Composed of grassland, and desert brush. Urban area = 0.6 square miles or 6.0 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of way, and vegetative cover. Paved area = 0.2 square miles or 20.0 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 20 Winter, 1 year- 10 Summer, 2 year- 40 Winter, 2 year- 30 Summer,10 year- 80 Winter,10 year- 70 Summer, 25 year -110 Winter, 25 year -100 Summer, 50 year -I60 Winter, 50 year -150 Summer, 100 year -200 Winter, 100 year -180 b. Peak flows for given frequencies in cubic feet per second. 2 year- 400 50 year -1200 10 yeasr- 800 100 year -1400 25 year -1000 Summer Winter Units Storms Storms a.Total dissolved solids = mg /1 250 220 b.Suspended solids = mg/ 1 2000 1000 c.Chemical oxygen demand = mg /1 280 130 d.Temperature = °C 27 15 e.ph = 7.7 7.0 f.Bacterial density = (1) Total coliforms = # /100 ml 15 x10; 10x104 (2)Fecal coliforms = # /100 ml 10 x10' 70 x 103 (3) Fecal streptococci = # /100 ml 50 x103 30 x 103 *Assuming transposition ofwater qualitydatafrom Railroad Watershed (urban). 4. Possible Water Uses Although volumes of storm runoff from this source are relatively small, consideration should be given for possibly using the water for irrigating a landscaped area between the 1 -10 Freeway and the Santa Cruz River. WATER SOURCE NO. I2- Congress Street Storm Sewer 1.Description of the Water Source Congress Street has numerous storm sewers that drain the downtown business district Tucson. The storm drain descriptions, obtained from the City of Tucson Engineering Division, in January, 1976, are as follows: Direction of Structure Type of Entering the Location from Size Structure Santa Cruz River Congress Street 60 inch Reinforced East 1600 feet upstream concrete pipe 8 footConcrete East 800 feet upstream x 4 foot box culvert 54 inch Reinforced East 500 feet upstream concrete pipe two- Reinforced East Bridge Abutment 42 inch concrete pipe -18 inch Reinforced \Vest Bridge Abutment concrete pipe

374 36 inch Reinforced East 800 feet downstream at concrete pipe an Alameda Street Abutment 48 inch Reinforced West 1200 feet downstream concrete pipe 2. Quantities of Water The effective watershed area of the storm sewers in the downtown business district was not readily available and, therefore, volumes and peak flows were not calculated. Presently, refrigeration cooling water quantities ranging from 500 to 1000 gallons per day per high rise building in the downtown area are piped directly into the sewer system. This wastewater could be easily directed into the storm sewer system through a T- connection, a valve and small amount of pipe, and allowed to flow down the River channel. 3. Qualities of Water Water samples, see Table 7, were taken at the following locations:1) A storm sewer with a flow of less than 0.1 cubic feet per second on the east abutment of the Congress Street Bridge; and, 2) a seepage pipe from the north side of the Desert Inn Motel. The flow from the seepage pipe, which was less than 0.1 cubic feet per second, was probably excess lawn irrigation water. 4. Possible Water Uses Storm runoff from the storm drains would be difficult to control by a reservoir. This water should be allowed to flow downstream and to recharge within the present stream channel. The authors suggest at this point that either a waterway loop between Congress Street and St. Mary's Road be considered or a new park established on the west side of the Santa Cruz River. The vacant land totaling approximately 45 acres could easily be converted into a recreational development. Waters from this source can be used in partially maintaining the prospec- tive development.

Table 7.Valet Quality Anah.s s(ron Two Locations Near (:umgreis St reu bridge Crossing. Santa Cruz River

Congre.s Street Seepage Pipe From ChemicalCunstiutems Units S loor,,, Sewer De.ertónt . pii 7.5 8.1 Elec. C:)nductivitr mmhtwïcm 098 0.82 Temperature 'C 15.0 14.8 Turbidity mg/ 5 29 Su.prra)nl Sdids nog, 27 172 LLlmde Susp. 501K is mg/ 11 16 COI) mg. 25 21 (7.4- nrg/ rt8 19 ttg mg/ 15 15 Total llardmcsnlC.JCOs) mg/ 280 283 NY - mg/ 154 100 co, ' ing/ U () H(:Os- mg/ 199 269 Cl- mg/ 42 15

1.' row I I I I NIt.-N mgt 0.1 0.1 I.jeidahl-N mg/ I.1 0.5 S,i.-NNt YE- N nrgt I.t) 2.5 lbu)(.,üG.nns t/ltg)nd I.t)xlo. 5.2xIOr FetalGdilbrms t/ü>rtnd 2.1x It cl PeolSueptrc.cti t1)00m) '2.5.xIII, 4.5x111.

WATER SOURCE NO. l3- Tucson Arroyo 1.Description of the Area a.Overview The watershed of this water source is located in the central business and residential district of Tucson, Arizona. General slope of the land isto west- northwest at about 50 feet per mile with an average elevation of 2101)

375 feet above mean sea level. The watershed has a well defined channel passing through and collecting runoff from the soil- vegetation surfaces, paved and nopn -paved streets and building roofs. Storm runoff water from the urbanized area is also drained by the channel. The urban area includes single and multiple family dwellings, several types of roofing materials, paved and unpaved areas and lawns. The developed area of the watershed has a primary influence on runoff volumes, flow depths and peak arrival times, whereas the grassy portion of Randolph Park has a moderating affect on the runoff hydrographs. A major structural asset of the watershed is the uniform concrete -lined channel which permits a larger potential channel flow and a descreasing flood hazard in the surrounding urban areas. The flood water is discharged into the Santa Cruz River through a three span -l2 feet by 12 feet concrete box culvert. Overall, the watershed has a fairly uniform, urban water flow pattern which produces uniform storm runoff hydrographs. Pattern of the streets arrangements will affect the drainage performance. h. Drainage area = 10.0 square miles to Interstate I -IO. c.Watershed composition by land use types. Desert area = 0.1 square miles or 1.0 percent. -Composed of grassland, desert brush, cacti and low vegeta Live cover. Urban area = 6.7 square miles or 67.0 percent. -Composed of single and multi-family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. The University of Arizona campus is included in this area. Suburban area = 0.2 square miles or 2.0 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of- way, and vegetative cover. Paved area = 1.8 square miles or 18.0 percent. -Composed of paved surfaces and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 0.2 square miles or 2.0 percent. -Composed of low- density, vegetative cover and bare soil. Parks, grassed areas = 1.0 square miles or 10.0 percent. 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, 1 year- 130 Winter, 1 year-80 Summer, 2 year- 350 Winter, 2 year- 310 Summer,10 year- 770 Winter,10 year- 730 Summer, 25 year -1070 Winter, 25 year - 920 Summer, 50 year -1480 Winter, 50 year -1250 Sumner. 100 yea r -1830 Winter, 100 year -1550 h. Peak flows for given frequenciesin cubic feet per second. 2 year -1100 50 year -4600 10 y' ear- -2200 100 year -6000 25 year -30QU 3.Jlc:ut Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg /1 250 220 b.Suspended solids = mg/1 1500 70() c.Chemical oxygen demand = mg/ 1 980 130 c1. Temperature = °C 27 15 C.pH = 8 7.7 7.0 f.Bacterial density = (I )Total conforms = # 1100 ml 15 x 104 10x' (2) Fecal conforms = #1100 ml 10 x 10' 70 x 103 (3) Fecal streptococci = #1100 nil 50 x 10' 30 x 10' *Assuming transposition of .water quality data from Railroad Watershed (urban). 4. Possible Water Uses The volute of storm runoff from this water source is adequate for maintaining a waterway loop in the immediate area. We suggest that the loop could be constructed on the west side of the Santa Cruz River between Congress Street and St. Mary's Road. An open or covered storage basin should be constructed within the immediate area. A covered storage basin would also provide a location for tennis courts or a miniature putting course. Light business could be developed around the waterway. If the waterway loop is not constructed, the vacant land adjacent to the west side of the Santa Cruz River and south of St. Mary's Road could be developed as a park. Park vegetation could be maintained by storm runoff from this Water Source. The proposed waterway loop with dimensions of 40 feet x 6 feet x 3000 feet would only require about 16.5 acre feet of water to fill. Ample storm runoff with storage can provide sufficient flow even during the years of lowest rainfall to maintain the waterway loop. WATER SOURCE NO. 14 -St. Mary's Road Storm Sewer 1. Description of the Water Source St. Mary's Road has a storm sewer that drains the western downtown business district of Tucson and nearby residential area. The storm drain descriptions obtained from the City of Tucson Engineering Division in January, 1976, are as follows: Type of Direction of Structure Location from Size Structure Entering the Santa Cruz RiverSt. Mary's Road 21 inch Reinforced Nest Downstream of concrete pipe bridge abutment 2. Quantities of Water The effective watershed area of the storm water system in the western downtown business district was not readily available and, therefore, volumes and peak flows were not calculated. Presently, refrigeration cooling water quantities ranging from approximately 100 to 200 gallons per day per large commercial building in the western business district are piped directly into the sewer system. This wastewater could be easily directed into the storm sewer system through a simple pipe adaptation. 3. Qualities of Water The chemical quality of storm runoff from the western downtown area has not been sampled. 4. Possible 1Vater Uses Water from the storm drains would be difficult to control and should be allowed to flow and recharge along the stream channel. In addition, if the proposed waterway loop were developed, these waters would combine with the discharged water from the loop to help maintain a flowing channel for an unknown distance downstream. WATER SOURCE NO. 15- Speedway Boulevard Storm Sewer 1. Description of the Water Source Speedway Boulevard has a drainage channel and numerous storm sewers that drain the surrounding residential and commercial area. The drainage channel and storm drain descriptions, obtained from the City of Tucson Engineering Division in January, 1976, are as follows: Direction of Structure Type of Entering the Location from Size Structure Santa Cruz River Speedway Boulevard 2 spanConcrete box East 1200 feet upstream 6 foot xculvert (Drainage channel from a 3 foot small residential area) 36 inchCorrugated East 500 feet upstream metal pipe

177 36 inchReinforced West 30 feet upstream concrete pipe 36 inchCorrugated East 30 feet upstream metal pipe 36 inchCorrugated East 200 feet downstream metal pipe 2. Quantities of 'Water The effective watershed area of the storm hater system was not readily available anti, therefore, volumes and peak flows were not calculated. 3. Qualities of Water The chemical duality of storm tvater from this area has not been sampled. 4.Possible \Vater Uses \Water from the storm drains would be difficult to control and should be allowed to flow and recharge along the stream channel. In addition, if the proposed waterway loop were developed, these waters would combine with the discharged water from the loop to help maintain a flowing channel for an unknown distance cftrnstrc:un. WATER SOURCE No. 16- Extended Silvercroft \Vash 1.Description of the Area a. Overview The watershed of Extended Sifyercroft Wash is located near the northwestern huurt(Lii01.111e city lírnti1s, anel within111(2foothills ;uul mountain range of the Tucson Mountains. This watershed is composed of two subwatersheds named Silyercroft Wash, 2.8 square tuiles. and Rille It ;urge Wash. 0.5squate miles. General slope of the land is to the cast -northeast at about IOU feet per mile with an average elevation of 2400 feet above meant sea level. The watershed has tiro defined channels %cull small rivulets extending over a small region. Surface drainage is fairly rapid from the steep, relatively impermeable hills, ;uul moderate runoff occurs front the gently sloping foothills and valley. Slopes range from 0 to 3 percent in the alluvial bottom, to greater than 45 percent on the rock slopes of the foothills. In the middle reach of the watershed, Pima Community College and associated paved surfaces are drained by both ephemeral channels. In the lower reaches of the tv;tershed, the channel has a moderate growth of riparian vegetation producing an areal spreading of floodwaters. A wide trioiety of trees, shrubs, grasses, and cacti cover the tv :ucrshed. Rock outcrops and shallow soils with a clayey horizon or caliche (-1r, ids) over bedrock composes the major portion of soil association in the watershed. 'The minor soil classification of 'the watershed is E,Ni.co1s, primarily Fluzents. Fitments are related to water transport of soil materials and exhibit no natural distinctive horizon or layers, except that their subsurface usually exhibit stratifications of differently textured materials. The composite soil associations and geology its the watershed produces a complex drainage environment, whereby, low seasonal and annual runoff volumes arc associated with long non-runoff periods. However, the small developed portion of the watershed has a considerable influence on the runoff volumes, !low rates, and peak arrival times. As the potential rainfall intensity increases over the infiltration capacity. the potential peak flows become greater than peak flows from some urban watersheds. even though the Iluyent soils have greater infiltration capacity than some of the other soil associations, which may reduce somewhat the summer storm peak flows. It is obvious that arty structural design should account for the skewed frequency distribution of peak flows. I).Drainage area = 3.3 square utiles to just below West Spec(Iway Boulevard Bridge crossing and the Silyercroft Wash Diversion Channel. c.Watershed composition by laud use type's. Desert area = 2. 7 square miles or 81.8 percent. -Composed of grassland, desert brush and cacti population. Urban area = 0.3 square tuiles or 9.1 percent.

378 -Composed of single and mufti- family units on land parcels smaller than one acre including rooftops, paved and non - paved rights-of-way, and vegetative coter. Suburban area = 0.1 square mile or 3.0 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and vegetative cover. - Paved area = 0.2 square miles or 6.1 percent. -Composed of pared surface area, ancf large rouf areas associated with commercial or industrial facilities. `_). Quantities of \Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 20 winter, I year- I Summer. 2 tear - 40 Winter, 2 year- 30 Summer,10 dear -100 winter,10 year- 96 Sumpter, 25 year -160 Winter, 25 tear -120 Sununet. 50 rear -210 Winter, 50 year-160 Summer, 100 sear -270 Winter, 100 year -200 b.Peak flows for given frequenciesin cubic feet per second. 2 year- 300 50 year- 2900 10 year -1501) 100 year -3300 25 vear -2600

3.Mean Water Qualities from Watershed Area* Summer Winter Units Storms Storms

a. Total dissolved solids = m g/ 1 180 150 b.Suspended solids = mg /1 3500 2000 c.Chemical oxygen demand = ntg/1 200 125 d.Temperature = oc 25 13 e.i)! 1= 7.9 7.5 f.Bacterial density = ( I) Total colilì)rms = #/100 nil ti0x 10' 70 x 102 (2)Fecal coliforms = #1100 ml 20x 10' 40 x 102 (3) fecal streptococci = #1100 ml 15 x 10' 1 0 x ' *.Assuming transposition of water quality datafrom Atterburv Watershed (desert). 4.Possible Water Uses Water from this source and Water Source No. 17 can be used for maintaining the \Vest Side Park and about a three-acre recreational lake in the park. In years of excess water, beyond the water needed for maintenance of the lake and park, the storm runoff can be used as .a supplemental supply for irrigation of the El Rio Golf Course, or maintenance of promising greenbelt areas along Silvercroft Wash between Grant Road and the confluence ol' the Silvercroft 'Wash Channel with the Santa Cruz. Rivet. t\'. \"l'ER SOURCE NO. 17- Extended :\nklam Wash 1.Description of the Area a.Overview The watershed of Extended : \nklam Wash is located near the northwestern boundary of the city limits and within the foothills and mountain range of the Tucson Mountains. General slope of the land isto the north- northeast at about 120 fret per mile with an average elevation of 26)))) ft above the mean sea level. The watershed has a defined channel with small rivulets extending over a small region. Surface drainage is rapid from the steep. relatively impermeable hills. and moderate runoff occurs from the gently sloping foothills and valley. Slopes range liotu 0 to 3 percent in the alluvial valley bottom, to greater than -15 percent on the rock slopes of the foothills. In the lower reaches of the watershed, the channel has a heavy growth of riparian vegetation producing an areal spreading of floodwaters..\ wide variety of trees, shrubs, grasses. and cacti coyer the watershed.

379

Nos Rock outcrops and shallow soils with a clayey horizon or caliche (Argil.,) over bedrock composes the major portion of the soil association in the watershed. The composite soil association and geology in the watershed produces a complex drainage environment. whereby, low seasonal and annual runoff volumes are associated %with long non -runoff periods. I low- ever, as the potential rainfall intensity increases over the infiltration capacity, the potential peak flows become exceedingly large. Itis obvious that any structural design should account for the skewed frequency distribution of peak flows. b. Drainage area = 2.9 square miles to Silverbell Road. c.Watershed composition by land use types. Desert area = 2.7 square miles of 93.1 percent. -Composed of grassland, desert brush and a large cacti population. Suburban area = 0.1 square miles or 3.4 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, payed and non -paved rights -of- way, and vegetative cover. Payed area = 0.1 square miles or 3.5 percent. -Composed of payed surface area, and large roof areas associated with commercial or industrial facilities. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 10 \!'inter, 1 year- 5 Summer, 2 year - 20 Winter, 2 year- 15 Summer,10 year- 60 Winter,I O year- 50 Summer, 25 year -100 Winter, 25 year - 60 Sumner, 50 year -140 Winter, 50 year- 90 Summer, 100 year -170 Winter, 100 year -120 b. Peak flows for given frequencies in cubic feet per second. 2 year- 200 50 year -4000 10 year -2500 100 year -1800 25 year -3500 3. lean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg/ I 180 150 b. Suspended solids = mg /I 3500 2000 c.Chemical oxygen demand mg/ I 200 125 d. Temperature = oC 25 13 e. pH= 7.9 7.5 f.Bacterial density = (1) Total coliforms = #/100 ml 50 x 104 70 x 10= (2) Fecal coliforms = #/100 nil 15x 104 40x 102 (3) Fecal streptococci #/100 ml 15x104 10x10' *Assuming transposition of waterquality datafrom Atterbury \Vater- shed (desert). 4. Possible Water Uses See description of possible %valet' uses for this water sourceinthe%,'linen narrative for Water Source No. 16.

WATER SOURCE NO. I8- University Heights Wash 1.Description of the Area a.Overview '!rite watershed of University Heights Wash is located in the north- central portion of the City of Tucson, Arizona. General slope of the latol is to the west at idiom 50 test per mile with an average elevation of 2400 feet above meat sea level. Tile watershed has a well defined channel passing through and collecting runoff front the soil -vegetation surfaces, payed andnon- paved streets and building goofs. Storm runoff water from an urbanizes!

380 area is also drained by the channel. The urban area includes single and multiple family dwellings, several types of roofing materials, paved and unpaved -areas, and lawns. The developed area of the watershed has a major influence on runoff volumes, flow rates and peak arrival time. Pattern of the street arrangements will also affect the drainage performance. A major channel problem in certain reaches of the channel is the vegetation and debris clogging the channel bottom, thereby reducing channel capacity and increasing flood hazard in the surrounding urban areas. Overall, the watershed has a uniform urban drainage pattern which produces a simplified storni runoff hychogra ph. b. Drainage area = 1.1 square miles to Interstate I -10 c.Watershed composition by and use types. Desert area = 0. l.square miles or 9.1 percent. -Composed of grassland, desert brush, cacti and low vegetative cover. Urban area = 0.9 square tuiles or 81.8 percent. -Composed of single and multi- family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Paved area = 0.1 square miles or 9.1 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Quantities of Water a.Water volumes for given frequencies in acre-feet. Summer, 1 year - 25 Winter, 1 year- 15 Summer, 2 year- 50 Winter, 2 year - 40 Summer,10 tear -100 Winter,10 year- 90 Summer,25 year -13() Winter,25 year -120 Summer,50 year -180 Winter,50 year -170 Summer, 100 vcar -230 Winter, I00 year -200 b. Peak flows for given frequenciesin cubic feet per second. 2 year- 500 50 year -1000 10 year- 1 150 100 year- I SOO 25 year -1400 3.Mean Water Qualities from Watershed.area* Sumner Winter Units Storms Storms a.Total dissolved solids = mg/ I 200 190 b. Suspended solids = mg/ 1 800 500 c.Chemical oxygen demand = mg /1 300 150 d. Temperature = °C 28 16 e. pH = - 7.3 6.9 f.Bacterial density = (I) Total coli(orms = #1100 ml 15 x I0' 12 x 10' (2)Fecal coliforni_s = #1100 m1 10 xI O' 40 x 103 (3) Fecal streptococci = #/100 ml 60 x 101 35 x 101 *Assuming transposition of water quality data from High School Water- shed (turban). 4. Possible Water Uses This urban storm runoff could maintain a greenbelt area between In- terstate 1 -11) and the Santa Cruz River. The storni runoff with appropriate storage facilities can supply irrigation water for vegetation maintenance consistently throughout the calendar year.

WATER SOURCE NO. 19 -Grant Road Storm Sewer 1.Description of the Water Source Grant Road has two storms sewers that drain the surrounding urbanized ancf commercial areas. The storm drain descriptions, obtained front the City of Tucson Engineering Division in January. 1976, are as follows:

381 Direction of Structure Entering the Location from Size Structure Santa Cruz River Grant Road 24 inch Reinforced East Upstream of concrete pipe bridge abutment 42 inch Tidal Irate- East Downstream of reinforced bridge abutment concrete pipe 2. Quantities of Water The effective tvat ers hed of the storm water system in the urban area was not readily available, and, therefore, volumes and peak flows were not calculated. 3. Qualities of Water The chemical quality of storm water from the surrounding urbanized area has not been sampled. 4. Possible Water Uses See description of possible %eater uses for this water source in the written narrative for Water Source No. 20. WATER SOURCE NO. 20- Tucson Gas and Electric Company Plant at Grant Road (De.\loss -Pct rie Plant) 1. Description of the Water Source ßlowdown effluent from the power plant cooling towers is discharged into an open ditch which crosses Interstate 1 -10 via u two -barrel culvert. Storm runoff water from a portion of the nearby urban- industrial area also discharges into the Tucson Gas and Electric Company ditch. The major portion of the industrial flow is intercepted by a diversion structure and transported through an 8 -inch asbestos -cement line to the Water Resources Research Center ( \VRRC) Field Laboratory for artificial recharge studies. The remainder of the blowdown effluent flows into the Santa Cruz River by an open ditch. 2. Quantities of Water The industrial discharge is continuous, but flow rates vary with operational requirements of the plant. Discharge varies from 100 -200 gallons per minute with an estimated annual flow of about 250 acre- feet. No data available on the amount of storm runoff from the nearby industrial-urban area. 3. Qualities of Water A complete chemical analysis of industrial discharge from the De\loss- Petrie Plant is given on Table 8. Values of pH, electrical conductivity, total dissolved solids. and chloride in effluent samples taken on various dates in 1973, 197-land 1975 are reported in Table 9. River samples are occasionally obtained near the \WRRC Field Laboratory to determine chemical quality of storm runoff water. "These samples and corresponding quality, represent a composite of eater from upstream discharge points. Two representative analyses are reported on Table 10.

-r.rla.a (AK I ct,.rr:.rrr,a 1:,0.14 w.,.r Fulr,rnl Is Irr th \I,n..Pestle r:.,r,r s,rr,l,uea.,1 Ilse 1% girt Itr.,,u..rs I:r.r.rr, Is...met 11"1.11s,,, l' ,,,r \rl,,. rrJ.,1. Ir; 1i t\rl.,,,r,et :J,1,7r, l-,l,

i.,,; Is urq 41 "i;ri F

r -I he ilei , .. .0,,..ii, . oI ,i,I,ri,; ..,1rr ,..., ,I,cl'I.,n,.rr.l r...l,,: . ru,r,l I"r l' S. Gurr.,, 1 Hrrl,i,ulú r, i,,,,.l.,rr,,.r ,.r.r i.,r'I'I.rr,l

382 TJ1Je 9.136-Itical Charte. ter ti G.JIn4 Water i. I fluent 1880 the DeMosá- Petrie Plam Sampled at the Water Resources Rrsearrh Cotter 1106101g l' ,,n t 00 Cari. o,Days l\ti ü on, et al. 19701.

Electrical Total Dissolved condo. ?kite SdiJ+ (:hlnride Moe pll 0001h..,, oll (99/1) 9,94'1) 2:92.13 6.58 293 2923 410 7/5173 6.83 330 2415 403 7/9173 6.80 3.68 2510 400 8/11/73 6.88 3.43 2307 460 11/1/73 003 2.49 1718 313 1 1.29/73 0.90 :1. -18 2.1111 4.10 12/772 6.84 3.519 2477 409 1/38/74 6.95 303 2730 5116 5P314/74 6.88 3.69 2540 430 7/10'74 7.04 3.20 2208 440 8n6/74 7.01 3.39 2277 438 9/11174 7.411 3.51 2432 441 11/18074 7.32 3.311 2277 410 9.26/74 7.69 2.-13 16,70 205

114'2.74 7 73 .1.181 37101 1 1140,74 7:10 3.91 2)00 314i 11/1)674 7.02 3 .30 221)8 414 12:1874 7.57 I.70 1173 301 1212:1174 7 a)í 2.13 1 1ná 3:)11 1/J75 7.57 3.73 1918 375 1.9/73 7 74 3.,,0 31170 499 1;23/79 7.7» 3 111 2130 1112 1/31/75 731 2.5)1 1725 :1,13 ,721675 7.03 2.01 1098 :1)17 117175 -- 235 1Ná1 :11!1 3i21'75 Ii81 2.68 1849 3616 Noír rit t111u0t0 Al [hr., tirk...r..n tualh :, ,,I .,.Jing ».It's Dom the l'l:uu .end ,..rliur..:urr tete r1 I,,r a l'. S. Btu.ur ,,I 8u, latoion rran.11.mer ne .II tIi ll't,un.

Tattle i0. 121-1/14,4111:111,l. (:F9rnn1.,1:1,,.dtv,,,l SIntm 80,,,11111119, the Saut.1(:I Io River tu 1-wn Dil lc, rt. D.u.1(1:il..,o, s-t al.l'.n1x1.

Mors (:hemual (:nnstiturnrs Unit 7,12!1i8 .i 14.ri8 Total Diswlvrd m4: 1 397 14'9 H .ir. t-rral 1:u.6191603 1108110 11.45 11.22 ('ririulll lut' I 51 3144nrsit0l In4' I Sldlut, ul4' i 4 17 (:11Il,ride nl4/I 53 13 Stllate u,4'1 911 36 C:ul.,nat- ,Ig:I i) t Ix mate m4, I 1:17 43 Nitrate roe I 0 1.3 Ink 6.8 ,.5

4. Possible Water Uses The volume of industrial water and storm runoff from Water Source No. 20 are adequate and continuous enough to maintain a one -half mile greenbelt area and a landscaped lake between Interstate I -I O and the Santa Cruz River- Such an arca would provide an excellent demonstration of the use of cooling water and Storm runoff for landscape irrigation. Surplus water- could be used for artificial ground -!water recharge either on the greenbelt area or at the nearby \VRTRC Field Laboratory. Incidentally, guidelines for the design and management of the greenbelt recharge facilities could he based on the results of more than 10 year of experimentation at the Field Laboratory (Wilson, 1971a, 1971h, and 1976). WATER SOURCE NO. 21- Treated Sewage Effluent on the Southern and Eastern Irrigated Fields, City of Tuc- son Farm 1. Description of the Water Source and Area of Use "Treated sewage effluent can be delivered to the head of the southern and eastern fields, 2.10 acres, Of the City of "Tucson Farms by an 1S-inch pipeline. The principal crops grown are !wheat and maize. 2. Quantities of Water The line can deliver effluent at a maximum flow rate of approximately six cubic feet per second at this point. 3. Qualities of Water The quality of the treated sewage effluent with regard to chemical constituents makes the effluent ideal for use ill landscape irrigation. Chemical quality of sewage effluent data from the City of Tucson Wastewater Treatment Plant are shown in "Table 11.

383 4. Possible Water Uses The present pipeline could, of course, continue to irrigate land from this point down gradient to the City of Tucson 'Wastewater Treatment Plant. Since treated sewage effluent is not the limiting factor, a new enlarged pipeline can be extended to the south and effluent can be used for irrigating lands on both sides of the Santa Cruz River. With extension of the enlarged pipeline to the south, treated sewage effluent can he used conjunctively with storm- runoff for irrigation of the El Rio Golf Course, the West Side Park, and possibly the proposed golf course and park development along the River near the center of the City. Further, greenbelt areas designed for nutrient removal from sewage effluent can be constructed in selected locations along the Santa Cruz River. WATER SOURCE NO. 22- Extended Flowing Wells Wash I.Description of the Area a. Overview The watershed of Extended Flowing Wells Wash is located in the north - central portion of the City of Tucson. General slope of the land is to the west -northwest at about 25 feet per mile with an average elevation of 2350 feet above mean sea level. The watershed has a %yell defined channel passing through and collecting runoff front the soil -vegetation surfaces, paved and non -paved streets and building roofs. Storm runoff water from an urbanized area is also drained by the channel. The urban arca includes single and multiple family dwellings, several types of roofing materials, paved and unpaved areas, and lawns. The developed area of the watershed has a primary influence on runoff volumes, flow rates. and peak arrival time, whereas the grassy area of the cemetery has a moderating influence on the runoff hydrograph. Pattern of the streets will affect the drainage performance. A major structural asset of the watershed is the uniform concrete -lined channel which permits larger potential channel flows and decreasing flood hazards in the surrounding urban areas. Overall, the watershed has a fairly uniform type of urban water flow pattern which produces a uniform storm runoff hydrograph. b. Drainage area = 4.2 square miles to Interstate I -10. c.Watershed composition by land use types. Desert area = 0.2 square miles or 4.8 percent. -Composed of grassland, desert brush, cacti and low vegetative cover. Urban area = 3.0 square miles or 71.4 percent. -Composed of single and mufti- fancily units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square miles or 2.4 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of- way, and vegetative cover. Paved area = 0.5 square miles or 1 1.9 percent. Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Parks or grassed areas = 0.4 square miles or 9.5 percent. -Composed of high density vegetative cover with essentially no exposed soil areas. 2. Quantities ofWater a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 60 Winter. 1 year- 50 Summer, 2 year - f 70 Winter, 2veau-160 Sumner,10 year -3.10 Winter.10 year -330 Summer,25 year-470 Winter,25 veau- -450 Summer,50 year -650 Winter,50 year -630 Summer, 100 near -790 Winter, 100 vear -7l0 b.Peak flows for given frequencies in cubic feet per second.

384 2 year - 950 50 year -2600 10 year -IS50 100 year -3100 25 year -2300 3.Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = ing/ I 200 190 b. Suspended solids = mg /I 800 500 c.Chemical oxygen demand = mall 300 150 d. Temperature = °C 28 16 e. pH = - 7.3 7.0 f.Bacterial density = (1) Total coliforms = #/100 tn1 15 x 104 12 x 104 (2) Fecal coliforms = # /l00 ml 10 x 104 40 x I03 (3) Fecal streptococci = # /100 ml 60 x 103 35 x 103 *Assuming transposition of waterquality data from High School Water- shed (urban). 4. Possible Water Uses Storm runoff from this source warrants consideration for use in the proposed City park and golf course development in this area. Because of the characteristics of the storm runoff, storage and treatment., either grass and /or grass -soil filtration and chlorination would be needed. WATER SOURCE NO. 23- Treated Sewage Effluent on Western Irrigated Field, City of Tucson Farm

1.Description of the Water Source and Area of Use Treated sewage effluent can be delivered to the western irrigated field of GO acres on the City of Tucson Farm on the west side of the Santa Cruz River by a 12 -inch pipeline. The principal crops grown are wheat and maize. 2. Quantities of Water The pipeline can deliver effluent at a maximum flow rate of approximately three cubic feet per second at this point. 3. Qualities of Water The quality of the treated sewage effluent makes it ideal with regard to chemical constituents for use in landscape irrigation. Chemical quality of sewage effluent data from the City of Tucson tVastewater Treatment Plant

are shown in Table 11. .

Table 1I. Qu..it tifa Composite S.+mpirul 7Yra,rd Sewai{e F:Illurnl at Ott, of -Ems." N'a.{s-water Tl rauneu( I'lann (All mot. mc nulli4n:,,,,s per liter except Pi l l

Chemical Tucson Cottitimitc ('.n,.iìnenla 1. w':.KC F.Ilitam

t.,.c,iwmtr weiKlue,l et florin sample c.iog average.lars ,li.t harp" hoot 1971.72. I)ata I,uhlythe.l Its 11,e l 1972h :cParut>n cl xwhum an.l )w.nass.un, w.,s made tran, s. tufi ies ,.,Le,, t, die \tatrr Itr..u,rre. Research Center.

385 4. Possible Water Uses The present pipeline could continue to irrigue land From this point to the north. Since treated sewage effluent is not the limiting factor, a new, enlarged pipeline can he used for irrigating lands on the western sicle Of the Santa Cruz River. Further, a demonstration greenbelt area for nutrient removal from sewage effluent by grasses can be developed along the Santa Cruz River. WATER SOURCE NO. 24 -City of Tucson Wastewater Treatment Plant 1.Description of the Water Source and Area of Use The city -county sewage collection system carries most of the composite domestic-industrial sewage load of greater Tucson to the City treatment plant. The City of Tucson Wastewater Treatment Facility is composed of three treatment plants summarized as follows: Plant 1is a 12 million gallons per day (45,500 cubic meters per day or 18.6 cubic feet per second) standard activated sludge plant with tapered aeration; Plant 2 is a.12 million gallon per clay high -rate trickling filter plant; and Plant 3 is a 12.9 mullion gallon per clay (48,900 cubic meters per day or 20.0 cubic feet per second) activated sludge plant with step aeration. However, Plant 3is presently being operated as a conventional activated- sludge plant. 2. Quantities of Water Two 36 -inch pipelines discharge sewage effluent into the Santa Cruz River. The average daily flow is 50 cubic feet per second with sinusoidal variations of 2S cubic feet per second at low flow and 70 cubic feet per second at high flow. Average effluent discharges from the three treatment facilities are shown in Table 12.

TwLlr I t. :\seeigr tir., agr 1..111114-to 11ir h.n gr. [non l'I.nu. I. 7:mJ 3. Cin ol 110 wu \C.ni. wmrr l7cai0nt Ham. 1971. 1177, YrarklA..h.irgcs Avrragr\tonthI. Acnagrltuls Ih..large. a.,r-lrrt a.,r-lrrt .uir"Ir.t

1'L.nt 1 1.21 110 1.111 a IIN 371.Io. limo 11.95Ia 10' 0.75 2.17. 10' Ylant S I.:tva111' 1.1ía 10' 9-77z Ifs' l'ut..l 3.I9a 10' -nI o Io' 9_55a Iu'

Ue (1975).

3. Qualities of Water The quality of treated sewage effluent makes it ideal with regard to chemical constituents for use in landscape irrigation. Water quality of sewage influent and effluent data from the City of Tucson Wastewater Treatment Plant arc shown itt Table 13. Extensive studies regarding biophysico- chemical transformations of sewage effluent as it flows down the Santa Cruz River are also available from theses by Sebenik (1975a, 1975b), University of Arizona. 4. Possible Water Uses The volumes of treated sewage effluent from the Tucson Wastewater Treatment Plant are such that, the amount of water is probably not the limiting factor. Possible seater uses are discussed in the previous sections. However, sewage effluent uses should be restrictive, if the biochemical quality effects of effluent to the environment are unknown. WATER SOURCE NO. 25 -City of "Tucson, El Camino Del Cerro I folding Pond I.Description of the Water Source and Area of Use Treated sewage effluent is stored in a ,12-acre holding pond from which effluent discharges can be regulated. A portion of the flocs from Plant 3 of the City of Tucson Wastewater Treatment Plant is diverted down a concrete lined ditch into the pond. Eutrophie nutrients such is nitrogen and phosphorus :Ire constantly being added to the pont) water. 2. Quantities of Water The pond contains approximately 330 acre -feet of sewage effluent ancf the effluent overflow is released to the Santa Cruz River through a concrete sirop -inlet structure and culvert.

386 3. Qualities of Water The quality of treated sewage effluent in the pond is summarized in Table 14. 4. Possible Water Uses The pond, of course, provides storage for treated sewage effluent for any of the possible uses discussed for the effluent in the previous sections. Under proper wastewater management techniques, the Camino del Cerro Holding Pond provides a tertiary treatment to the effluent by removing nitrogen in the form of ammonia (NH3) through the utilization of the photosynthetic action of algae. Pennington (1970) suggests that rock -lined shallow basins with a depth of two feet and gentle side slopes\wouldpro- vide best design for ammonia nitrogen removal. Basins could be baffled so that detention times of one day could be attained with maximum ammonia removals of greater than 60 percent.

Tatar 19. Qualm of influent and Effluent Sewage Flows at the (Srs .d lia .r at wastrwarcr Treatment Plant. 1974-1975.

Wastewater Flilurnl Chemxal Con.GwenL. 1111111. .10 flaut I Plant 2 1'1.11 3 10t.1 lhswrhrd Solids. f:ral.,rauou (105°C) 92(1 6411 ,i449 656 Suspa-uda

NIIs-N 19.7 17.5 19.9 18.9 NOI-N - 0.1 9 1 11 2 \U,-N - 1141 11.1 11.11 g.nxN 12.8 7.tí 51.7 8.2 Tutal-N 52S 23.2 29.8 27..1

Silica (Skid 51 411 42 42 Aluminum t Iron (AlOh k Feral) 29 25 23 Total Irin l Fsarro,.I 11.5 1.3 (1.3 r0.4 Cal. 74 74 434 614 \lagnesi,rn 19 18 17 17 I liminess Wit/Cal) 16 Ili 17 Ili

Cldnrule 98 93 92 92 carl.nrare 9 n o 9 ni,ariMnate 359 546 34:4 338 Phi ..Plute. Ort su 21 15 214 18 Sulfate 151 155 147 146 Sodium S Potassium (N:\' & K'1 117 115 117 116

.ill data Irian Annuel Rep.. Is of the I\'asters mer I)isisinnMettop,.lirio 1'ú1íu\fanas;rmrm: \g1.11,sr Ike,1075.

,ill units a mg'l curiasil or ued. flints I mid 4sse .uurmrrI sludgy . and Haut - n a'raiding filter tun. 1,11111.1f ell limo i,cs IrSOIluent iambi, data.

Table 14. Quahrs of T, cared Sewage Effluent m FI (assurto Del (.erro I11111mg fond arar Tos son. A risona

Rein e lame Aserage (.osonr,ls C ons I).,,Ir l'alo-. U,swdsrd(ssgrn u,g/I 65 pli - 7 14 tc.nrr Temperature C l'I (:Id,rr,les trigs 80

Isr..l,rni,al "hi grit Ilrnraod 1:g I 3,1 I o,..l :\Ikalioilr l(a(iu) ng- I 231 [1 )1) tow! I I.I .\ 1(,. \' no:l l'I 0 7s11.-N mg l ,I'4 Ni lr.\ g i ( h g.nw. N rg, í

or.,l.\ ,ng 1 I l . r ,. r 1ur oohrd is h. F I l l urhl,w1, ,1Y41. (:hrnosl. ( : o s of To, xro l\asrrwalr,I, ralrror 1'1 .1l oI.,hl,shr,l ,l.u., l,rl' I. Sei.-o,k11J74i%rarerKrw.o,rsKrxahl:rutrr.,hungral,00s sampling i.tuIs1, I"7.3 ,o71

387 REFERENCES CITED Arizona State Depanneil of Ile:Alb Services. Rules and RegW.unmfor Stung., Swan. and Tntntera !Cork., Ah irooz State lkparo- ment u( )Iealhh, Phoenix, Alu.. Clapier 2. Article 2. Pan 3. August 17. 196 2. Arizona State Department Of Health Services. IPaze. gunner Standards for Sufare {(átm in .lnwna. Arizona Slate Department of Fleahh. Phoenix, Arizona, Article 6, Pan 2. June 18. 19tì8.

Adana Stale Deparuorna ttI Rabb S..sa es. !tubs und liegmdanaru Jar Rerfannnl ti'astn. Arizona Stale Department of I lrahh, !'hoenic. A nztnu. Al tide ti. l'an i. 1972. Arknbach, D. B.. T. P. Glavin and J. A. R. Rojas. "Protratted Recharge of Treated Sewage into Sand. Part I- Qtuliry Chango in Vert ita i l'ans n,n Thom,. the Sand." Vol. 12, N... 3. Ground 'Parer, Star -June. 1974. Barfield. B. J.. D. T. V. Kao, and E. W. "Pullner, "Avulses IIIthe Srdimenl Filtering Arii.n Of Grassed Media.' University of Kentucky Water Resources Institute. Research Repon No. 90, December, 1973. Bouwer, 11., J. C. lance. and SI. S. Riggs. 'f sigh -Rate land Treatment 11: Water Quality and Ecru tonne Aspens of the Flushing Meadows Project,' Jaurnal oflatin Polla:tun Control Fel,i,non, Vol. 46, No. 5, Slay. 1974. dim Duns- It E. -1kpletiom of Strumlluw be Inlilaat in in the Main Channels of the Tricorn Basin, S.nnhracierii Arizona.' U. S. Geel. Survey \Pater -Supply laper 1939 -II. 1170. (_-slilbrnia State Nnrr Pollution Band, -Waste Water Rn Carra. Ens in Relation w Gunned Water I'ullmi.n ;' I'ul.licaiiont Bet krley. Sanitary Eng. Research lab.. Uiii.enny of C :ddiirnia. 1955. Daniel. W. H.. "Purr -Wick Rout:one System for Turf," .tfizlaru Turf .Veins and Rnmrrh, Department of Agromony, Purdue Cninrssit., Report Nu. 10. Starch, 1974. DeC ol, K. J.. -Economic Feasibility of Selective Adjusurena its Use of Salvageable Waters in the l'ai win Region, Arizona," l'lyf). Discertatunl, Universin of Anones, 1970.

Dugan. C. 1... R. H. F. Voting, I.. S. loti, P. C. Edens. and It (:. S.I oh, -Inns Dispovl of W.orrwater in I /mown/ it/ IPatn Polluiou Control Fninntan, Vol. 47. No. 8, August. 1975. Dye. E. O.. Ikpr nierai of fearer and Sewers. Wastewater Diiisim. A mural Repti. 1971-1977. City of T10,00. 1972. the. E. O., Depart mein of Water astil Sewers. Wastewater Dr visa m. Amiiiai Repot 197.1. 1975. Ginn of Put son. 1975. Enterai Water Pollution Control Admirustrainm. "Report of the Con uriure on Wate Quality (a inni... U. S. Department of she Intel ion, icashntgunt. D. C.. 19l irt. Greene, G. S. and Associates."Master Pian for the Santa Cruz Linear Park. Proposal Submit etl tu the City of Tucson, September 2, 1975. Kasper. 1). R.. 'Organic Qualiry of Gt numbs-aim" Annual Repay Nu. 12, Of lie e of (carer Rex-atvh and Tedtudogv Pnu it, Nu. A- O67- A R17.. August I. 1976. l.r6oat. G. S., "Soil and Gran Filtration of CLmtesuir Sewage f illurnt lia the Retutial of I Lace Element." lilt.D. Dissertation,

- Universiu of Arizona. 1968. Madnk, W. G.. P. R. Davis and R. L Roth. -Sewage Effluent Pollution of a Ground's-au, Aquifer,' .menant Bunn of egrrn.lrural F.ugrnrrrs, Winter Sleeting. Chicago. Illinois. December 11.15, 1972. Mt /:ati ber. P. 11. and R. B. Ktone. "Soil Mantle as a \castewauer Treatment Si stem.' t niveru tt tl t:obbnma, Ber ',elm. Sanitary Engineering Resean h latorau,rs. December, 1967. McKee. J. E., mod H. W. Wulf.' \cater Quality CI iteria ;' .l'he Resources Agency of California. Stale Water Control Board Publica. non No. 3 -A. 1063. Orlob. G. T.. and R. G. Birder. -Art Investigation of Sewage Spreading on Five California Sills." let h. Bulletin Nit. 12,I ER Series 37. Berkeley: Sanitary Engineering Research lab., Unisersity of California, June. 1955.

l'e - Ron. J..... ".1utn.tsnta Dissipo on During Plummy minors of algae ;' SI. S. Thesis. U t.tenity fit A rituIra. 1970. Poplin. B. 13. "Effect of Mixed-Grass Cover and Native -Soil Filter on Urban Runoff Quality; SIS. Then*, University of Arizona. 1973. l'orges. K, .ttiI C. J.I IopGns, 'Broad Field Disposal of Ben Sugar Wastes;' Srmoge anti baronet( O'mte,. Vtl. 27. No. I0. p. 1160 -1170. 1953. Searle. S, S., "-Ilse Use of Grass Filtration .Arras for Sewage IL riliratiti.' Paper presented tu the 12th Annual Cunl erence of Sewage Engineers and Operators. 1949. Sebeoik, P. G., "Physinihentiwl Transformationsass of Sewage El fluent Releases in All Ephemeral Stream Chaotic-1.- Sts. Theses. Uttiv uviii u! Arizona, 11175a. Scbenik, P. C..' ReLnionship s of Di"uoilveil Oxygen and Biochemical Uxyger' Demand in Sewage Fflluen Releases." M.S. Thesis, Vinci-ruts tif Ariwn.i. 19756. Sidle. R. C.. and G. \'. Johnson. 'Evaluation of a Turfgrass -Soil Synent to Utilize and Purifs Si unit ipal \Corte Wader,' Pr-eon/tugs 9r the .l workers !Darn Rrtaurnt .iuortanan and the Anconanco,na .iradrnr of.Sriere. Prescott. Arizona, Vol. 2. 1972. Slone. R. and W. F. Garber. -Sewage Rceauaton by Spreading Basin infiltration," Prneedutgt .iwniran Stun Cid Faóinn, S'01. 77. September. 1951. U.S. Public Health Srrviie.' Public i irait h Servie Diinling Nouer Sramtards," Public Health Srite Puldii :.noon No. 950 11/62. Wda.t,L.G., "()Cau cation un Water Content Changes in Stralilled Sediments Ihning fui Res liar gr. Grimed 'Gan, 913), pp. 79 -411. 1971a. Wilson. I.. G. "Insmirgations on the Sob...face Disposal tti Waste Flflunu at Inland Sits," l'. S. Del ketones. of the lutte ma 01 fur of Salute Water, Research and Deselupmenl Progress Report No. 650. 1971 6. Wilson, L. G.. and G. S. Lehman. -Grass Farr-arum of Sewage Effluent for Quality Improvement l'rior it At Urinal Recharge. American S.mvas 4dgn, Admen/ Farnern, Paper No 6i -7I6, 11106. Wilson. L. G.. D. O'Donnell and W. O. Rasmussen, "Feasibility of Modeling the Influences of Pit Recharge on Groundwater Levels anal Qtalirs in Alluvial Basino." C utpteii,o Reimrt. Project Nu. A056 -ARV., Water Resources Research Center, Juby. 1976. N'iltt,. L G.. P. S. Osborne aid D. J. Percinn, -131100 00 of an Industrial Waste Ef0uent wah River Water in the Vdtiase Region During Pit Recharge.' .Carman Sorrels of .lgrvuhurnl Eu.gtnern, Winter Sleeting, Chicago. Illinois, Paper No. 68.727. Dec. 17, 1968.

388

14 APPENDIX Z

389 COLORADO RIVER MAIN STE!: 31

09724190 COLORADO RICER AQUEDUCT .NEAR SAN JACINTO, CA (National stream- quality accounting network station)

wATi.ái;ILILITY NECURPS

LOCATION --.Lat 33 °49'18 ",long 116 °58'01 ",in NE% sec.I5, T.4 S., R.1 W., San Bernardino County, at west portal of San Jacinto Tunnel, 1.7 mi(2.8 km) southeast of Gilman Hot Springs, and 2.5 ni(40 km) north of San Jacinto.

PERIOD OF SECOYD.- -pater year 1.:,70 to current year. CHEMICAL ANALYSES: Water year 1975 to current scar. SEDIMENT RECORDS: Water year 1975 to current year (parti::1- record star on:.

REM:1RkS...(ischarge values were furnished by Metropolitan 'n;:tcr District frog the aqueduct records.

CHEMICAL ANALYSES, WATER YEAR OCTOBER:..., TO S.CI'TÜMBER I977

SRE- SRE- CIFIC CIFIC INSTAN- CON - INSTAN- CON - TANEOUS DUCT- TANEOUS DUCT- OIS- ANC( TEMRER- DIS- ANCE TEMPER- T1NE CHARGE (MICRO- ATORE 71 HE CHARGE IMICRO- ATORE DATE (CES) MHOS1 IDEO C1 DATE (CFSI NMOSI (DEG Cl

OCT DEC 04... 0700 925 O50 23.0 09... 0650 924 1070 3.0 05... 0650 925 040 23.5 0900 924 1040 3.0 06... 0710 960 060 23.5 12... 0650 924 1070 2.0 07... 0650 943 060 22.0 14... 0655 911 1060 3.0 11... 0710 936 070 22.0 15... 0645 920 1060 3.0 920 12... 0650 940 050 22.0 16... 0655 1060 3.0 13... 0650 940 060 22.0 0830 911 1060 2.0 14... 0650 940 050 22.0 0830 909 1060 2.0 18... 0705 940 060 22.0 0815 909 1060 2.0 19... 0650 940. 050 22.0 0820 909 1070 2.0 22... 1115 S30 CEr 22.5 0820 683 1070 2.0 26... 0684 684 030 21.0 1830 690 1070 2.0 2T... 0684 684 050 21.0 JN 28... 0687 687 040 19.0 0705 690 1060 1.0 29... 0687 687 040 18.0 0700 490 1060 1.0 NOV 0655 707 1060 1.0 01... 0637 637 030 19.0 0645 456 1060 1.0 02... 0645 678 040 19.0 0700 452 1060 0.0 03... 0650 653 040 19.0 0650 452 1060 0.0 04... 0645 653 040 19.0 06SS 452 1160 0.0 08... 0700 686 040 19.0 1000 452 1060 0.0 09... 0650 673 030 19.0 0700 910 1080 0.0 10... 0645 705 030 19.0 0650 150 1090 1.0 11... 0650 717 040 18.0 0650 150 1080 1.0 15... 0705 705 040 18.0 1520 120 1080 1.0 16... 0650 687 040 18.0 20... 0645 140 1090 1.0 17... 0650 687 040 18.0 24... 0700 120 1080 2.0 18... 0650 687 040 18.0 25... 0650 120 1080 1.5 22... 0705 657 040 18.0 0650 120 1080 2.0 23... 0650 675 040 18.0 27... 0650 510 1080 2.0 24... 0645 675 040 17.0 31... 0700 250 1080 2.0 FER 24... 0930 675 020 17.0 29... 0655 674 070 12.0 01... 0650 300 1080 2.0 30... 0705 674 070 12.0 02... 0650 700 1080 2.0 DEC 03... 0650 680 1080 1.0 01... 0700 674 060 12.0 07... 0700 680 1080 1.0 02... 0700 674 070 12.0 08... 0650 680 1090 2.3 06... 0650 933 070 14.0 09... 0650 680 1080 2.0 07... 0655 924 070 14.0 10... 0650 680 1080 2.0 OB... 0650 924 070 14.0 11... 1000 690 1080 2.0 COLORADO RIVER MAIN STEM

)9::4 I90 COI.ORARO RIVER AQUEDUCT NEAR SAN JACI'TO, CA-- Centinucd

CHEMICALANALYSES. WATER YEAR OCTORIIR 1975 TO S1:PTTMTI 197-

SPE- SPE- CIFIC CIFIC INSTAN- CON- INSTAN. CON - TANfOUS DUCT- TAHE0U5 DUCT- DIS- ANGE )EMPER- OIS- ANCE TEMT-ER- 71E CHARGE IMICRO- ATURE TIME CHARGE )MICHO- ATOME DATE (CFSI 8H05) (DEG C) DATE (CFS) MH0S1 TOEG C)

FES APR 0700 14... 0700 1680 090 11.5 18... 1710 l0ß0 18.0 15... 0650 1680 090 11.5 20... 0645 1690 (080 18.5 21... 16... 0650 1680 110 13.0 0640 (690 1090 18.0 17... 0650 1680 090 13.0 25... 0700 1870 (090 18.5 21... 0700 1680 100 13.5 26... 0650 1870 1070 19.0 26... 22... 0700 1680 ORO 13.5 1030 1870 (090 20.5 27... 0650 23... 0650 1680 1,00 13.5 1870 (070 19.5 24... 0645 1660 100 28... 0645 1880 (080 (9.0 13.5 MAY 28... 0700 1690 090 13.5 MAP 02... 0650 1860 (080 18.5 03... 01... 0650 1690 080 13.5 1700 1860 1070 19.5 05... 0650 1870 02... 0650 1700 100 13.5 1060 20.0 06... O650 1860 03... 0650 1830 080 13.5 1070 20.0 09... 0650 07... 1230 1820 100 14.5 I870 1070 19.0 10... 0700 1870 08... 0650 1820 ORO 14.5 1070 19.0 0645 09... 0650 1820 100 15.0 11.... 1880 1060 19.0 12... 0645 1880 In... 0645 1930 100 14.5 IOb0 19.0 16... 0650 1870 1070 20.0 14... 0645 1830 090 13.5 17... 0700 1880 1070 20.0 15... 0650 1850 100 13.5 18... 0645 1890 16... 0650 1860 090 13.5 1060 19.0 19... 0650 1890 1080 19.5 17... 0650 11430 100 13.5 21... 0700 21... 0700 1850 100 14.5 1900 1070 23.5 22... 0645 1900 22... 0650 1050 090 14.5 1070 23.5 23... 23... 0650 1850 090 14.5 0645 1900 1060 23.5 24... 0650 1850 090 15.5 23... 0650 1860 1080 20.5 24... 0645 28... 0650 1860 090 14.5 1870 1070 20.5 24... 1870 29... 0640 1860 070 14.5 1015 1080 20.5 25... 0645 29... 1000 1860 090 15.5 1870 1080 19.5 30... 0645 1860 090 14.5 26... 0645 1730 1070 26.0 26... 0650 1880 31... 0650 1860 060 14.5 1080 20.0 APR 27... 0650 1930 1060 24.0 31... 0700 1880 04... 0650 1960 090 14.5 1070 22.0 JIIN 05... 0650 1860 OTO 14.5 01... 0645 0b... 0650 1960 070 15.5 1900 1080 23.0 02... 07... 0645 1860 040 15.5 0645 1900 (080 23.0 03... 0645 11... 1220 1860 060 18.0 1900 1070 23.0 06... 0100 (900 1070 12... 0445 1860 080 16.5 24.0 01... 0650 1910 13... 0650 1870 080 16.5 (070 24.0 GB... OEA^ 14... 0645 1870 090 18.0 '10 1070 24.0 09... 0645 19(0 23.5 17... 0645 1710 040 18.5 1070 COLORADO RIVER MAIS STEM 43

094.4190 COLORADO RIVER AQUEDUCT NEAR SAN JACI7TT, CA-Continue

CHEMICAL ANALYSES, WATER YEAR OCTOBER 1976 TO SEPTi,MPLR 1977

SPE- Srt- CIFIC C1FIC INSTAN- CON - INSTAN- CON- TANFOUS OUCT- TAMFOUS DUCT- 01S- ANCE TEMPER- DIS- ANCE TEMPER- TINS TIME CHARGE )MICRO- ATORE CHARGE 181040- ATORE DATE ICES) RH051 IDEE C1 DATE (CFS) MHOSI (DEG CI

JUN AU. 13... 0645 1900 1070 23.5 18... 0650 1930 1050 25.0 14... 0700 1890 1080 23.5 22... 0645 1720 1060 26.5 15... 0650 1900 1070 23.0 23... 0700 1730 1060 26.5 16... 0100 1990 1070 23.5 24... 0650 1740 1050 25.5 20... 0930 1900 1070 23.5 25... 0645 1720 1050 25.5 22... 0945 1900 1060 25.5 25... 1045 1740 1020 27.5 28... 0650 1920 1070 24.0 29... 0650 1750 1060 25.5 29... 0650 1920 1050 25.0 30... 0650 1730 1060 25.5 1070 25.5 30... 0650 I900 1070 25.5 31... 0650 1560 JUL SEP 25.5 04... 1130 1900 1070 25.5 01... 0700 1730 1040 0850 1070 26.5 05... 0650 1900 1070 25.0 06... 1920 06... 0650 1900 1060 24.5 07... 0650 1920 1060 26.5 07... 0650 1890 1070 25.0 98... 0650 1910 1070 26.5 11... 0700 1900 1060 24.5 19... 1530 1360 1060 25.0 25.0 12... 0645 1910 1070 25.0 2n... 1530 1370 1070 13... 0645 1890 1070 25.0 21... 0945 1730 1060 25.0 14... 0650 1890 1080 25.0 22... 0650 1730 1060 2.0 18... 0650 1900 1070 26.5 23... 0945 1930 1060 25.5 19... 0450 1910 1070 26.5 28... 0600 1930 1040 24.0 20... 0655 1910 1060 25.5 27... 0645 1930 1060 24.0 21... 0650 1910 1070 25.5 28... 0640 1930 1060 24.0 25... 0650 1910 1070 25.5 30... 1630 1920 1060 24.0 26... 0700 1920 1060 25.5 27... 0645 1930 1070 26.0 27... 1000 1930 1060 21.5 28... 0650 1930 1050 26.0 29... 0655 1910 1060 26.0 AUG 01... 0650 1920 1070 26.5 02... 0645 1920 1070 26.5 03... 0650 1920 1060 26.5 04... 0645 1920 1060 26.5 08... 0650 1920 1070 26.5 09... 0650 1910 1070 26.5 10... 0650 1900 1060 26.5 11... 0645 1910 1060 26.5 15... 0650 1910 1060 26.5 16... 0650 1910 1060 26.5 17... 0650 1930 1050 26.5 CO LORAUO RIPER MAIN STEM

09.124I90 COLORADO RIVER AQUEDUCT NEAR SAN JACINTO, CA-- Continued CHEMICAL ANALYSES. rAT£R YEAR OCTOBER 197$ ID S£PTEMRER 1477

FECAL DIS- FECAL STREP- NON- DIS - SOLVED INSTAN- COLI- TOCOCCI CAR. SOLVED MAD. DIS - TANFOUS Tug. FORM KF AGAR HARO- BONATE CAL- NE- SOLVED OIS- PM RID- .7IUM MF I COL. NESS HARO- CIUN SIDS SODIUM TIrE CHARGE ITY ICA.MG) NESS (CA) (MG) (NA) DATE (CFc) (UNITS) (JTU1 100 ML) 100 ML) (MG /LI IMG /L) (MG /L1 IMG /L) IMG /L1

()rT 930 7?... 1115 8.2 1 RI N16 310 190 77 29 100 NOV 24... 0930 675 8.3 1 82 89 310 210 76 28 100 DEC 924 R.1 09... 0900 1 RO 89 310 200 78 29 100 ,(AN 12... 1000 452 4.2 1 91 FI 340 210 86 30 100 FEN 8.2 11... 1000 1690 1 FO R2 340 210 83 31 110 MAP

29... 1000 1860 ' 8,2 2 RO 89 340 210 R5 31 100 APP

26... 1030 1870 8.0 1 90 142 330 200 80 31 100 MAV

74... 1015 1870 7.9 1 BB 330 200 83 29 100 JON 22... 0945 1900 7.8 2 BO 71 330 200 85 29 100 JUL 27... 1000 1930 8.0 2 HO Ble 330 200 83 30 110 ur.

25... 1045 1740 7.8 1 88 28 320 200 78 30 100 çFP 23... 0945 1930 1.7 2 02 31 320 200 80 30 92

DIS- SOOIUM SOLVED als- OIS- PO- AD- ALrA- DI5- SOLVED SOLVED OIS- çORP. TAç- BIGAR- CAR. UNITY CARSON SOLVED CMLO- FLUG- SOLVED PERCENT TION SIUM BORATE BONATE AS DIOXIDE SULFATE RIDE RIDE SILICA RATIO tKl SODIUM (8CO3) tCO3) CAC03 (CO?) (5047 (CLI tEl 15102) DATE 184/LI IMG/L) tMG/L) (MG/L) (HD/Li (MG /LI (MG /L1 tMG /l) (MG /L)

n T Al 22... 2.5 5.1 14H 0 122 1.5 300 90 .3 NOV 8.3 41 2 .. 2.5 5.3 114. 0 94 .9 290 88 .4 7.8 DEC 09... 40 2.5 5.3 742 0 116 1.8 290 90 .4 8.8 ,) A4 39 12... 7.4 4.9 157 0 129 1.6 290 88 .4 FE' 7.8 41 2.6 5.1 154 0 126 1.6 310 98 .3 1.7 MAP ?9... 39 2.4 4.7 157 0 129 1.6 290 93 .4 8.4 4PR ?6... 39 2.4 4.8 160 0 130 2.6 290 93 .4 6.6 MAY 24... 40 7.4 5.0 160 0 130 3.2 280 85 .4 6.7 JUN 39 ?2... 2.4 4.8 160 0 130 4.1 280 87 .3 7.7 .'L 27... 42 2.6 4.9 160 0 130 2.6 290 88 .3 8,1 AuG 25... 40 2.4 4,8 150 0 120 3.8 280 93 .3 8.6 cEP 73... 38 2.2 4.R 150 0 120 4.8 290 88 .3 9.0

.. Results based on colony court outside the acceptablerange (non -ideal colony count). COLORADO RIVER MAIN STTM

09424190 COLORADO RIVER AQUEDUCT NEAR SAN .JACINTO, CACont lnuod CNENICAL ANALYSES. WATER YEAR OCTOBER 1976 TO SEPTENBEN 1977

DIS- DIS- TOTAL TOTAL SOLVED SOLVED DIS - DIS- TOTAL KJEL- PNYTO- SOLIOS SOLIDS SOLVED SOLVED NITRITE DANI TOTAL TOTAL TOTAL PLANK - (RESI- (SUN OF SOLIDS SOLIDS PLUS NITRO- NITRO- NITRO- PNOS- TON DUF AT CONSTI- (TONS (TONS NITRATE GEN GEN GEN PNORUS (CELLS 140 C) TUENTS) PER PER (N) (N) (NI (N01) (P) PER DATE (mG /L) (NG /LI AC -FT) DAY) (MG /LI (wG /I) (MG /LI (NG /L) (NG /LI Nl1

OCT 22... 692 683 .94 1740 .16 .27 .4) 1.9 .01 700 NOV 24... 703 652 .96 1280 .15 .00 .15 .66 .03 4600 DEC 09... 713 672 .97 1780 .38 .20 .59 2.6 .03 3200 JAN 12... 716 685 .97 874 .19 .14 .33 1.5 .00 5500 FEB 11... 721 721 .98 3290 .24 .64 .88 3.9 .01 450 .AR 29... 728 690 .99 3660 .13 .54 .67 3.0 .05 APR 26... 722 685 .98 3650 .13 .38 .51 2.3 .01 MAY 24... 707 668 .96 3570 .15 .22 .37 1.6 .01 2000 JUN 22... 686 673 .93 3520 .12 .54 .66 2.9 .03 26000 JUL 27... 71? 693 .97 3710 .31 .45 .76 3.4 .01 7100 AUG 25... 688 669 .94 3230 .11 .49 .60 2.7 .02 300 SEP 23... 681 668 .93 3550 .09 .02 27000 COLORADO RIVER MAIS STEM

n94'41 ?O COLORADO RIVER AQUEDUCT NEAR SAN JACINTO, CA -- Continued

CHEMICAL ANALYSES. wATER YEAR OCTOBER 1976 TO SEPTEMBER 1977

SUS- 015- SUS- DIS- SUS- 01S- TOTAL PENDED SOLVED TOTAL PENDED SOLVED SuS- TOTAL PENDED SOLVED CAD- CAO- CAD- CLARO- CMRO- CMRO- TOTAL PENDEO ARSENIC ARSENIC ARSENIC MIUM MIUM MIUM MIUM MIUM MIUM COBALT COBALT TIME (AS1 (A5) (AS) (CD) (CO) (CD) (CR) (CR) (CR) (C01 (CO) DAIE (UG /L1 IUG /L1 (UG /LI IUG /L1 IUG /LI IUG /L1 (UG /LI (UG /L) (UG /L) (UG /L) (UG /LI

OCT

22... 1115 2 0 2 <10 <9 1 0 0 0 <50 <47 JAN

12... 1000 2 1 1 <10 <10 0 0 0 o <50 <50 APR

26... 1030 2 2 0 <10 <9 1 0 0 0 <50 <50 JUL 27... 1000 1 -- 2

SUS - DIS- SUS- DIS- DMS- SUS- 015- TOTAL PENDED SOLVED TOTAL PENDED SOLVED TOTAL SOLVED TOTAL PENDED SOLVED MAN- MAN - COBALT COPPER COPPER COPPER IRON IRON LEAD LEAD LEAD GANESE GANESE (CO) (CUI (CU) (CU) (FE) (FE) (PB) (PS) (PR) (MN) INN) DATE tUG /L1 lUG /L1 IUG /LI (UG /L1 (UG /L1 10G/L1 IUG /L) IUG /LJ (UG /L) IUG /LI (VG/L1 OCT 22... 3 <10 <8 2 100 20 100 97 3 10 0 JAN 12... a <10 <9 1 60 10 <100 <98 2 10 0 APP 26... 0 <6 <10 50 IC <100 <99 I 20 20 JUL 0 27... 10 6 60 30 <(00 <9l 9 8 8

DIS- SUS- DIS- SOLVED SUS- OIS- TOTAL PENDED SOLVED SUS- DIS- TOTAL MAN. TOTAL PENDED SOLVED SELE- SELE- SELE- TOTAL PENDED SOLVED ORGANIC GANESE MERCURY MERCURY MERCURY NIUM NIUM NIUM ZINC ZINC ZINC CARBON (MN) IMO) (MG) tMGI (5EI (SE) (SE) (ZN1 (ZN) (2N) ICI DATE IUG /L) IUG /L1 1UG /LI lUG /L1 IUG /Li lUG /l) IUG /LI IUG /L1 (UG /L) lUG /L1 (MG /L)

OCT 22... 10 -- .0 3 0 3 10 0 20 2.9 JAN 12... 10 .0 .0 .0 0 30 0 20 4.0 APR 26... 0 .0 .0 .0 1 3 10 0 10 5.6 JUL 27... .0 .0 .1 -- 30 20 8 6.7

395 COLORADO !:IVE ?LAISSTI''t 37

n9424190 COLORADO RIVER AQUEDUCT NEAT:SAN JACINTO,CA- -Continued

QUALITATIVE AND ASSOCIATED QUANTITATIVE ANALYSES OF BIOLOGICALDATA, WATERYEAR OCTOBER 197bTO SEPTEMBER 1977

î INTO Pi t':!: iI': DATE OCT22.76 NOV 24.76 DEC 9.76 JAN 12.77 FEB11.77 TIME 1115 0930 0900 1000 1000

TOTAL CELLS /ML 700 4600 3200 5500 450

DIvERSITYt DIVISION 0.6 1.6 1.1 0.6 1.1 .CLASS 0.6 1.6 1.1 0.6 1.1 ..ORDER 1.2 2.4 1.9 1.5 1.3 ,.,FAMILY 2.1 2.8 2.7 1.6 1.6 ....GENUS 2.1 3.0 2.9 1.8 1.7

CELLS PER- CELLS PER- CELLS PER- CELLS PER- CELLS PER. ORGANISM /ML CENT /ML CENT /ML CENT /ML CENT /ML CENT

CMLOROPNYTA (GREEN ALGAEI .CMLOROPMYCERE ..CI+LOR000CCALES ...COELASTRACEAE ....COELASTRUM 0 ...MICRACTINIACEAE ....GOLENKINjA ....MICRACTINIUM ...00OYSTACEAE ....ANKSSTROOESMUS 130 3 23 1 -- -

....OICTYOSPMAERIUM 200 4 -- - 28 1 ....FRANCEI4 ....KIRCMNERIELLA TO 2 0

....000YSTIS 5e 1 ....SELENASTRUM ....TETRAEDRON 0 ...SCENEDESMACEAE . ..SCENEDESMUS 580 13 230 7 120 2 34 7 .TETRASPORALES ..C000OMYAACEAE ELAKATOTMRIIt .,2ALMELLACE6E GLOEOCYSTIS . SPMAEROCYSTIS ..ULOTRICNALES ...ULOTRICMACEAE .. .MoRMIO1UM 87 2 ..vOLVOCALES ...CMLAMYDOMONADACEAE

CMLAMYDOMONAS 87 2 23 1 13 3 ...vOLVOCACEAE

. ..GONILIM .ZYGNEMATALES ...DESMIDIACEAE ....STAUPASTMUM

See footnotes at end of table. COLORADO RIVER MAIN STIM

(3 2419(1 COLORADO RIVER AQUEDUCT NEAR SAS JACINTO, CAuntinut.d

QUALITATIVE AND ASSOCIATED QUANTITATIVEANALYSESOF BIOLOGICALRATA, WATER YEAR OCTOBER 1)7uTO SLPTIHER1977

PitYTOPLANi;TO': DATE MAT 24.77 JUN 2207 JUL 27.77 AUG 2507 SEP 23.77 T1ME 1015 0945 1000 1045 0945

TOTAL CELLS/ML 2000 26000 1100 300 27000

UlvENSTTrI DIVISION 1.9 0.5 1.6 1.0 1.4 .CLASS 2.1 0.5 1.8 1.1 1.4 ..ORDER 2.5 0.6 2.2 2.1 2.3 ...Family 3.0 0.6 2.6 2.4 2.6 ....GENUS 3.0 0.6 2.6 2.4 3.2

CELLS PER- CELLS PER- CELLS PER- CELLS PER_ CELLS PER - ORGANISM /ML CENT /ML CENT /ML CENT /ML CENT AML CENT

CMLOROPMTT4 (GREEN ALGAE) .CHLOROPHYCEAE ..CHLOOOCOCCALES ...COELASTRACEAE ....COELASTRUM 0 ...MICRACTINIACEAE ....GOLENKINIA .- - -- - 1500 5 ... MICRACTINIUM -- - 200 3 ... TStACEAE ....AN915TR00ES9US -- - 5 2 340 1 ....01CTYOSPHAERIUM ------1600 6 ....FPl9CE14 -- - .....IRCMNERIELLA -- - ....00Cr5T15 -- - 230 1 19 6 -- - ....SELENASTRUM 140 7 - ....TETRAE0P0N -- - 0 -- - 230 1 ...SCENEOESMACEAE 9 . ..SCENEDESMUS 120 6 32o 670 57.19 ..TETPASPORALES ...COCCOMY u CEAE .. .EtA!:TOiMPtx 23 1 -- ...PALMELLACEAE ....GLOEOCYSTIS -

. .,SPHAEROCYSTIS - -- 140.68 ..uLOTRICNALES ...uLOTRICMACEAE , ..MORMIDIUM - ..VOLVOCALES ...CNLAMrOOMONAOACEAE ....CNLAMYOOMONAS 210 10 340 5 - 570 2 ...0LVOC4CEAE CONIUM 140 7 - ..ZrGNEMATLES ...OESMiDIACEAE ....sTAUPASTRUM 14 5

CMRTSOPNYTA .aCILLARIOPNYCEAE "CENTRALES ...COSCiNnOISCACEAE 9 - 2000 8 ....CYCLOTELLA 12 1 -- - 640 ....RELOSi0A -- - -- _ -- -

. ..STEPMANOOISCUS 0 340 1 ..PENN:LES ...ACMNANTMACEAE ....ACMNANTMES -- -- - ., .00000NEIS -- - -- ...CYMRELLACEAE

....aMPHORA 12 1

....CYMBELLA 12 1 -- -- - ...DIAT0MACEAE .. .DIATOMA -- - ...FPAGiLARiCEAE ....ASTERIONELLA ------, ,.FRAGILARIA 200 1 ------

....SYNEORA 1000 4 - 1200.18 2700 10 ...GOMPMONE14ATACE4E ....GOMPHONEMA ...NAVICULCEAE ....NAVICULA 59 3 0 0 24 8 910 3 ....PINN(ILAPI -- - -- _ -- _ -- ...NITZSCMIaCEaE ..NITISCHIA 23 1 340 1 .C..9YSOPMrCE4E ..CtiPYSO4.ONA04LE5 ...MALLOMONADACEAE ....MALLOMONaS o -- ...00MPOONaOACEAE

....01NOPRYON -- - 390 1 130 2 340 1 ...,GCMROMONAS 160 8 ------

Sec ïootnctes aten..

397 COLORADO RIVER MAIN STEM 49

09424190 COLORADO RICER AQUEDUCT SPAR NAN .1AUINTII,:.A-- Continued QUALITATIVE AND ASSOCIATED QUANTITATIVE ANALYSES OF BIOLoGICAL DATA, RATER YEAR OCTOBER 17ío TO SEPTEMBER 1977

P:IYTOI'LANATCN

....MELOStR 110116 -- - 120 4 800a17 -- - . ..STEPNANOOISCUS -- - ..PENNALES .,.ACHNANTNACEAE 4 ...ACMNANTHES 23 3 150 3 810125 200 4 I ....00000NEIS -- - 0 -- - ...CYMtlELLACEAE ....AMPHORA -- - -- ' ------_ 1 25 6 J 44 1 190 6 28 ....CYMBELLA " 23 ...OIATOMAC£AE ....DIATOMA o 93 3 0 I ..FRAGILARIACEAE ....ASTERIONELLA ------0 - - 21 5 .,,,FRAGILARIA 0 46 1 28 1 0 -- - .. SYNEDRA 0 -- - ...GONPHONEMATACEAE 1 - -- - .. .GONPMONENa . 0 23 - ..NAVICULACEAE 4 1 46 1 57 1 ....NAVICULA 90 13 58 I 46 I ...PINNULARIA ------_- - ...NITISCMIACEAE 13 3 ..NITZSCHIA 340148 58 1 23 1 .CMRYSOPHYCEAE ..CHRYSONONAOALES ...MALLOMONAOACEAE ....MALLONONAS ...00NROMONADACEAE ....GINORRYON ...00MROMONAS

DATE OCT22.76 NOV24.76 DEC 9.76 JAN12,77 FEB11.77 TINE 1115 0930 0900 1000 1000

CELLS PER. CELLS PER- CELLS PER- CELLS PER- CELLS PER - ORGANISM /ML CENT /ML CENT /ML CENT /ML CENT /NL CENT

CYANOPHYTA (BLUE-GREENALGAEI .CYANOPNYCEAE ..CMR000OCCALES ...CNR000OCCAEAE ....AGMENELLUM ....ANACTSTIS 510 11 2100. 39 ..NORMOGONALES ...OSCILLATORIACEAE ....LYNGRYA ....MICR000LEUS ------27001 49 ....OSCILLATORIA 1101 IR 1700 37 370 12 140 3

I 0 ....SPIRULINA -- - . -- - 23 ...R1vuLARIACEAE

. ..RAPMIDIOPSIS ..CMROCCOCCALES ...CMR000OCCAEAE ....GOMPHOSPHAERIA

EUGLENOPMYTA IEUGLEN0I051 .CRYPYOPNYCEAE ..CRYpTOMONIDALES ...CPYPTOCMRYSIDACEAE ....CMROOMONAS 23 I O ...CRTPTOMONODACEAE ..CRYPTOMONAS 0 330 72 .EIIGLENOPMYCEAE ..EUGLENALES ...EUGLENACEAE ....EUGLENA -- -- ....PHACUS ...TRACMELOMONAS PYRRMOPNTTA (FIRE ALGAEI .OINOPHYCEaE ..PERIDtNIALES ...GLENOOINIACEAE ....GLENOOINiUM 44 1 ...PERIOtxIaCEA£ ....PERIDINIUM

See footnotes at end of Table. COLORADO RIVER MAIN STEM

09424190 COLORADO RIVER AQUEDUCT NEAR SAN JAL) YTU, CA -- Continued

QUALITATIVE AND ASSOCIATED QUANTITATIVE ANALYSES OF BIOLOGICAL DATA. ;WATER YEAR ,^.CTOBLRI9YYo TO SEPTEMBER 1977

PHYTOPLANKTO.N

(WE MAT 24.77 .JUN 22.77 JUL 27.77 AUG 25.77 SEP 23.77 T1M£ 10I5 0945 1000 1045 0945

CELLS PER - CELLS PER - CELLS PER. CELLS PEA- CELLS RE" ORGANISM /ML CENT /ML CENT /ML CENT /ML CENT /ML CENT CTANOPHTTA )BLUE -GREEN ALGAE) ,CYANOPMYCEAC .. CMRQCCOCCALES ...CMR000OCCAEAE .... AGMENELLUM 1800 7 .. A NACYSTIS h80r 33 73000 27 HoRMOGONALES 0 ...OSCILLATORIACEAE ....LTNGRY* 3100s 44 -- - 6300. 23 ....MICR000LEUS ....OSCILLATORIA 19 6 680 3 ....SPIRULINA ...RIYULARIACEAE . ..AAPHiOIOPSIS 270 ..CHao000CCALES ..CNR000OCCAEAE ....GOMPHOSPHAERIA 240000 91

EUGLENOPHYTA JEUGLENOIDS) .Cara7nPMrCEAE ..CRYPTOMONIOALES ...CRYPTOCHaYSjOACEAE

....CrR00M0NA5 350. 17 100 1 9 3 ...CRYPTOMONOOACEAE ..CRYPTOMONAS 94 S .EUGLENOPMYCEAE ..EGc ES .EUGLENACEAE g11GLENA 0 +- ....PMACUS 0 ....tPACMELOMONAS 5 2 RYRRMOPHYTA (FIRE ALGAE: .0INOPMYCEAE ..PERIOINIALES .,.GLENOOINIACEAE ....GLENODINIUM ...PERIDINIACEAE

....PERi01NIUM o o

NOTE: 4 - DOMINANT ORGANISM, EQUAL TO OR GREATER THAN I5% - OBSERVED ORGANISM. MAY NOT HavE BEEN COUNTED; LESS IMAM 1/21

PERI PIIYTON

Biomass (b;a') Chlorophyll Chlcrophyll Length of exposure Biomass a b pigment Sampling Date (days) Dry weight Ash weight (mg7m') (mg7m:i ratio method Sept. 9. 1976 29 10.3 8.77 .1.14 .111 SO:: Polyethylene strip July :7,1977 35 0.0 0.0 0.0 0.001 Polyethylene strip Data not previously published. APPENDIX K

400 Appendix K. Froth Flotation Effluent Reuse Study..

Comparative Metallurgical Summary for Standard Water and Sewage Effluent Flotation Systems

Concentrate Tail C Recovery Water Type Wt . % % Cu % M( Mo Cu Mo Standard 6.8 6.52 0.1 7035 89.7 ±1.0 71.7'`1.0 Sewage 8.5 5.09 0.0" 0058 87.3 ±0.9 55.5 ±1.7 Comparative Metallurgical Summary for Foam Fractionation Tests Cu % Mo Water Recovery Recovery Standard Water 89.7 71.7 Sewage Effient 87.8 55.4 Foam Fractionated Sewage Efflue;_*_ 88.4 55.8

Comparative Metallurgical Summary` for Ion Exchange Tests

7 Cu % Mo Recovery Recovery Standard Water 89.7 71.7 Sewage Effluent 87.2 56.5 Filtered Effluent 87.2 56.3 Cationic Exchange 87.5 64.9 Anionic Exchange 89.5 71.9 Cationic -Anionic

Exchange - 89.2 69.6 'Effect of Sewage Effluent Ozonatior. on Flotation Response

`fo Recovery Recovery Standard Water 82.06 70.57 Filtered Effluent 79.26 58.66 6 min. Ozonation 79.97 67.14 20 min. Ozonation 82.20 69.12 60 min. Ozonation 82.01 72.95 'Comparison uir. - - - -. Sewage Effluent and Standard Water Containing Humic Acid (HA) % Cu Mo TOC, Recovery Recovery o ^m Standard Water 82.06 70.57 <0.5 Filtered Effluent 79.25 58.66 10.0 10 ppm C as HA 80.41 67.03 8.0 20 ppm C as HA 51.32 64.88 20.8 40 ppm C as HA 79.68 60.20 35.9

401 Appendix K. (Cont.)

Comparison of Flotation Response for Standard Water, Filtered Effluent, and Lime Treated Effluent % Cu % Mo TOC, Recovery Recovery ppm Standard Water 82.06 70.57 <0.5 Filtered Effluent 75.42 48.46 22.0

Lime Treatment 83.41 65.42 ' 7.4

402 APPENDIX X

403 system in Arizona. Appendix XX. Well- numbering

e A

i SALT r(R aSC.ME et t , f I t,

C r , .- 4 1 f.--- tr

RSC lfI1fjji

.I a 0' It! ¡ i

Is tt . .f , 14, U a 11T.J01i1;1,I,IJ. )a'rr!i,,NA

n M

The well numbers used by the Geological Survey in Arizona are in accordance with the Bureau of Land Management's system of land subdivision.The land survey in Arizona is based on the Gila and Salt River meridian and base line, which divide the State into four quadrants. These quadrants are designated counterclockwise by the capital letters A, B, C, and D.All land north and east of the point of origin is in A quadrant, that north and west in B quadrant, that south and west in C quadrant, and that south and east in D quadrant. The first digit of a well number indicates the township, the second the range, and the third the section in which the well is situated. The lowercase letters a, b, c, and d after the section number indicate the well location within the section. The first letter denotes a particular 160 -acre tract, the second the 40- acre tract, and the third the 10 -acre tract.These letters also are as- signed ina counterclockwise direction, beginning in the northeast quarter. If the location is known within the 10 -acre tract, three lowercase letters are shown in the well number.In the example shown, well number (D- 4- 5)19caa designates the well as being in the NE.`- ,NE`, -SWsec.19, T. 4 S., R. 5 E.Where more than one well is within a 10 -acre tract, consecutive nlirnhers 1707irnin7 t.tttlre `: n ?c ci. "r,-

404 APPENDIX Y

405 DIVERSIONS

Sec. O Site Location Abe

1. AA12005 T13S R13E 06 Pre -Historic

1. AA12006 T13S R13E 06 Pre -Historic

1. AÁ12020 T13S R13E 06 Pre -Historic

2. AÁ12024 T13S R13E 09 Pre -Historic

3. AA12007 T12S R13E 32 Pre -Historic

4. AA12008 T12S R13E 28 Pre -Historic

5. AA12009 T13S R13E 07 Pre- Historic

5. AA12010 T13S R13E 07 Pre -Historic

5. AÁ12055 T13S R13E 07 Historic

6. AA12027 T12S R12E 17 Pre -Historic

6. AA12057 T12S R12E 17 Pre -Historic

6. AÁ12058 T12S R12E 17 Pre -Historic

6. AA12089 T12S R12E 17 Pre -Historic

7. AA12011 T13S R13E 08 Pre -Historic

7. AA12017 T13S R13E 08 Pre -Historic

7. AA12022 T13S R13E 08 Pre -Historic

7. AA12023 T13S R13E 08 Pre- Historic

8. AA12012 T13S R13E 17 Pre -Historic

8. ÁA12013 T13S R13E 17 Pre -Historic

9. AA12031 T13S R13E 22 Pre -Historic

9. AA12032 T13S R13E 22 Pre -Historic

9. AÁ12033 T13S R13E 22 Pre -Historic

9. AA12037 T13S R13E 22 Pre -Historic

10. AA12014 T13S R13E 16 Historic

10. ÁA12018 T13S R13E 16 Pre -Historic

10. AA12026 T13S R13E 16 Historic

10. AA12028 T13S R13E 16 Pre -Historic

11. ÁA12015 T13S R13E 21 Pre -Historic

11. ÁA12090 T13S R13E 21 Pre -Historic

11. ÁA12091 T13S R13E 21 Pre -Historic

11. ÁA12103 T13S R13E 21 Pre -Historic

11. Canals T13S R13E 21 Historic

12. BB09027 T12S R13E 27 Pre -Historic

406 Sec. II Site Location Age

12. ÁA12016 T13S R13E 27 Pre -Historic

12. AA12034 T13S R13E 27 Pre -Historic

12. AA12037 T13S R13E 27 Pre -Historic

12. AÁ12085 T13S R13E 27 Pre -Historic

13. AA12036 T11S R12E 33 Pre -Historic

14. AA12039 T11S R13E 28 Pre -Historic

14. AA12049 T11S R13E 28 Pre -Historic

15. AA12040 T12S R13E 31 Pre -Historic

16. AA12042 T13S R12E 01 Historic

17. AA12044 T13S R13E 34 Pre -Historic

17. AA12056 T13S R13E 34 Pre -Historic

17. AA12099 T13S R13E 34 Pre -Historic

17. BB13023 T13S R13E 34 Pre -Historic

17. historic canal, T13S R13E 34 Historic Flow. Wells Div. Siphon

18. AA12046 T13S R13E 20 Pre -Historic

18. AA12103 T13S R13E 20 Pre -Historic

19. ÁA12049 T11S R13E 29 Pre -Historic

20. AA12058 T12S R12E 08 Pre -Historic 21. AA12059 T12S R13E 06 Pre -Historic

22. AA12061 T12S R12E 05 Pre -Historic

23. AA12074 T12S R13E 31 Pre -Historic

24. AA12077 T12S R12E 18 Pre -Historic

25. AA12087 T12S R12E 07 Pre -Historic

26. Aä12093 T13S R13E 28 Pre -Historic

26. AA12095 T13S R13E 28 Pre -Historic

26. AA12104 T13S R13E 28 Pre -Historic

27. ÁA12107 T13S R13E 33 Pre- Historic

28. AA16003 T14S R13E 34 Pre -Historic 28. AA16025 T14S R13E 34 Pre -Historic 28. AA16045 T14S R13E 34 Pre -Historic

28. AA16046 T14S R13E 34 Pre -Historic

28. AA16053 T14S R13E 34 Pre -Historic

407 Sec.# Site Location Age

29. AA16007 T15S R13E 21 Pre -Historic

29. AA16008 T15S R13E 21 Historic

29. AA16009 T15S R13E 21 Historic

30. AA16007 T15S R13E 22 Pre -Historic

30. Berger Ranch R15S R13E 22 Historic

31. AA16011 T15S R13E 34 Historic

32. AA16012 T16S R13E 06 Pre -Historic

33. AA16017 T15S R13E 28 Pre -Historic

34. AA16028 T15S R13E 09 Historic

35. AA16029 T14S R13E 03 Pre -Historic

35. BB13023 T14S R13E 03 Pre -Historic

35. BB13085 T14S R13E 03 Pre -Historic

36. AA16040 T14S R13E 15 Pre -Historic

37. AA16049 T15S R13E 03 Pre -Historic

38. AA16050 T14S R13E 27 Pre -Historic

39. BB09001 T11S R14E 34 Pre -Historic

40. BB09003 T12S R14E 07 Pre- Historic

40. BB09075 T12S R14E 07 Historic

41. BB09004 T12S R14E 08 Pre -Historic

42. BB09007 T13S R14E 30 Pre -Historic

42. BB09009 T13S R14E 30 Pre -Historic

43. BB09011 T13S R14E 29 Pre -Historic

44. BB09014 T13S R14E 35 Pre- Historic

45. BB09014 T13S R14E 36 Pre -Historic

45. BB09072 T13S R14E 36 Historic

46. BB09032 T13S R15E 16 Pre -Historic

47. BB09033 T13S R15E 31 Pre -Historic

47. Univ. Canal T13S R15E 31 Historic

47. Doe Ditch T13S R15E 31 Historic

48. BB09038 T11S R14E 24 Pre -Historic

48. BB09067 T11S R14E 24 Pre -Historic

49. BB09039 T11S R13E 25 Pre -Historic

49. BB09088 T11S R13E 25 Pre -Historic

408 Sec. 4{ Site Location Age

50. BB09046 T13S RISE 29 Pre -Historic

51. BB09047 T12S R14E 04 Pre -Historic

52. BB09050 T13S R15E 14 Pre -Historic

53. BB09052 T11S R14E 33 Historic

53. BB09060 T11S R14E 33 Pre -Historic

54. BB09054 T13S R14E 25 Pre -Historic

54. Kennedy Ditch T13S R14E 25 Historic

54. Bingham Ditch T13S R14E 25 Historic a.k.a. Bayless Ditch

54. Cole Ditch T13S R14E 25 Historic

54. Corbett Ditch T13S R14E 25 Historic

55. BB09058 T13S R15E 32 Pre -Historic

55. Daily Ditch T13S RISE 32 Historic

55. Campbell Ditch T13S R15E 32 Historic

55. Romero Ditch T13S R15E 32 Historic

56. BB09067 T11S R14E 24 Pre -Historic

57. BB09068 T11S R14E 23 Pre -Historic

58. BB09073 T13S R15E 17 Pre -Historic

58. BB09076 T13S R15E 17 Pre -Historic

59. BB09077 T13S RISE 33 Pre -Historic

60. BB09079 T13S R15E 22 Pre -Historic

61. BB10003 T13S R16E 29 Pre -Historic

62. BB10006 T13S R16E 19 Pre -Historic

63. BB10019 T12S R18E 03 Pre -Historic

63. Warner Mill T14S R13E 14 Historic 63. Manning Canal T14S R13E 13 Historic 64. BB13008 T15S R13E 23 Pre -Historic 64. BB13008 T15S R13E 23 Pre -Historic 64. BB13048 T15S R13E 23 Pre -Historic 65. BB13010 T15S R15E 35 Pre -Historic 66. BB13012 T16S R14E 18 Pre -Historic 67. BB13012 T16S R14E 07 Pre -Historic 68. BB13015 T15S R13E 11 Pre -Historic 68. BB13074 T15S R13E 11 Pre -Historic

409 Sec. 11 Site Location Age

90. BB14079 T14S R16E 32 Historic

91. Santa Catalina T13S R14E 28 Historic Ditch & Irr. Co.

92. Diaz Ditch T13S R15E 30 Historic

92. Westbrook Ditch T13S R15E 30 Historic

93. Davidson Ditch T13S R14E 26 Historic

94. Aqua de la Mission T15S R13E 26 Historic

95. Acequia de la T15S R13E 35 Historic Punta de Agua

96. Flood Control T16S R13E 13 Historic

97. Canals (Warner's T14S R13E 10 Historic tailwater)

98. il il T14S R13E 11 Historic Not mapped BB10019 T12S R18E 03 Pre -Historic

411 APPENDIX B

299 i 191 f-,ti'.

Stochastic Process

If X(t) is the output from a stochastic process, the usual case, especially in hydrology, is a single time series of the process. That is, only one sample function is available from a process. Repeated samples are not available as is often the case for random variables. Therefore, the problem is much more complex and requires more assumptions or knowledge of the physical system. While this concept is elementary and obvious, it is quite often unsaid or overlooked. For stochastic processes the limit laws are of primary importance. 'The degree of uncertainty relative to random variables and stochastic processes is shown in the attached sketch (Figure 2). While this sketch is not all inclusive of the differences between random variables and stochastic processes, it does serve to illustrate the primary differences for hydrologic time series. It is obviously a simplification of the concepts of random variables and stochastic processes.

THUNDERSTORM RAINFALL MODEL

Many assumptions and simplifications are involved in developing a model of a physical process. This is certainly true in modeling thunderstorm rainfall. The physical processes causing a thunderstorm at a certain time and place are very complex, as are the processes determining depths, duration, and areal eNtent of the thunderstorm rainfall. Thus, many assumptions and simplifications are necessary to make model solutions practical.

A stochastic air -mass thunderstorm rainfall model for generating runoff- producing rainfall based upon certain assumptions and simplification has been proposed (Osborn, Lane, and Kagan, 1971). This model (CELTH -5) is developed in two parts. The first part, or routine, determines whether a storm will occur, and if so, the time of occurrence. The second part generates runoff -producing rainfall through addition of individual synthetic storm cells.

I. All runoff -producing storms for small (100- square -mile and less) watersheds in southeastern Arizona result from air -mass thunderstorms. These thunderstorms are the runoff "design" storms for small watersheds. Moist air for air -mass thunderstorms generally comes from the Gulf of Mexico.

300 2. Frontal activity is not impurtaniin runoff design in southeastern Arizona, although tropical storms off Baja California may move moist Pacific air into Arizona, particularly in September (Sellers, 1960). In southeastern Arizona (Walnut Gulch) storms occurring from "Pacific" air are still considered air -mass for small watershed design.

3. Storm probability of occurrence is based on 12 years of Walnut Gulch data. The process is assumed stationary, and the 12 -year record is assumed to adequately represent a longer record.

6. No two storms can occur within Less than 3 hours; two or more storms can occur in one day. There is a 1/5 chance of two storms occurring on the same day, 1/25 chance of three occurring, and so on. The fractions for multiple occurrence are multiplied times the regular probabilities. For example, ifthe model indicates the chance of a storm occuring before 2100 hours is 0.4, there would be a.08 probability of a second storm occurring on the same day.

7 Thunderstorms are assumed to be made up of three or more circular cells.

8. Individual cell center depth varies according to a negative exponential distribution.

9. Cells have a fixed diameter at near zero rainfall (.01 inch).

10. Cell depth -area relationship is linear from the center out to a radius of J (the radius for an area of one square mile).

At this radius the depth is 857, of center depth. From this "isohyet" down to .01 the relationship is logarithmic.

11. Cells within each thunderstorm develop sequentially both in tize and direction, although they may occur almost simultaneously. individual cells are temporally contiguous.

301 12. The model generates runoff -producing rainfall (0.5 in /hr or greater) continuously at any point, and this rainfall can be adequately described by depth, duration, and centroid.

13. The first thunderstorm cell can be centered anywhere in a specified field. Its location is random as determined by a uniform distribution.

14. The preferred direction of the second cell in respect to the first cell is random as determined with a uniform distribution.

MODEL VALIDITY

In order to test the validity of the storm rainfall model and thus determine whether the assumptions and simplifications incorporated are reasonable, itis necessary to compare observed with simulated rainfall characteristics. Also, since the objective in simulating thunderstorm rainfall is to obtain peak discharge predictions through a deterministic functional relation of rainfall and runoff, model validity can be tested by comparing observed peak discharge rates with those obtained with the rainfall- runoff functional relation and simulated rainfall. In this paper both types of comparisons are made. The functional relation used to obtain peak discharge for a given simulated thunderstorm rainfall is one previously developed for the Walnut Gulch watershed.

In addition to testing validity of assumptions and simplifications in the rainfall model, a sensitivity analysis was done to evaluate the uncertainty in values of rainfall model parameters.

2.6 - S

302 APPENDIX C

303 f-r,i r

Table 1.-- Period of record for streamfloo- gaging stations included in the statistical summaries-Continued 3

Period of record Gaging station

Name Page number

COLORADO RItTR 3ASL:- Continued amLO RI \TAR BASIN- Continued Santa Cru: River- Continued Taniue Verde Creek -Continue)

09484560 Cieneca Creek near Pantano 248 ' 09454590 Davidson Canyon hash near Vail 250 09484600 Pantano Nash near Vail 252

09485000 Rincon Creek near Tucson '-54 09486000 Rillito Creek near Tucson 257 09486300 Canada del Oro near Tucson 262 09486500 Santa Cruz River at Cortaro :64 09486800 Altar Nash near Three Points r '-68 09488500 Santa Rosa wash near Vaiva Vo, near Sells 70 09489000 Santa Cruz River near lancen l7+ 09489070 North Fork of East Fork Black River near Alpine 276 00489100 Black River near Maverick 278 09489200 I I Pacheta Creek at Maverick 280 09489499 Black River above Willow Creek diversion, near Point of Pines 282 00489700 Big Bonito Creek near Fort : Spathe 284 09490500 Black River near Fort :Spathe _86 09490800 North Fork White River near Greer 288 09491000 North Fork 'White River near 't.iare 290 09492400 East Fork White River near Fort Apache 292 09493000 White River near Fort Apache 294 Salt River: 09494300 Carrizo Creek above Corduroy Creek, near Show (ow 296 09494500 Corduroy Creek above Forestial° Creek, near Show low 298 11M11111=111 09495500 Forestial° Creek near Show low 300 09496000 Corduroy Creek near mouth, near Show Low 302 09496500 Carrizo Creek near Show low 305 Unnamed tributary: 09496600 Cibecue :m.1, tributary to Cerrito Creek, near Show low 307 09496700 Cibecue No. 2, tributary to Carrito Creek, near Show Low 309 09497500 Salt River near Cirvsotile 311 09497800 Cibecue Creek near Cirvsotile 315 09497900 Cherry Creek near Young 317 09497980 Cherry Creek near Globe 319 09499000 Salt River near Roosevelt 321 09498800 Tonto Creek near Gisela 326 1111=l 09498870 Rye Creek near Gisela 328 09499000 Tonto Creek above Gun Creek, near Roosevelt 330 Big Chino Wash (head of Verde River): - 09502800 Williamson Valley Wash near Paulden 334 Verde River:

Ì 09503000 Granite Creek near Prescott 336 095037,00 Verde River near Paulien 338 09504000 Verde River near Clarkdale 540 09504500 Oak Creek near Coenville 342 09505200 Wet beaver Creek near Rimrock 340 09505250 Red Tank Draw near Rimrock 148 Dry Beaver Creek: 09500300 Rattlesnake Canyon near Rimrock 09505350 Dry Beaver Creek near Rimrock 352 09505800 West Clear Creek near Co rop Verde 354 09507600 East Verde River near Pine 356 09507700 Webber Creek above West Fork Webber Creek, near Pine 358 09507980 360 ; East Verde River near Childs 09508300 Wet Bottom Creek near Childs 362 09508500 Verde River below Tangle Creek, above horseshoe Dam 364 09510070 West Fork Sycamore Creek above !tFarland Canyon, near Sunflower 3.6S 09510080 West Fork 5yeamore Creek near Sunflower 099510100 East Fork Sycamore Creek near Sunflower 99510150 Sycamore Creek near Sunflower Mesquite Wash: 09510180 Rock Creek near Sunflower 3"6 09510200 Sycamore Creek near Fort McDowell 3'8 09512300 Indian bend Wash at Scottsdale 56: 09512200 Salt River tributary in South !fountain Park, at Phoenix 392 09512400 Cave Creek at Phoenix 394 0'61'500 Agua Fria River near Payer 306 09512900 Agua Fria River near Rock Springs 390 09513730 New River near Rock Springs 59- 09513800 New River at New River 394 09513835 New River at Bell Road, near Peoria 396 09513860 Skunk Creek near Phoenix 398 09515500 Hassayampa River at Box damsite, near wickenburg ano 09517500 Centennial Wash near Arlington 403 09518000 Gila River above diversions, at Gillespie Jam 4P5 09520170 Rio Corne: near Ajo 409 SULFI3JR SPRING VALLEY

i WHlTLIm :L3Dì DRAW BASIN whitewater Draw: 09537200 Leslie Creek near 't.':eal ill 09537500 Whitewater Draw near Douglas 413

304 Table O. -- Flood- frequency data fOr selected streRmfloR- gaging stations -- Continued

DRAINAGE FL000 MAGNITUDE. IN CURIO FEET! PER COND. AREA FON INDICATED RECURRENCE INTER L. 1 YEARS STATION (IN SAUARE NUNBER STATION NAME PPRIUO 00 RECORD 411.451 02 OS 010 925 05 0104

04499500 SAN FRANCISCO RIVER AT 1491,1905-07, 2766.00 7230 17600 28000 45000 6)200 89160 CLIFTON, ARIL. 1911.75

09003500 BILLON CR NR POINT 0F PINES NR 1045-67 102.00 620 1510 2330 3670 4470 6256 NORENCI, ARIZ.

09446000 NTLLOM CR NR DOUBLE CIRCLE 1944 -67,1973 100.00 1040 3220 5630 9980 14300 19900 RANCH NR MORENCI. ARIZ.

09446500 EAGLE CR NR UOUPLE CIRCLE 1049. 67.1973 577,00 2500 6330 10000 10200 21800 20400 RANCH NR MURENC L ARIZ.

09497000 EAGLE Co ABV PUMPING PLANT NO 1032,1944 -75 613.00 2330 6200 10100 16700 22800 30100 MORENCI. ARIZ.

09446500 GILA R AT HEAD OF SAPPORO 1014.75' 7896.00 9700 20000 31600 99500 66900 86800 VALLEY NR SOLOMON. ARIL.

00456000 SAN SIMON RIVER NR SAN SIMON. 1923,1931 -41 814.00 2670 4680 6200 8290 9950 11700 ARIZ.

4840 7830 9950 10700 14000 17100 - 09457000 SAN SIMON RIVER NR SOLOMON, 1931 -75 2192.00 ARIZ.

00466540 GILA RIVER AT CALVA. ARIZ. 7930 -75 11470.00 6000 13800 22100 37800 54400 76406

00440500 SAN CARLOS RIVER NEAR PERTDOT. 1916,1930 -75 1027.00 7220 15400 22500 33000 02740 53000 ARIZ.

04070500 SAN PEDRO RIVER AT PALUMINAS. 1930-37,193590, 741.00 6390 10100 120410 16300 19000 21000 ARIZ. 1950-7,5

09471000 SAN PEDRO RIVER AT CHARLESTON. 1916-75 1210.06 6050 12500 17500 26000 34100 43e04 ARIZ.

09472000 SAN PEDRO RIVER NEAR 1026,1943-75 2030.00 7750 15200 27400 30400 39006 9R100 REDINOTON. ARIZ.

09972500 SAN PEDRO RIVER NR 4ARMOTM, 1926.1931-40 3610.00 16400 29300 39200 52800 .63840 75300 ARIZ.

00473000 ARAVAIPA CREEK NEAR MAMMOTH, 1914-21,1931-41. 741.00 9946 9530 13200 18400 22700 27900 ARIZ. 1066-75

09979000 GILA R Al KELVIN. ARIZ. 1891,1906.1007, 18011.00 19400 04000 70500 120600 173000 244400 1912.28

09074000 GILA R AT KELVIN. ARIZ. 1029-75 5125.00 7820 15000 21800 33100 44500 54310 DRAINAGE AREA BL COOLIDGE DAM

00078500 QUEEN CR AT 64ITLOR DAMSITE NR 1917-20.1948-59 144.00 9030 10600 17000 27900 38100 50100 SUPERIOR, ARIZ.

09480000 SANTA CRUZ RIVER NEAR LOCNIEL, 1949-15 02.20 1530 2760 3116 5020 6000 7196 ARIZ.

09900500 SANTA CRUZ RIVER NEAR NOGALES. 1030.75 533.00 4100 1146 9480 12700 15400 16200 ARIZ.

09901500 SONOITA CREEK NEAR PATAGONIA, 193002 200.00 2710 5320 7420 10400 12400 15400 ARIZ.

04402000 SANTA CRUZ RIVER AT 1940.47.19S2-75 1662.00 4270 0020 11000 13200 18600 22200 CONTINENTAL ARI7.

09402400 AIRPORT RASH AT TUCSON, ARIO. 1466-15 35.20 320 S72 764 1030 1240 1470

09482500 SANTA CRUZ RIVER AT TUCSON. 1915.75 2222.00 3160 8700 11300 14800 17500 20304 ARIZ.

09483100 TANQUE VERDE CREEK NEAR 196045 43.00 1180 2206 3010 4150 SO40 6080 TUCSON, ARIZ.

09489000 SABINO CREEK NEAR TUCSON, 1033.15 35.30 1030 2300 3450 5670 7400 9560 ARIZ.

00489200 BEAR CREEK NEAR TUCSON, ARIZ. 1960-74 16.30 269 700 1140 1090 2590 3426

09444600 FINIANO WASH NEAR VAIL. ARIZ. 195605 457.00 4330 10800 11000 27300 36600 47600

00405000 RINCON CREEK NEAR TUCSON, 1053475 44.80 1060 2980 5010 ROSO 12000 16100 ARIZ.

09484000 RTLLITO CREEK NEAR TUCSON, 197S.75 892.0ß 4460 9130 12300 16700 20200 23P00 ARIZ.

305 Table 2. -. Flood- frequency data for selected streamflo4- gaginq stations -- Continued 14 URATNAGE FLOOD MAGNITUDE, IN CUBIC FEET PEN SECOND. AREA FON INDICATED NECUN4ENCF TNTERVAL. IN TEARS STATION TIN SDUARE RUNNER STATION NAME PEHIU0 OF RECORD MILE3) 02 05 010 02S 050 0100

09466300 CANADA DEL ORO NEAR TUC504. 1966 -75 250.00 2010 5410 0670 14400 70000 27100 ARIZ.

09906500 SANTA CRUZ RIVER AT CORTARO, 1990. 47,1950 -75 3503.00 6100 12700 15900 19900 22600 25400 ARIZ.

09466600 ALTAR 448H NEAR THREE POINTS, 1966.75 463.00 5310 10100 10100 19900 24000 30100 ARIZ.

09488500 SANTA ROSA NASN NR VAOVA V0. 1955-75 1702.00 1450 0490 0000 14700 21600 10400 ARIZ.

09409000 SANTA CRUZ RIVER NEAR LADEEN, 1940- 46.1910 -75 0501.00 1030 2690 4360 7240 9900 13300 ARIZ.

09409070 NORTH FORO OF EAST FORK SLACK 1966 -75 $0.10 216 603 1000 1690 2360 3150 RIVEN NR ALPINE, ARIZ.

09009100 SLACK ROVER NEAR MAVERICK. 1967.75 719.00 1950 3090 4520 6690 0560 10600 ARIZ.

09409200 RACHETA CREEK NEAR MAVERICK. 1950.75 14.00 101 102 244 730 396 472 ARIZ.

09969494 BLACK N ASO MILLON CR OTO NR 1954 -75 560.00 INNO 4350 0440 9640 12400 15600 POINT OF PINES, ARIZ.

09469700 BIG BONITO CREEK NO FORT 1950 -75 119.00 611 1150 1570 2180 2600 3200 APACHE, ARIZ.

09490500 BLACK RIVER NEAR FORT APACHE. 1950 -75 1232.00 4850 12300 19600 31800 63000 96100 ARIZ.

09090800 NORTH FORK WHITE RIVER NEAR 1066.75 39.00 196 291 354 433 492 551 GREER, ARIZ.

09491000 NORTH FORK WHITE RIVER NEAR 1906.1946 -75 66.00 390 643 906 1210 1460 1720 HCNARY, ARIZ.

09492400 EAST FORK MMITE RIVER NO FORT 1450 -75 38.80 241 376 47I 593 645 778 APACHE, ARIZ.

09444000 4417E RIVER NEAR FURT APACHE. 1958.75 632.00 3270 5340 6830 6810 10300 11000 ARIZ.

04444300 CARRIZU CR A0V CORDUROI CR NR 1454-66 225.00 1960 3870 5440 7730 9650 11700 SHEIK LOW, ARIZ.

09496000 CORDUROY CHEEK NEAR ROUTH, 1952 -75 203.00 1020 1810 7350 14500 22200 32300 NEAR SHOM LOO. ARIZ.

09496500 CARRIZO CREEK NEAR 31104 LON. 1952 -75 439.00 2840 7320 11800 19200 26100 34200 ARIZ.

45 96 04496600 CIBECUE 1 TRIO TO CAR4I20 CR 1958-70 .1u 140 206 263 327 NO SRO. OM. ARIZ.

09996700 CIOECUE 2 TRIM TO CARRIZO CO 1950 -70 .06 42 93 122 146 170 NR SOON LOH. 0411.

04997500 SALT RIVER NEAR CMRYSOTTLE. 1416.1925 -75 2814.00 9170 21000 32300 51100 66700 09700 ARIZ.

09497800 CT/SEGUE CREEK NEON CHNSOTILE, 1954 -75 295.00 3630 6620 9500 13300 16500 19000 ARIZ.

09997900 CHERRY CREEK NEAR 10061. ARIZ. 1903.75 62.10 1360 3220 0430 7640 10500 12400

09097980 CHERRY CREER NEAR GLOBE. ARIZ. 1466.75 200.00 1970 0300 6360 9530 12300 15300

09490500 SALT RIVER NEAR 4003E0EL1. 1916,192575 4306.00 12800 31800 51500 86500 121000 164000 ARIZ.

09046000 TONTO CREEK NEAR GISELA, ARIZ. 1965 -75 430.00 0920 21600 33500 52900 70500 90700

04498870 RYE CREEK NEAR GISELA. ARIZ. 1063,1966 -75 122.00 2640 6390 9500 19600 19000 23900

09499000 TONTO CREEK ABOVE GUN CO, NR 1941 -75 675.00 9640 21800 32700 49400 65000 62200 0003EVELT. 0012.

09502000 MILLIAMSUN VALLEY 4050 NR 1965.73 255.00 733 1730 2720 9348 5030 7590 PAULDEN. ANTI.

09503000 GRANITE CREEK NR PRESCOTT. 193367.1967.1966 36.60 715 1660 2560 4040 5390 6470 ARIZ.

306 228 GILA RIVER BASIN

09482000 SANTA CRUZ RIVER AT CONTINENTAL, AZ

'.00ATION. --Lat 51 °51'1G ", long llu °58'40 ", in NE:NE4 sec.23, T.16 S., R.13 E.(unsurveyed), Pima County, Hydrologic Unit 15050301, in Spanish land grant of San Ignacio de la Canoa, near left bank on downstream side of pier of highway bridge at Continental.

.AI.NAGE AREA.- -1,6Ó2 mil (4,305 km2), of which 395 mil (1,023 km2) is in Mexico.

WATER ANNUAL PEAK GATE GAGE HEIGHT OF CUOE ANNUAL MAX DATE aATEN TOTAL VOLUME. YEAR DISCH,CFS ANNUAL PEAK.FT GAGE MT.FT YEA4 ACRE -FI

1940 12100 08 -14 -40 8.85 1941 2000 1441 3670 08 -09 -41 5.4 1442 3560 1442 2700 07 -28 -42 4.95 1943 10100 1943 4050 08 -01 -43 5.55 1944 4070 1944 4040 08 -12 -44 5.80 1945 I6600 1945 7620 08 -04 -45 7.25 1946 12460 1946 4120 09 -09 -46 5.94 NM 6.00 07 -27 -46 1452 3760 1947 5330 10 -01 -46 6.40 1953 6970 1952 1820 08 -15 -52 4.20 1994 17800 1953 4910 07 -16-53 6.20 145n 49700 1954 14600 08 -05 -54 10:10 1956 1010 1955 17500 08 -19 -55 11.34 1957 1120 1956 3090 07 -29 -56 4.0 195e 14700 1957 1690 08 -21 -57 3.62 1954 5970 1958 5620 08 -05 -58 5.b3 196u 14100 1959 3900 08 -17 -59 5.43 1961 6850 19b0 3740 01 -12 -60 5.70 1962 6 ?30 1961 4820 08 -23 -61 5.80 1963 13700 1962 2460 01 -25 -62 4.80 1964 24800 1963 4220 08 -06 -63 5.65 1965 184 1964 14000 09 -10 -64 10.13 1966 64400 1965 370 09 -12 -65 6.15 1467 3490 1966 5990 12-23 -65 9.34 1968 42100 1967 3730 07 -27 -67 8.81 1969 2960 1468 18000 12-20 -67 15.3 1970 3690 1969 1680 08 -05 -69 5.79 1971 12600 1970 3720 07 -20 -70 7.80 1972 1950 1971 3270 08 -20 -71 7.30 1973 11700 1972 3290 07 -14 -72 8.72 197u 4510 1973 2130 03 -14 -73 7.20 1975 4460 1974 3450 09 -03 -74 8.10 1975 3350 09 -01 -75 8.15

NM Not maximau gage height for water year. GILA RIVER BASIY 229

09482000SANTA CRUZ RIVER AT CQ\TINE \TAL, AZ-- CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 SCMARBE. IM CUBIC FEET PER SECOND .N

CLASS 0 1 2 3 4 S 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 2829 303132 3334 YEAR NUMBER OF DAYS IN CLASS

1941 337 1 1 1 1 3 4 1 1 6 1 1 1 l 1 2 1 1

1942 339 2 3 2 1 2 1 2 4 2 3 3 1

1943 317 1 1 5 1 4 5 3 1 2 4 3 8 5 2 1 1 1

1944 348 2 3 1 1 3 1 2 1 1 2 1

1945 330 3 1 1 2 2 1 5 1 1 6 3 2 1 4 1 1

1946 311 11 3 3 1 2 3 3 1 2 3 4 1 3 3 2 2 1 1 1 1952 329 3 1 2 1 1 3 1 1 2 1 3 3 2 1 3 3 1 1 1953 330 2 3 1 2 1 3 1 2 1 2 3 1 1 1 1 1 3 2 1 2 1 1954 306 3 1 2 2 1 1 4 2 1 2 4 5 1 3 3 1 6 2 2 6 1 2 2 1 1

1955 320 2 1 2 1 1 1 1 1 1 2 1 3 1 1 1 1 2 3 4 5 3 3 1 2 1

1956 355 1 2 1 1 3 1 1 1 1957 338 1 1 1 1 2 1 5- 2 1 2 3 2 1 1958 318 1 2 1 2 5 3 2 1 2 2 1 2 2 1 4 3 3 4 1 1 2 1 1 1959 319 1 1 1 1 2 2 2 1 5 4 4 3 2 2 1 3 4 1 1 1 1960 322 1 2 1. 1 3 4 I 4 2 9 1 2 4 3 3 1 2 1 2 2 2 1

1961 319 1 2 3 5 3 2 3 1 1 2 1 S 3 1 3 1 2 2 1 1962 346 1 1 2 1 1 3 2 2 1 1 1 1 1 1

1963 319 1 1 2 2 2 2 1 2 4 2 4 2 2 4 3 3 2 2 1 1 3 1964 323 2 1 1 2 2 1 1 4 3 3 1 6 1 3 4 1 3 2 1 1 1965 354 1 1 1 2 1 3 1 1

1966 288 1 2 3 1 1 2 2 1 4 3 4 5 5 4 6 3 6 2 3 2 6 l 3 4 2 1 1967 330 1 1 1 1 1 5 1 4 5 4 2 2 2 3 1 1 1968 318 2 1 2 1 3 2 3 2 6 1 2 3 5 1 2 1 1 1 2 3 2 1 1 1969 323 2 1 5 2 4 1 3 5 4 2 3 1 3 1 2 2 1 1970 318 3 3 4 3 1 2 1 2 4 4 1 1 3 1 1 1 1 2 1 3 1 2 1 1

1971 309 1 2 1 2 1 2 3 3 3 2 3 2 1 4 3 S 3 4 2 2 1 2 1 1 1 1 1972 344 1 1 2 1 2 1 1 3 2 2 2 1 2 1 1973 346 1 1 1 1 2 1 3 1 1 2 1 1 2 3 1974 342 1 2 1 1 1 1 2 2 1 3 2 2 2 1 1975 340 1 1 1 1 2 1 1 3 2 3 3 3 1 2

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 9838 10957 100.0 12 5.5 33 773 7.1 24 300 30 148 1.3 0.10 28 1119 10.2 13 7.7 60 740 6.8 2S 420 33 118 1.0 0.20 17 1091 10.0 14 11.0 47 680 6.2 26 590 30 85 .7 3 0.30 19 1074 9.8 15 15.0 57 633 5.8 27 820 19 55 .5 4 0.40 14 1055 9.6 16 21.0 47 578 5.3 28 1100 16 36 .3 S 0.50 21 1041 9.5 17 29.0 52 529 4.8 29 1600 7 20 .1 6 0.70 15 1020 9.3 18 41.0 65 477 4.4 30 2200 6 13 .1 7 1.00 57 1005 9.2 19 57.0 53 492 3.8 31 3100 3 7 s 1.40 23 948 8.7 20 79.0 59 359 3.3 32 400 2 4 9 2.00 53 925 8.4 21 110.0 55 300 2.7 33 6100 Z .2 10 2.80 40 872 8.0 22 150.0 64 245 2.2 34 II 3.90 59 832 7.6 23 220.0 33 181 1.7

308 230 GILA RIVER BASIN

09482000 SANTA CRUZ RIVER AT CONTINENTAL, AZ-- CONTINUED

LOWEST WEAN VALUFANOOANKTN0 FURTMF FUI L067141;NUMBFMUFCuNSFCIIT TVEDAYS INYEAHENUihfSEPTEMBER30 CHARGE.IN COMIC FEFT PFMSECnND

YEAR 1 3 7 Ia 30 h0 00 17U 143 1941 0.00 1 0.00 1 0.00 1 4.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.4625

1942 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 1 1943 4.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 2 1944 0.00 4 0.00 a 0.00 4 0.00 0 0.00 4 0.00 4 0.00 4 0.00 4 0.00 3 1945 0.00 S 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4

1946 0.00 b 0.00 6 0.00 e 0.00 b 0.00 6 0.00 6 0.00 6 0.00 6 0.00 5 1952 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6 1953 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 6 0.00 8 0.00 8 0.00 7 1954 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 1.1930 1955 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.00 8

1956 0.0011 0.00 11 0.00 11 0.0011 0.0011 0.0011 0.0411 0.00 11 0.00 9 1957 0.0012 0.0012 0.0012 0.0012 0.0012 0.0012 0.0012 0.0012 0.0010

1958 0.0013 0.0013 0.0013 . 0.0013 0.0013 0.0013 0.0013 0.0013 0.00il 1959 0.0014 0.0014 0.0014 0.0014 0.00la 0.0014 0.0014 0.0014 0.00to 1960 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0013

1961 0.0016 0.0016 0.0016 0.0016 0.0016 0.0016 0.0016 0.0016 0.0014 1962 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.1428 1963 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0015 1964 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.0016 1965 0.00?0 0.0020 0.0020 0.0020 0.0070 0.0020 0.0020 0.0020 0.0017

1966 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 0.0071 10.0031 1967 0.0022 0.0022 0.0022 0.0072 0.0022 0.0022 0.0022 0.0022 0.0018 1968 0.0073 0.0023 0.0073 0.0023 0.0023 0.0023 0.0023 0.0023 0.6529 1969 0.00?a 0.0024 0.00?4 0.0074 0.0028 0.0024 0.0024 0.0074 0.0019 1970 0.0025 0.00?5 0.0425 0.0025 0.0025 0.0025 0.0025 0.0025 0.0524

1971 0.00Pb 0.00Pb 0.0026 0.0026 0.0026 0.0026 0.0026 0.0026 0.0020 1972 0.0027 0.0027 0.0077 0.0077 0.0077 0.0027 0.0027 0.0077 0.0021 1973 0.0028 0.0428 0.0078 0.0078 0.0028 0.0028 0.0028 0.0028 0.1126 1974 0.0079 0.0029 0.0079 0.00?9 0.0079 0.0029 0.0029 0.0029 0.0022 1975 0.0030 0.0030 0.00IO 0.0030 0.0030 0.0030 0.0030 0.0030 0.0023

309 GIIA RIVER BASIN 231

094820U0 SANTA CRUZ RIVER AT INTINENTAL, AZ--CONTINIJED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1941 363.024 161.025 71.027 35.027 28.026 15.027 10.027 7.527 4.927 1942 474.022 234.022 116.021 69.021 41.023 25.023 20.022 15.022 9.822 1943 861.017 454.015 274.014 160.014 137.013 81.013 57.013 43.013 20.013 1944 528.021 296.018 195.017 129.016 65.017 34.020 23.020 17.020 11.020 1945 1330.010 754.010 500.0 8 406.0 6 247.0 6 133.0 6 90.0 6 68.0 6 440 6

1946 1150.012 606.013 327.013 221.012 145.012 92.011 65.011 49.011 32.011 1952 311.026 135.036 79.025 49.026 34.025 22.025 16.025 12.025 7025 1953 1090.013 853.0 8 401.0 9 201.013 117.014 59.014 39.014 29.014 19.014 1954 4290.0 4 1690.0 5 1200.0 4 768.0 4 510.0 3 294.0 208.0 4 157.0 4 103.0 4 1955 3500.0 5 2080.0 4 1440.0 3 936.0 2 786.0 1 414.0 1 276.0 1 207.0 1 136,0 1

1956 227.0as 84.0 as 31.028 21.028 17.028 8.529 5.729 4.229 2.829 1957 110.029 48.029 31.029 19.029 16.029 10.028 6.828 5.128 3.428 1958 1410.0 9 122.011 330.0'12 274.0 9 192.0 9 112.0 8 80.0 7 60.0 7 39.0 7 1959 878.016 400.011 266.015 146.015 83.015 47.016 31.017 23.017 15.017 1960 2500.0 6 1320.0 6 761.0 6 368.0 7 199.0 7 100.010 66.010 50.018 33.018

1961 931.015 422.016 182.018 100.018 69.016 47.017 32.016 24.016 16.015 1962 1300.011 539.014 232.016 108.017 54.019 49.015 33.015 25.015 16.016 1963 972.014 655.012 366.011 248.011 191.010 114.0 7 77.0 8 58.0 8 38.0 8 1964 6110.0 2 2510.0 3 1190.0 5 570.0 5 423.0 5 248.0 5 166.0 5 124.0 5 81.0 S 1965 32.030 18.030 9.230 4.630 2.330 1.530 1.130 0.830 0.530

1966 5190.0 3 2960.0 2 1470.0 2 852.0 3 436.04 295.0 3 216.0 3 102.0 3 106.8 3 1967 650.018 253.021 110.023 65.022 46.022 26.022 19.023 14.023 9.423 1968 9800.0 1 5370.0 I 2760.0 1 1360.0 1 681.0 2 341.0 2 234.0 2 175.0 2 115.0 ;2 1969 341.025 133.027 75.026 55.024 38.024 24.024 17.024 22.024 8.124 1970 545.020 269.020 116.022 61.023 49.020 30.021 20.021 15.021 10.021

1971 1430.0 8 765.0 9 369.010 307.0 8 199.0 8 106.0 9 71.0 9 53.0 9 35.0 0 1972 284.027 169.024 100.024 51.025 27.027 15.026 10.026 7.626 5.026 1973 1470.0 7 1060.0 7 548.0 7 256.010 181.011 90.012 60.012 45.012 31.022 1974 579.019 283.019 151.019 80.019 62.018 37.018 25.019 19.019 12.019 1975 404.023 191.023 121.020 78.020 49.021 35.019 28.0 111 21.018 14.020

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS CALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUO SEPT BY ROWS (MEAN.VARIANCE.STANDARD DEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE 1.98 0.15 37.5 8.82 8.88 4.97 0.00 0.00 0.30 33.7 96.6 20.6 2636 21.3 0.64 19670 1280 1500 516 0.00 0.00 0.85 2081 24660 4.62 0.80 140 35.8 38.7 22.7 0.00 0.00 0.97 45.6 157 51.4 5.01 2,77 5.48 3.9 4.91 4.97 5.29 5.48 3.38 2.94 2.94 2, ;; 5.34 3.74 .05 4.36 4.57 5.48 ..N4 3.06 1.35 1.63 2049 45.2 0.93 0.07 17.6 .13 4.16 2.33 0.00 0.00 0.14 15.8 9.66

DISCHARGE. IN CUBIC FEET PER SECOND STATISTICS ON NORMAL ANNUAL MEANSCALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CDR* 18.0 477' 21.8 1.97 1.21 0.150

*** ** Skewness and coefficient of variation could not be computed owing to a zero-value month.

310 232 GIL1 RIVER BASIN

09482400AIRPORT WASH AT TUCSON, AZ

LOCATION.- -Lat 32 °09'09 ", long 110 °58'52 ", in NE4SE4 sec.2, T.15 S., R.13 E., Pima County, Hydrologic Unit 15050301, 25 ft (7.6 m) upstream from Santa Clara Avenue, 0.7 mi (1.1 km) upstream from mouth, 4.3 mi (6.9 Ion) downstream from confluence of North and South Forks, and 4.9 mi (7.9 km) south of city hall in Tucson.

DRAINAGE AREA.- -23.0 mi= (59.6 km2).

WATER ANNUAL PEAK DATE GAGE HEIGHT OFAATEH TOTAL VOLUME, YEAR DISCH,CFS ANNUAL PEAK,FT YEAH ACRE FT

1966 322 09-11-66 4.25 1966 333 1967 106 07-17-67 3.66 1947 58 1968 385 08-20-68 4.39 1948 173 1969 118 08-28-69 3.71 1949 97 1970 823 07-20-70 4.14 1970 811 1971 549 10-02-70 3.44 1971 718 1972 310 07.16-72 3.67 1972 252 1973 159 10-19-72 2.88 1975 272 1974 689 07-07-74 2.41 1974 417 1975 377 07-12-75 2.01 1975 198

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE.IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 2S 262728293031323334 YEAR NUMBER OF DAYS IN CLASS 1966 333 4 2 1 2 1 3 1 2 1 4 1 1 2 1 1 1 1967 348 1 2 2 3 2 1 3 1 1 1 1968 347 1 2 1 5 1 3 1 2 1 1 1 1969 347 2 3 1 3 1 1 2 3 1 1 1970 348 1 1 1 1 1 1 2 2 1 1 1 1 1 1 1

1971 340 1 1 1 2 1 2 1 2 3 2 1 1 1 I 1 3 1 1972 343 2 1 1 1 1 1 1 1 1 2 7 2 1 1 1973 340 3 1 1 1 1 1 1 5 1 3 1 1 3 1 1 1974 343 2 1 1 1 2 1 1 3 1 2 3 1 1 1 1 1975 354 1 1 1 1 2 1 1 2 1

SS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0.00 3443 3652 100.0 12 0.5 18 161 4.4 24 17 6 '24 .6 0.01 2 209 5.7 13 0.7 9 143 3.9 25 22 3 18 .4 2 0.02 0 207 5.7 14 1.0 11 134 3.7 26 30 4 15 .4 3 0.03 0 207 5.7 15 1.3 13 123 3.4 27 40 5 11 .3 4 0.04 2 207 5.7 16 1.1 13 110 3.0 28 53 1 6 .1 5 0.05 0 205 5.6 17 2.3 7 97 2.7 29 70 3 5 .1 6 0.07 0 205 5.6 18 3.0 14 90 2.5 30 93 2 7 0.09 1 205 5.6 19 4.0 11 76 2.1 31 120 2 2 8 0.10 15 204 5.6 20 5.3 19 65 1.8 32 9 0.20 13 189 5.2 21 7.1 9 46 1.3 33 10 0.30 6 176 4.8 22 9.E 7 37 1.0 34 11 0.40 9 170 4.7 23 13.0 6 30 0.8

311 GIL1 RIVER BASIN 233

09482400 AIRPORT WASH AT TUCSON, A;.- -CONTINUED

LOWEST MFAN VALUEC4ORANKIN'.FUR TF FULLPbTNG NUMbER OF CUNSFCIITTVFPAYS INYEAHbNU1hf,SEPTFMNLR10 PISCNAPGE.IN ruRIr FEFT PFRSECOn' MEAN

YEAR I 3 7 14 30 60 60 120 I93 0.00 1 0.00 1 0.00 1 1 0.00 I 1966 0.00 0.00 1 0.00 1 0.00 1 0.07 11 0.00 2 0.00 2 0.00 2 0.1,0 2 0.00 0.00 1967 2 2 0.00 2 0.00 2 V.00 1 1968 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.0 3 0.01 8 U.Ut 9 4 4 1969 0.00 0.00 4 0.00 U.00 4 0.00 4 0.00 4 0.00 4 0.01 9 O.U1 7 19'10 0.00 5 0.00 5 0.00 5 u.VO 5 0.00 5 0.00 5 0.00 5 0.01 10 0.01 8

1971 0.00 b 0.00 6 0.00 b 0.00 6 0.00 b 0.00 b 0.00 6 0.00 3 0.00 2 1972 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 U.UO 7 0.00 4 0.00 3 1973 0.00 8 0.00 8 0.00 0 0.00 8 0.00 8 0.00 6 0.00 8 0.02 11 0.0410 9 9 1974 0.00 9 0.00 9 0.00 0.00 9 0.00 0.00 9 0.00 9 0.00 5 0.00 4 10 1975 0.0010 0.0010 0.00 0.0010 0.0010 0.00IO 0.0010 0.00 6 0.00 5

HIGHEST MEAN VALUE ANO RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE.IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1966 32.0 7 14.0 7 6.0 7 3.3 5 2.8 5 2.2 4 1.4 4 1.1 4 0.7 4 1967 15.0 9 5.0 9 2.2 9 1.3 9 0.710 0.410 0.310 0.210 0.210 1968 44.0 5 15.06 6.3 6 3.0 6 1.5 8 0.8 8 0.5 8 0.4 8 0.3 8 1969 12.010 4.110 1.810 0.910 0.7 9 0.5 9 0.4 9 0.3 9 0.2 9 1970 170.0 1 97.0 1 42.0 1 20.0 1 10.0 1 6.7 1 4.5 1 3.4 1 2.2 1

1971 71.0 4 32.0 3 20.0 2 9.6 3 7.5 2 4.3 2 2.9 2 2.2 2 1.5 2 1972 26.0 8 11.0 -8 4.9 8 2.7 8 2.5 6 1.6 6 1.1 6 0.8 6 0.5 6 1913 74.0 3 31.0 _4 13.0 4 6.1 4 3.5 4 1.9 5 1.3 5 1.0 5 0.7 S 1974 I24.0 2 45.02 19.0" 3 9.7 2 6.2 3 3.2 3 2.3 3 1.7 3 1.1 3 1975 39.0 6 15.0 5 6.4 5 3.0 7 1.5 7 1.0 7 0.7 7 0.5 7 0.4 7 DISCHARGE, IN CUBIC FEET PER SECOND STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS (MEAN.VARIANCE.STANDARD DEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 0.73 0.15 0.25 0.00 0.06 0.04 0.03 0.00 002 2.49 0.99 0.68 1.76 0.06 0.15 0.00 0.02 0.00 0.01 0.00 000 9.26 0.82 0.80 1.33 0.24 0.39 0.01 013 006 0.08 001 0.06 3.04 0.91 0.89 1.74 1.50 119 3.16 273 1.61 2.88 316 3.13 1.55 0.99 2.16 1.82 1.59 1.55 3.16 2.33 1.69 2.33 3.16 2.94 1.22 0.91 1.32 13.4 2.73 4.64 0.03 1.05 0.67 0.60 0.08 0.37 45.7 18.3 12.4

DISCHARGE. IN CUBIC FEET PER SECOND STATISTICS ON NORMAL ANNUAL MEANSIALL OATS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 0.46 0.12 0.35 1.10 0.76 0.197

312 234 GIL1 RIVER BASIN

09482500 SANTA CRUZ RIVER AT TUCSON, AZ

LOCATION.--Lat 32 °13'16 ", long 110 °58'52 ", in NEkNEk sec.15, T.14 S., R.13 E., Pima County, Hydrologic Unit 15050301, on downstream side of center pier of Congress Street Bridge in Tucson.

.RAINAGE AREA. --2,222 mi2 (5,755 1043), of which 395 mi' (1,023 í4K1)is in Mexico, adjusted for 15.2 mi2 (39.4 lm') of Tucson Arroyo drainage area contributing to this station effective July 1956.

HATER ANNUAL PEAR DATE HIGHEST GAGE NEIGNT OF CODE CATER TOTAL VOLUME. YEAR DISCM,CFS SINCE ANNUAL PEAK,FT VERA ACRE -FT

1915 15000 12 -23 -14 1905 1906 27000 1916 5000 01 -20 -16 1915 81000 1917 7500 09 -08 -17 1916 37310 1918 4900 08 -07 -18 1917 28400 1919 4700 08 -02 -19 1918 4930 1920 1950 08 -09 -20 1919 27500 1921 4000 08 -01 -21 1920 7920 1922 2000 07 -20 -22 1921 32100 1923 1900 08 -17 -23 1922 10800 1924 2050 11 -17 -23 1923 15700 1925 3400 09 -18 -25 1924 3700 1926 11400 09 -28 -26 1925 6940 1927 1950 09 -07 -27 1926 20200 1928 1600 08 -01 -28 1927 3140 1929 10400 09 -24 -29 1928 2920 1930 1770 08 -07 -30 1929 24300 1931 9200 08 -10 -31 1930 8080 1932 4200 07 -30 -32 1931 37300 1933 6100 08 -21 -33 1932 14700 1934 6000 08 -23 -34 1933 77400 1935 10300 09 -01 -35 1934 7570 1936 5400 07 -26 -36 1935 20400 1937 3280 07 -10 -37 1936 8770 1938 9000 08 -05 -38 1937 8260 1939 8000 08 -03 -39 1938 7620 1940 11300 08 -14 -40 1939 24400 1941 2490 08 -14 -41 1940 13500 1942 1670 08 -09 -42 1941 4990 1943 4510 08 -02 -43 1942 3060 1944 6530 08 -16 -44 1943 11100 1945 10800 08 -10 -45 1944 9760 1946 4260 08 -04 -46 1945 20700 1947 2960 10 -01 -46 1946 14900 1948 3860 08 -16 -48 1947 6510 1949 3800 08 -08 -49 1948 8650 1950 9490 07 -30 -50 1949 10500 1951 5020 08 -02 -51 1950 28900 1952 3820 08 -16 -52 1951 7230 1953 5900 07 -15 -53 1952 6050 1954 9570 07 -24 -54 1953. 9710 1955 10900 08 -03 -55 1954 36000 1956 2610 07 -29 -56 1955 50200 1957 3050 08 -31 -57 1956 1290 1958 6350 07 -29 -58 9.85 1957 2230 1959 4420 08 -20 -59 9.15 1958 17700 1960 6140 08 -10 -60 10.24 1959 6870 1961 16600 08 -23 -61 15.60 1960 13000 1962 4980 09 -26 -62 7.90 1961 16300 1963 4670 08 -26 -63 12.82 1962 8250 1964 13000 09 -10 -64 18.05 1963 16200 1965 1190 07 -16 -65 8.49 1964 38100 1966 5500 08 -19 -66 12.30 1965 936 1967 5860 07 -17 -67 12.17 1966 43100 1968 16100 12 -20 -67 17.24 1967 5890 1969 8710 08 -06 -69 13.92 1968 38200 1970 8530 07 -20 -70 13.81 1969 5200 1971 8000 08 -17 -71 NM 1970 8660 1972 3470 07 -15 -12 íC.03 1971 11800 1973 4710 10 -19 -72 10.86 1972 5230 1974 7930 07 -08 -74 13.44 1973 13200 1975 2480 07 -12 -75 9.55 1974 7790 1975 5800 NM Not maximum gage height for water year. GILA RIVER BASIN 235

09482500 SANTA CRUZ RIVER AT TUCSON, A2--CO\TI`.UED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 )15CO3R6E. IN CUBIC FEET PER SECOND IEAN

.:LASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 YEAR NUMBER OF DAYS IN CLASS 1915 247 1 3 1 3 2 1 1 8 24 B 8 10 9 11 9 3 1 3 1 1 2 1 1 2

1916 299 2 1 7 I 1 14 3 3 2 2 3 7 7 6 1 1 1 2 2 1 1917 321 3 3 1 3 1 3 2 3 4 4 2 4 3 1 3 2 1 1 1918 348 4 3 1 1 1 1 2 1 1 1919 324 2 2 I 1 1 1 4 1 4 3 3 2 5 3 2 5 1 1 1920 274 1 4 12 14 5 10 16 3 4 7 6 2 2 3 1 1 1

1921 309 1 1 1 7 2 2 1 2 3 2 1 4 1 3 2 8 7 3 3 2 1922 299 4 2 1 3 10 9 11 2 1 4 2 1 1 3 3 3 2 1923 314 5 7 2 3 2 2 3 2 3 3 2 2 4 4 2 3 2 1924 294 4 1 18 16 21 3 2 1 2 1 1 3 1 1925 335 2 I 2 2 1 1 2 3 1 1 1 4 3 2

1926 299 26 9 * 4 1 3 3 2 3 2 1 1 2 I 1 1 1 1 1927 295 3 10 6 17 10 4 1 6 4 6 1 1 1 2 1928 348 3 3 1 2 1 3 1 1929 326 5 3 I 1 2 1 2 1 4 5 2 3 1 2 1 1 1930 320 3 2 1 4 2 3 3 2 5 3 3 5 2 I 3 3

1931 291 1 1 S 1 2 1 2 4 2 4 5 3 4 4 3 4 5 6 1 3 2 1 1 1932 331 3 2 3 2 1 2 1 2 2 3 .3 3 4 1 2 1 1933 339 2 2 I 1 1 1 1 2 2 1 1 1 1 2 1 2 1 1934 314 13 2 1 3 2 2 8 1 4 4 1 3 1 3 2 1935 307 6 2 4 3 7 5 1 2 1 4 I 2 4 4 2 1 2 1 1 1

1 1936 279 27 21 6 8 2 1 2 2 I 1 6 1 1 1 5 ) 1937 320 e 2 4 I 3 2 3 4 2 1 4 3 3 1 1 2 I 1938 322 16 5 1 2 2 3 2 1 1 1 3 1 1 1 1 1 1 1939 315 2 2 4 3 3 2 Z 1 3 1 1 4 3 2 3 3 1 2 :2 2 1 1940 318 15 1 1 3 2 4 2 4 1 3 3 2 3 1 1 1

1941 320 7 5 1 1 4 3 3 2 2 2 2 2 3 3 5 1942 305 27 4 1 3 2 2 3 1 3 6 2 3 1 1 1 1943 309 5 1 2 1 2 5 1 2 3 6 4 6 5 4 3 1 1 1944 340 3 2 1 2 3 1 3 1 2 2 2 1 1 1 1 1 1945 324 2 2 2 2 1 2 4 4 3 2 1 3 1 1 2 1 1 2

1946 300 3 2 2 1 6 4 4 4 7 2 4 5 5 4 3 3 3 2 1 1 1947 328 6 1 1 1 1 1 1 4 2 2 2 3 2 2 2 1 1 1948 330 4 1 3 1 2 2 5 3 2 2 2 4 3 1 1949 312 2 2 1 2 7 6 2 3 1 1 2 2 3 2 2 1 2 2 2 2 I 2 2 1 1950 318 1 2 1 5 2 1 2 1 4 3 2 1 3 5 1 2 1 1 1 3 1

1951 328 2 1 1 5 3 1 1952 316 3 3 2 1 1 2 3 2 3 3 1 3 3 2 2 3 3 2 4 1 I 2 1953 330 2 I 1 2 3 2 3 2 1 1 2 2 1 5 1 1 7 2 2 1 1954 269 3 3 1 5 1 3 1 6 2 3 3 1 3 2 3 4 2 6 2 S 2 2 3 5 1955 315 2 1 3 2 2 1 2 1 1 1 2 1 2 1 3 2 5 t 5 3 2 I

1956 349 1 3 l 1 1 2 2 2 1 1 I 1 1957 319 6 5 4 1 1 1 2 1 2 1 5 1 2 1 3 5 3 1 1 1958 292 5 5 2 3 2 2 3 1 4 5 2 2 3 3 1 1 3 6 1 3 3 3 I 1 1959 318 2 3 4 1 2 1 3 2 1 1 6 i 1 2 3 2 1 4 1 1960 313 3 2 2 2 3 2 2 2 2 5 1 1 2 2 1 3 2 3 2 2 2 2 1

1 1961 324 1 2 2 2 4 2 2 2 4 3 2 1 4 2 1 3 1 2 1962 335 2 2 2 1 1 1 1 4 I 1 1 2 1 2 I 2 i 1 1963 312 1 3 1 1 I 1 1 3 2 1 4 2 2 2 5 1 4 2 5 1 1 2 2 1 1964 311 1 3 1 1 4 1 3 3 1 2 2 2 I 4 6 3 4 1 4 5 1 1 i 1965 331 2 2 2 1 2 3 3 3 3 3 1 2 2 2 2 1

1946 289 1 2 2 3 2 3 1 2 1 3 3 2 3 4 1 2 5 2 9 3 4 3 5 .2 1 1 1 I 1967 330 1 1 I 2 2 3 1 1 1 3 2 1 2 2 6 1 2 1 1966 295 3 2 1 1 4 7 4 4 1 3 5 4 3 2 3 2 2 3 2 1 2 1 1 1 1 1f69 339 1 1 2 3 2 1 2 1 2 2 1 3 3 1 i I470 299 20 1 2 2 3 2 6 2 3 3 2 2 2 2 I 3 2 2 1 1

1972 323 5 7 1 1 9 3 S 4 3 1 2 1 1972 320 5 4 1 2 2 2 4 1 4 2 1° 3 1 1 3 1 1 2 I 3 1 1 1f73 318 3 1 3 3 I 1 1 3 3 2 1 6 2 1 4 1 1 2 3 1 2 ¡ 1974 271 5 13 12 17 6 4 1 1 3 1 2 5 1 1 1 1 1975 315 3 3 2 2 1 3 1 2 2 2 5 1 1 1 1 1 2 2 2 7 2 21 1 236 GILA RIVER BASIN

09482500 SANTA CRU: RIVER AT TUCSON, AZ--CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 -- Continued SCMARGE. IM CUBIC FEET PER SECOND AM

CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT 92 300 1.3 0 0.00 19155 22280 100.0 12 6.2 118 1949 8.7 24 380 8.2 25 540 58 208 .9 1 0.10 87 3125 14.0 13 8.7 153 1831 760 .6 2 0.20 57 3038 13.6 14 12.0 140 1678 7.5 26 62 150 88 3 0.30 37 2981 13.4 15 17.0 155 1538 6.9 27 1100 38 .3 4 0.40 62 2944 13.2 16 24.0 164 1383 6.2 28 1500 17 50 .2 33 .1 5 0.60 33 2882 12.9 17 34.0 129 1219 5.5 29 2100 15 7 6 0.80 278 2849 12.8 18 49.0 131 1090 4.9 30 3000 18 4200 11 7 1.10 30 2571 1I.5 19 68.0 131 959 4.3 31 6 3 5 8 1.60 154 2541 11.4 20 96.0 150 828 3.7 32 6000 9 2.20 118 2387 10.7 21 140.0 129 678 3.0 33 8400 2 2 34 10 3.10 115 2269 10.2 22 190.0 135 549 2.5 11 4.40 205 2154 9.7 23 270.0 114 414 1.9

315 GIIa RIVER BASIri 237

09482500 SANTA CRU: RIVER AT N60N, .1i.-- CONT. I\LZD

llyE9T MFAN VALUF ANnOANKTNG FU0 TNF FUIlnntnf. NUMtlFR UF CI19SFpITTVE nAVS INVEAM ENOTNGSEaTEMPEQ10 niSCMAQOF.IN CUPIC FEFT vFR SECONO E AN

VEAN 1 3 7 14 10 60 90 17O 103 1906 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 1915 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.5261 1.8096

1916 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 2 8.5061 1917 0.00 4 0.00 a 0.00 4 0.00 4 0.00 4 0.00 4 0.00 a 0.00 3 0.00 2 1918 0.00 5 0.00 5 0.00 5 0.00 S 0.00 5 0.00 5 0.00 5 0.00 4 0.1339 1419 0.00 b 0.00 b 0.00 b 0.00 b 0.00 6 0.00 b 0.00 6 0.00 5 0.00 3 1920 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.0493 1.1053

1921 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 6 0.00 4 1922 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 7 0.9251 1923 0.0010 0.0010 0.0010 0.0910 0.0010 0.0010 0.0010 0.00 6 0.00 5 1924 0.00 11 0.00 11 0.00 il 0.0011 0.00 11 0.0011 0.2162 1.1962 1.1054 1925 0.0012 0.0012 0.0012 0.0012 0.0012 0.0012 0.0011 0.00 9 0.00 6

1926 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0012 0.2S59 0.2646 1927 0.0014 0.0014 0.0014 0.0014 0.0014 0.0014 0.0013 0.0010 0.0324 1928 0.4015 - 0.0015 0.0015 0.0015 0.00IS 0.00IS 0.0014 0.0011 0.1440 1929 0.00lb 0.0016 0.0016 0.0016 0.0016 0.0016 0.0015 0.0012 0.00 7 1930 0.0017 0.0017 0.0017 0.00 17 0.u017 0.0017 0.00lb 0.0013 3.7059

1931 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0756 0.0349 13.0063 1932 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.00 17 0.0014 5.9060 1933 0.0070 0.0020 0.00?0 0.0070 0.0020 0.0020 0.0018 0.0015 0.02'22 1934 0.0021 0.0021 0.0021 0.0071 0.00?1 0.0021 0.0019 0.0016 0.1034 1935 0.0022 u.0022 0.0072 0.0022 0.8022 0.0022 0.0020 0.0017 1.0052

1916 0.0073 0.0023 0.0023 0.0073 0.0023 0.0023 0.00?1 0.0018 0.46as 1937 0.0024 0.0024 0.00H 0.0074 0.0024 0.0024 0.0022 0.0019 0.01 16 1938 0.00?5 0.0025 0.0025 0.0025 0.0025 0.0025 0.0023 0.0020 0.0620 1919 0.002b 0.0076 0.0076 0.0076 0.0026 0.0026 0.0024 0.0021 0.01 17 1940 0.0027 0.0027 0.0077 0.0077 0.0077 0.0077 0.0075 0.0022 0.7950

1941 0.0028 0.0028 0.0078 0.0078 0.0028 0.0028 0.1861 0.1456 1.9057 1942 0.0029 0.0029 0.0079 0.0079 0.0029 0.0029 0.2?63 0.1857 0.2544 1943 0.0010 0.0030 0.00i0 0.0010 0.0030 0.0030 0.0026 0.0023 0.1035 1944 0.0011 0.00 31 0.0011 0.0011 0.0031 0.0031 0.0027 0.0024 0.00 8 1945 0.0032 0.0032 0.0032 0.0012 0.0032 0.0032 0.0078 0.0145 0.01 18

1946 0.0013 0.0033 0.0033 0.0033 0.0033 0.0033 0.0029 0.0025 0.1441 1947 0.0014 0.0034 0.0014 0.0014 0.0014 0.0014 0.0030 0.0146 0.1136 19a6 0.0015 0.0015 0.0015 0.0035 0.0035 0.0035 0.0031 0.0026 0.0119 949 0.001b 0.0036 0.0016 0.00 16. 0.0036 0.0036 0.0032 0.0077 0.1137 950 0.0017 0.0037 0.0017 0.0037 0.0037 0.0037 0.0033 0.0026 0.00 9

1951 0.0018 0.0038 0.0038 0.0018 0.0038 0.0038 0.0014 0.0029 0.0010 1952 0.0019 0.0019 0.0039 0.0019 0.0039 0.0039 0.0035 0.0010 0.0425 1953 0.0040 0.0040 0.0040 0.00AO 0.0040 0.0040 0.0036 0.0031 0.0120 1954 0.0041 0.0041 0.0041 0.00al 0.0041 0.0041 0.0017 0.0147 0.5049 1955 0.0042 u.0042 0.0042 0.0042 0.0042 0.0042 0.0038 0.0032 0.0011

1956 0.0043 0.0043 0.0043 0.0043 0.0043 0.0043 0.0019 0.0033 0.0012 1957 0.0040 4.0044 0.0044 0.0044 0.0044 0.0044 0.0040 0.03SO 0.0426 1958 0.0045 0.0045 0.0445 0.0045 0.0045 0.0045 0.0860 0.2258 0.25as 1959 0.0046 0.0046 0.00ab 0.0046 0.0446 0.0046 0.0041 0.0014 0.0013 - 1960 0.0047 0.0047 0.0047 0.0047 0.0047 0.0047 0.0042 0.0035 0.0933

1961 0.0048 0.0048 0.0048 0.0008 0.0048 0.0048 0.0043 0.0036 0.0323 1962 0.0009 0.0049 0.0049 0.0049 0.00as 0.0049 0.0044 0.0037 0.2143 1963 0.0050 0.0050 0.0050 0.00SO 0.00SO 0.00SO 0.0458 0.0351 0.1942 1964 0.0051 0.0051 0.0051 0.0051 0.0051 0.0051 0.0045 0.0352 0.0427 1965 0.0052 0.0052 0.00 9 2 0.0052 0.0052 0.0052 0.0046 0.01a8 0.0832

1966 0.0053 0.0053 0.0053 0.0053 0.0053 0.0053 0.0047 0.0018 12.0062 1967 0.0054 0.0054 0.0054 0.0054 0.0054 0.0054 0.0048 0.0019 0.0014 1968 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0049 0.1055 2.9056 1969 0.0056 0.0056 0.0056 0.0056 0.00S6 0.0056 0.0450 0.0040 0.0729 1970 0.0057 0.0057 0.0057 0.0057 0.0057 0.0163 0.0257 0.4060 0.3547

1971 0.0058 0.0058 0.0056 0.0056 0.0058 0.0057 0.0051 0.0041 0.0015 1972 0.0059 0.0059 0.059 0.0459 "0.0059 0.0058 0.0052 0.0042 0.1338

1973 0.0060 0.0060 " 0.0060 0.0060 0.0060 0.0059 0.0053 1.1963 1.19 55 1974 0.00Al 0.0061 0.00A1 0.0061 0.0061 0.0060 0.0054 0.0143 0.0830 1975 0.0062 0.0062 0.0062 0.0062 0.0062 0.0061 0.0155 0.0144 0.0221

316 258 GITA RIVER BASIN

09482500 SANTA CRUZ RIDER AT TUCSON, AZ-- CONTINUED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYSIN YEAR ENDINGiEPTENBER30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1915 8510.0 1 6970.0 1 3830.0 1 1850.0 1 937.0 1 629.0 1 444.0 1 335.0 1 221.0 1

1916 4000.0 9 2830.0 4 1550.0 3 832.0 5 422.0 8 211.011 141.012 106.012 70.012 1917 2710.017 1090.018 669.018 415.016 273.016 216.0 9 158.0 9 119.0 9 78.0 9 1918 1490.028 762.026 327.032 153.040 77.044 41.048 27.051 21.047 14.047 1919 2750.015 1390.016 631.019 457.015 372.010 212.010 153.010 115.010 75.010 1920 550.051 285.054 154.052 118.046 64.048 39.050 28.047 21.048 14.048

1921 2080.021 946.021 759.015 537.014 434.0 7 262.0 6 179.0 7 135.0 7 88.0 7 1922 630.049 337.052 229.044 183.032 129.029 86.025 58.027 44.027 29.028 1923 900.044 597.035 441.023 278.020 208.020 132.020 88.020 66.020 43.020 1924 830.047 338.051 149.054 71.056 38.057 25.055 17.055 13.055 9.455 1925 460.055 365.047 178.050 86.052 65.047 55.043 39.041 29.041 19.043

1926 6150.0 4 3000.0 3 1290.0 5 619.0 7 312.013 162.017 109.016 82.016 54.015 1927 378.057 135.059 74.058 38.059 27.059 20.058 14.058 11.058 7.158 1928 700.048 353.049 153.053 73.054 43.055 23.056 16.056 12.056 7.956 1929 4710.0 5 1850.010 792.014 374.018 2I7.019 192.014 136.014 102.014 67.013 1930 539.092 360.048 210.046 111.047 77.045 54.044 37.044 28.044 22.036

1931 3460.012 2260.0 6 1280.0 6 770.0 6 454.0 5 257.0 7 181.0 6 137.0 6 90.0 6 1932 1330.031 706.028 357.028 233.027 I20.031 82.027 55.028 41.028 27.029 1933 880.045 564.038 242.043 152.041 91.041 59.040 39.042 29.042 19.044 1934 1060.040 475.041 311.033 171.035 110.037 60.039 41.038 31.038 20.040 1935 4620.0 6 1880.01 873.011 562.012 297.015 164.015 110.015 82.015 54.016

1936 1500.027 623.031 268.039 148.042 118.033 66.034 44.035 33.036 22.037 1937 905.042 394.045 287.036 164.036 97.039 64.035 46.034 35.034 23.035 1938 1910.022 736.027 331.030 202.030 117.034 62.036 42.037 31.037 21.038 1939 2420.018 1450.015 1070.0 9 601.011 350.011 202.012 137.013 103.013 67.014 1940 4270.0 8 1560.013 692.017 334.019 194.022 106.022 74.023 55.023 36.023

1941 252.060 141.058 99.057 71.055 47.054 33.054 23.053 17.053 11.053 1942 536.053 228.055 113.055 68.057 38.056 21.057 16.057 12.057 7.957 1943 1120.038 565.037 282.038 155.039 119.032 78.030 61.025 46.025 30.026 1944 2740.016 937.022 444.022 257.024 130.028 81.028 55.029 41.029 27.030 1945 3820.010 1470.014 753.016 549.013 316.012 162.016 108.017 81.017 53.017

1946 1340.030 623.032 300.035 219.028 150.024 104.023 77.022 58.022 38.022 1947 1140.035 389.046 167.051 78.053 48.053 34.053 23.054 17.054 11.054 1948 1130.036 396.044 254.040 215.029 132.027 67.033 48.032 36.032 24.033 1949 1190.034 618.033 364.026 177.034 111.036 85.026 58.026 44.026 29.027 1950 3120.013 2170.0 7 1220.0 8 833.0 4 453.0 6 240.0 8 162.0 8 121.0 8 80.0 8

1951 1730.023 767.025 363.027 197.031 113.035 60.037 40.039 30.039 20.041 1952 495.054 345.050 204.048 98.049 63.049 40.049 28.048 21.049 14.049 1953 1070.039 957.020 530.021 268.023 158.023 79.029 53.030 40.030 26.031 1954 2390.019 1220.017 668.012 603.0 9 479.0 4 269.0 5 192.0 5 150.0 5 99.0 5 1955 3010.014 1650.012 1340.0 863.0 3 721.0 2 420.0 2 280.0 2 210.0 2 138.0 2

1956 286.059 95.060 41.060 21.060 19.060 10.060 6.960 5.260 3.460 1957 356.058 170.057 73.059 54.058 33.058 19.059 12.059 9.359 6.159 1958 1720.024 703.029 304.034 272.022 231.017 138.018 97.018 73.018 48.010 1999 554.050 313.053 244.042 158.037 87.042 57.041 38.043 29.043 19.042 1960 2180.020 1060.019 568.020 277.021 146.025 73.031 49.031 37.031 24.332

1961 4570.0 7 1810.0 11 816.013 391.017 202.021 128.021 85.021 64.021 42.021 1962 1320.032 493.040 213.045 100.048 51.052 43.046 28.049 21.050 14.050 1963 1580.026 845.024 386.025 242.026 230.018 135.019 90.019 68.019 44.019 1964 6400.0 3 2750.0 5 1250.0 7 601.010 414.0 9 307.0 3 208.0 3 156.0 3 102.0 3 1965 121.061 58.061 26.061 13.061 7.461 6.961 4.761 3.561 2.361

1966 3680.011 2150.08 976.010 604.0 8 308.014 200.013 149.011 112.011 73.0 11 1967 1600.025 549.039 329.031 157.038 94.040 48.045 33.045 25.045 16.045 1968 7750.0 -2 4790.0 2 2400.0 2 1180.0 2 593.0 3 298.0 4 203.0 4 153.0 4 101.0 4 1969 1120.037 442.043 209.047 123.044 71.046 42.047 28.050 21.051 14.051 1970 1020.041 586.036 251.041 120.045 90.043 68.0 32. 47.033 35.033 23.034

1971 900.043 700.030 344.029 246.025 144.026 96.024 65.024 48.024 32.025 1972 858.046 457.042 196.049 94.050 63.050 35.052 26.052 20.052 13.352 1973 1410.029 849.023 387.024 181.033 '121.030 60.038 40.040 30.040 35.02+ 1974 1300.033 604.034 283.037 143.043 98.038 56.042 43.036 33.035 21.039 1975 432.056 193.056 108.056 93.051 52.0 51' 37.051 31.046 23.046 15.046

317 GILA RIVER BASIN 239

09482500 SANTA CR02 RIVER AT TUCSON, A2-- CONTINUED

DISCHARGE, IN CUBIC FEET PER SECOND

1 STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

12 OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT 9 47 BY ROWS (MEAN.VARIANCE,STANOARD OEVIATION,SKEWNESS,COEFF. OF VARIATION,PERCENTAGE OF AVERAGE VALUE) 0.07 10 3.57 5.62 30.7 14.8 10.8 3.52 0.10 1.37 52.9 102 34.6 48 146 752 18770 3267 1461 184 0.08 0.11 20.2 5356 13880 3928 12.1 27.4 137 57.2 38.2 13.5 0.29 0.33 4.49 73.2 118 62.7 7 5.81 7.39 5.33 5.56 4.05 4.97 3.99 5.96 4.27 3.07 2.55 3,23 28 3.38 8.88 4.46 3.86 3.53 3.85 2.95 4.65 3.29 1.38 1.15 1.81 20 1.37 2.16 11.8 5.69 4.16 1.35 0.04 0.03 0.53 20.3 39.2 13.3 55 43

15 58 56 13 DISCHARGE, IN CUBIC FEET PER SECOND 36 STATISTICS ON NORMAL ANNUAL MEANSCALL DAYS) 6 29 MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 44 22.0 398 20.0 2.04 0.91 0.030 40 16

37 35 38 14 23

53 57 26 30 17

22 54 33 27 8 91 31 5 2

60 59 18 42 32

21 50 19 3 61

11 45

51 34

25 52 24 39 46

318 240 GILA RIVER BASIN

09483100 TANQUE VERDE CREEK NEAR TUCSON, AZ

LCCATIQ1.- -fat 32 °14'48 ", long 110 °40'46 ", in sec.2, T.14 S., R.16 E., Pima County, on right bank 4.4 mi (7.1 )on) east of Tanque Verde School, 7.4 mi (11.9 lan) upstream from Aqua Caliente Wash, 7.8 mi (12.o km) northwest of Spud Rock, and 17.5 mi (28.2 km) east of City Hall in Tucson.

DRAI.NAGE AREA.- -43.0 mi= (111.4 fans).

h ATER ANNUAL PEAR DATE GAGE NEIGST OF nATFR TOTAL VULUME. TEAR 0I5CR,CFS ANNUAL PEAK.FT YEAR ACRE -FT

1960 789 01-11-60 2.83 1960 8P10 1961 1260 09-08-61 2.85 1961 1900 1962 925 12-16-61 2.94 1442 6950 1963 1585 02-11-63 3.50 1963 3960 1964 2630 09-10-64 4.8b 1964 5160 19155 828 09-09-65 3.21 1965 3760 1966 2760 12-22-65 4.93 1966 23090 1967 12b0 07-16-67 3.71 1967 766 1968 3080 12-20-67 5.14 1968 11390 1969 278 01-15-69 2.37 1959 1690 1970 1060 03-02-70 3.50 1970 3850 1971 2350 08-21-71 4.64 1971 3370 1972 1190 07-16-72 3.64 1972 3580 1973 2120 10-19-72 4.38 1973 16A5n 1974 804 07-08-74 3.18 1974 2540 1975 210 - - 2.19

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGEIN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 262728293031323334 YEAR NUMBER OF DAYS INCLASS 1960 166 1 4 10 7 11 3 8 8 5 11 2 2 9 9 10 16 i6 13 11 4 11 5 9 3 5 4 3

1961 23610 11 30 3 1 5-4 2 5 5 1 3 7 3 5 4 4 5 5 4 4 4 2 2 1962 123 5 S 11 2 10 8.4 1 3 7 5 9 12 7 12 27 30 30 27 7 4 6 3 2 1 1 2 1 1963 163 3 4 7 2 6 3 19 7 11 11 17 14 I5 12 8 20 12 10 8 3 3 2 1 1 1 1 1 964 241 7 7 6 4 5 13 6 13 8 3 5 3 3 3 4 2 4 5 4 2 4 3 1 3 2 1 S 132 30 17 11 21 14 6 8 16 11 25 20 19 7 8 5 6 4 2 2 1

A.66 159 12 9 5 9 3 4 5 5 7 6 13 2 11 22 )5 19 13 11 6 8 6 5 4 2 2 1967 207 89 20 4 10 4 5 4 4 2 6 1 3 3 1 1 1 1968 133. 23 12 7 10 4 7 11 5 7 5 21 32 23 19 15 6 7 8 1 2 2 3 1 2 1969 183 32 15 6 4 6 3 20 19 13 23 14 7 8 5 2 2 1 1 1 1970 142 62 16 7 12 8 11 17 7 10 4 9 9 5 6 7 2 1 2 3 3 2

1971 282 25 4 1 3 1 4 2 2 2 1 3 8 2 5 3 5 3 3 2 3 2 1972 118 52 19 22 17 11 13 10 12 11 14 12 11 13 7 7 5 5 6 1 1973 93. 23 5 6 6 5 5 11 13 23 17 16 25 20 37 11 6 10 10 8 5 2 3 1 2 2 1974 226 70 4 3 14 2 5 3 3 2 1 5 4 1 3 2 2 4 1 2 1 1 1

CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT 0 0.00 2604 5479 100.0 12 1.2 125 1644 30.0 24 78 44 139 2.5 1 0.01 26 2875 52.5 13 1.8 132 1519 27.7 25 110 33 95 1.7 2 0.02 28 2849 52.0 14 2.5 124 1387 25.3 26 160 21 62 1.1 3 0.03 65 2821 51.5 15 3.5 133 1263 23.1 27 220 22 41 .7 4 0.05 20 2756 50.3 16 4.9 189 1130 20.6 28 310 7 19 .3 5 0.07 32 2736 49.9 17 7.0 184 941 17.2 29 440 4 12 .2 6 0.10 462 2704 49.4 18 9.9 153 757 13.8 30 620 6 8 .1 7 0.20 173 2242 40.9 19 14.0 170 604 11.0 31 880 2 2 8 0.30 96 2069 37.8 20 20.0 90 434 7.9 32 9 0.40 143 1973 36.0 21 28.0 80 344 6.3 33 10 0.60 100 1830 33.4 22 39.0 67 264- 4.8 34 11 0.90 86 I730 31.6 23 56.0 58 197 3.6

319 GILA RI \ER BASIN 241

09483100 TANQUE VERDE CREER \EAR TUCSON, A_-- CONTINUEP

L UME4I NFAN VALUE .N44AN6TN4 FURTHE FULLfMI..G NUMBER OF FUNSFCIITTVF DAYS INYEARENDINGSEPTEMBE4 30 DISCHARGE.IN CUBIC FEFT PFN SECOND MEAN

YEAR 1 3 7 14 ZU AO 90 120 193 1960 0.00 1 0.04 1 0.00 1 0.04 1 0.04 1 0.00 1 0.00 1 0.00 1 0.14 5

1961 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.31 6 1,462 0.00 3 0.04 3 0.00 3 0.00 3 0.00 3 0.00 3 0.0613 0.2712 1.6010 1963 0.00 4 0.00 9 0.00 4 0.00 4 0.00 4 0.04 4 0.00 3 0.41 13 1.8011 1964 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4 0.00 3 0.09 3 1965 0.00 b 0.00 6 0.00 6 0.00 6 0.04 b 0.00 b 0.00 5 0.01 7 1.19 9

1966 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.0411 1.1914 4.1014 1967 0.00 8 0.00 8 0.00 8 0.00 6 0.00 8 0.00 8 0.00 6 0.00 4 0.00 1 1968 0.00 9 0.00 9 0.04 9 0.00 9 0.00 9 0.00 9 0.3615 1.9015 2.6012 1969 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.0210 0.09 9 0.6? 7 1970 0.0011 0.00 11 0.00 11 0.00 11 0.00 11 0.00 11 0.0912 0.2610 4.7015

1971 0.0012 0.0012 0.0012 0.0412 0.0012 0.0012 0.00 7 0.00 5 0.01 2- 1972 0.0013 0.0013 0.00t3 0.0013 0.0013 0.0013 0.00 8 0.01 6 0.14 4 1973 0.0014 0.0014 0.0014 0.0014 0.0014 0.01 15 0.0914 0.27 11 3.8013 1974 0.00IS 0.0015 0.0015 0.0015 0.0015 0.0014 0.00 9 0.03 8 0.92 6

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE.IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1960 300.0 7 241.0 6 208.0 4 139.0 3 106.0 3 65.0 3 46.0 4 36.0 4 24.0 .4

1961 92.015 50.015 38.013 24.014 20.013 15.013 9.913 7.413 .4.913 1962 453.0 5 296.0 5 158.0 6 92.0 6 50.0 6 40.0 6 30.0 5 26.0 5 19.0 5 1963 518.0 4 304.0 4 154.0 7 79.0 7 42.0 8 25.0 8 19.0 8 14.0 8 9.5 7 1964 422.0 6 186.0 7 159.0 5 123.0 5 68.0 5 43.0 5 29.0 6 21.0 6 14.0 6 1965 122.012 57.012 52.011 31.012 24.011 19.0 9 15.0 9 12.0 9 8.4 9

1966 090.0 1 657.0 1 362.0 1 341.0 1 213.0 1 124.0 1 107.0 1 06.0 1 ST.0 1 1967 102.014 62.013 28.015 16.015 12.015 6.115 4.115 3.115 2.015 1968 851.0 2 464.0 J 230.0 3 124.0 4 80.0 4 58.0 4 53.0 3 44.03 30.0 3 1969 122.013 61.014 30.014 24.013 14.014 9.614 8.014 6.514 4.314 1970 250.0 0 141.0 9 69.0 9 60.0 9 32.0 9 11.010 11.012 8.511 7.011

1971 189.010 170.0 8 109.0 8 77.0 8 49.0 7 28.07 19.0 7 14.0 7 9.3 8 1972 140.011 83.011 43.012 35.010 20.012 16.011 .15.010 12.010 7.810 1973 748.0 3 530.0 2 269.0 2 149.0 2 142.0 2 91.0 .2 65.0 2 51.0 2 43.02 1974 226.0 9 110.010 62.010 32.011 31.010 16.012 11.011 8.112 S.3I2

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG 'SEPT BY ROWSIMEAN.VARIANCE.STANOARO OEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTAGE OfAVERAGE VALUE) 4.56 2.05 24.7 14.8 21.2 15.0 3.45 0.31 0.05 3.17 8.24 9.62

142 - 11.8 2639 587 939 688 27.3 0.80 0.04 '23.4 148 352 11.9 3.44 51.4 24.2 30.6 26.2 5.23 0.90 0.21 4.84 12.2 18.8 3.11 1.89 3.11 2.85 1.27 2.79 2.05 3.67 3.87 1.88 1.46 2.87 2.61 1.68 2.08 1.64 1.45 1.74 1.51 2.93 3.86 1.53 1.47 1.95 4.25 1.91 23.1 13.8 19.8 14.0 3.22 0.29 0.05 2.95 7.69 8.97

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANSCALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 8.90 73.1 8.55 1.78. 0.96 -0.460

320 242 GILA RIVER BASIN

09484000 SABINO CREEK NEAR TUCSON. AZ

LOCATION. --Iat 32 °19'01 ". long 110 °48'36 ", in SE1/4NE4 sec.9, T.13 S., R.I5 E., Pima County, on right bank 0.5 mi (0.8 km)north of Coronado National Forest boundary and 12 mi (19.3 km) northeast of City Hall in Tucson.

,AINAGE AREA.--35.5 mil (91.9 km2).

A ATER ANwUAL PEAK GATE COOES GAGE HEIGHT OF r.ATFo TOTAL VOLUME, YEAR DISCH.CFS ANNUAL PEAK,FT YEAS ACHE -FT

1933 510 09-10-33 4.13 1933 5300 1934 u72 09-22-34 4.59 1994 904 1935 540 02-0b-35 4.85 1935 11400 1936 500 01-29-36 4.69 1430 4330 1931 2020 02-07-37 6.51 1937 0510 1938 3200 03-03-38 7.13 1998 4490 1939 385 08-00-39 3.96 1939 2150 1940 904 02-23-40 4.98 1940 L600 1941 3180 12-30-40 7.13 1941 21000 1942 449 09-10-42 4.34 1942 8990 1943 5b7 03-05-43 4.56 1943 3030 1944 175 07-08-44 3.31 1944 3340 1995 916 07-30-45 5.15 1945 0430 1946 2000 08-23-46 6.30 1946 SAbn 1947 227 12-26-46 3.47 1947 1070 1948 300 08-06-48 4.06 1940 1560 1949 1430 08-08-49 5.78 1949 9400 1950 2260 07-07-50 6.50 1950 1670 1951 750 08-02-51 5.11 1951 2040 1952 1640 01-13-52 6.25 1992 14000 1953 861 07-16-53 5.31 1953 3630 1904 5110 03-23-54 8.43 1954 12700 1955 2000 08-03-55 6.55 1995 5790 1956 55 08-11-56 2.33 1996 377 1957 2030 01-09-57 6.65 1997 8210 1958 1500 03-22-58 5.85 1958 15000 1959 4240 07-26-59 7.85 1959 4190 1960 1000 12-24-59 5.95 1960 15500 1961 910 08-30-61 5.25 1961 1840 1962 1010 09-26-o2 5.44 1962 11600 1963 2070 08-15-63 6.54 1965 5950 1964 1310 09-13-64 5.82 1964 5110 1965 244 02-07-65 4.24 1965 7700 1966 6400 08-10-66 9.65 1900 34900 1967 788 07-17-67 5.67 1967 ¿Pb 0 1968 2340 12-19-67 7.30 1968 19100 1969 310 01-14-69 4.99 1969 5490 1970 7730 09-06-70 10.21 1970 9830 1971 660 08-10-71 5.52 1971 3100 1972 1710 10-01-71 6.87 1972 6420 1973 2750 10-19-72 7.68 1973 23400 1974 117 07-20-74 4.78 1974 1400 GILL RIVER BASIN 243

09484000 SABINO CREEK NEAR TUCSON, A2-- CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER30 OISCMARSE, IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 2627 2829 303132 3334 YEAR NUMBER OF DAYS IN CLASS 1933 14 13 10 34 30 4 9 19 14 17 6 11 14 15 12 15 22 16 24 18 30 12 3 1 j134 37 31102 37 23 20 12 15 7 14 6 8 8 7 14 10 2 4 2 2 1 3 1135 14 33 20 7 13 7 4 15 4 9 16 6 14 12 17 24 19 17 22 24 14 19 16 7 6 3 1

1936 41 14 10 4 26 11 6 11 12 7 23 10 27 33 8 13 23 21 19 16 8 6 9 5 2 1 1 1937 36 44 11 24 22 6 7 3 8 5 23 10 11 11 8 6 7 8 13 39 14 21 14 4 4 2 2 1 1 1938 38 78 32 39 20 8 8 8 4 7 16 7 13 13 12 9 11 8 4 7 8 '5 5 1 1 1 1 1 1939 19 19 15 3 1940 13 27 29 15 14 9 3 11 29 25 39 22 23 24 28 16 11 6 2 2 1 2 1

1141 16 15 9 21 15 4 3 6 8 10 12 15 14 16 10 13 13 29 26 23 27 16 14 18 2 4 2 1 1 1942 36 23 12 6 11 6 .8 7 6 10 6 9 8 12 14 15 25 29 32 38 20 14 8 5 2 2 1 1143 66 16 58 11 16 9 4 34 10 7 4 11 19 26 21 12 8 9 6 2 3 5 3 1 1 1 1944 7 13 10 2180 35 14 8 8 10 5 7 10 14 19 24 13 15 20 16 7 7 2 1 1945 38 1648 -4 S 6 9 7 5 5 3 11 15 10 14 20 31 21 30 29 23 11 S 3 1

1146 45 25 5 13 14 23 9 10 6 10 5 16 16 9 30 40 32 14 14 12 8 5 3 1 1847 15 23 7 1016. 7 2 2 19 13 28 20 44 35 23 13 9 6 5 2 2 :2 1 1 1948 44 13 12 I7 22 23 6 28 30 43 14 20 17 13 10 13 18 12 3 2 2 2 1 1 1949 6 15 12 5 3 65 18 17 4 12 4 12 9 12 9 7 12 28 34 30 19 9 14 2 3 1 1 2 r980 18 153146 24 19 21 11 6 10 16 27 34 44 11 9 4 3 3 6 5 1 1 j151 48 15 71 27 11 3 '3 14 4 .3 4 13 14 13 14 13 10 5 6 4 S 2 1 2 1152 32 35 15 4 4 4 .3 6 5 8 3 6 12 17 19 22 23 15 28 23 26 20 14 8 6 1 1 3 1 1153 96 28 23 3 9 S 7 4 10 10 22 26 27 29 17 22 8 11 10 S 2 5 1 2 1 44 3 1 1 j95S 342 325 23'24 37 13 11 11 15 6 12 13 17 27 23 16 6 5 5 11 4 7 3 2 1

1154 69110 22 16 10 21 31 16 8 6 S 11 13 8 14 6 5 2 1957 123 37 7 5 4 2 5 3 4 6 12 9 9 6 11 9 17 13 25 24 10 7 6 4 4 2 I 1958 43 11 5 2 2 1 3 6 3 6 6 13 25 23 16 19 32 24 22 24 15 13 19 16 9 1 2 1 1 1959 61 17 5 2 6 3 9 29 18 23 29 28 35 23 20 11 8 6 9 6 6 1 2 2 3 3 1960 42 32 13 30 10 9 12 8 3 7 S 9 22 11 11 16 16 13 20 16 14 23 IS 12 S 2 2 1 2 1

1961 121 53 38 3 3 1 :2 16 10 7 14 15 23 8 11 7 7 6 3 7 2 2 3 1 1ri2 93 15 8 2 6 2 1 9 4 4 3 S 21 17 9 10 5 3 15 32 21 37 27 5 3 1 1 1963 44 25 9 7 6 5 12 18 20 10 7 10 6 21 I7 41 21 21 21 14 8 9 6 1 3 1 1964 78 15 9 3 6 1 45 23 15 19 14 12 12 16 18 11 13 6 6 6 7 5 2 1 2 2

1165 73 . 14 10 2 15 2 20 17 33 27 18 15 18 13 24 35 16 I1 3 1

1966 73 30 9 2 S 3 4 S 7 9 8 15 11 8 24 24 36 26 29 22 5 1 4 1 1 2 1 1917 60 2 2 1 1 5 1 4 S 4 33 26 50 41 32 23 15 13 10 15 5 3 4 1 2 1 3948 40 1 1 4 22 5 13 16 2 10 4 7 8 13 12 18 13 25 21 3 17 51 28 15 10 6 1 .2 1961 74 1 S 4 1 4 3 '9 10 3 1 12 8 11 19 21 24 18 37 36 33 11 8 2 3 1 1171 49 7 8 7 11 16 14 3 3 2 2 26 41 29 32 32 21 17 13 11 10 10 4 1 1 2 1 1

1971 67 2 3 6 13 11 3 22 12 26 49 27 37 15 12 12 10 6 2 7 S 3 8 2 3 1 1 1112 105 3 4 3 2 3 4 7 3 9 5 10 42 32 14 23 21 13 12 19 6 9 4 4 4 2 1 1973 29 1 2 1 17 1 3 2 5 10 15 8 49 43 26 26 22 19 20 24 15 11 4 1 2 3 2 1174 1 6 4 1 5 5 8 5 2 22 S 3 15 19 21 22 23 11 6 13 9 6 S 1 4

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 1 0.00 2291 15340 100.0 12 0.8 662 7569 49.5 24 72 183 -443 2.8 1 0.01 968 13049 85.1 13 1.2 779 6921 45.2 25 100 124 250 1.6 2 0.02 729 12081 78.8 14 1.8 710 6148 40.1 26 150 55 126 .8 3 0.03 437 11352 74.0 15 2.6 650 5438 35.4 27 220 24 71 .4 4 0.04 5S7 10915 71.2 16 3.7 716 4788 31.2 28 320 22 47 .3 5 0.06 462 10356 67.5 17 5.4 655 4072 26.5 29 460 11 25 .1 1 0.09 48 9696 64.5 18 7.8 559 3417 22.3 30 660 8 14 T 0.10 385 9648 64.2 19 11.0 646 2858 18.6 31 960 3 6 I 0.20 527 9463 61.7 20 16.0 580 2212 14.4 32 1400 1 3 1 0.30 348 8936 58.3 21 24.0 A49 1632 10.6 33 2000 2 2 18 0.40 580 8588 56.0 22 34.0 452 1183 7:7 34 11 0.60 419 5008 52.2 23 49.0 298 731 4.8 244 GILA RIVER BASIN

09484000 SABINO CREEK NEAR TUCSON, AZ-- CONTINUED

IU4E5T MEAN VALUE e,Nn44N0N4PLOT TkF FU1Lpnin1NUwBFkUFrU45Et1'TTvFDAYSINIE414EdUTN.SEPTEMnE930 nISCMAaGF,IN CUMir FhFT NFk SFCnNn ut4N

7 30 TtAR l 3 14 60 90 120 143 1933 0.01 41 8.01 41 0.91 ni 0.01 3g 0.0441 0.3739 8.7330 1.00 28 3.20?3

1934 0.00 1 8.80 1 u.un 1 u.u0 1 0.04 1 O.Un 1 0.01 7 0.03 6 0.27 3 1935 0.00 2 u.00 2 0.00 2 0.00 2 0.611 15 0.1717 1.0034 2.40 13 8.1016

1936 0.00 3 U.00 3 0.80 3 0.00 3 0.04 2 0.00 2 0.0619 1.30 29 3.0022 1431 0.04 4 0.00 4 0.00 4 0.00 4 0.00 3 0.00 3 0.02t3 0.35 17 2.2018 1918 0.00 5 0.00 5 0.00 5 9.00 5 0.00 4 0.01 21 0.01 8 0.02 4 2.1020 1919 0.00 6 8.00 b 0.00 6 0.00 b 0.04 5 0.0330 0.1223 0.74 23 2.9021 1940 0.00 7 0.00 7 0.04 7 47.00 1 47.01 36 0.0915 0.4979 0.93 25 1.4014

1941 0.0142 0.01 42 0.01 42 0.01 39 0.0117 0.3448 3.5041 4.90 42 7.9015 1442 0.00 8 0.00 8 0.00 8 e.01 8 0.04 6 0.00 4 0.0516 0.42 20 4.2026

1943 0.04 9 8.00 9 0.0n 9 0.00 v O.Un 7 0.04 5 0.00 1 0.22 11 1.8016 1944 0.00 tu 0.00 70 0.04 10 0.01 40 0.01 38 0.0411 0.0511 0.32 16 4.4027 1945 0.00 11 0.00 11 9.1,0 11 0.00 10 0.00 8 0.0122 0.7912 4.00 18 6.2032

1946 0.00 12 0.00 12 0.00 12 0.01 11 0.00 9 0.00 b 0.0314 0.67 22 2.6019 1947 0.00 13 0.0 13 0.e1 13 0.00 12 0.0010 0.00 7 0.00 2 0.01 1 0.11 2 1948 0.00 14 0.04 14 0.04 14 v.9n 13 0.00 11 0.00 8 0.0518 0.26 13 1.6015 1949 0.00 15 0.00 15 0.un 15 0.01 41 0.01 19 0.0A34 1.4037 4.80 41 7.7034 195v 0.00 lb 0.00 16 0.00 lb U.00 14 0.01 40 0.0228 0.0971 0.41 19 1.3012

1991 0.00 17 0.00 17 0.04 17 0.00 15 0.0012 0.0123 0.01 9 0.02 5 0.08 1 1952 0.00 18 0.00 18 0.00 18 0.00 lb 0.0013 0.1918 1.5018 2.80 14 8.7037 1953 0.00 19 0.00 19 0.00 19 0.00 17 0.0014 0.0124 0.2375 1.70 32 4.0024 1954 0.00 20 0.00 20 0.00 20 0.00 18 0.00IS 0.00 9 0.0710 0.01 2 13.0040 1955 0.00 71 0.00 21 0.00 71 0.00 19 0.0016 0.0125 0.0315 0.27 14 2.0017

1956 0.00 22 0.00 22 0.00 22 0.00 20 0.0017 0.00 10 0.00 3 0.02 3 0.37 4 1957 0.00 23 0.00 73 0.00 23 0.00 21 0.0018 0.0011 0.00 4 0.93 26 5.1n28 1958 0.00 24 0.00 24 0.0n 74 0.00 22 0.0419 0.0432 1.8039 3.20 36 12.0039 1959 0.00 25 0.00 25 0.00 25 0.00 23 0.0070 0.0012 0.0111 0.09 8 0.46 6 1960 0.00 Pb 0.00 Pb 0.00 76 0.04 74 0.0021 0.0013 0.3228 0.56 21 1.4013

1961 0.00 77 0.00 27 0.00 27 0.80 75 0.0022 0.0014 0.00 5 0.06 7 0.46 7 1962 0.00 28 0.00 28 0.80 78 0.00 26 0.0023 0.0729 0.2926 0.22 t2 5.7031 1963 0.00 29 0.00 29 0.00 79 0.00 27 0.0024 0.012b 0.1424 1.30 30 5.4079 1964 0.00 10 u.00 30 0.00 10 0.00 78 0.0025 0.0127 0.3021 0.29 15 0.83 9 1965 0.00 31 0.00 31 0.00 11 0.00 29 0.0n26 0.0015 0.0820 0.93 77 5.5030

1966 0.00 32 0.00 32 0.00 32 0.00 30 0.0077 0.1036 1.1935 4.10 39 70.0042 1967 0.00 33 0.00 33 0.00 33 0.00 Ni 0.0028 0.0016 0.7431 0.91 24 0.91 11 1968 0.00 34 3.00 34 0.00 34 0.04 32 0.0029 0.4441 2.5040 4.20 40 8.9038 19h9 0.00 35 8.00 35 0.00 15 0.00 33 0.0030 0.0017 1.3036 2.80 15 4.0025 1970 0.00 36 0.80 36 0.On 36 0.00 14 0.0031 0.0733 0.8333 1.50 31 6.3033

1971 0.00 17 0.00 37 0.00 37 0.00 35 0.0032 0.0018 0.0112 0.15 10 0.45 5 1972 0.00 98 0.00 98 0.00 18 0.00 36 0.0033 0.0019 0.1022 0.13 9 0.49 8 1973 0.00 39 0.00 39 0.00 39 0.01 42 0.0842 1.5042 4.9042 4.00 37 14.0041 1974 0.00 40 0.00 40 0.00 40 0.00 17 0.0014 0.0020 0.00 6 0.39 18 0.8610 GI)A RIVER BASIN 24

09484000 SABINO CREEK NEAR TUCSON, AZ -- CONTINUED

MI6HEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECOND MEAN

143 YEAR 1 3 7 15 30 60 90 120 183 3.20P3 1933 99.035 58.035 43.032 38.030 33.027 28.021 22.021 18.022 13.021 0.27 3 1934 64.039 42.039 19.040 10.040 6.040 5.340 4.040 3.041 2.041 16 8.10 1935 383.014 304.011 180.011 109.012 72.012 57.0 8 46.0 7 37.0 9 25.010

3.0022 1936 183.026 110.027 61.028 43.027 38.023 23.026 17.025 14.025 9.725 18 2.20 1937 655.010 345.010 175.012 124.0 8 78.010 36.0 9 43.010 34.010 23.0 11 2.7020 1938 670.0 9 436.0 7 211.0 8 110.0 11 57.016 29.019 20.024 15.024 11.024 2.9021 1939 108.033 69.033 39.034 24.036 13.038 8.437 6.136 5.336 4.835 14 1.80 1940 436.012 190.017 93.022 46.024 28.028 16.031 11.031 8.432 6.4 '1 15 7.90 1941 803.0 5 542.0 5 290.0 5 182.0 6 124.0 6 34.0 5 87.0 2 76.0 2 54.0 2 4.2026 1942 265.021 154.022 102.020 61.022 39.021 32.017 32.015 28.015 23.012 1.8016 1943 395.013 226.015 127.018 69.019 37.024 20.028 14.028 11.028 7.029 4.4027 1944 84.038 44.038 32.037 24.037 23.033 18.029 14.029 11.029 8.326 6.2032 1945 142.032 87.030 - 48.031 36.031 28.029 24.024 22.022 19.021 14.018

2.6019 1946 215.023 110.028 63.026 42.028 25.030 16.030 12.030 8.730 5.933 0.11 2 1947 -61.040 38.040 19.041 10.041 6.041 4.141 3.641 3.240 2.340 1.6015 1948 97.036 48.037 38.036 25.035 14.037 7.138 4.939 3.639 3.937 7.7034 1949 357.017 189.018 140.014 80.016 67.013 42.014 36.013 32.012 22.0I3 1.3012 1950 175.029 80.038 39.03S 22.038 15.036 8.836 5.937 4.437 3.638

0.04 1 1951 176.028 104.029 50.030 26.032 25.031 14.032 9.634 7.233 6.132 37 8.70 1952 460.011 231.014 197.0 9 117.0 9 83.0 9 48.012 44.0 8 42.0 8 35.0 1 4.0024 1953 179.027 122.028 62.027 40.029 25.032 13.033 9.932 8.731 5.127 90 13.00 1954 2010.0 2 1130.0 1 522.0 1 251.0 2 127.0 5 64.0 7 43.011 33.011 31.0 8 2.0017 1955 246.022 173.019 130.015 95.013 74.011 41.015 28.018 21.018 14.019 . 0.37 4 1956 10.042 7.142 4.942 4.842 3.342 2.042 1.442 1.042 0.942 5.1028 1957 869.0 4 388.0 9 185.010 94.014 66.014 44.013 36.014 28.013 18.015 12.0039 1958 758.0 7 420.0 8 277.0 6 185.0 4 :29.0 4 87.0 4 63.0 6 48.0 6 37.0 6 0.46 6 1959 211.024 148.023 71.025 43.025 36.025 23.025 16.026 12.026 7.730 1.4013 1960 754.0 8 484.0 6 274.0 7 168.0 7 147.0 2 95.0 3 72.0 5 57.0 5 42.0 5

0.46 7 1961 90.037 57.036 28.038 26.033 20.034 12.034 8.135 6.035 4.236 5.7031 1962 267.019 157.021 98.021 76.017 59.015 54.011 44.0 9 42.0 7 31.0 9 5.4029 1963 266.020 212.016 128.017 81.015 49.017 29.020 22.023 17.023 12.023 0.83 9 1964 284.018 232.013 129.016 74.018 41.019 31.018 26.0 19 19.019 13.022 5.5030 1965 104.034 64.034 55.029 43.026 36.026 33.016 30.017 26.016 18.016 20.0492 1966 1570.0 3 966.0 2 491.0 2 357.0 1 240.0 1 138.0 1 117.0 1 105.0 1 72.0 1 n.41 11 1967 152.031 74.032 41.033 26.034 17.035 12.035 9.633 7.234 5.334 38 1968 380.015 293.0I2 172.013 112.010 88.0 8 81.0 6 76.0 3 69.0 3 49.0 4 25 1969 206.0as 128.024 75.023 56.023 39.020 26.023 22.020 19.020 14.020 33 1970 2130.0 1 877.0 3 434.0 3 208.0 3 107.0 7 55.010 37.012 28.014 22.014

0.45 5 1971 170.030 115.026 73.024 64.021 38.022 22.027 16.027 I2.027 7.928 0.49 8 1972 374.016 160.020 106.019 65.020 44.018 27.022 31.016 25.017 17.0I7 41 14.00 1973 776.0 6 579.0 6 333.0 4 182.0 5 141.0 3 100.0 2 76.0 62.0 4 52.0 3 0.8610 1974 41.041 31.041 19.039 15.039 10.039 5.53S 5.038 3.738 2.539

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC IAN FEB MARCH APRIL NAY JUNE JULI AUG SEPT

8Y ROWS(MEAN,VARIANCE,STANDARODEVIATION,SKEwNESS,COEFF. OF VARIATION,PERCENTAGE OFAVERAGE VALUE) 5.09 3.43 16.6 16.1 20.9 26.4 9.78 1.85 0.33 5.36 12.0 9.07 212 34.8 1426 551 727 944 169 11.9 0.90 57.6 183 472 14.5 5.90 37.6 23.5 27.0 30.7 13.0 3.45 0.95 7.59 13.5 21.7 4.57 2.56 4.11 1.97 1.40 1.58 1.93 3.05 3.87 1.69 2.36 3.82 2.86 1.72 2.28 1.46 1.29 1.16 1.33 1.87 2.85 1.42 1.13 2.39 4.01 2.71 13.1 12.7 16.5 20.8 7.70 1.45 0.26 4.22 9.45 7.15

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION 5KE HIESS COEFF. OF VARIATION SERIAL CORR 10.5 96.0 9.80 1.91 0.93 -0.233

324 246 GILA RIVER BASSIN

09484200 BEAR CREEK NEAR TUCSON, AZ

LGCATION.- -Lat 32 °18'22 ", long 110 °48'03 ", in NWT sec.15, T.13 S., R.15 E., Pima County, on left bank 0.8 mi (1.3 km) upstream from mouth and 15 mi (24 km) northeast of City Hall in Tucson.

DRAINAGE AREA. --16.3 nil (42.2 km2).

RATER ANNUAL PEAK OAtO GAGE HEIGHT OF AT<< TUTAL VULUME, YEAR DISC$.CFS ANNUAL AEAK.FT YEAR ACRE -FT

1960 575 01-11-80 2.30 960 6210 1961 53 09-12-61 1.27 961 99 1962 225 10-18-61 1.96 962 4400 19b3 357 02-11-63 2.17 463 2130 1904 433 09-13-04 2.38 969 2080 1965 192 02-07-65 1.90 965 3130 1966 1150 12-22-e5 4.90 966 11400 1967 13 09-25-67 1.46 967 286 1968 621 12-20-67 3.36 968 6180 1969 214 01-15-69 2.40 969 1420 1970 b70 09-06-70 3.60 970 2420 1971 495 08-19-71 3.16 911 182 1972 247 10-01-71 2.33 972 1760 1573 618 10-19-72 3.35 973 8480 1974 57 01-09-74 1.31 974 371

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1? 18 19 20 21 22 23 24 25 26 27 2829 303132 3334 YEAR NUMBER OF OAYS IN CLASS 1960 129 40 7 8 S IS 16 3 5 6 8 20 9 2 9 7 5 7 14 19 6 4 12 4 1 2 2 1

1961 255 11 5 15 22 29 6 8 6 2 1 2 1 1 1 1962 167 6 6 32 7 4 4 2 1 1 2 2 4 7 11 14 15 16 22 21 10 5 1 1 1963 65 4124 40 27 17 12 16 5 4 9 21 16 17 9 9 7 2 5 8 5 2 1 1 1 1 1964 165 2244 7 9 7 7 10 5 6 6 13 10 15 9 5 3 4 1 4 4 3 2 3 2 1965 140 7 22 20 14 12 19 4 6 14 16 13 15 15 18 14 8 6 1 1

1966 134 1 11 9 9 3 3 17 16 14 9 6 9 9 19 19 10 18 23 8 3 2 2 1 2 1967 126 47 27 54 42 27 24 11 3 1 1 2 1968 140 23 13 13 4 1 12 13 6 5 10 14 21 11 16 23 10 13 6 6 1 2 1 9 140 35 18 14 18 4 17 25 26 24 18 10 7 1 4 2 1 1 7 146 22 13 29 36 27 17 11 6 il 9 6 2 4 3 12 4 1 1 1 1 1

1971 316 16 6 3 4 2 3 3 2 2 1 3 1 1 2 1972 212 14 14 9 9 7 14 22 11 6 4 13 6 3 3 5 4 4 2 2 1973 77 3 8 10 10 4 7 11 7 6 29 18 16 24 21 16 1: 15 9 16 6 7 2 1 2 2 1 1974 191 8 3 24 33 20 17 13 6 3 3 12 2 7 8 5 1 2 1

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 2411 5479 100.0 12 0.9 145 1641 30.9 24 43 59 130 2.3 1 0.01 126 3068 56.0 13 1.2 206 1496 27.3 25 60 33 11 1.2 2 0.02 92 2940 53.7 14 1.7 135 1290 23.5 26 83 13 38 .6 3 0.03 134 2848 52.0 15 2.4 143 1155 21.1 21 110 10 25 .4 4 0.05 0 2714 49.5 16 3.3 135 1012 18.5 28 160 4 15 .2 5 0.06 113 2714 49.5 17 -4.5 125 877 16.0 29 220 5 11 .2 6 0.09 0 2601 47.5 18 6.3 108 752 13.7 30 300 4 6 .1 7 0.10 275 2601 47.5 19 8.6 89 644 11.8 31 410 2 2 8 0.20 190 2326 42.5 20 12.0 116 555 10.1 32 9 0.30 210 2136 39.0 21 16.0 147 439 8.0 33 10 0.50 ITS 1926 35.2 22 23.0 83 292 5.3 34 11 0.70 110 1751 32.0 23 31.0 79 209 3.8

325 GILA RIVER BASIN 247

09484200BEAR CREEK NEAR TUCSON, AZ-- CONTINUED

IUNEST MiAN VALUF Ann4ANKInG Fe)RTMi FUILnNTNGNUM9FNuFCUNSFCNTIVF DAYS INYEAHEnutnGSEPTFM4ER iU 'ISCHARGF,IN f.UAIC FEET PER SECO.O =AN

10 YEAR 1 3 7 tu 60 90 120 183 1960 0.00 1 0.00 1 0.00 1 0.00 I 0.00 1 0,00 1 0.00 1 0.00 1 0.03 4

1961 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.01 3 1962 0.00 3 U.00 3 0.00 3 0.00 3 0.00 3 u.00 3 0.00 3 0.00 3 0.62 8 1963 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.01 11 u.0 9 1.101u 1964 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4 0.00 4 0.05 5 1965 0.00 b 0.00 b 0.00 6 0.00 6 0.00 6 0.00 6 0.00 5 0.00 5 1.3012

1966 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.0?13 0.1713 S.20t5 1967 0.00 8 0.00 8 0.00 e 0.00 ö 0.00 8 0.00 4 0.0114 0.11 12 0.10 b 1968 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 b 0.4214 1.1011 1969 0.0010 0.0010 3.00 10 0.0010 0.0010 0.0010 0.01 12 0.07 11 0.64 9 1970 0.00tl 0.00 11 0.00 11 0.00 11 0.0011 0.00 11 0.00 7 0.0610 1.6013

4 1911 0.0012 0.0012 0.0012 . 0.0012 0.0012 0.0012 0.00 0.00 b 0.00 1 1972 0.0013 0.0013 0.0013 0.0013 0.0013 0.001S 0.00 9 0.00 7 0.00 2 1973 0.0014 0.0014 0.0014 0.00t4 0.00t4 0.1115 0.5915 0.4525 2.8014 1974 0.0015 -0.0015 0.0015 0.0015 O.UO15 0.0014 0.0010 0.01 ö 0.10 7

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE.IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1960 316.0 3 225.0 3 138.0 2 92.0 2 66.0 2 44.0 3 31.0 3 25.0 3 17.0 3

1961 23.013 10.014 4.914.- 2.414 1.214 0.615 0.415 0.315 0.215 1962 129.0 8 18.0 8 50.0 8 39.0 6 29.0 5 26.0 5 21.0 5 20.0 5 13.0 5 1963 153.0 6 110.0 6 69.0 6 43.0 5 24.0 6 14.0 8 9.7 8 7.3 9 4.8 9 1964 106.0 9 82.0 7 64.0 7 36.0 7 20.0 7 15.0 6 11.0 7 8.3 7 5.7 7 1965 97.010 48.011 30.011 24.010 19.0 8 15.0 7 14.0 6 13.0 6 8.4 6

1966 468.0 1 321.0 1 176.0 1 142.0 1 99.0 1 56.0 1 51.0 1 43.0 1 29.0 1 1967 5.615 3.515 2.215 1.415 1.115 0.714 0.814 0.714 0.514 1968 265.0 5 154.0 5 87.0 4 58.0 4 38.0 4 35.0 4 30.0 4 25.0 4 16.0 4 1969 142.0 7 68.0 9 34.010 22.011 13.011 7.811 6.310 5.010 3.411 1970 361.0 2 163.0 4 76.0 S 36.0 8 18.0 9 9.3 9 6.211 4.811 4.010

1971 16.014 13.013 7.813 4.413 3.013 1.513 1.013 0.813 0.513 1972 80.011 56.018 44.0 9 25.0 9 15.010 8.110 9.0 9 7.4 8 4.9 8 173 314.0 4 228.0 2 130.0 3 74.0 3 63.0 3 44.0 2 31.0 2 26.0 2 21.0 2 74 28.012 18.012 9.512 6.612 3.912 2.112 1.412 1.112 0.712

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT . BY ROWS (MEAN.VARIANCE.STANDARD DEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 3.15 1.03 12.7 10.2 12.4 8.82 2.07 0.22 0.00 0.66 1.80 3.63 55.0 2.02 533 223 233 138 12.3 0.45 0.00 4.14 5.88 45.2 7.41 1.42 23.1 14.9 15.3 11.7 3.50 0.67 0.01 2.03 2.42 6.72 2.94 1.10 2.89 2.43 0.91 1.63 2.36 3.83 3.85 3.66 1.24 1.96 2.35 1.38 1.82 1.46 1.23 1.33 1.69 3.10 3.66 3.09 1.35 1.85 5.56 1.82 22.4 18.0 21.8 15.6 3.66 0.38 0.00 1.16 3.18 6.41

DISCHARGE IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 4.69 21.7 4.65 1.19 0.99 -0.452

326 248 GITA RIIER BASíN

09484500 CIE \EGA CREEK NEAR PANTANO, A.

LOCATION. --Lat 31 °59'08 ", long 11035'57 ", in NIA sec.1, T.17 S., R.17 E., Pima County, on downstream end of first pier from right abutment of bridge on Interstate Highway 10, and 1.2 mi (1.9 km) southeast of Pantano.

DRAINAGE ARFA. --289 mil (749 km2).

HATE. ANNUAL PEAK OATE GAGE HEIGHT OF nATFR TUTAL VOLUME, YEAR DISCH, CF6 ANNUAL PEAK.FT YCA.t ACNE -FT

19b6 1470 07 -2b -b8 4.06 190,9 60q 1969 990 07 -29 -69 3.40 1970 1790 1970 1770 07 -20 -70 3.98 1971 2740 1971 2240 05 -03 -71 4.51 1472 1140 1972 1930 09 -13 -72 4.46 1 '#73 730 1973 678 02 -22 -73 4.10 1974 4.500 1974 2570 07 -19 -74 5.05 1975 393 1975 1550 09 -02 -75 4.40

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 YEAR NUMBER OF DAYS IN CLASS 1969 346 1 1 3 1 1 3 3 1 4 1 1970 340 1 1 1 1 2 2 1 2 2 1 2 1 1 1 3 3

1971 332 1 1 1 1 2 4 2 3 2 1 1 1 2 6 1 1972 338 2 1 2 2 6 2 1 2 2 1 1 1 2 1 1 1 1973 346 1 1 3 1 1 2 2 2 2 1 1 1 1 1974 344 2 1 1 2 1 1 1 2 1 2 3 1 2 1 1975 352 1 1 1 1 1 1 1 1 2 1 2

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 2398 2556 100.0 12 0.8 14 131 5.1 24 38 7 47 1.8

1 0.01 I 158 6.2 13 1.2 7 117 4.6 25 52 10 40 1.5 2 0.02 2 157 6.1 14 1.6 11 110 4.3 26 71 8 30 1.1 3 0.03 0 155 6.1 15 2.2 6 99 3.9 27 97 9 22 .8 4 0.04 3 155 6.1 16 3.0 7 93 3.6 28 130 6 13 .5 5 0.06 1 152 5.9 17 4.1 7 86 3.4 29 180 4 7 .2 6 0.09 0 151 5.9 18 5.6 5 79 3.1 30 250 2 3 .1 7 0.10 3 151 5.9 19 7.7 11 74 2.9 31 350 1 1 B 0.20 5 148 5.8 20 11.0 4 63 2.5 32 9 0.30 2 143 5.6 21 15.0 4 59 2.3 33 10 0.40 4 141 5.5 22 20.0 3 55 2.2 34 11 0.60 6 137 5.4 23 27.0 5 52 2.0

LOWEST MEAN v4LUE ANn RANKTNT. FOR THE FOLLDMInG NUMBER OF CONSECUTIVE DAYS IN TEAR ENDING SEPTEMBER 30 DISCHARGE. IN CURIO FEET PER SECOND MEAN

TEAR 1 3 7 14 10 50 90 120 143

1969 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 1970 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2 0.00 2

1971 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 1972 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 0.00 4 1973 0.00 5 0.00 5 0.04 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.54 7 1974 0.00 b 0.00 6 0.00 6 0.00 6 0.00 6 0.00 6 0.00 6 u.00 6 0.00 5 1975 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6

327 GILA RIVER BASIN 249

09484560 CIEtiEGA CREEK NEAR P.ANTANO, A2-- CO\TINUED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN/EAR ENDING SEPTEMBER30 DISCHARGE,IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1969 53.0 7 32.0 7 21.0 7 13.0 7 8.1 6 5.1 5 3.4 5 2.5 5 1.7 6 1970 166.0 5 79.0 3 56.0 3 29.0 3 19.0 3 14.0 3 10.0 3 7.5 3 4.9 3

1971 238.0 2 135.0 2 92.0 1 60.0 2 40.0 2 22.0 2 15.0 2 12.0 2 7.6 2 1972 213.0 3 77.0 4 50.0 4 25.0 4 13.0 8.6 4 5.7 4 4.3 4 2.8 4 1973 200.0 4 74.0 5 32.0 5 15.0 5 8.8 5 4.4 6 2.9 6 2.2 6 2.0 S 1974 486.0 1 212.0 1 91.0 2 81.0 1 60.0 1 31.0 1 25.0 1 19.0 1 02.0 1 1975 95.0 6 56.0 6 26.0 6 13.0 6 6.4 7 3.3 7 2.2 7 1.6 7 1.1 7

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS (MEAN.VARIANCE.STANOARD OEVIATION.SKEWMESS.COEFF. OF VARIATION.PERCENT8E OF AVERAGE VALUE) 0.31 0.00 0.00 0.00 1.13 0.17 0.00 0.00 0.32 11.3 9.16 55S 0.54 0.00 0.00 0.00 9.00 0.22 0.00 0.00 0.83 319 170 29.1 0.73 0.00 0.00 0.01 3.00 0.47 0.00 0.00 0.91 17.9 13.1 5.40 2.60 2.65 2.65 2.65 2.83 2.83 2.45 2.07 0.50 2.40 2.65 2.65 2.65 2.83 2.83 1.58 1.42 0.97 1.09 0.00 0.00 0.01 4.06 0.59 0.00 0.00 1.16 40.5 32.8 19.8

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS' COEFF OF VARIATION SERIAL CORR 2.35 4.16 2.04 1.33 0.87 -0.584

Skewness and coefficient of variation could not be computed owing to a zero -value month.

328 250 GIIA RIVER BASIN

09484590 OAVIDSIX4CANYON WASH NEAR VAIL, AZ

LOCATION.- -Lat 31 °59'37 ", long 110 °38'40 ", in SASE,: sec.31, T.16 S., R.17 E., Pima Canty, on right bank 0.3 mi (0.3 km)upstream from Interstate Highway 10, 2.0 mi (3.2 km) upstream from mouth, and 5.5 mi (8.8 km) southeast of Vail.

DRAINAGE AREA.- -50.5 mil (130.8 km2).

RATER ANNUAL PEAK DATE GAEL HEIGHT OF ah1FN TOTAL VOLUME, YEAR DISCN,CFB ANNUAL PEAK,FT ',LAN ACRE -FT

1968 3040 07-26-68 5.19 1964 470 1969 587 08-05-69 3.80 147u 1040 1910 6860 07-20-70 7.45 1971 935 1971 1490 08-10-71 3.73 1972 256 1972 1320 09-07-72 3.b1 1473 0 1913 28 10-19-72 2.22 1974 754 1974 14b0 09-21-74 4.0 1975 708 1975 788 07-08-75 3.20

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 IT 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 YEAR NUMBER OF DAYS IN CLASS 1969 49 1 1 1 5 4 10 10 36 12 78 106 21 15 11 3 1 1 1970 342 2 2 3 1 1 2 3 1 2 1 1 2 1 1

1971 233 11 S 5 4 15 12 4 34 12 13 2 1 1 1 2 1 1 1 3 1 1 2 1972 331 2 2 2 1 3 I 5 5 5 3 I 2 1 1 1 1973 362 1 2 1974 344 1 2 1 3 1 1 1 1 1 1 2 2 3 1 1975 359 1 1 1 1 2

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUN PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 2020 2556 100.0 12 0.5 81 284 11.1 24 16 2 27 1.0 1 0.01 14 S36 21.0 13 0.7 108 203 7.9 25 21 4 25 .9 2 0.02 8 522 20.4 14 0.9 22 95 3.7 26 28 5 21 .8 3 0.03 12 514 20.1 15 1.2 IT 73 2.9 27 38 4 16 .6 4 0.04 7 502 19.6 16 1.6 12 S6 2.2 28 50 6 12 .4 5 0.05 23 495 19.4 17 2.2 4 44 1.7 29 66 3 6 .2 6 0.07 19 472 18.5 18 2.9 2 40 1.6 30 88 2 3 .1 T 0.09 10 453 17:7 19 3.9 1 38 1.5 31 120 1 1 8 0.10 57 443 17.3 20 5.1 4 37 1.4 32 9 0.20 31 386 15.1 21 6.8 3 33 1.3 33 10 0.30 54 355 13.9 22 9.1 1 30 1.2 34 11 0.40 17 301 11.8 23 12.0 2 29 1.1

LOWEST MEAN VALUE AND RANKING FOR TNF FOLLfWTNG NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMAER TO DISCHARGE, IN CUBIC FEET PER SECOND MEAN

YEAR i 3 7 l4 30 60 90 120 183

1969 0.00 1 0,00 1 0.00 1 0.00 1 0.01 7 0.26 7 0.33 7 0.38 7 0.41 7 1970 0.00 2 0.00 2 0.00 2 0.00 2 0.00 1 0.00 1 0.00 1 0,00 1 0.00 1

1971 0.00 3 0.00 3 0.00 3 0.00 3 0.00 2 0.00 2 0.00 2 0.00 2 0.04 6 1972 0.00 4 0.00 4 0.00 4 0.00 4 0.00 3 0.00 3 0.00 3 0.00 3 0.00 2 1973 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4 0.00 4 0.00 4 0.00 4 0.00 3 1974 0.00 6 0.00 6 0.00 6. 0.00 6 0.00 5 0.00 5 0.00 5 0.00 5 0.00 4 1975 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6 0.00 b 0.00 b 0.00 6 0.08 5

329 GIL4 RIVER BASIN 251

09484590 DAVIDSON CANYON WASH NEAR VAIL, AZ-CONTINUED

HIGHEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEARENDING SEPTEMBER30 OISCHARGE.IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 I20 183 1969 22.0 6 7.8 6 4.3 6 2.2 6 1.4 6 1.2 6 1.0 6 1.0 5 0.9 1970 231.0 1 112.0 1 40.0 1 23.0 1 18.0 1 8.8 1 5.8 1 4.4 1 2.9 1

1971 70.0 4 53.0 2 23.0 2 19.0 2 12.0 2 6.8 2 4.5 2 3.4 2 2.3 2 1972 117.0 2 40.0 4 17.0 4 8.0 4 4.0 4 2.0 4 1.3 4 1.0 4 0.7 S 1973 0.2 7 0.1 7 0.0 7 0.0 7 0.0 7 0.0 7 0:0 7 0.0 7 0.0 7 1974 75.0 3 45.0 3 20.0 3 9.4 3 8.0 3 4.9 3 4.2 3 3.2 3 2.1 3 1915 49.0 5 16.0 5 7.0 5 3.3 5 1.7 5 1.5 5 1.2 5 0.9 6 0.6 6

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS(NEAN.VARIANCESTANOARD DEVIATION.SKEWNESS.COEFF. OF VARIATION,PERCENTA6E OFAVERAGE VALUE) 0.10 0.14 0.23 0.11 0.18 0.20 0.15 0.11 0.07 2.48 3.40 2.06 0.07 0.13 0.26 0.08 0.10 0.10 0.06 0.04 0.02 15.5 15.9 7.68 0.27 0.36 0.51 0.28 0.31 0.31 0.24 0.20 0.13 3.93 3.99 2.77 2.65 2.65 2.49 2.64 1.46 1.30 1.31 1.45 1.57 1.86 1.22 1.71 2.61 2.65 2.21 2.55 1.77 1.57 1.61 1.78 1.88 1.58 1.17 1.34 1.11 1.47 2.49 1.17 1.90 2.17 1.58 1.23 0.75 26.9 36.8 22.4

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 0.70 0.28 0.53 0.11 0.75 -0.000

330 252 GILA RIVER aASIrr

09484600 PANTANO WASH NEAR VAIL, AZ

LOCATION.- -Lat 32 °02'09", long 110 °40'37 ", in SASE's sec.14, T.16 S., R.16 E., Pima County, on right bank 60 ft (18 m) upstreamfrom dam, 2.2 mi (3.3 km) southeast of Vail, 2.4 mi (3.9 km) southwest of Pistol Hill, and 20 mi (32 km) southeast of City Hallin Tucson.

DRAI.NAGE AREA. --457 mi= (1,184 km1).

EATER ANNUAL PEAK UATE GAGE HEIGHT OF r.ATE. TOTAL VuLUME. YEAR DISCH,CFS AqNUAL PEAA,FT YEA. ACRE -FT

1958 36600 08-11-58 24.00 1960 4660 1959 9310 0017-59 9.6U 1961 SPoO 1960 7300 08-09-60 8.30 1962 2000 1961 5260 06-28-61 6.87 1963 75.0 1962 1500 09-26-02 3.65 1964 93400 1963 9750 08-25-63 10.90 1965 2460 1964 9960 09-15-64 11.06 1966 9710 1965 5660 09-12-65 8.23 1967 6180 1966 7410 08-13-66 9.25 1960 6620 1967 7680 08-18-67 9.54 1969 1660 1968 2640 12-25-67 5.46 1970 3680 1909 857 08-05-69 3.40 1971 6480 1970 6850 67-20-70 8.95 1972 1860 1971 8700 08-19-71 10.34 1973 2930 1972 1460 09-07-72 4.65 1974 2`;u0 1973 371 10-04-72 3.10 1974 1700 07-20-14 7.05 1975 1700 09-02-75 6.70

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 35 2627 2B293031323334 YEAR NUMBER OF DAYS IN CLASS 1960 57 167 49 34 16 10 1 4 2 1 2 12 4 2 1 2 1 1

1961 54 116107 50 2 3 1 1 5 1 4 1 4 3 2 1 1 3 1 5 1962 2 90 140 84 28 4 2 2 3 2 1 3 1 1 1 1

1963 47200 52 25 6 2 4 3 2 2 1 1 3 I 5 5 2 2 1 1 1964 2 2 3 50 150102 5 13 4 4 3 3 1 4 4 2 2 2 1 4 2 1 1 1 1965 2 15 16 21 50 47 95 76 26 7 1 1 1 2 1 1 1 1 1

1966 6 20 18 33 32 29 43 34 59 19 5 6 5 4 L3 6 6 3 6 4 2 4 3 2 1 1 1 1967 1 I 5 22 25 94 79 82 21 10 6 7 2 4 2 3 1 1 3 1 2 1 1 1 1968 7 14 19 61 69 41 57 37 17 3 8 1 1 6 5 3 3 1 3 1 1 1 1 1969 4 4 17 36 40 23 44 48 88 50 1 1 2 1 1 1 1 1 1 1 1970 11 20 27134 82 48 16 6 1 2 2 2 1 2 1 I 2 1 1 2 1 1 1

1971 19 8 16 20 35 24 65 37 50 41 4 5 6 7 3 5 1 1 1 3 1 3 3 2 2 1 2 1972 3 20 31 68 25 73 80 41 1 2 1 4 2 2 I 1 1 3 1 1973 17 2? 15 25 22 14 22 32 47 42 33 12 9 7 6 6 6 7 5 4 1 4 1 1 1974 20206 56 22 11 4 13 7 4 1 2 1 2 1 1 2 6 2 3 1

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 56 5479 100.0 12 3.7 127 600 11.6 24 100 26 19 1.4 1 0.10 241 5423 99.0 13 4.9 60 473 8.6 25 140 18 53 .9 2 0.20 97 5182 94.6 14 6.4 46 413 7.5 26 180 15 35 .6 3 0.30 107 5085 92.8 15 8.5 48 365 6.7 27 240 6 20 .3 4 0.40 161 4978 90.9 16 11.0 27 317 5.8 28 310 4 14 .2 5 0.50 162 4617 87.9 17 15.0 42 290 5.3 29 410 3 10 .1 6 0.70 467 4655 85.0 18 20.0 41 248 4.5 30 550 4 7 .1 7 0.90 770 4188 76.4 19 26.0 36 207 3.8 31 720 1 3 a 1.20 1053 3418 62.4 20 34.0 20 111 3.1 32 950 2 2 9 1.60 896 2365 43.2 21 45.0 33 151 2.8 33 10 2.10 539 1469 26.8 22 59.0 21 118 2.2 34 11 2.80 330 930 17.0 23 78.0 18 97 1.8

331 GITA RIVER BASIN 253

09484600 PANTANO WASH NEAR VAIL, AZ--CO\TItiUED

LUwEST MFAN VALUF ANn 4A44I4G FU° Tif FULLnwTnG NW"bFk UF C1Y1SFC1i1TVF RAYS IN YEAk ENUTN6 9ERTFnRER lu nISCkARGF, IN CUAIC FEFT REM SFCRNn MEAN

YEAR 1 3 7 iu 10 60 9U 1?0 I43 1960 0.90 14 0.90 14 0.90 t2 0.90 11 1.40 10 .1° 12 1.40 12 1.54 ti 2.20 12

1961 1.00 15 1.00 15 1.00 15 1.00 13 1.00 lt .10 9 1.19 8 1.30 7 1.50 b 1962 0.84 13 0.87 13 0.9n 13 0.9; 12 1.10 12 .14 10 1.19 9 1.30 8 1.70 9 1963 0.70 12 0.77 12 0.79 10 0.74 9 0.86 8 .91 8 0.93 b 0.91 S 0.96 4 1944 0.40 SO 0.47 9 1.00 14 1.10 14 1.10 13 .19 11 1.30 10 1.40 1u 1.50 7 1965 0.30 8 0.40 e 0.40 8 0.40 7 0.91 9 .40 13 1.60 13 1.70 12 1.60 10

1966 0.20 4 0.20 4 0.24 4 0.26 4 0.33 4 4.64 5 1.30 11 1.7n 13 7.00 15 1967 0.40 9 0.57 10 0.89 11 1.30 15 1.50 15 1.6n 15 1.84 15 1.710fY 2.30 13 1968 0.60 11 0.60 11 0.61 4 0.8? 10 1.14 14 1.50 14 1.60 14 2.24 15 3.10 14 1969 0.20 5 0.20 5 0.24 5 u.39 6 0.46 5 0.53 a 0.91 5 1.30 9 1.80 11 1970 0.30 b 0.30 6 0.31 b 0.36 5 O.61 b 0.8? 7 0.86 4 0.87 3 0.64 3

1971 0.00 1 0.00 1 0.00 I 0.00 1 0.14 2 0.24 2 0.41 2 0.71 2 0.83 2 1972 0.30 7 0.30 7 0.34 7 0.46 d 0.64 7 0.74 b 0.7A 3 0.95 b 1.19 5 1973 0.00 2 0.00 2 0.00 2 0.00 2 0.15 3 0.33 3 1.00 7 0.84 4 1.70 8 3 1974 0.00 0.00 3 0.00 3 0.00 3 0.05 1 0.1n 1 0.10 1 0.10 1 0.10 1

HIGHEST MEAN VALUE ANO RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE, IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1960 337.0 8 196.0 8 89.0 7 46.0 9 27.0 10 15.0 11 10.0 11 8.1 11 5.9 11

1961 220.0 it 169.0 9 89.0" 8 71.0 7 51.0 6 35.0 5 24.0 6 18.0 6 13.0 6 158.0 12 56.0 13 24.0 14 13.0 14 9.1 14 6.3 14 5.4 13 4.3 13 3.3 13 3334 1962 1963 898.0 3 396.0 3 234.0 3 148.0 3 95.0 3 58.0 2 39.0 2 30.0 2 20.0 2 1964 2230.0 1 818.0 1 379.0 1 205.0 1 106.0 1 66.0 1 48.0 1 36.0 1 24.0 1 1965 297.0 9 100.0 11 44.0 12 21.0 12 17.0 12 9.4 12 7.8 12 6.2 12 4.7 12

1966 550.0 6 381.0 4 178.0 4 94.0 4 53.0 4 38.0 4 30.0 4 23.0 4 16.0 4 1967 490.0 7 203.0 7 162.0 6 90.0 5 52.0 5 33.0 6 26.0 5 20.0 5 14.0 S 1968 952.0 2 355.0 5 173.0 5 86.0 6 45.0 8 25.0 7 18.0 7 15.0 7 11.0 7 1969 74.0 15 31.0 15 17.0 15 10.0 15 6.7 15 4.9 15 3.5 15 2.8 15 2.5 15 1970 568.0 5 204.0 6 88.0 9 58.0 8 46.0 7 25.0 8 18.0 8 14.0 8 9.3 8

1971 603.0 4 500.0 2 275.0 2 153.0 2 96.0 2 53.0 3 37.0 3 27.0 3 18.0 3 1972 140.0 14 52.0 14 27.0 13 17.0 13 9.3 13 7.1 13 4.9 14 3.9 14 3.0 14 1973 146.0 13 83.0 12 51.0 10 29.0 11 25.0 11 18.0 9 13.0 10 9.8 10 7.0 9 1974 245.0 10 104.0 10 46.0 11 40.0 10 27.0 9 16.0 10 14.0 9 10.0 9 6.8 10

DISCHARGE. IN CUBIC FEET PER SECOND STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS (MEAN.VARIANCESTANOARD DEVIATIONSKEWNESS.COEFF. OF VARIATIONPERCENTAGE OF AVERAGE VALUE) RCT 2.36 1.44 7.82 2.99 4.84 3.06 1.80 1.22 1.08 14.0 27.2 14.0 I.4 4.34 0.58 253 16.8 80.5 18.4 1.34 0.22 0.38 179 877 613 .9 2.08 0.76 15.9 4.09 8.97 4.28 1.16 0.47 0.62 13.4 29.6 24.8 .6 1.19 0.31 2.41 3.47 3.31 3.34 1.79 . -0.73 0.65 1.41 1.36 3.72 .3 0.88 0.53 2.03 1.37 1.85 1.40 0.64 0.38 0.57 0.96 1.09 1.77 .2 2.89 1.77 9.56 3.65 5.91 3.74 2.20 1.49 1.32 17.1 33.2 I7.1 .1 .1 DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 6.70 14.2 3.77 0.49 0.56 -0.111

332 254 GILA RIVER BASIN

09485000 RINCCN CREEK NEAR TUCSON, AZ

LOCATION. --Lat 32 °07'46 ", long 110 °37'32 ", in NikNE4 sec.I7, T.15 S., R.17 E., Pima County, on left bank 0.2 mi (0.3 km)north of Sentinel Butte, 9 mi (14.5 km) upstream from mouth, and 22 mi (35.4 km) southeast of City Hall in Tucson.

DRAINAGE AREA. --44.8 mi' (116.0 km2).

HATER ANNUAL PEAK DATE GAGE HEIGHT OF CODE ANNUAL MAX DATE WATER TOTAL VOLUME, YEAR OISCH,CFS ANNUAL PEAK,FT GAGE MT.FT YEAR ACNE -FT

1953 194 07 -30 -53 3.78 1953 591 1954 2160 06 -19 -54 6.50 1954 2770 1955 8250 08 -03 -55 9.90 1955 4760 1956 150 07 -20 -56 4.35 1956 52 1957 3570 01 -09 -57 7.37 1957 5410 1958 492 03 -22 -58 5.46 NM 5.60 08 -24 -58 1958 4160 1959 5220 10 -21 -58 8.50 1959 2230 1960 747 01 -12 -60 5.69 1960 5660 1961 2600 08 -22 -61 6.92 1961 7b4 1962 227 01 -24 -62 4.36 1962 4530 1963 3420 08 -25 -63 7.47 1963 4370 1964 948 09 -23 -64 5.30 1964 1240 1965 311 08 -18 -65 4.68 1965 9b6 1966 3100 12 -22 -65 7.25 1966 17600 1967 157 08 -13 -67 3.90 1967 73 1968 1860 02 -12 -68 6.26 1968 6600 1969 548 09 -06 -69 4.88 1969 988 1970 1200 08 -01 -70 5.67 1970 1600 1971 9660 08 -19 -71 10.50 1971 4970 1972 360 07 -16 -72 4.55 1972 2600 1973 1440 10 -19 -72 5.89 1973 11900 1974 664 08 -01 -74 4.94 1974 260 1975 340 09 -02 -75 4.63

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE°Iv CUUIC FEET PER SECOND MEAN

CLASS G 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 262728293031323334 YEAR NURSER OF DAYS IN CLASS 1953 296 20 13 2 5 2 1 2 5 1 1 2 4 2 3 3 3 1954 295 12 8 5 5 1 1 3 3 4 1 5 2 1 8 2 2 1 1 2 2 1 1955 29S 7 3 8 2 4 5 1 2 1 3 3 2 2 6 4 5 1 2 3 2

1956 25', 89 21 1 2 1 1 1 957 238 12 7 5 17 16 10 13 10 11 8 8 6 5 6 6 5 2 3 1 1 1 .958 153 19 28 33 23 9 7 8 12 11 5 2 2 5 8 14 12 7 3 2 1 1 1959 181 73 25 6 15 12 2 5 4 6 4 5 5 5 4 4 1 1 4 2 1 1960 204 15 15 3 3 8 4 5 12 7 4 5 9 14 18 14 5 5 8 5 1 1 1

1961 316 9 5 3 4 1 2 1 2 5 3 2 1 4 2 1 7 6 2 2 1962 191 16 IC 6 14 1 1 2 1 11 35 25 17 15 3 1963 213 1C 14 2 16 8 6 7 6 12 11 8 7 9 9 9 3 7 1 1 4 1 1 1964 322 3 3 4 2 2 2 4 3 1 4 2 3 3 1 3 1965 137 71 18 8 15 4 11 13 20 15 18 21 5 6 3

1966 114 13 18 9 9 8 9 16 8 6 7 8 8 12 4 15 24 34 18 16 3 2 2 1 1 1967 289 25 4 26 18 1 1 1 6 6 6 7 12 31 28 17 14 6 8 6 2 3 1 1 1 1968 139 1 3 14 13 13 16 12 23 10 10 11 6 3 3 1 1969 238 1 1 1 1 2 6 5 6 8 5 21 3 4 1970 172 7 18 32 36 13 12 7 9 20 5 2 4 4 2 3 4 3 1 1 1 1

7 1 1 1 1 7 4 3 2 3 1 1 1 1971 286 3 2 2 1 1 1 4 19 12 1 21 7 10 9 6 11 5 11 11 2 1 1 1972 155 2 1 3 2 3 14 7 18 24 8 12 22 6 1973 89 4 4 6 2 3 17 3 3 11 16 26 35 11 13 17 12 14 19 12 10 7 5 11 1 2 3 1 1 1 2 1 1 1 1 1 1974 3',5 4 2 4 2 2 21 8 1 1 4 3 1

4 Not maxime gage height for water year.

333 GIIA RIVER BASIN 255

09485000 RINCON CREEK NEAR TUCSON, AZ-- CONTINUED

DURATIONTABLE OFDAILY VALUES FORYEAR ENDING SEPTEMBER30--Continued OISCHAFGE. INCUBIC FEETPERSECOND .EAN

CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERCT 0 0.00 4848 8035 100.0 12 1.2 176 1677 20.9 24 77 40 105 1.3 1 0.01 11 3187 39.7 13 1.7 172 1501 18.7 25 110 24 65 .8 2 0.02 18 3176 39.5 14 2.4 130 1329 10.5 26 150 15 41 .5 3 0.03 34 3158 39.3 15 3.5 131 1199 14.9 27 220 12 26 .3 4 0.05 42 3124 38.9 16 4.9 145 1068 13.3 28 310 1 14 .1 5 0.07 45 3082 38.4 17 6.9 125 923 11.5 29 430 1 7 6 0.10 470 3037 37.8 18 9.7 158 798 9.9 30 610 5 6 T 0.20 246 2567 31.9 19 14.0 149 640 8.0 31 860 1 1 8 0.30 159 2321 28.9 20 19.0 129 491 6.1 32 9 0.40 226 2162 26.9 21 27.0 111 362 4.5 33 10 0.60 142 1936 24.1 22 39.0 82 251 3.1 34 11 0.90 117 1794 22.3 23 54.0 64 169 2.1

LOHEST MEAN VALUE ANDRANKING FORTHE FOLLOWINGNUMBEROFCONSECUTIVE DAYS INYEARENDINGSEPTEMBER 30 OI5CMARGE. IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 14 30 60 90 120 183

1956 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 2 1957 0.00 5 0.00 5' 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.0717 1.5016 1958 0.00 6 0.00 6 0.00 6 0.00 6 0.00 6 0.00 6 0.0719 0.7121 3.7020 1959 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.00 6 0.0112 0.04 8 1960 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 7 0.00 5 0.08 9

1961 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 8 0.00 6 0.00 3 1962 0.0010 0.0010 0.0010 0.0010 0.0010 0.0010 0.00 9 0.00 7 0.6613 1963 0.0011 0.00 11 0.0011 0.0011 0.0011 0.00il 0.00f0 D.061 4.0021 1964 0.0012 0.0012 0.0012 0.0012 0.0012 0.0012 0.0011 0.00 8 0.00 4 1965 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0012 0.0715 0.8715

1966 0.0014 0.0014 0'.0014 0.0014 0.0014 0.0014 0.3621 0.6420 4.4022 1967 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015 0.0013 0.00 9 0.00 5 1968 0.0016 0.0016 0.0016 0.0016 0.0016 0.0016 0.1720 0.9922 1.70I7 1969 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.0014 0.1018 0.56 11 1910 0.0018 0.0018 0.0018 0.0018 0.0018 0.0122 0.05ib 0.0716 0.8314

1971 0.0019 0.0019 0.0019 0.0019 0.0019 0.0018 0.0015 0.0010 0.00 6 1972 0.0020 0.0020 0.0020 0.0020 0.0020 0.0019 0.0117 0.0513 0.1410 1973 0.0021 0.0021 0.0021 0.0021 0.0021 0.0020 0.4522 0.3719 3.5019 1974 0.0022 0.0022 0.0022 0.0022 0.0022 0.0021 0.0016 0.0011 0.04 7

334 256 GIIA RIVER BASIN

09485000RINCON CREEK NEAR TUCSON, AZ-CONTINUED

HIGHE,T MEAN VALUE ANO RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENOING SEPTEMBER 30 DISCHARGE.I. CUBIC FEET PER SECOND MEAN

YFAF. 1 3 7 15 30 60 90 120 183 1953 32.019 27.016 21.017 12.018 6.319 3.219 1 19 1.619 1.619 1954 395.0 6 235.0 6 115.0 7 56.0 9 30.010 17.011 11.2.012' 8.412 7.611 1955 392.G 7 185.0 8 106.0 8 91.0 4 71.0 3 40.0 6 27.0 6 20.0 6 13.0 6

1956 7.522 2.822 1.322 0.722 0.422 0.322 0.221 0.221 0.121 1957 754.0 3 329.0 4 154.0 5 72.0 7 44.0 8 22.010 15.010 12.010 7.810 1958 249.010 146.010 105.0 9 71.0 8 47.0 7 29.0 7 19.0 7 15.0 8 11.0 8 1959 225.012 97.012 74.012 41.011 23.013 12.013 7.913 5.913 3.914 1960 269.0 9 190.0 7 125.0 6 94.0 3 64.0 4 42.0 3 31.0 4 24.0 4 16.0 4

1961 138.013 65.014 31.016 17.016 11.016 6.416 4.318 3.218 2.118 1962 104.0 14 68.013 46.013 33.015 25.011 23.0 9 19.0 8 19.0 7 12.0 7 1963 248.(: 11 136.011 77.011 54.010 39.0 9 24.0 8 16.0 9 12.0 9 8.5 9 1964 102.015 57.016 45.015 35.014 19.015 10.015 6.915 5.215 3.415 1965 17.020 13.020 13.0.19 8.919 6.818 5.517 4.517 3.816 2.516

1966 977.0 1 590.0 1 297.0 1 209.0 1 150.0 1 91.0 1 42.0 1 68.0 I 45.0 1 1947 13.J21 4.321 1.921 0.921 0.621 0.321 0.222 0.222 0.122 1968 684.0 4 331.0 3 176.0 3 89.0 5 50.0 6 41.0 4 32.0 3 26.0 3 17.0 3 1969 76.017 36.017 17.018 13.017 7.417 5.318 4.616 3.617 2.317 1970 276.0 8 159.0 9 80.010 38.012 20.014 11.014 7.114 5.414 4.113

1971 634.0 5 324.0 5 161.0 4 81.0 6 59.0 5 41.0 5 27.0 5 21.0 5 14.0 5 1972 77.016 60.015 47.014 35.013 23.012 14.012 13.011 10.011 7.012 1973 Bn8.0 2 550.0 2 278.0 2 141.0 2 124.0 2 79.0 2 55.0 2 42.0 2 32.0 2 1974 50.018 20.019 10.020 4.7-20 2.420 1.220 0.820 0.620 0.420

DISCHARGE IM CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT BY ROWS (MEAN.VARIANCE.STANDARO DEVIATION.SKEWNESS.COEFF. OF VARIATION,PERCENTAGE OF AVERAGE VALUE) 2.09 0.59 9.48 8.25 11.6 10.4 2.38 0.16 0.08 1.09 12.1 5.29 32.4 1.38 783 266 509 329 22.1 0.18 0.10 7.31 310 110 9.69 1.17 28.0 16.3 22.6 18.1 4.70 0.42 0.32 2.70 17.6 10.5 3.05 2.11 4.15 2.39 2.15 2.60 2.55 3.93 4.55 4.04 1.66 2.66 2.72 2.00 2.95 1.98 1.94 1.75 1.98 2.60 3.78 2.47 1.46 1.99 3.30 0.92 14.9 13.0 18.3 16.3 3.75 0.26 0.13 1.72 19.0 8.32

DISCHARGE, IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANSCALL DAYS)

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORK 5.28 33.2 5.76 2.08 1.09 -0.445

335 GILA RIVER BASPr 257

09486000 RILLITO CREEK NEAR TUCSON, AZ

LOCATION.- -Lat 32 °17'41 ", long 110 °59'00 ", in SN'.SEi sec.14, T.13 S., R.13 E., on right bank 000 ft (183 m) downstream fromPima Canyon, 1,800 ft (549 m) downstream from bridge on U.S. Highway 89, 4.8 mi (7.7 km) upstream from mouth, and 5.4 mi (8.7 km) north of City Hall in Tucson.

DRAI.NAGE AREA.- -918 mi2 (2,378 km2). At former site (sta 09485850), 892 mi2 (2,310 km2).

RATER ANNUAL PEAK DATE CODES GAGE HEIGHT OF 44TF9 TOTAL VOLUME, TEAR UISCH,CFS ANNUAL PEAK,FT YEAR ACRE -FT

1915 17000 12-23-14 1914 8410 1916 7620 01-19-16 1916 523v0 1917 10000 08-11-17 1917 9770 1918 5300 03-01-18 1916 12600 1919 9250 07-27-19 1919 37700 1920 7600 02-21-20 197,4 2b0u0 1921 16000 07-31-21 2921 42980 1922 3250 08-09-22 1912 3030 1923 4000 08-26-23 1973 6670 1924 1980 .12-26-23 1474 57b0 1925 3500 09-17-25 1975 4720 1926 1750 09-27-26 1926 1940 1927 2200 09-12-27 1927 4500 1928 4500 08-01-28 1976 17d0 1929 24000 09-23-29 1979 76400 1930 4600 08-08-30 1930 18600 1931 7200 08-10-31 1931 12000 1932 7200 07-29-32 1932 14900 1933 4400 09-10-33 1933 1650 193a 3000 07-17-34 1934 2100 1935 13400 08-31-35 1915 18300 1936 4500 08-17-36 191b 3600 1937 2980 08-17-37 1937 4450 1938 3000 03-04-38 1918 2500 1939 9710 08-03-39 1939 6480 1940 13200 08-13-40 1940 8350 1941 9900 12-31-40 1941 29400 1942 1600 09-14-42 1942 2170 1943 3850 08-15-43 1943 2600 1944 4100 06-09-44 1944 3190 1945 7000 08-10-45 1945 3490 1946 4160 08-31-46 1946 3040 1947 7660 08-15-47 1947 4120 1948 779 09-26-4d 1946 960 1949 1640 09-15-49 1949 2920 1950 94190 07-30-50 1950 72b0 1951 9500 07-25-51 1951 4140 1952 1630 11-11-51 1952 6160 1953 5470 07-16-53 1953 1740 1954 7680 07-24-54 1954 13000 1955 8070 07-21-55 1955 12300 1956 2050 07-29-56 6.30 1456 315 1957 4500 01-09-57 7.14 1957 4220 1958 8930 08-12-58 9.64 1998 11300 1959 7710 08-17-59 8.86 1959 5250 1960 3610 01-12-60 6.98 1960 13500 1961 4140 07-22-61 7.36 1961 2720 1962 2690 09-26-62 6.48 1962 4360 1963 7640 08-26-63 9.20 1963 5730 1964 9420 09-10-64 8.58 1964 9500 1965 754 09-12-65 5.20 1965 1030 1966 17900 12-22-65 10.36 1966 53300 1967 3100 08-19-67 ES 6.84 1967 1890 1968 7740 02-12-68 5.44 1974 445 1969 2220 08-05-69 7.00 1975 555 1970 7000 09-06-70 1971 9290 08-20-71 8.49 1972 1620 08-12-72 6.35 1973 5160 10-20-72 6.2 1974 1440 08-02-74 6.94 1975 2270 07-16-75

ES Discharge estimated from another site.

336 258 GITA RIVER BASIN

09486000 RILLITO CREEK NEAR TUCSON, AZ-- CONTINIUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCNARBE. IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 2829 303132 33 YEAR NUMBER OF DAYS IN CLASS 34

1914 331 1 2 1 6 1 1 3 4 S 2 3 1 1 1 2 1916 272 1 1 2 2 1 10 5 3 5 4 11 7 9 7 5 9 6 1 3 1 1 1917 333 1 1 1 1 3 2 2 3 2 4 3 2 1 2 1 1 2

1918 343 2 2 3 3 1 1 1 1 1 1 1 1 1 2 1

1919 276 S 6 2 8 2 2 21 le 2 4 2 3 I 2 2 2 4 2 1 1920 267 7 2 2 9 3 8 6 9 8 14 14 5 7 4 1

1921 328 2 1 3 6 2 4 4 2 5 1 2 1 3 1 1922 341 1 1 T 1 4 1 3 2 2 2 1923 329 3 3 1 4 1 2 4 4 2 5 2 1 2 2 1924 333 1 2 5 1 3 4 5 2 2 3 3 2 1925 342 2 2 1 1 1 1 2 3 2 1 3 2 2

1926 338 3 5 3 1 3 4 3 1 2 1 1

1927 309 3 1 1 11 3 4 6 8 8 5 2 2 1 1

1928 352 1 3 3 2 1 1 1 1 1

1929 331 3 2 1 2 1 6 3 2 1 6 2 2 1 1 1

1930 330 3 3 1 4 2 2 1 4 2 2 1 3 4 2 1

1931 321 2 4 2 3 6 3 3 1 6 1 3 3 1 1 2 2 1 1932 286 6 8 3 4 3 5 6 8 9 9 7 6 1 2 2 1 1933 320 10 5 S 9 1 10 2 1 1 1

1934 338 e 2 1 2 3 1 2 2 3 1 1 1 1935 312 10 4 2 9 5 1 3 2 2 5 2 1 3 2 1 1

1936 338 4 4 3 3 3 1 2 1 2 1 3 1 1937 331 5 1 3 6 4 2 2 2 1 5 1 1 1

1938 344 3 4 4 3 1 1 1

1939 345 2 2 1 2 3 2 1 3 1 1 1 1

1940 346 4 2 1 2 3 1 1 2 1 1 1 1

1941 286 9 4 6 2 2 4 3 12 6 7 7 4 5 3 1 1942 332 4 2 1 2 3 3 2 8 2 3 1 1 1 1943 343 2 3 1 1 2 3 3 2 2 1 2

1944 342 6 I 5 2 2 1 1 1 1 1 1 1 1

1945 318 9 3 2 9 4 4 4 5 2 2 2 1

1946 339 2 1 3 2 3 4 1 3 2 2 2 1 19.7 348 1 3 3 1 1 2 1 1 1 1 1 1 1948 347 1 1 1 1 3 3 4 2 2 1 1949 333 3 1 1 5 1 4 3 1 3 1. 2 3 2 1 1 1950 343 1 1 3 2 3 2 1 2 4 1 1 1

1951 346 1 2 1 2 1 2 2 4 1 1 2 1952 321 1 1 2 5 5 6 3 5 7 2 2 4 1 1 1953 349 1 3 1 1 1 1 1 1 1 1 2 1 1

1954 328 1 3 1 3 6 5 6 1 4 4 2 1 1955 329 2 1 1 1 1 3 1 6 2 4 6 2 2

1956 357 2 3 1 1 1 1

1957 342 1 1 3 2 3 1 5 1 1 1 1958 301 1 1 3 1 2 5 2 2 3 6 2 10 7 8 5 1 3 2 1959 336 1 1 3 4 1 1 1 9 3 2 2 1

1960 322 1 2 1 1 2 2 2 6 5 6 6 1 1 2 2 2 1 1

1961 348 1 1 1 1 1 2 2 1 1 2 1 1 2

1962 323 2 1 2 2 4 3 3 4 7 3 2 1 1 1 2 1963 339 2 1 1 1 1 1 4 5 5 1 2 1 1 1964 337 1 1 1 1 2 3 1 1 2 4 3 1 1 1 1 1 1965 327 1 1 2 1 2 5 3 5 3 7 4 4

1966 284 2 1 4 1 2 5 2 11 4 11 7 7 7 8 4 2 1 2

1967 356 2 1 2 1 1 1 t

1974 357 1 1 2 2 1 1 1975 357 1 2 2 2 1

CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE "TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT 0 0.00 1812 20088 100.0 12 1.6 97 1741 8.7 24 300 81 219 1.0 1 0.01 1962 9.6 13 2.5 71 1651 8.2 25 470 59 138 .6 2 0.02 1961 9.8 14 3.9 178 1580 7.9 26 720 30 79 .3 3 0.03 1961 9.8 15 6.1 99 1402 7.0 27 1100 22 49 .2 0.05 1961 9.8 16 9.4 108 1303 6.5 28 1700 14 27 .1 5 0.07 1961 9.8 17 14.0 184 1195 5.9 29 2600 10 13 6 0.10 1 1961 9.8 18 22.0 162 1011 5.0 30 4100 3 3 7 0.20 1 1946 9.7 19 34.0 183 849 4.2 31 6300 e 0.30 1932 9.6 20 53.0 135 666 3.3 32 9700 9 0.40 2 1924 9.6 21 82.0 132 531 2.6 33 15000 10 0.70 14 1898 9.4 22 130.0 103 399 2.0 34 11 1.10 1 1758 8.8 23 200.0 77 296 1.5

337 GILA RIVER BASIN 259 09486000 RILLITO CREEK BAR TUCSON, A2-- CO!TPvUED

LUVEST MFN VALUF oNf1Re487Nf: FURTMF FUILnhTNF.NU4MFMOFGUNyFCIfTTVFnAYSIN YEAM ENDING.SEPTFMRED16 OISLNaPGF,IN f,UPIC FEET PFBSFLflNO 4E4N

233 34 7 30 90 YEAR 1 1 14 60 120 183 19 19 1914 0.00 1 0.00 1 0.00 1 u.00 1 0.00 1 8.00 1 O.On 1 O.U1 2.30 1916 0.00 2 0.00 2 O.On 2 O.Un 2 U.6n 2 2 6.6A 2 2.8855 15.0054 3 1917 0.00 S 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 1 3.3042 1918 0.00 a 0.0A 4 0.00 4 u.00 a U.00 4 4 0.00 4 0.00 2 13.0052 1919 0.00 5 0.00 5 O,uA 5 0.00 5 6.U0 5 N y u.I154 0.2650 S.SA43 1920 0.00 b 0.00 b u.00 e v.00 6 0.00 6 0.00 b 0,00 5 0.5053 7.1047

1921 0.00 7 u,UA 7 0.00 7 0.00 7 0.00 7 0.08 7 O.On b 0.00 3 0.00 1 1922 0.00 8 0.00 8 0.60 8 0.00 b 0.00 8 O.OA 8 0.00 0.00 4 0.2925 1923 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.0A 8i 0.00 5 0,00 2 1924 0.0010 0.0010 0.0010 0.00to 0.00to 0.00/0 0.00 9 0.00 6 0.4417 1925 0.0011 0.0011 0.00 11 0.0011 0.00 11 0.00 11 0.00tu 0.00 1 U,00 3

1926 0.0012 0.0012 0.0012 0.0012 0.0012 0.0412 0.0011 0.0140 0.5010 1927 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0012 0.1648 3.6044 1928 0.0014 0.0014 0.00ta 0.0014 0.0014 0.0014 0.0013 0.00 8 0.00 4 1929 0.00IS 0.0015 0.0015 0.0015 0.0015 0.0015 u.0014 0.00 9 0.00 5 1930 0.0n1b 0.0016 0.09lb 0.00lb 0.00lb 0.0016 0.00IS 0.0010 9.2049

1931 0.0017 0.0017 0.0017 0.0017 0.0017 0.0017 0.00lb 0.0011 15.0053 1932 0.0018 0.00t8 0.0418 0.0018 0.00tö 0.0018 0.0017 0,10S1 10.0050 1933 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.00lb 0.0141 0.5129 1934 0.0020 0.0020 0.0020 0.0070 0.0020 0.0070 0.0019 0.0012 0.00 b 1935 0,0011 0.0021 0.0021 0.0021 0.0021 0.0071 0.0020 0.0013 4.00as

1936 0.0022 0.0022 0.0022 0.0022 0.0022 0.0022 0.0021 0.0014 3.1041 1937 0.0023 0.0023 0.0073 O.OA13 0.0013 0.00?3 0.0022 0.0142 2.8040 1938 0.0024 0.0024 0.0024 0.0024 0.0024 0.0024 0.0023 0.0015 1.7037 1939 0.0025 0.0025 0.00?5 0.0025 0.0025 0.0075 0.0074 6.00IN 0.00 7 1940 0.0026 0.0026 0.0026 0.00Pb 0.0026 0.0026 0.0025 0.0243 6,7114

1941 0.0027 0.0027 0.002_7 0.0077 0.0027 0.0027 0.0076 0.0444 7.3048 1942 0.0028 0.0028 0.0076 0.0028 0.0028 0.0028 0.0027 0.0017 0.6433 1943 0.0029 0.0029 0.0029 0.0079 0.0079 0,00?9 0.0028 0.0018 1.7038 1944 0.0030 0.0010 0.0030 0.0010 0.0030 0,0030 0.0079 0.0019 0.00 8 1945 0.00il 0.0011 0.6011 0.0031 0.0031 0.00Ti 0.0030 0,1449 1.0036

1946 0.0012 0.0032 0.0032 0.0032 0.0032 0.0032 0.0831 0.00a0 0.00 9 t947 0.0033 0.0033 0.0013 0.0013 0.0033 0.0033 0.0032 0.0021 0.0010 1948 0.0014 0.0034 O.OAi4 0.0014 0.0014 0.0014 0.0033 0.0022 0.00 11 1949 0.0035 0.0035 0.0035 0.0015 O.OnIS 0.0035 0.0034 0.0023 0.0122 1950 0.0016 0.00lb 0.0016 0.00lb 0.00lb 0.0036 0.0015 0.0074 0,0012

1951 0.0017 0.0037 0.0037 0.0037 0.0037 0.0037 0.0036 0.0025 0.0013 1952 0.0038 0.0038 0.0038 0.00t8 0.0018 0.0038 0.1153 0.4A52 0.6632 1953 0.0039 0.0039 0.0019 0.0039 0.0039 6.0039 0.0817 0.0076 0.0473 1954 0.0040 0.0040 0.0040 0.0040 0.0040 0.0040 0.0038 0.0027 17.On55 1955 0.0041 0.0041 0.0041 0.0041 0.0041 0.00al 0.0019 0.0078 0.0014

1956 0.0042 0.0042 0.0042 0.0042 0.0042 0.0042 0.00a0 0.0079 0,0724 1957 0.0043 0.0043 0.0043 0.0043 0.0043 0.00e} u.Onai 0.0545 0.5028 1958 0.0044 0.0044 0.0044 0.0044 6.004a O.OA4g 0.4855 1.305a 11.0051 1959 0.0045 0.0045 0.00a5 0.0045 0.0045 0.00as 0.0042 0,0A30 0.0015 1960 0.0046 0.0046 0.0046 0.004b 0.0046 0.004b 0.0043 0.0031 0.00Ib

1961 0.0047 0.0047 0.0047 0.0047 0.0047 0.00a7 0.0044 0.0032 0.0017 1962 0.0048 O.uO48 0,0048 U.004ö 0.0048 0.004b 0.0045 0.1147 0.3A26 1963 0,0049 0.0049 O.OA49 0.0049 0.0049 0.0049 0.0046 0.0013 0.6511 1964 0.0050 0.0050 0.0050 0.00SU 0.0050 0.0nS0 0.0047 0.0014 0.0018 1965 0.0051 0.0051 0.0nai 0.0051 0.0051 0.0051 0.0152 0.1146 0.8915

1966 0.0052 0.0052 0.0052 0.0052 0.0052 0.0052 0.0048 0.0015 5,0046 1967 0.0053 0.0053 0.0053 0.0053 0.0053 0.0053 0.0049 0.0016 0.0019 1974 0.0094 0,0054 0.0054 0.0054 0.0054 0.0454 0.0950 0.0017 0,0020 1975 0.0055 0.0055 0.0055 0.0055 0.0055 0.0055 0.0051 0.0038 0.0021

338 260 GILA RIVER BASIN

09486000 RILLITO CREEK NEAR TUCSON, Az-- C044TINUED

MIOMEST MEAN VALUE AND RANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

YEAR 1 3 7 15 30 60 90 120 183 1914 1250.020 424.027 183.027 92.031 88.022 47.023 45.016 34.016 22.020 1916 4900.0 2 3720.0 -2 1830.0 2 1240.0 1 655.0 2 349.0 2 240.0 2 180.0 2 118.0 2 1917 1410.017 536.020 295.020 160.020 126.013 68.012 48.013 36.014 24.018 1918 2130.0I3 866.013 397.014 261.010 131.012 65.013 67.011 52.0 9 35.010 1919 2790.0 6 1880.0 5 1140.0 S 828.0 4 517.0 4 293.0 4 198.0 4 148.0 4 101.0 4 1920 2450.0 8 1120.010 563.0 9 349.0 8 196.0 9 135.0 7 110.0 7 90.0 T 66.0 7

1926 451.040 151.044 65.045 32.046 16.049 8.649 6.549 4.949 5.244 1927 487.038 190.040 90.040 50.043 41.036 23.037 17.037 13.035 8.435 1928 200.050 87.050 51.049 25.049 I9.046 11.047 7.248 5.448 3.549 1929 4640.0 3 2790.0 3 1210.0 4 571.0 5 304.0 5 217.0 5 150.0 5 013.0 5 74.0 6 1930 1040.024 -- 539.019 237.022 123.023 100.020 57.018 41.017 30.019 29.016

1931 1180.023 771.0)5 399.013 200.017 105.019 54.021 36.023 27.023 32.013 1932 1420.016 554.018 257.021 159.021 115.015 61.016 47.014 46.012 30.014 1933 333.044 112.048 48.050 22.050 13.050 6.8SO 4.752 3.552 2.392 1934 320.045 107.049 58.047 29.047 16.041 13.046 10.044 7.645 5.045 1935 2360.0 9 1470.0 7 650.0 8 393.0 7 200.0 8 105.0 8 70.0 9 52.010 36.0 8

1936 490.037 190.041 84.042 72.034 40.037 20.040 14.040 10.040 7.340 1931 748.030 417.026 180.028 102.028 51.031 29.029 19.030 14.031 9.931 1938 783.029 314.031 135.0 34 63.038 32.038 16.042 11.041 8.142 6.941 1939 1890.015 774.014 346.Ò'16 167.019 89.021 57.019 39.020 29.020 19.022 1940 2270.0I2 1170.0 9 505.011 238.013 120.014 64.0}4 45.015 34.015 22.019

1941 3990.0 4 1880.0 6 841.0 6 440.0 6 243.0 6 151.0 6 143.0 6 113.0 6 75.0 5 1942 226.049 122.046 53.048 25.048 16.048 10.048 10.045 7.546 4.947 1943 274.048 139.045 60.046 45.044 29.042 17.041 11.042 8.441 6.442 1944 560.034 348.030 152.031 78.033 50.032 26.033 18.033 13.036 8.834 1945 1230.021 434.026 191.026 104.027 57.029 29.030 19.031 14.032 10.030

1946 497.036 194.038 83.043 67.035 42.035 24.035 17.034 12.037 8.237 1947 888.026 303.032 177.029 127.022 63.028 33.028 22.029 16.029 11.028 1948 88.054 34.054 23.053 14.052 11.051 6.352 5.350 4.050 2.650 1949 316.046 167.042 93.039 43.045 31.040 15.043 10.046 T.744 5.046 1950 2010.014 686.016 315.018 207.015 109.017 61.015 41.018 31.017 20.021

1951 667.031 349.029 163.030 122.024 67.027 35.027 23.028 17.028 11.029 1952 485.039 242.036 129.035 64.036 44.034 22.038 25.027' 19.027 17.024 1953 426.043 231.037 119.037 57.039 29.043 15.044 9.747 7.347 4.846 1954 2320.010 1050.011 462.012 216.014 108.018 54.022 37.021 28.021 33.022 1955 914.025 436.0a4 301.015 243.012 169.010 103.010 69.010 92.011 34.011

1956 110.053 37.053 16.0SS 8.654 4.555 2.355 1.555 1.155 0.8SS 1957 1310.018 464.0aa 199.025 93.030 50.033 25.034 17.035 13.033 8.336 1958 863.027 476.022 316.017 203.016 111.016 58.017 39.019 30.018 29.015 1959 1210.022 435.025 232.023 118.025 77.024 43.025 29.025 22.025 14.026 1960 2300.011 1200.0 8 653.0 7 325.0 9 206.0 7 105.0 9 73.0 8 55.0 8 36.0 9

1961 428.042 185.042 81.044 55.041 30.041 23.036 15.039 11.039 7.539 1962 601.032 284.033 122.036 57.040 28.044 27.031 18.032 15.030 9.632 1963 1290.019 510.021 222.024 104.026 52.030 26.032 17.036 13.034 8.933 I964 2650.0 7 917.012 525.010 259.011 134.011 77.011 53.012 40.013 26.011 1965 48.055 29.055 17.054 8.355 8.052 5.553 3.853 3.053 2.153

1966 3520.0 5 2670.0 4 1390.0 3 927.0 3 585.0 3 295.0 3 260.0 1 203.0 1 133.0 1 1967 578.033 193.039 104.038 52.042 26.045 15.045 11.043 8.043 5.243 1974 174.051 70.051 30.051 16.051 7.953 6.751 4.751 3.651 2.351 1975 147.052 49.052 .23.052 12.053 6.254 3.454 2.354 1.754 1.154

339 GILA RIVER BASIN 261

09486000 RILLITO CREEK NEAR TUCSON, AZ-- CONTINUED

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS)

OCT NOV OEC JAN FEB MARCH APRIL MAY JUNE JULY AUG SEPT 183 22.0 20 BY ROWS (MEAN.VARIANCE.STANDARO DEVIATIONSKEWNESSCOEFF. OF VARIATION.PERCENTAGE OF AVERAGE VALUE) 18.0 2 0.72 2.47 48.6 25.1 27.7 17.2 0.76 1.26 0.59 31.9 37.9 16.1 ?4.0 18 2.78 68.0 57950 8678 5378 1340 5.76 86.3 3.88 7661 2342 2049 35.0 10 1.67 8.25 241 93.2 73.3 36.6 2.40 9.29 1.97 81.5 48.4 45.3 11.0 4 2.87 3.88 6.55 5.22 4.29 2.57 3.53 7.42 3.83 4.64 2.40 5.20 :.6.0 7 2.31 3.34 4.95 3.71 2.65 2.12 3.18 7.38 3.34 2.75 1.28 2.80 0.34 1.17 23.1 12.0 13.2 8.19 0.36 0.60 0.28 15.2 18.0 7.68 :7.0 3 7.7 38 8.0 23 .6.0 25 DISCHARGE. IN CUBIC FEET PER SECOND .3.0 27 STATISTICS ON NORMAL ANNUAL MEANS(ALL DAYS) 5.2 44 MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF OF VARIATION SERIAL CORA 8.4 35 0.072 3.5 49 13.6 288 17.0 2.27 1.25 '4.0 6 9.0 16

12.0 03 '0.0 14 2.3 92 5.0 45 6.0 8

7.3 40 9.9 31 6.9 41 9.0 22 2.0 19

5.0 5 4.9 47 5.4 42 1.8 34 1.0 30

(.2 37 .0 28 '.6 50 .0 46 ,0c-

.0 .0 24 .8 48 .0 22 .0 11

.8 55 .3 36 .0 15 .0 26 .0 9

.5 39 .6 32 .9 33 .0 17 .1 53

.0 1 .2 43 .3 51 .1 54

340 262 GILA RIVER BASIN

09486300 CANADA DEL ORO NEAR TUCSON, AZ

LOCATION. --Lat 32 °22'27 ", long 111 °00'31 ",in SB$.NWh sec.22, T.12 S., R.13 E., Pima County, Hydrologic Unit 15050301, on right bank at upstream side of Overton Road, 4.7 mi (7.6 km) upstream from mouth, and 10.5 mi (16.9 km) north of City Hall in Tucson.

DRAINAGE AREA.- -250 mil (648 km2).

REFNRKS.- -Records poor. :ago del Oro- -capacity 9,400 acre-ft (11.6 hml) --lo mi (26 km) upstream, has contained no storage since May 4, 1971, as gates were opened by court order; however, peak flows are regulated while passing through the lake.

WATER ANNUAL PEAK GATE GAGE .EIGHT OF aATFR TOTAL VOLUME, TEAR UISCH,iFS ANNUAL PEAK,FT YEAN ACVE -F1

1966 2290 12-22-65 4.53 1987 93 1967 652 08-05-67 3.7b 1968 5460 1968 13900 12-20-0 7.65 191+9 44 1969 454 07-22-49 3.51 1974 10V0 1970 1950 0d-18-70 4.37 1v71 1830 1971 4200 08-17-71 5.20 1972 133 1972 728 08-12-72 4.17 1973 133 1973 3750 .30-19-72 3.85 1974 857 1974 7700 07-20-74 5.80 1975 44 1975 454 09-04-75 3.50

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER 30 DISCHARGE,IN CUBIC FEET PER SECOND MEAN

CLASS O 1 2 3 4 5 6 1 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 262728293031323334 YEAR NUMBER OF DAYS IN CLASS 1967 361 1 1 2 1968 358 1 1 1 2 I 1 1 1969 363 1 1 1970 356 3 1 2 1 1 1

1971 348 2 1 1 1 I 3 1 2 1 1 1 I 1 1972 357 3 1 1 1 1 1 1 1913 356 3 1 1 1 1 1 1 1974 355 1 1 1 1 1 1 1 1 1 1 1975 361 1 1 1 1

SS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT CLASS VALUE TOTAL ACCUM PERCT 0,00 3215 3287 100.0 12 1.0 2 51 1.6 24 57 2 12 .3 i 0.01 1 72 2.2 13 1.5 0 49 1.5 25 79 2 10 .3 2 0902 0 71 2.2 14 2.0 49 1.5 26 110 2 8 .2 3 0.03 0 71 2.2 15 2.8 4 45 1.4 27 150 1 6 .1 4 0.05 0 71 2.2 16 4.0 4 41 1.2 28 220 2 S .1 5 0.07 0 71 2.2 17 5.5 4 37 1.1 29 300 2 3 6 0.10 10 71 2.2 18 1.7 2 33 1.0 30 420 1 7 0.20 0 61 1.9 19 11.0 5 31 0.9 31 590 1 1 8 0.30 4 61 1.9 20 15.0 7 26 0.8 32 9 0.40 2 57 1.7 21 21.0 4 19 0.6 33 10 0.50 2 55 1.7 22 29.0 3 15 0.5 34 11 0.80 2 53 1.6 23 41.0 0 12 0.4

341 GILA RIM BASIN 263 09486300 CANADA DEL ORO NEAR TUCSON, AI- CONTINUED

LoWE RANKThf. FUR '7,,FFlg LnAT.G MU`BFp UF t'UNsFCnTTVF D15CMARGF.IN fUR1C ma's 1N YEAR LNOTN. SERTEMRER 10 MtAN

3 YEAR 1 7 '4 TO A9 ou 0.00 1 143 1967 0.00 t 0.un I t t2u 0.00 0.00 1 0.00 1 1 0.00 2 u.un 2 0.90 1 0.00 1 0.00 1968 2 0.00 u.0n 2 0.00 2 0.00 0.00 2 u.00 2 0.00 2 0.04 10 3 u.00 3 0.00 3 0.00 3 1969 0.00 3 0.00 3 2 0.00 0.00 4 0.00 3 0.00 3 0.00 010 4 0.40 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 4 0.00 3 1971 0.0n 5 0.00 5 5 5 0.00 0.00 o.un 5 0.0n 5 4 0.00 b 0.00 5 0.00 5 0.00 1972 0.00 b 0.00 b 0.00 6 b 0.00 0.00 6 6 0.00 5 0.00 7 7 0.00 0.00 6 0.00 0.0n 7 7 '973 0.00 0.04 7 0.00 7 0.OD 7 0.00 6 0.00 ä 0.00 B 0.00 ö 0.00 7 *q74 4.00 6 0.00 8 0.00 6 7 0.00 8 0.00 tl 0.00 1975 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 9 0.00 8

HIGHEST MEAN VALUE AND MANKING FOR THE FOLLOWING NUMBER OF CONSECUTIVE DAYS IN YEAR ENDING SEPTEMBER30 DISCHARGE. IN CUBIC FEET PER SECOND REAR

YEAR 1 3 7 15 30 60 90 19.0 8 6.3 8 2.7 8 10:3 7 1967 1.3 8 0.9 7 0.6 7 0.5 7 lÓ 7 1 873.0 1 I 1968 2400.0 390.0 1 182.0 1 91.0 1 46.0 1 30.0 1 23.0 1 1SÍ0 22.0 7 7.3 7 3.1 7 0.1 8 1969 1.5 7 0.7 8 0.4 8 0.2 8 0.2 8 348.0 3 116.0 4 56.0 4 27.0 4 17.0 2.8 3 1970 3 8.4 3 5.6 3 4.2 3 2 290.0 4 161.0 2 95.0 2 58.0 2 31.0 2 15.0 2 10.0 2 7.7 2 5.0 1971 5 33 34 1972 24.0 5 8.0 5 4.6 5 2.6 5 2.1 5 1.1 5 0.7 5 0.6 S 0.4 6 24.0 6 8.0 6 4:6 6 2.6 6 2.1 6 141 0.7 6 0.6 6 0.4 1973 6 1gT4 375.0 2 136.0 3 59.0 3 28.0 3 14.0 4 7.2 4 4.8 4 3.6 4 24 4 9 11.0 9 3.7 9 1.6 9 0.7 9 0.4 9 0.4 9 0.2 9 0.2 9 04 1975

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS) SEPT mOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AUG OCT OF VARIATION.PERCENTAGE OF AVERAGE VALUE) BY uOWS (MEAN.VARIANCE.STANDARODEVIATION.SKEWNESS.COEFF. 1.86 0.00 0.00 0.00 0.00 1.48 3.12 o.00 0.00 12.S 0.00 0.02 I7L5 0.00 861 0.00 0.01 0.00 0.00 0.00 0.00 17.4 84.7 0.00 9.20 4.16 0.00 29.3 0.00 0.08 0.00 0.00 0.00 0.00 4.17 0.00 3.14 3.10 2.97 :T 2.36 3.16 3.16 . 2.82 2.48 2.22 3 .** 2.28 3.16 3.16 943 0.00 0.00 0.00 7.39 18.6 3 0.00 0.00 64.4 0.00 0.12 0.00 2

1 DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANSIALL DAYS) COEFF. OF VARIATION SERIAL CORR MEAN VARIANCE STANDARD DEVIATION SKEWNESS 0.381 1.94 1.42 1.68 5.64 2.38

Skewness and coefficient of variation could not be computed owing to azero-value month. GILA RIVER BASIN 264 09486500 SANTA CRUZ RIVER AT CORTARO, AZ

LOCATION.- -Lat 3Z °21'04 ", long 111 °05'38 ", in NW'sNWA sec.35, T.12 S., R.12 E., Pima County, Hydrologic Unit 15050302, on downstream side of right bridge pier 0.5 mi (0.8 km) southwest of Cortaro, 2.6 mi (4.2 km) downstream from Canada del Oro, and 3.7 mi (6.0km) downstream from Rillíto Creek.

DRAINAGE AREA.- -3,503 mi2 (9,073 km2), of which 395 mi2 (1,023 km2) is in Mexico.

SAYER ANNUAL PEAK GATE GAGE HEIGHT OF CUOE ANNUAL MAX DATE SA TEA TOTAL OULUME, YEAR 0I5CH,CFS ANNUAL PEAK,FT GAGE HT.FT TE AN ACRE -FT

1940 17000 08-14-40 1940 76100 1941 7600 12-31-40 1941 24560 1942 1550 06-09-42 1942 0770 1943 5500 09-24-43 1943 17200 1944 5b50 08-16-44 1944 14190 1945 14000 08-10-45 1445 74100 1946 4440 Ob-04-46 1946 16500 1947 7500 08-15-47 1951 11500 1950 12900 07-30-SO 9.1 1952 13700 1951 6820 07-25-51 6.50 1953 14400 1952 6100 08-14-52 6.2 1954 53100 1953 10800 07-14-53 8.10 1955 67400 1954 9150 07-24-54 7.53 1956 1580 1955 16600 08-03-55 9.90 1957 4810 1956 3150 07-29-56 5.00 1958 20500 1957 4400 09-01-57 5.69 1959 13700 1958 7890 08-12-58 7.03 1920 22PÚ0 1959 8000 08-20-59 6.70 NM 6.73 08 -17 -59 1961 17440 1960 6420 08-11-60 6.12 1962 12760 1961 14700 08-23-61 9.00 1983 70190 1962 11200 09-26-62 9.22 1964 141790 1963 7240 08-26-63 7.10 1965 2270 1964 15900 09-10-64 9.29 1966 53300 1965 2710 07-16-65 3.83 1927 d3Ú0 1966 16800 12-22-65 8.60 1968 53100 1967 5740 07-17-67 9.04 NM 9.13 07 -11 -67 1969 5840 1968 15800 12-21-67 12.17 1970 26500 1969 8400 08-06-69 11.64 1971 45200 1970 11200 07-20-70 12.65 1972 73400 1971 9100 08-20-71 12.70 1973 45800 1972 7050 08-12-72 11.35 1974 43100 1973 9000 10-19-72 12.10 1975 43700 1974 11700 07-08-74 13.02 1975 5200 07-12-75 10.35

NM Not maximum gage height for water year.

343 GILA RIVER BASIN 265

09486500 SANTACRUZRIVER AT CORTARO, AZ-- CONTINUED

DURATION TABLE OF DAILY VALUES FOR YEAR ENDING SEPTEMBER30 DISCHARGE,IN CUBIC FEET PER SECOND MEAN

CLASS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 262728293031323334 YEAR NUMBER OF DAYS IN CLASS 1940 317 4 7 1 3 2 7 4 5 5 1 1 3 2 1 2 1

1941 304 5 1 1 1 7 1 2 4 2 5 3 7 2 2 6 3 4 1 1942 314 3 1 1 1 13 3 2 2 2 1 2 1 2 2 3 1 5 1 1 1943 307 4 3 1 3 3 2 3 2 2 2 2 6 4 5 4 3 2 3 1 2 1 1944 334 2 2 1 1 2 1 1 2 3 1 1 2 1 3 1 2 1 1 1945 315 9 6 1 2 1 3 4 3 1 2 3 3 2 1 1 1 2 1

1946 305 3 6 1 3 1 2 4 5 3 5 4 3 7 2 3 1 4 2 1 1951 228 7 7 3 10 12 15 18 IS 7 9 3 3 1 4 4 6 2 3 1 1 2 1 2 1 1952 22913 12 5 13 4 13 19 8 3 3 2 1 3 1 1 2 9 4 6 2 5 4 3 1 1953 324 3 2 1 2 1 2 1 2 3 2 3 5 2 2 2 2 1 1 1954 297 1 1 2 2 1 2 5 3 l 2 6 1 1 5 4 2 3 6 4 4 1 5 2 1955 305 1 1 2 1 2 2 2 I. 3 1 1 1 S 1 2 4 2 1 5 3 1 3 4 1 5 3 2

1956 347 1 1 1 1 1 2 1 2 2 1 1 1 2 2 1957 334 _ 3 1 1 1 1 3 3 2 2 4 3 1 2 1 1 1 1 1958 274 4 1 2 2 2 1 4 4 4 4 1 2 5 3 8 3 9 3 3 7 2 5 6 2 2 1 1 1959 316 1 1 2 1 1 2 3 2 4 2 3 3 3 5 1 3 1 5 1 2 1 1960 322 1 2 1 3 1 2 1 2 1 4 2 4 2 1 3 3 2 2 1 2 2 1 1

1961 330 1 1 2 2 1 1 2 3 1 2 2 1 5 4 1 I 2 I 1 1 1962 340 1 1 1 1 1 2 1 1 3 1 1 1 4 1 1 2 1 1 1963 316 1 3 3 3 2 4 3 1 4 2 3 4 5 4 1 3 1 1 1 1964 316 1 1 1 2 3 3 5 1 1 1 4 4 3 6 2 3 1 5 2 1 1965 334 1 1 1 2 1 1 3 3 1 1 1 2 5 2 2 2 1 1

1966 300 2 2 1 2 2 1 2 1 3 2 2 3 1 5 2 6 4 6 4 4 4 1 2 1 1 1 1967 330 2 1 1 3 2 1 1 1 2 l 4 I 2 2 2 3 2 1 1 1 1 1968 315 1 1 3 2 3 2 1 2 3 7 4 5 4 2 3 1 2 1 1 1 1 1 1969 333 1 1 1 1 1 1 3 2 2 3 3 3 2 4 2 I 1 1970 12 3 2 3 18 13 3 10 23 26 40 36 35 33 32 36 18 4 2 3 2 5 1 2 1 2

1971 1 1 1 12 2 11 35 44 63 109 46 15 3 1 3 2 5 3 3 1 1972 11 1 I 5 2 7 15 19 37 107 116 14 12 6 6 1 2 2 i 1 1973 55 1 1 S 8 5 17 23 21 21 43 50 29 35 25 4 4 3 2 3 1 3 1 3 1 1 1974 1 2 3 57 232 48 5 4 2 3 1 3 1 1 1 1 1975 10 175 124 36 7 2 5 3 2 1

CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PERLT CLASS VALUE TOTAL ACCUM PLRCT 0 0.00 8170 11688 100.0 12 6.2 111 2769 23.7 24 380 56 213 1.8 1 0.10 43 3518 30.1 13 8.7 131 2668 22.7 25 540 44 157 1.3 2 0.20 38 3475 29.7 14 12.0 205 2527 21.6 26 760 40 113 .9 3 0.30 25 3437 29.4 15 17.0 298 2322 19.9 27 1100 23 73 .6 4 0,40 59 3412 29.2 16 24.0 377 2024 17.3 28 1500 24 50 .4 5 0.60 32 3353 28.1 17 35.0 646 1647 14.1 29 2100 I2 26 4 6 0.80 98 3321 28.4 18 49.0 338 1001 8.6 30 3000 5 14 .1 7 1.10 61 3223 27.6 19 69.0 135 663 5.7 31 4300 9 8 1.60 95 3162 27.1 20 97.0 107 528 4.5 32 6000 5 9 2.20 65 3067 26.2 21 140.0 53 421 3.6 33 8500 1 1 10 3.10 93 3002 25.7 22 190.0 81 368 3.1 34 11 4,40 140 2909 24.9 23 270.0 74 287 2.5

344 266 GILA RIVER BASIN

09486500 SANTACRUZ RIVERAT CORTARO, AZ-- C1.TINUED

LuwEST FAN yALUF Aw0 9AN8TN6cup TNF FULoNeTnGNUMbFRuFCUMSECIITTVFnATSIN YEAwENOTNC.SEPTFMBEp30 SCMAaGF,jN Cuwir FEET vEN SECnNO N

TEAR 1 3 7 14 30 60 90 120 143

1940 0.00 1 0.00 1 0.04 1 0.00 1 0.00 1 0.00 1 0.00 1 0.3474 2.0019

1941 3.00 2 0.00 2 0.00 2 U.00 2 0.00 2 0.00 2 0.0474 0.1572 14.0076 1942 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.00 3 0.2926 0.2273 1.3017 4 1943 0.00 4 0.00 4 0.00 0.00 4 0.00 4 O.uO 4 0.00 2 0.04 1 1.1016

1944 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.00 5 0.un 3 0.00 2 0.00 1 1945 0.00 b 0.00 6 0.00 b 0.00 b 0.00 b 0.00 6 0.00 4 0.0421 0.03 6

1946 0.00 7 0.00 7 0.00 7 0.00 7 0.00 7 0.04 7 0.00 5 0,00 3 0.00 2 1951 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 8 0.00 6 0.00 4 0.03 7 1952 0.00 4 0.00 9 0.00 9 0.00 9 0.00 9 0.0226 0.1075 1.4025 5.4021 1953 0.00t0 0.0010 0.0010 0.0010 0.0010 0.00 9 0.00 7 0.00 5 0.03 8 1954 0.0011 0.00 11 0.0011 0.00 11 0.00 11 0.0010 0.00 8 0.00 6 17.0027 1955 0.0012 0.0012 0.0012 0.0012 0.0012 0.00 II 0.00 9 0.00 7 0.03 9

1956 0.0013 0.0013 0.0013 u.0013 0.0013 0.0012 0.0010 0.00 8 0.3013 1957 0.0014 0.0014 0.0014 0.0014 0.0014 0.0013 0.0011 0.00 9 0.2512 1958 0.0015 0.0015 0.0015 0.00IS 0.0015 0.0014 0.0472 1.9076 11.0024 1959 0.0016 0,00ib 0.016 0.0016 0.0016 0.0015 0.0012 0.0010 0.00 3 1960 0.0017 0.0017 0.0017 0.0017 0.0017 0.0016 0.0013 0.00il 0.0310

1961 0.0018 0.0018 0.0018 0.0018 0.0018 0,0017 0.0014 0.0012 0.6715 1962 0.0019 0.0019 0.0019 0.0019 0.0019 0.0018 0.00IS 0.0013 0.4814 1963 0.0070 0.0020 0.0070 0,0020 0.0070 0.0019 0.0423 0.0320 5.1020 1964 0.0071 0.0021 0.0071 0.0071 0.0021 0.00?0 0.0016 0.0014 0.0711 1965 0.0072 0.0022 0,0022 0.0022 0.0022 0.0021 0.0017 0.0015 1.4018

1966 0.0023 0.0023 0.0073 0.0073 0.0023 0.0022 0.0018 0.0016 13.0n25 1967 0.0074 0.0074 0.0024 0.0024 0.0024 0.0023 0.0019 0.0017 0.02 5 1968 0.0025 0.0025 0.0075 0.0075 0.0075 0.0024 0.0020 0.0018 7.7023 1969 0.0026 0.0026 0.0026 0.0026 0.0076 0.0075 0.0071 0.0019 0.00 4 1970 0.0027 0.0027 0.3628 2.a028 3.5078 5.4027 6.3027 6.3027 6.9022

1971 0.0078 0.0028 5.6010 9.1030 12.0410 14.0030 70,0030 26.0030 78.0030 1972 0.0079 0,7029 1.0029 7,1029 11.0079 13.0029 16.0029 18.0029 72.0029 1973 0.0030 0,0030 0.0077 0.0027 0.9827 7.6028 8.8028 11.0028 71.0028 1974 10.0031 13.0031 18,0011 74.0011 29,0411 35.0031 17.0011 18.0031 99.0031 1975 30.0033 32.0033 33.0033 35.0013 17,0013 39.0033 39.0033 41.0033 46.0033

345 GILa RIVER BASIN 267

09486500 SANTA CRU: RIVER AT CORTARO, A2-- Cc7TINUED

HIGHEST MEAN VALUE ANORANKING FORTHE FOLLOWING NUMBER OFCONSECUTIVEOATSIN YEAR ENDINGSEPTEMBER 30 DISCHARGE. IN CUBIC FEET PER SECOND MEAN

.63 YEAR 1 3 7 15 30 60 90 120 183 .0019 1940 7490.0 3 2650.0 4 1150.0 6 542.0 8 296.0 9 157.0 9 108.010 82.010 54.012

.0076 1941 4000.0 8 1730.011 758.012 382.013 202.015 122.0 18 95.015 77.013 50.015 .30 17 1942 447.030 210.030 107.030 58.030 32.030 22.030 17.029 12.030 8.330 .10 16 1943 1150.024 867.020 381.022 244.022 175.019 132.015 96.014 72.016 47.017 12 955.017 19 371.0 20 39.0 .00 1 1944 2800.0 455.0 14 200.017 120.0 80.020 60.020 22 .03 6 1945 5210.0 6 1910.0 7 965.0 8 677.0 6 385.0 6 196.0 7 131.0 7 98.0 8 64.010

.00 2 1946 1820.020 731.023 352.023 240.023 173.021 123.017 90.017 67.017 44.018 .03 7 1951 1860.016 888.018 420.021 307.015 174.020 95.023 64.023 48.024 32.024 .u021 1952 761.028 569.025 304.025 148.026 90.027 55.027 37.027 28.027 23.026 .03 8 1953 1430.023 1400.012 867.0 9 428.011 239.012 121.019 80.021 60.021 40.020 .0077 1954 2370.013 1740.010 1350.0 5 804.0 4 618.0 351.0 4 254.0 4 198.0 4 136.0 4 .03 9 1955 3990.0 9 2050.0 5 1700.0 3 1160.0 3 950.0 1 563.0 1 376.0 1 282.0 1 185.0 1

.6715 1961 5380.0 5 1890.0 8 855.010 431.010 223.013 134.014 89.018 67.018 44.019 .4810 1962 2990.011 1110.014 477.018 223.024 115.026 59.026 40.026 30.026 20.027 .1020 1963 1800.021 883.019 437.020 295.016 263.011 154.010 103.012 77.014 51.014 .0711 1964 6900.0 4 2690.0 3 1370.0 4 705.0 5 394.0 5 312.0 5 214.0 5 161.0 5 105.0 5 .4018 1965 201.032 111.032 54.032 33.031 18.032 11.032 7.432 5.532 4.232

.0025 1966 8460.0 2 5730.0 2 2710.0 2 1660.0 1 878.0 2 457.0 2 353.0 2 264.0 2 173.0 2 02 5 1967 2000.015 744.022 307.016 245.021 130.024 67.025 45.025 34.025 23.025 7023 1968 8760.0 1 5880.0 1 2890.0 1 1420.0 2 711.0 3 381.0 3 277.0 3 208.0 3 139.0 3 00 4 1969 1110.025 439.027 232.028 131.027 73.028 47.028 32.028 24.028 16.028 9022 1970 1850.017 1050.015 505.017 261.020 159.022 137.013 106.011 82.011 56.011

0030 1971 2240.014 1240.013 709.013 569.0 7 359.0 7 218.0 6 160.0 6 129.0 6 98.0 7 0029 1972 1060.026 511.026 233.027 128.028 115.025 74.024 60.024 51.0B3 39.021 0028 1973 3330.010 1780.0 9 761.011 421.012 323.0 8 173.0 8 121.0 8 93.0 9 103.0 6 0031 1974 1840.018 1000.016 518.015 282.019 222.014 141.012 116.0 9 98.0 7 80.0 8 0033 1975 649.029 298.028 245.026 198.025 131.023 102.022 92.016 80.012 66.0 9

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL MONTHLY MEANS (ALL DAYS/

OCT NOV DEC JAN FEB MARCH APRIL MAY JUNE JULY AU8 SEPT BY 70W5 (MEAN,VARIANCE,STANOARO DEVIATION.SKEWNESS.COEFF. OF VARIATION.PERCENTABE OF AVERAGE VALUE) 16.1 7.22 62.6 18.7 21.7 19.1 5.25 5.00 7.18 74.1 136 45.6 1796 182 35820 2017 2124 1391 170 147 195 7292 26490 4684 42.4 13.5 189 44.9 46.1 37.3 13.1 12.1 14.0 85.4 163 68.4 4.81 2.67 3.70 4.42 2.89 2.91 2.78 2.60 1.78 2.09 3.09 3.32 2.63 1.87 3.03 2.40 2.12 1.96 2.49 2.42 1.94 1.15 1.19 1.50 3.84 1.72 14.9 4.47 5.18 4.55 1.25 1.19 1.71 17.7 32.6 10.9

DISCHARGE. IN CUBIC FEET PER SECOND

STATISTICS ON NORMAL ANNUAL MEANSIALL DAYS/

MEAN VARIANCE STANDARD DEVIATION SKEWNESS COEFF. OF VARIATION SERIAL CORR 35.2 745 27.3 1.20 0.78 -0.139

346 APPENDIX D

347 f hQ( l-L !/ d.{. . \. ` i ..-t r tr.P p /*- Tatte=5:errtii- Ranking of Total Dissolved Solids Loading by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Total Dissolved Solids (TDS) (lbs /ac /yr) Watershed

More than 100 134 N4 123 N9 122 N2 121 N11 120 E7, N7 114 N8, N12 111 A4 110 E4, N17 108 E5, N3, N10 107 E3 105 N6

100 or Less

100 El 99 E10, H11 97 Ki, N13, N15 95 E8, 02 94 C2, E7 93 M3, 01 92 Cl, C4, Ml, N14 91 81, B2, B4, B5, B6, 05,06 90 C3, C5, C6, J3 89 B3, M2 88 C7, F2, G1, I2 87 C8, El + 2, H2, H4, 14,16,15,14+ 5 86 F1, H6, N16 85 C9, I1, J4, N5, 03 84 E2 83 H10, I3 82 Al, C10, E9, Ji 81 H7, L2, L5

80 -- Dl, K2, L4 79 H9, L3 78 H3, H8 77 H5 74 H1 69 L1

348 Ranking of Suspended Sediment Loading by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Suspended Sediment (lbs /ac /yr) Watershed

More than 900 1013 E-3 997 N-11 992 E-1 990 E-5 989 E-11 982 0-2 973 E-10, H-11, N-10 957 N-17 955 N-9 947 B-1 946 B-4 943 0-1 940 0-5 939 B-3 937 B-5 934 B-6, E-1 + 2 929 E-4 923 0-6 918 E-2, 0-3 915 N-16 911 A-1 909 G-1, N-13 908 E-9

750 to 900

900 J-3 898 F-2 891 A-4, N-12 886 D-1 881 N-14 878 N-4 873 B-2 863 C-2 862 N-8 861 N-2 360 C-3 859 C-9 855 H-10 835 E-7 831 N-7 Tab4-e.-3_1_,LiCont4nued )

Suspended Sediment (lbs /ac /yr) Watershed

750 to 900 (Con't) 818 C-5 814 C-10, E-8 813 C-1, K-1 812 C-8 796 C-4 794 H-8 793 N-15 789 N-3 788 H-5 780 C-6 776 H-3 768 J-1 755 F-1 753 M-3

600 to 750

740 H-7 729 I-1 720 N-6 705 H-6 703 M-1 696 C-7 676 K-2 665 N-1 663 M-2 641 I-6 637 H-9 619 L-5, N-5 610 L-4 607 H-1, H-2 603 L-2

Less than 600 588 L-3

512 . L-1 488 H-4 442 J-5 376 I-3 363 I-5 337 (I-4 + I-5) 317 I-2 266 I=4

350 -r

Table---3-3- Ranking of Organic Loading (as Indicated by CO2) by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Chemical Oxygen Demand (COD) (lbs /ac /yr) Watershed

More than 300 317 E3, H11 314 El, E5

311 . ElO 308 N9 307 Nil 306 02 305 El + 2 304 81, B3, B4 303 E2 302 Al 301 E9

250 to 300

300 B5, B6, H10, N3 299 N12, 03 298 E4 296 Ell, N13 295 Di, H5, N8 294 C3, M3 293 H3 292 C4, F2, N4, N14 291 H8 290 C9, E7, N7, N16 289 M1 288 E8 287 B2, C2, C10, M2, N15 283 N5, N17 282 L2, 15 280 J1, N2 279 L3 278 05

276 . C5, L4 272 N6 268 C8 267 Kl, K2 265 H7 261 N1 260 L1 259 C7 256 Cl, 01 253 C6

351 Chemical Oxygen Demand (COD) (1bs /ac /yr) Watershed

Less than 250

248 H1 244 F1 236 I1 232 H9 231 H6 221 A4 216 N10 209 I6 208 H2 161 H4 137 J4 119 13 110 I5 101 I4 + I5 90 12 76 14 "rd'ffa T 9_ Ranking of Nutrient Loading (Nitrate) by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Nitrate (NO3).

(l bs /ac /yr) Watershed

More than 2.00

3.41 I2 2.80 I4 2.74 C7 2.64 N6 2.63 C7 2.51 Cl 2.48 N1 2.34 H4 2.23 N5 2.22 Li 2.12 H6 2.11 A4 2.10 H1, I4 + I5, L3 2.06 L2 2.04 N4 2.02 I6

1.01 to 2.00 2.00 L4 1.99 M2 1.98 L5, M1 1.89 N7 1.87 I1 1.85 C8 1.84 I5 1.81 M3 1.79 N2 1.78 .N3 1.73 E4 1.72 E8 1.64 H2 1.63 N15 1.62 C5 1.61 C4 1.60 N8 1.58 K2 1.57 H7 1.56 F1 1.54 E7, E11 1.53 H9 bblems.l .9iCo ' Hued)

Nitrate (NO3)

(1bs /ac /yr) Watershed

1.01 to 2.00 (Con't)

1.47 C2 1.43 N12 1.39 J4 1.38 B2 1.32 Kl

1.28 - N9 1.22 J1 1.17 C3, N11 1.15 H3, N10 1.08 N17 1.07 H5 1.01 H8 1.00 N13

Less. than 1.00

.93 Hli .92 C10

.89 E5, H10 .88 N14 .84 C9 .81 E10 .78 J3 .73 F2 .72 G1 .71 E3 .70 01

.68 B5 .66 I3 .60 B6 .58 El .57 B4 .55 06 .53 N16 .52 Bi, B3, 02 .51 05 .47 03 .46 El + 2 .43 El .42 Al .41 E9

354 T-ab-l-e 0 Ranking of Nutrient Loading (Phosphate) by Watershed Within and Contiguous to the Urban Window, Pima County, Arizona

Phosphate (PO4)

(ls /ac /yr) Watershed

.16 I2, I3, N10

.15 Fi, Il, I4, I5, I4 + 5, J4, 01, 05

.14 _ Al, Bi, B3, D1, E2 + 1, E9, F2, G1, H4, H6, I6, N16, 02, 03, 06

.13 B2, B4, B5, B6, Cl, C2, C3, El, H1, H7, H9, H10,

Hil, N13, N14 .

.12 C5, C6, C8, C9, E3, E5, E10, H1, H3, H5, H8, J3, N11, N17

.11 C4, C10, E4, E7, E8, Ell, Jl, K1, N8, N9, N12, N15

.10 A4, C7, K2, M3, N2, N4, N7

.09 . L1, L2, L3, L4, L5, Ml, M2, N1, N3, N5, N6

355 -1 -ab-Té 33Tú1 Ranking of Bacterial Loading (as Indicated by Fecal Coliform) by Watershed within and Contiguous to the Urban Window, Pima Country, Arizona

Fecal Coliform (FC) (Counts /100 ml = 1012) Watershed

More than .300

.415 Ll .381 L3

.376 L2

.368 - N5

.364 - . L4 .362 L5 .344 M2

.318 M1 .306 N1 .301 K2

.200 to .300

.296 N6 .283 M3 .282 H1, N3 .264 C7 .258 N7 .240 E7 .238 N15 .237 J1 .236 N4 .231 E8, H3 .230 A4 .228 C4 .219 N8 .217 H5 .216 N2 .213 N12 .211 Kl .210 H8, N17 .202 H9

.100 to .200 .200 N10 .194 C10, H7 .189 N9 .183 C5 .182 H2 .179 E4, H4

356 -Tab fie-3.1:11 Continíed)

Fecal Coliform (FC) (Counts /100 ml 1012) Watershed

. 100 to .200 (Con't)

.172 H10 .164 C3 .162 I4, I6 .160 C6, 01

.159 C2 -

.158 C8

.156 - - Ell, I2

. i56 C9 .155 E5 .154 N14 .151 Hil .149 B2, I4 + 5, J3 .147 E10, H6 .145 I5 .139 N13

.138 Nil .135 Cl .129 B6 .127 .126 I1 .125 B5, E3 .121 Fi .119 B4 .118 N16, 05 .117 G1 .114 B3, I3 .113 B1 .112 F2 .110 D1, 02 .108 Ei, 06 .104 03 .103 El + 2 .102 Al, E2 .100 E9

357 APPENDIX E

358 4178

GENERAL CONCEPTS AND PROCEDURES Each watershed area or water source in the area of study was evaluated in its present environmental condition, and the general physiographic and hydrologic condition of each source area was noted. A fairly detailed study of die land use types contained within the specific watershed area was also made through analyses of topographic maps and aerial photographs. These land use types reflect fairly uniform hydrologic groups which have similar infiltration capacities and runoff hydrographs. The numerical values for the water quantity section were determined, where possible, from actual field data collected over many years by the U.S. Geological Survey and the Water Resources Research Center. Water quantity data were estimated by transposing known data to similar areas when actual field data were not available. With the actual and estimated runoff volumes and peak flows, statistical frequency analyses were made for specific watershed areas and hydrologic groups. The authors have conser- vatively estimated the storm runoff volumes, and have slightly overestimated peak flows for design purposes for each frequency level. At locations which have flowing water, such as, San Xavier Rock and Material's Company and the Congress Street Storm Sewer, a water sample was taken for detailed water quality analyses. At the majority of the water sources, however, mean water quality values were estimated through the transposition of water quality data from similar urban and desert watersheds, which have been sampled for the past eight years by personnel front the Water Resources Research Center. Lastly, possible uses of the water in the development of the Santa Cruz Riverpark are discussed for each Water Source. The locations of all Water Sources are shown in the map at the beginning of the report, and the detailed discussion of Water Source Locations No.. 1 through 25 presented below in approximate downstream order. WATER SOURCES \V.VFER SOURCE NO. 1- Hughes Wash I. Description of -the Area a. Overview The drainage area of Hughes Wash is located in alluvial valley fill in the central part of the'fucson Basin. General slope of the land is to the west - northwest at about -It) feet per mile, and ridges on the watershed are nearly parallel to stream channels. Average elevation is 2600 feet above ntcan sea level. The vegetation can be described as desert growth with the creosote bush probably ranking first in population. Near sites of surface ruoff, mesquite density ranges From moderate to heavy and commonly is accost panicd by good grass coverage. In addition, cholla, ocotillo and barrel cactus are mime! of cactus ate numerous.

359 b. Drainage area = 9.0 square miles to Interstate 1 -19. c.Watershed composition by land use types. Desert area = 8.7 square miles or 96.7 percent. -Composed of grassland, desert brush and a large cacti population. Paved area = square miles or 2.2 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 0.1 square miles or 1.1 percent. -Composed of low- density vegetative cover, and bare soil. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year -30 Winter, 1 year- 10 Summer, 2 year -100 Winter, 2 year- 30 Summer,10 year -300 Winter,10 year- 60 Summer, 25 year -390 Winter, 25 year -190 Summer, 50 year -550 Winter, 50 year -250 Summer, 100 year -730 Winter, 100 year -320 b. Peak flows for given frequencies in cubic feet per second. 2 year- 600 50 year -1500 10 year -1000 100 year -1900 25 year -1300

3.Mean Water Qualities from Watershed Area* Summer tiVintcr Units Storms Storms a.Total dissolved solids = mg/ 1 2I0 200 b. Suspended solids = mg /1 6,000 2,700 c.Chemical oxygen demand = mg/ 1 400 190 cl. Temperature = °C 24 12 e. pH = - 8.7 7.9 f.Bacterial density = (1) Total coliforms = #/100 ml 25 x 104 80 x 102 (2) Fecal coliforms = # /100 ml 30 x 103 40 x 102 (3) Fecal streptococci = # 1100 ml 10 x 104 12 x 103 *Assuming transposition of water quality data from Atterbury Water- shed (desert).

4. Possible Water Uses A Luge meander on the Santa Cruz River, 1500 feet north of Los Reales Road, is perhaps the best location for a storage basin within the river channel in the Linear Park. The Santa Cruz River bed can be straightened, then protected by rip -rap material, permitting the meander to function as a recharge pit and storage basin. The site could store flood seater flows from the Santa Cruz River as well as desert and urban storm runoff. The straightening of the stream channel will also prevent further erosional cutting on the west side of the meander. San Xavier Rock & Materials Company would be willing to build the detention basin and the proposed channel for rights to the gravel. Specific details regarding recharge front a storage basin are discussed in an earlier section of this report. \.VFER SOURCE NO. 2 -San Xavier Rock & Materials Company Wash

I. Description of the area a. Overview The watershed encompassing this wash is located in alluvial valley fill in the central part of the Tucson Basin. General slope of the land is to the west - northwest at about 40 feet per mile. Average elevation is 2600 feet above mean sea level and vegetation can be described as desert growth. Throughout most of the watershed, the larger washes have well defined

360 channels. The smaller washes consist of a large number of small rivulet extending over a wide region. Upstream erosion, redeposition of sedi ment, and heavy growth of vegetation have been accompanied by partii choking of the principal washes. Floódwaters spread out in certain section of the watershed. Storni runoff from a small portion of the Tucson Airpot drains into the main wash producing increased surface flows. Hughes Aircraft Company plant located within the watershed area is pre sently discharging industrial processing waters into a waste ditch. Thi ditch conveys the effluent approximately one -half mile to a pond fror whichthe water is dissipated by evaporation and seepage. DeCook (197( made intermittent measurements of the combined industrial effluent Ilol between 1966 -1969 and found an average discharge of approximately 30 acre -feet per year. Chemical analysis of the industrial effluent is suir marized in Table 4, and the water quality data indicates that this saIvagt able water cannot be used in its present state. However, according to Et %yard C. Spaulding, Plant Supervisor, (Oral communication, 1976) a ne' reverse osmosis treatment plant will be completed by March, 1977. How ever, properly treated industrial effluent of this kind may possibly be use for recreational and aesthetic purposes.

Lrhlr 4. Chrini.al (Ian rnrr arnl (:nurm ol Tract }tctats in Indust; id El limnt at llughas aircraft (bngr.rnv ¡Lair. 11A'C]wr 19701.

Chianti .d Constituents _ C,ncennation i mg111` Calcium 75 Magnesium 10 Sodium .48 Chloride )25 Sulfate 138 Bicarbonate 173 Boon 0.26 Mum idc 1.2 Potassium 2.8 pif 8.0 Nu rate, : \lh lift rh.nphate as ro, 34 Silica 4S0.10 Toul Dissolved Solids 5;52 Trace ?trial

Iron 0.31,

Manganese - 0.0 Cl.nuniuo.' 1.85 Nis kel 0.20 Copper 0.03 'tam 0.02 lead 1.16 Cadmium 0.01 Cobalt 0.13 rm,m.m 0.72 Average of f. usr samples taken at rariuus flow rases during normal operation, July- September, 1966. "1 -or.t.Monition Om sample .n.:rlyrr,l by Sutr I lcaltb 1k 1,.uooeut ,bowed hrsav:dru, clrrnrourn, a 11.178 mg/ 1.

b. Drainage area = 1.7 square miles to Interestate I -19. c.Watershed composition by land use types. Desert area = 0.7 square miles or 41.2 percent. -Composed of grassland, desert brush and cacti. Urban area = 0.4 square Miles or 23.5 percent -Composed of single and multi -family units on land parce smaller than one acre including rooftops, paved and not paved rights -of -way, and vegetative cover. Suburban arca = 0.1 square miles or 5.9 percent. -Composed of single family units on land parcels greater I ha one acre, including rooftops, paved and non -paved rights -o way. and vegetative Cover. Paved area = 0.2 square miles or 11.3 percent. -Composed of paved surface area, and large roof areas assi dated with commercial or industrial facilities. Denuded, or bare area = 0.3 square miles or 17.6 percent. -Composed of low- density vegetative cover and bare soil.

361 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, 1 year- 20 Winter, 1 year- 10 Summer, 2 year- 40 Winter, 2 year- 30 Summer,10 year -100 Winter,10 year- 80 Summer,25 year -130 Winter,25 year -100 Summer,50 year -180 Winter,50 year -140 Summer, 100 year -230 Winter, 100 year -170 b. Peak flows for given frequenciesin cubic feet per second. 2 year - 400 50 year -1200 10 year- 800 100 year -1400 25 year -1000 3.Mean Water Qualities from WatershedAreas* Summer Winter Units Storms Storms a. Total dissolved solids = mg /1 220 160 b. Suspended solids = mg /I 1,500 900 c.Chemical oxygen demand = mg /1 300 130 d. Temperature = °C 24 12 e. ph = - 8.7 7.8 f.Bacterial density = (1) Total coliforms = #1100 ml 80 x I W 20 x 103 (2) Fecal coliforms = #/100 ml 30 x 104 40 x 102 (3) Fecal streptococci = #/100 ml 50 x 10' 10 x 103 *Assuming transposition of water quality data from Atterbury Watershed (desert). Supplemental water samples were taken at various locations on the property owned by San Xavier Rock & Materials Company for a detailed chemical analysis. Sediment -laden water discharging at approximately one cubic foot per second from the gravel- washing operation into the dry channel of the Santa Cruz River was also sampled. As the gravel -washing effluent proceeded downstream, an additional water sample was taken. The water quality analysis for each- eater source sampled is summarized in Table 5.

Table 5.51'ater Quality Analyses From Various taxations arrhe San Xavier Rock k \lateriats Company and a Sanq,iing Slal if Duanstrra,

(1.5 mile 11.,,vn- Chemical Faut West Pumping I)ivh:ugeIrmo suean,frmn, C+mdmrnu Units Pond Pond U'ril Gravel Plain 5'aicmi..R,.,d pH - 8.2 7.5 8.5 8.0 8.5 Elmo-4- I (:umins;,itv mmh..vc,n 0.79 575 1.611 0.78 11.80

Trmlxratmr '(: 16.1 16.3 199 21 1 21.2

'Ili,iuidirr JCU 1 7 (1.4 1:250 55 Suspended Solids mgil 13 28 3 I68211 9 Volatilr Su.p. Solids mg/1 8 111 3 HI 7 Co!) mg/1 46 4 236 31 Ca"' 111W1 72 1'80081 85 87 75 51g' mg!1 13 13 30 15 13 1i.1.11 I I." tint,. ICaC0,1 mg/I 23-1 256 316 278 240 Na' tug/1 116 112 2142 112 I14 (:(h.;glI II 11 5 I) 11 II(:tluigil 228 274 122 2 2'19 C higa I 33 21 IP) 2!1 29 A' u,g/I 8 4 13 10 11 NI1.1N mg/1 011 11. 11.1 0 0.3 Airldahl-N mg/1 0.4 11 0.8 II 11.5 N(h:N.N(h:N 51gi1 0 2.8 .1-.nalla.l;lorms I;118H1 <1-

4. Possible Water Uses The effluent from the gravel- washing operations presently Flows for several miles along the Santa Cruz River; and with minor bank landscaping, this natural stretch of the river can be even more scenic than it is at present.- :1potential also exists for using the two small settling lakes for landscaping or other water -related activities.

362 WATER SOURCE NO. 3- Mission Manor Area 1.Description of the Area a. Overview The watershed of -the Mission Major area is located near the southern city boundary of Tucson, Arizona. General slope of the land is to the west - northwest at about 40 feet per mile with an average elevation of 2550 feet above mean sea level. The watershed has a well -defined channel passing through and collecting storm runoff from the soil -vegetation surfaces, paved and non -paved streets and building roofs. Storm runoff from portions of the Tucson International Airport, a surrounding urbanized area, and a large desert area is drained by the channel. The urban area includes single and multiple family dwellings, several types of roofing materials, paved and unpaved areas, and lawns and gardens subject to fertilization and chemical pest control. The small developed portion of the watershed has a considerable influence on the runoff volumes, flow rates, and peak arrival times. In addition, pattern of street arrangements will affect the drainage performance. This watershed has a composite type of street pattern which produces a complex storm runoff hydrograph. b. Drainage area = 1.9 square miles to Interstate I -19. c.Watershed composition by land use types. Desert area = 1.0 square miles or 52.6 percent. -Composed of grassland, desert brush and cacti. Urban area = 0.6 square miles or 31.6 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square mile or 5.3 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and nun -paved rights -of -way, and vegetative cover. Paved area = 0.1 square mile or 5.3 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 0.1 square mile or 5.2 percent. -Composed of low- density vegetative cover and bare soil. 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, 1 year- 20 .Winter. 1 year- 10 Summer, 2 year- 50 Winter, 2 year- 40 Summer,10 year-110 t 'inter,10 year- 90 Summer, 25 year -I50 Winter, 25 year -110 Summer, 50 year -210 Winter. 50 year -160 Summer, 100 year -260 kVinter, 100 year -180 b.Peak flows for given frequenciesin cubic feet per second. 2 year -450 50 year-1150 10 year -750 100 year -1400 25 year -950 3.M1lcan Water Qualities from WatershedArea* Summer Vinter Units Storms Storms a.Total dissolved solids = mg/ 1 220 160 b. Suspended solids = mg/ 1 1,700 500 c.Chemical oxygen demand = ntg% l 330 150 d. Temperature = °C 26 14 e.ph = - 7.1 7.1 f.Bacterial density = (1) Total conforms = # /l00 nil 90 x 10 50 x 10" (2) Fecal conforms = # 1100 ml 40 x 104 20 x 1W (3) Fecal streptococci = # 1100 ail 35 x 10' 90 x 102 *Assuming transposition of water quality data from Arcadia Satershed (Urban).

363 4. Possible Water Uses The desert and urban storm runoff from the small drainages that make up this water source can be diverted into broad- based, grassed terraces to create a greenbelt area along a development area with potential between I -19 Freeway and the Santa Cruz River. \VATER SOURCE NO. 4-Airport Wash 1. Description of the Area a. Overview The watershed contributing to Airport Wash is located in alluvial valley fill in the central part of the Tucson Basin. General slope of the land is to the west- northwest at about 45 feet per mile and ridges on the watershed are parallel to the stream channels. Average elevation is 2700 feet above mean sea level. The vegetation can be described as desert growth with the creosote bush probably ranking first in population. Near sites of surface runoff the mesquite density ranges from moderate to heavy and, commonly, is accompanied by good grass coverage. In addition, cholla, ocotillo, and barrel cactus are numerous. Throughout most of the watershed, drainage diverts into two main branches of Airport \%'ash. Only in a few locations do these washes have well defined channels. In most parts, the washes consist of a large number of small rivulets extending over a wide region. Upstream erosion, redeposition of sediment, and heavy growth of vegetation have been accompanied by partial choking of the principal drainageway above the University of Arizona Environmental Modification Facility. Floodwaters spread out and cross Country Club Road in a 600 -foot -wide overflow section, then are concentrated in the flood channel below. The channel extends on through the Tucson International Airport, through an area being developed for industry, and finally through several residential subdivisions before emptying into the Santa Cruz River. The Tucson Airport Authority has improved and maintained the channel through the airport area; it has been estimated that the existing channel can carry peak flows of 10 -year recurrence through this area. The remainder of the main channel has been progressively improved and maintained by the City of Tucson; however, the increasing encroachment of urbanization along both sides of the wash increases the probable damage that would result from any overflow. b. Drainage area = 23.5 square miles to Interstate 1 -19. C. \\':uershed composition by hind use types. Desert area = 21.5 square miles or 91.5 percent. -Composed of grassland, desert brush and a large cacti population. Urban area = 0.9 square miles or 3.8 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square mile or 0.4 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights-of- way, and vegetative cover. Payed area = 0.3 square miles or 1.3 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 0.7 square miles or '3.0 percent. -Composed of low- density vegetative cover and bare soil. 9.Quantities of Water :t.Water volumes for given frequencies in acre -feet.* Summer, 1 year- 70 Winter, 1 year- 20 Summer, 2 year- 200 Winter, 2 year- 120 Summer,10 year- 630 Winter,10 year- 530 Summer,25 year- 760 Winter,25year- 570 Sumner,50 year -1 150 Winter,50 year- 830 Sumner, 100 year -I -WO Winter, 100 'car -1030

364 *The extension of Country Club Road to the south into the Interna- tional Airport causes ponding of storm runoff above the road. Since we believe this condition to be only temporary, the volumes presented are corrected to what we believe they would be with unimpeded flow. b. Peak flows for given frequencies in cubic feet per second. 2 year- 650 50 year -2400 10 year -1500 100 year -2800 25 year -2000 3. Mean Water Qualities from Watershed Area* Summer Winter Units Storms Storms a. Total dissolved solids = mg /1 180 .150 b. Suspended solids = mg /1 3,500 2,000 c.Chemical oxygen demand = mg /1 200 150 d. Temperature = °C 25 13 e. pH = - 8.5 - 7.7 f. Bacterial density = (1) Total conforms = #1100 ml 40 x 104 80 x 10" (2) Fecal conforms = #1100 ml 16 x 104 30 x 102 (3) Fecal streptococci = #1100 ml 20 x 10' 14 x 10' *Assuming transposition of water quality data from Atterbury Watershed (desert). 4. Possible Water lises Desert and urban runoff possibly could be diverted from Airport Wash for storage in a detention basin between the I -19 Freeway and the Santa Cruz River. To facilitate diversion, a collapsible rubber dam could he located in the narrow portion of the wash downstream of the Freeway, provided backwater effects would not be a problem. Collected water could be used in the vicinity of the detention basin for maintenance of vegetation on the banks of the Santa Cruz River. Surplus water in the basin could be used for artificial groundwater recharge. WATER SOURCE NO. 5-Rodeo Wash 1. Description of the Area a. Overview The watershed of Rodeo Wash is located in the southern portion of the city of Tucson, Arizona. General slope of the land is to the west -northwest at about 40 feet per mile with an average elevation of 2600 feet above mean sea level. The watershed has a well -defined channel passing through and collecting runoff from the soil -vegetation surfaces, paved and non -paved streets and rooftops. Storm runoff water from the county fairgrounds, a surrounding urbanized area, and a large desert region is drained by the channel. The urban area includes single and multiple family dwellings, several types of roofing materials, paved and unpaved areas and lawns. The desert vegetation is composed of creosote bush, native grasses and cacti. The small developed portion of the watershed has a considerable influence on the runoff volumes, flow rates, and peak arrival times In addition, the pattern of the street arrangement will affect the drainage performance. In the upper reaches of the watershed, heavy growth of vegetation and debris have caused a partial choking oldie principal channel. b. -Drainage area = 6.1 square miles to Interstate 1 -19. c.Watershed composition by land use types. Desert area = 4.5 square tuiles or 73.8 percent. -Composed of grassland, desert brush and cacti. Urban area = 1.0 square miles or 16.4 percent. -Composed of single and multi-family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.2 square miles or 3.3 percent. -Composed of single family units on land parcels greater than one acre. including rooftops, paved and non -paved rights -of- way, and vegetative cover.

365 Paved area = 0.1 square mile or I.6 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 0.2 square mile or 1.6 percent. -Composed of low- density vegetative cover and bare soil. Parks or grassed areas = 0.2 square miles or 3.3 percent. -Composed of high density vegetative cover with essentially no exposed soil areas. 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, I year- 40 Winter, 1 year- 20 Summer, 2 year -110 Winter,2 year- 60 Summer,10 year -260 Winter,10 year -170 Summer, 25 year -360 Winter, 25 year -230 Summer, 50 year -500 Winter, 50 year -330 Summer, 100 year -660 Winter, 100 year -400 b.Peak flows for given frequencies in cubic feet per second. 2 year - 600 50 year -1800 10 Year-1200 100 year -2200 25 year -1 500 3. Mean Water Qualities from Watershed Area* Summer Winter Units Storms Storms a."Dotal dissolved solids = mg/1 200 190 b. Suspended solids= mg/1 800 500 c.Chemical oxygen demand = mg/1 300 150 d. Temperature = °C 28 16 e. pH = 7.3 7.0 f.Bacterial density = (1) Total coliforms = # /100 ml 15 x 104 12 x 10' (2) Fecal coliforms = # /100ml 10x10' 40x103 (3) Fecal streptococci = #/100 ml 60x 10' 35x 10' *Assuming transposition of waterquality data from High School Watershed (urban). .4.Possible Water Uses Desert and urban storm runoff could be diverted into broad based, grassed terraces, or a possible holding pond on a potential golf course site which could be developed along the banks of the Santa Cruz River, north of Ajo Road. The golf course site can provide a valuable demonstration of water conservation, control and treatment systems which can be used, such as, flood runoff storage, settling, grass filtration, grass -soil filtration, and chlorination. Possible uses can also be demonstrated, such as, landscape irrigation, water- related landscaping, fishing and boating, and swimming. Specific details regarding the above methods of control, treatment, and use are discussed at the beginning of this report. Serious consideration should be given at this point to the use of treated sewage effluent that has been chlorinated for maintenance of the golf course and park areas when storni runoff is not available. The effluent should be managed so that nutrient removal by grasses is an integral part of the plan. Direct recharge of secondary sewage effluent in the Santa Cruz River channel should not be permitted unless the treated effluent meets the required EPA 1983 Waste Treatment Standards (best practical technology) for this practice. Further, any wastewater recharge operation should include a comprehensive ground -water monitoring program. WATER SOURCE NO. 6-Julian Wash including Tucson Diversion Canal I.Description of the Area a. Overview The watershed associated with this wash is located in the south- central portion of the city. General slope of the lanci is to the west -northwest at about 40 feet per toile with an average elevation of 2600 feet above mean

366 influence on the runoff volumes, flow rates and peak arrival times. In addition, pattern of street arrangements and the Ajo Detention Basin will affect the drainage performance. The complexity of the watershed drainage pattern probably produces complex storm -runoff hydrographs. The following hydraulic information regarding the Julian Wash and the Tucson Diversion Channel System is from the U.S. Corps of Engineers, 1963. Drainage Design Area Discharges Stream or Channel Location (sq. miles) (cfs) Tucson Diversion Detention -Basin 17.8 15,300 Channel Inlet Tucson Diversion Detention -Basin 17.8 9,300 Channel Outlet Julian Wash Tucson Diversion 23.0 12,000 Channel Tucson Diversion Downstream from 45.8 17,000 Channel Julian Wash Confluence For Standard Project Storm Required basin capacity = 1,800, acre feet Approximate basin area = 110 acres \laximum depth = 17 feet The Irvington Road Power Plant of the Tucson Cas and Electric Company is presently discharging both cooling tower effluent and sanitary wastes into the City sewer system. Engineers at the plant have indicated that the cooling tower effluent could be easily directed to another discharge point, so that this water would be available for other uses such as landscape irrigation, water- related activities, etc. The cooling effluent is presently derived from four cooling tower units. The rate of outflow ranges approximately from 300 to 600 gallons per minute, and the yearly cooling effluent flow in 1974 was 809 acre feet. However, due to new generation facilities and more recycling of water, Dr. Charles McCauley, Senior Assistant Engineer of the Environmental Ser- vices Section, indicates that cooling water effluent flow will be maintained at approximately 350 acre feet per year (Oral Communication, 1976). The chemical concentration of the cooling water will also be much higher. The cooling water is supplied by pumping from wells, of .which six are about 1,000 feet deep and the fifth is 2,500 feet deep. The results of chemical analyses of waters front all these wells, as sampled in 1962, are illustrated in Table 6. The water from the wells is pumped to a surge tank for temporary storage, whence it supplies makeup water to the towers. This composite water becomes concentrated about five times during its use in the cooling process. In addition, sulfuric acid is added to neutralize the alkalinity of the incoming well water, chlorine is added for algae control, and hexa- metaphosphates are added to prevent scale formation and in- hibit corrosion. The chemical character of the effluent, sampled in Sep- tember 1967 from the main discharge line from the tower complex and April, 1974 is also illustrated in Table 6. b. Drainage area = 46.0 square miles to Interstate 1 -19. c.Watershed composition by land use types. Desert area = 32.5 square miles or 70.6 percent. -Composed of grassland, desert brush and cacti. Urban area = 2.5 square miles or 5.4 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non -paved rights -of -way, and vegetative cover. Suburban area = 0.8 square miles or 1.7 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and vegetative cover.

367 Paved area = 4.0 square miles or 8.7 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Denuded, or bare area = 6.0 square miles or 13.0 percent. -Composed of low- density vegetative cover and bare soil. Park or grassed areas = 0.2 square miles or 0.6 percent. -Composed of high density vegetative cover with essentially no exposed soil areas. 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Sumner,1 year- 250 Winter, 1 year- 100 Summer, 2 year 750 Winter, 2 year- 400 Summer,10 year -1900 Winter,10 year -1100 Summer, 25 year -2550 Winter, 25 year -1500 Summer, 50 year -3550 Winter, 50 year -2200 Summer, 100 year -4650 Winter, 100 year -2700 b. Peak flows for given frequencies in cubic feet per second. 2 year -1500 50 year -4800 10 year -3000 100 year -5800 25 year -3800 3. Mean Water Qualities from Watershed Area* Summer Winter Units Storms Storms a. Total dissolved solids = mg!I 210 220 b. Suspended solids = mg /1 900 500 c.Chemical oxygen demand = mg/ 1 280 120 d. Temperature = °C 28 16 e. pH = - 7.3 7.0 f.Bacterial density = (1) Total coliforms = #/100 ml 15 x 104 12 x 104 (2) Fecal coliforms = #/100 ml 10 x 104 40 x 10' (3) Fecal streptococci = # /100 ml 60 x 10' 35 x 10' *Assuming transposition of water quality data from High School Watershed (urban).

Table 6. Chemical Character of Water from Wens and Cooking Power Effluent at Irvington Road Stream Electric Generating Plant

Coot coil al f u,g' 1 ` Input Water Effluent Effluent (Composite From (Composite From (Composite From Emir Production Emir Cooling Four C..liog Wells) 'rowers) Tuwersl 1967 Sept.. 1967 April. 1976 C 6.mm-aa Corutituient Cakiuns 36 161 201) Magnesium 6 2! - Sosliunt 79 440 - Chloride O2 116 M) Sulfate 145 1,167 1,375 Ili,,,ri.outr 20 25 53 Temper rare. C 36. 33 - Boron 0.19 063 - Fimride 1.6 7.! pli 9.2 7.9 7.6 Nitrate a NO3 IA 6.0 - i7unph:nc.s PO. 0.55 3.47 - l'nussion 2.5 12.1 - Siliaa (Sith) 16 59 191 Tsui di.o.lceol solids 339 23m22 1.25 Ilardmv , - - blM)

Truer .Sf rn:l lt..s 03413 1)_21) :langar.rse 0.01r2 () 010 Chromium 0.001 t71/)I Nickel 0 0 Cnp)ar 0.014 I) 11:4 Zinc 1).004 0.1111) I.rad II_01,5 1) (:adm n 0 ofg)I Cubaitut u t) Slrououm 1 761 3 St IS Tcnlperautrr ranged f rom 31r to 55C. as a partial font tien of well depth.

Pt. G. MhLudes. Ass{stant Engineer of the Ensironmental Senors Section. locw.ts Ga k Electric Co. (01 :d tinnmumut.m. i'976ì)

368 4. Possible Water Uses Desert and urban storm water from Julian Wash can be stored in a detention basin betweenthe I -19 Freeway and the Santa Cruz River. The water could provide a water hazard for a golf course or a lake for a potential recreational area. All excess water can be discharged into the Santa Cruz River for recharge purposes. Serious consideration should be given at this point to the use of treated sewage effluent that has been chlorinated for maintenance of the golf course and park areas when storm runoff is not available. The effluent should be managed so that nutrient removal by grasses is an integral part of the plan. Direct recharge of secondary sewage effluent in the Santa Cruz River channel should not be permitted unless the treated effluent meets the required EPA 1983 Waste Treatment Standards (best practical technology) for this practice. Further, any wastewater recharge operation should include a comprehensive ground -water monitoring program. \ VATER SOURCE NO. 7- Robles Pass Wash 1.Description of the Area a. Overview The watershed of Robles Pass Wash is located near the western boundary of the city limits and within the eastern foothills of Tucson \fountain Range. General slope of the land is to the east at about 200 feet per mile with an average elevation of 2650 above mean sea level. The watershed has a defined channel with small rivulets extending over a small region. Sur- face drainage is rapid from the steep hills, and moderate from the gently sloping foothills and valley. Slopes range from 0 to 3 percent in the alluvial valley bottom, to greater than 45 percent on the rock slopes of the foothills. In the lower reaches of the watershed, the channel has a heavy growth of riparian vegetation producing an areal spreading of floodwaters. A wide variety of trees, shrubs, grasses and cacti cover the watershed. The foothills and ridges of the watershed are the result of Paleocene volcanic activity. The hills are flanked by alluvial and colluvial fans, terrace deposits and flood -plain alluvium. The common sediments are caliche, metallic dendrites and alluvium. Rock outcrops and shallow soils with a clayey horizon (Argids) over bedrock composes the major portion of soil association in the watershed. The Argids soils produce large runoff events when the soil- moisture regime has been satisfied and the soil infiltration capacity has been exceeded by rainfall. The gravelly alluvial terraces and coarse alluvial deposits in the streambeds have a high permeability and low runoff potential. The composite soil association and geology in the watershed produces a complex drainage environment, whereby low seasonal and annual runoff volumes are associated with long periods of non - runoff. Ptak flows are relatively small with return periods of less than five years. However, as the rainfall intensity increases over the infiltration capacity, the peak flows become exceedingly large. Itis obvious that any structural design should account for the skewed frequency distribution of these peak flows.

b. Drainage area = 1.9 square miles to Mission Road. c.\Vatershed composition by land use types. Desert area = I.7 square miles or 89.5 percent. -Composed of grassland, desert brush and a large cacti population. Urban area = 0.1 square mile or 5.3 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved ancf non - paved rights -of -way, and vegetative cover. Suburban area = U. I square miles or 5.2 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of way, anti vegetative cover.

369 2.Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 10 Winter, I year- 5 Summer,2 year- 20 1Vinter, 2 year -10 Summer,10 year- 40 Winter,10 year -20 Summer, 25 year- 70 Winter, 25 year -40 Summer, 50 year -100 Winter, 50 year -70 Summer, 100 year -120 Winter, 100 year -80 b. Peak flows for given frequencies in cubic feet per second. 2 year - 200 50 year -1900 10 year -1200 100 year -2300 25 year-1700 3. Mean Water Qualities from Watershed Area* Summer Winter Units Storms Storms a. Total dissolved solids = mg /1 180 150 b. Suspended solids = mg /1 3500 2000 c.Chemical oxygen demand = mg /1 200 125 d. Temperature = °C 24 12 e. pH = - 8.0 7.5 f.Bacterial density = (1) Total coli forms = #1100 ml 50 x 104 70 x 102 (2) Fecal coliforms = # /100 ml 20 x 10; 40 x 102 (3) Fecal streptococci = #/100 nil 12 x 10' 12 x 10't *Assuming transposition of water quality data from Atterbury Watershed (desert). 4. Possible Water Uses Desert and urban storm runoff should be allowed to flow and recharge along the west branch of the Santa Cruz River, This storm water could also be diverted into a natural storage basin, approximately one river mile downstream from Ajo Road, between the two branches of the Santa Cruz River. The potential storage basin is presently being used as sanitary landfill and. therefore, the site must have debris removed before any storm runoff water can be stored. If the basin cannot be completely cleared, then care must be taken, as by lining the basin with plastic, to prevent leaching of harmful landfill constituents into the ground water. Specific details regarding recharge in the river channel are discussed earlier in this report. WATER SOURCE NO. 8 -Big Wash 1.Description of the Area a. Overview The watershed for this source is located near the western boundary of the city limits and within the foothills and mountain range of the 'Tucson Mountains. General slope of the land is to the east -southeast at about 220 feet per mile with an average elevation of 2750 feet above mean sea level. The watershed has a defined channel with small rivulets extending over a small region. Surface drainage is rapid from the steep, relatively impermeable hills. and moderate runoff occurs from the gently sloping foothills and valley. Slopes range from 0 to 3 percent in the alluvial valley bottom, to grcatet than .15 percent on the rock slopes of the foothills. In the lower reaches of the watershed, the channel has a heavy growth of riparian vegetation producing areal spreading of floodwaters. A wide variety of trees, shrubs, grasses, and cacti cover the watershed. Rock outcrops and shallow soils with a clayey horizon or caliche (Argids) over bedrock composes the major portion of soil association in the watershed. The composite soil association and geology in the watershed produces a complex drainage environment, whereby low seasonal and annual runoff volumes are associated with long non -runoff periods. How- ever. as the potential rainfall intensity increases over the infiltration capacity. the potential peak flows become exceedingly large. It is obvious that any structural design should account for the skewed frequency distribution of peak flows.

S*- 370 b. Drainage area = square miles to Mission Road. c.Watershed composition by land use types. Desert area = 2.6 square miles or 92.9 percent. -Composed of grassland, desert brush and a large cacti population. Urban arca = 0.1 square miles or 3.6 percent. -Composed of single ancf multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square mile or 3.5 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and 'vegetative cover. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, I year- 10 Winter, I year- 5 Summer, 2 year- 20 Winter, 2 year- 10 Sumner,10 year- (30 Winter,10 year- 50 Summer,25 year -I00 Winter,25 year- 60 Summer,50 year -130 Winter,50 year- 90 Summer, 100 year -170 Winter, 100 year-110 b. Peak flows for given frequencies in cubic feet per second. 2 year- 300 50 year -2800 10 year -1800 100 year -3200 25 year -2500 3.Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a. Total dissolved solids = mg /I 190 160 b. Suspended solids = mg /1 3000 2000 c.Chemical oxygen demand = mg/1 150 100 oC d. Temperature = 24 12 e. pH = 8.0 7.4 f. Bacterial density = (1) Total coliforms = #/100 ntl 50 x loa 50 x 102 (2) Fecal coliforms = #/100 ni 30 x 102 (3) Fecal streptococci_ #/100 ntl IO x 10' 10 102 *Assuming transposition of water quality datafrom Atterbury Waterbury (desert). 4. Possible Water Uses Besicles using the storm runoff produced from Water Source No. 8 as previously recommended for runoff from Water Source No 7, consideration should be given to possibly using this water source for maintaining vegetation within the Santa Cruz Riverpark and for diverting part of this storm runoff to Kennedy Lake.

WATER SOURCE NO. 9 1. Description of the Area a. Overview The watershed of this water source is located near the western city bound - ary of Tucson, Arizona and within the foothills and mountain range of the Tucson Jfountains. General slope of the land is to the cast at about 90 feet per utile with an average elevation of 2550 feet above mean sea Icvcl. The watershed has a defined channel with small rivulets extending over a small region. Surface drainage is rapid from the steep, relatively impermeable hills and moderate runoff occurs from the gentI 'sloping foothills and valley. Slopes range from O to 3 percent in the alluvial valley bottom, to greater than 45 percent on the rock slopes of the foothills. In the lower reaches of the watershed. the channel has a moderate growth of riparian vegetation producing areal spreading of floodwaters. A wide variety of trees, shrubs, grasses and cacti -cover the watershed.

371 Rock outcrop and shallow soils with a clayey horizon or caliche (rlrgi ds) over bedrocks .composes the major portion of soil association in the watershed. The composite soil association and geology in the watershed produces a complex drainage environment, whereby low seasonal and annual runoff volujes are associatéd with long non -runoff periods. However, as the potential rainfall intensity increases over the infiltration capacity, the potential peak flows become exceedingly large. It is obvious that any structural design should account for the skewed frequency distribution of peak flows.

b. Drainage area = 1.1 square mile to Mission Road. c.Watershed composition by land use types. Desert area = 0.8 square miles or 72.7 percent. -Composed of grassland, desert brush and large cacti population. Urban area = 0.1 square miles or 9.1 percent -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.2 square miles or 18.2 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and vegetative cover. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 19 Winter, 1 year- 5 Summer, 2 year- 20 Winter, 2 year -15 Summer,10 year- 30 Winter,10 year -25 Summer, 25 year- 60 Winter, 25 year -40 Summer, 50 year.- 80 Winter, 50 year -60 Summer, 100 year -100 Winter, 100 year -70 b. Peak flows for given frequenciesin cubic feet per second. 2 year- 100 50 year -1200 10 year- 700 100 year -1400 25 year - l000 3.Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg /1 190. 160 b. Suspended solids = mg /1 3000 2000 c.Chemical oxygen demand = mg /1 150 0100 d. Temperature = °C 24 12 e. pH = - 7.9 7.4 f.Bacterial density = (1) Total coliforms = # /100 ml 50 x 104 50 x 102 (2) Fecal Coliforms = # /100 ml 10 x 10" 30 x 102 (3) Fecal streptococci = #1100 ml 10 x 10°' 10 x 102 *Assuming transposition of water quality data from Atterbury Watershed (desert). 4.Possible Water Uses Storm runoff volumes that can he expected on an annual basis from this source are relatively small and, hence, flood control is probably not feasible. WATER SOURCE NO. 10- Extended Cholla Wash 1.Description of the Area a. Overview The watershed of this water source is located near the western boundary of the city limits and within the foothills and mountain range of the Tucson Mountains. General slope of the land is to the east at about 100 feet per mile with an average elevation of 2600 feet above mean sea level. The b.Drainage area = 1.2 square miles to Mission Road. c.Watershed composition by land use types. Desert area = 0.9 square miles or 75.0 percent. -Composed of grassland, desert brush and a large cacti population. Urban area = 0.1 square miles or 8.3 percent. -Composed of single and multi- family unitson land parcels smaller than one acre including roof tops,paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square miles or 8.3 percent. -Composed of single family unjas on landparcels greater than one acre, including rooftops, pavedand non -paved rights -of -way, and vegetative cover. Paved area = 0.1 square miles or 8.4 percent. -Composed of paved surface area, and largeroof areas associ ated with commercial or industrial facilities. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 10 Winter, I year- 5 Summer, 2 year- 20 Winter, 2 year -15 Summer,10 year- 40 Winter,10 year -30 Summer, 25 year- 60 Winter, 25 year -50 Summer, 50 year- 90 Winter, 50 year -70 Summer, 100 year-110 Winter, 100 year -85 b. Peak flows for given frequencies in cubic feet per second. 3. Mean Water Qualities from Watershed .Area* Summer Winter Units Storms Storms a.Total dissolved solids = mg /1 190 160 b.Suspended solids = mg /1 3000 2000 c.Chemical oxygen demand= mg /1 150 100 d.Temperature = °C 25 13 e.ph = - 7.9 7.5 f. Bacterial density = (1) Total coliforms = # /100 ml 50 x 104 50 x 102 (2) Fecal coliforms = #1 100 ml 10 x 104 30 x 102 (3) Fecal streptococci = #1 100 ml 10 x 104 10 x 102 *Assuming transposition of water quality data from Atterbury Watershed (desert). 4. Possible Water Uses Although storm runoff volumes from this source a. e relatively small, consideration should be given to using this water source for irrigating a pros- pective park in the area and possible for maintaining a water -related recreation facility in the park. WATER SOURCE NO. 11 =-Old Julian Wash a.Overview The watershed of Old Julian Wash is located in the central business district of Tucson, Arizona. General slope of the land is to the north- northwest at about 70 feet per mile Nvitlt an average elevation of 2400 feet above the mean sea level. The watershed has a %veil defined channel passing through and collecting runoff from the soil- vegetation surfaces. paved and non - paved streets and building roofs. Storm runoff water from an urbanized area is also drained by the channel. The urban area includes single and multiple family dwellings. several types of roofing materials, paved arid unpaved areas, and lawns. The developed area of the watershed has a primary influence on runoff volumes, flow depths and peak arrival times. Pattern of the streets arrangements %viii affect the drainage performance. A major channel problem in certain reaches is the large quantity of debris clogging the channel, thereby reducing channel capacity and increasing flood hazard in the surrounding urban areas. Overall, the watershed has a composite type of

373 Ala urban water flow pattern which produces a complex storm runoff hydrograph. b. Drainage area = 1.0 square miles to the Santa Cruz River. c.Watershed composition by land use types. Desert area = 0.2 square miles or 20.0 percent. -Composed of grassland, and desert brush. Urban area = 0.6 square miles or 6.0 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of way, and vegetative cover. Paved area = 0.2 square miles or 20.0 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. 2. Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 20 Winter, 1 year- 10 Summer, 2 year- 40 Minter, 2 year- 30 Summer,10 year- 80 Winter,10 year- 70 Summer, 25 year -110 Winter, 25 year -100 Summer, 50 year -160 Winter, 50 year -150 Summer, 100 year -200 Winter, 100 year -180 b. Peak flows for given frequenciesin cubic feet per second. 2 year- 400 50 year -1200 10 yeasr- 800 100 year -1400 25 year -1000 Summer Winter Units Storms Storms a.Total dissolved solids = mg /1 250 220 b. Suspended solids = mg /I 2000 1000 c.Chemical oxygen demand = mg /1 280 130 d. Temperature = °C 27 15 e.ph = - 7.7 7.0 f.Bacterial density = (1) Total coliforms = #/100 ml 15 x 104 10 x 104 (2) Fecal coliforms = # /100 ml 10 x 104 70 x 10' (3) Fecal streptococci = # /100 ml 50 x 10' 30 x 10' *Assuming transposition of water qualitydata from Railroad Watershed (urban). 4. Possible Water Uses Although volumes of storm runoff from this source are relatively small, consideration should be given for possibly using the water for irrigating a landscaped area between the 1 -10 Freeway and the Santa Cruz River. WATER SOURCE NO. 12- Congress Street Storm Sewer 1.Description of the Water Source Congress Street has numerous storm sewers that drain the downtown business district Tucson. The storm drain descriptions, obtained from the City of Tucson Engineering Division, in January, 1976, are as follows: Direction of Structure Type of Entering the Location from Size Structure Santa Cruz River Congress Street 60 inch Reinforced East 1600 feet upstream concrete pipe 8 foot Concrete East 800 feet upstream x 4 foot box culvert 54 inch Reinforced East 500 feet upstream concrete pipe two- Reinforced East Bridge Abutment 42 inch concrete pipe 48 inch Reinforced Nest Bridge Abutment concrete pipe

374 36 inch Reinforced East 800 feet downstream at concrete pipe an Alameda Street Abutment 48 inch Reinforced West 1200 feet downstream concrete pipe 2. Quantities of Water The effective watershed area of the storm sewers in the downtown business district was not readily available and, therefore, volumes and peak flows were not calculated. Presently, refrigeration cooling water quantities ranging from 500 to 1000 gallons per day per high rise building in the downtown area are piped directly into the sewer system. This wastewater could be easily directed into the storm sewer system through a T- connection, a valve and small amount of pipe, and allowed to flow down the River channel. 3. Qualities of Water Water samples, see Table 7, were taken at the following locations: 1) A storm sewer with a flow of less than 0.1 cubic feet per second on the east abutment of the Congress Street Bridge; and, 2) a seepage pipe from the north side of the Desert I nn Motel. The flow from the seepage pipe, which was less than 0.1 cubic feet per second, was probably excess lawn irrigation water. 4. Possible Water Uses Storm runoff from the storm drains would be difficult to control by a reservoir. This water should be allowed to flow downstream and to recharge within the present stream channel. The authors suggest at this point that either a waterway loop between Congress Street and St. Mary's Road be considered or a new park established on the west side of the Santa Cruz River. The vacant land totaling approximately 45 acres cóuld easily be converted into a recreational development. Waters from this source can be used in partially maintaining the prospec- tive development.

Table 7. NVaicr Quality Analyses Cron Two taxations Near Congress Street Budge Cs truing, Santa Cruz River

Congress Street Seetvice Pipe From Chemical C tutiurents units Sarin Sewer 1k-sett !nu pH 7.5 8.1 Elec. Conductivity nimbus /cm 0.98 0.82 Temperature 'C 15.0 14.8 Turbidity mgil S 21

Suspended Solids mg, l . 27 172 Volatile Susp. Solids mg/1 11 16 COI) mgi l 25 21 Ca- mgr I 88 89 Mg mg/I IS I5 Toul H2rdnevs4C.tCO11 mg/1 280 - 281 Na mgi l 154 11C co,t mg/1 U 0 HCOs" nog/1 :139 319 Cr mgr l 42 55 IS utg/1 11 II N11. -N tigli I).t 0.1 Rjelrlahl N tog/1 1.1 0.5 Nd1 Nr iO, -N erg /1 LO 2.5 'total (:dilatons I 1118) tel 1.11x 111 5.2 x SUr Feral (alilisrms // 1181 nil 5.8x10, <1 Feral StIrpuxurri #41013 ml 2.Sx Ills 4.5 x M.

WATER SOURCE `'O. 13- Tucson Arroyo 1.Description of the Area a. Overview The watershed of this water source is located in the central business and residential district of Tucson, Arizona. General slope of the land isto west -northwest at about 50 feet per mile with an average elevation of 2100

375 feet above mean sea level. The ttiatershcd has a well defined channel passing through and collecting runoff from the soil -vegetation surfaces, paved and nopn -paved streets and building roofs. Storm runoff water from the urbanized area is also drained by the channel. The urban area includes single and multiple family dwellings, several types of roofing materials, paved and unpaved areas and lawns. The developed area of the watershed has a primary influence on runoff volumes, flow depths and peak arrival times, whereas the grassy portion of Randolph Park has a moderating affect on the runoff hydrographs. A major structural asset of the watershed is the uniform concrete -lined channel which permits a larger potential channel flow and a descreasing flood hazard in the surrounding urban areas. The flood water is discharged into the Santa Cruz River through a three span -12 feet by 12 feet concrete box culvert. Overall, the watershed has a fairly uniform, urban water flow pattern which produces uniform storm runoff hydrographs. Pattern of the streets arrangements will affect the drainage performance. b. Drainage area = 10.0 square miles to Interstate 1 -10. c.Watershed composition by land use types. Desert area = 0.1 square miles or 1.0 percent. -Composed of grassland, desert brush, cacti and low vegeta live cover. Urban area = 6.7 square miles or 67.0 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. The University of Arizona campus is included in this area. Suburban area = 0.2 square miles or 2.0 percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of- way, and vegetative cover. Paved area = 1.8 square miles or 18.0 percent. -Composed of paved surfaces and large roof arcas associated with commercial or industrial facilities. Denuded, or bare area = 0.2 square miles or 2.0 percent. -Composed of low- density, vegetative cover and bare soil. Parks, grassed areas = 1.0 square miles or 10.0 percent. 2. Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, 1 year- 130 Winter, 1 year-80 Summer, 2 year- 350 Winter, 2 year- 310 Summer,10 year- 770 Winter,10 year- 730 Summer, 25 year -1070 Winter, 25 year - 920 Summer, 50 year -1480 Winter, 50 year -1250 Summer. 100 ycar -1830 NVinter, 100 year -1550 h. Peak flows for given frequenciesin cubic feet per second. 2 year-1100 50 year -460( 10 year -2200 100 year -6000 25 year -30Q0 3.\lean Water Qualities from VatershctlArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg/1 250 220 b. Suspended solids = mg /1 1500 700 c.Chemical oxygen demand = rig /1 28O 130 d. Temperature = °C 27 15 e.pll _ 8 7.7 7.0 f.Bacterial density = (I) Total conforms = #1100 ml 15 x 10' 10 x' (2) Fecal conforms = # /100 inl 10 x 10' 70 x 10' (3) Fecal streptococci = #/100 ml 50 x 10' 30 x 10'

376 *Assuming transposition of .water quality data from Railroad Watershed (urban). 4. Possible Water Uses The volume of storm runoff from this water source is adequate for maintaining a waterway loop in the immediate area. We suggest that the loop could be constructed on the west side of the Santa Cruz River between Congress Street and St. Mary's Road. An open or covered storage basin should be constructed within the immediate area. A covered storage basin would also provide a location for tennis courts or a miniature putting course. Light business could be developed around the waterway. If the waterway loop is not constructed, the vacant land adjacent to the west side of the Santa Cruz River and south of St. Mary's Road could be developed as a park. Park vegetation could be maintained by storm runoff from this Water Source. The proposed waterway loop with dimensions of 40 feet x 6 feet x 3000 feet would only require about 16.5 acre feet of water to till. Ample storm runoff with storage can provide sufficient flow even during the years of lowest rainfall to maintain the waterway loop. WATER SOURCE NO. 14 -St. Mary's Road Storm Sewer 1. Description of the Water Source St. Mary's Road has a storm sewer that drains the western downtown business district of Tucson and nearby residential area. The storm drain descriptions obtained from the City of Tucson Engineering Division in January, 1976, are as follows: Type of Direction of Structure Location from Size Structure Entering the Santa Cruz RiverSt. Mary's Road 21 inch Reinforced West Downstream of concrete pipe bridge abutment 2. Quantities of Water The effective watershed area of the storm water system in the western downtown business district was not readily available and, therefore, volumes and peak flows were not calculated. Presently, refrigeration cooling water quantities ranging from approximately 100 to 200 gallons per day per large commercial building in the western business district are piped directly into the sewer system. This wastewater could be easily directed into the storm sewer system through a simple pipe adaptation. 3. Qualities of Water The chemical quality of storm runoff from the western downtown area has not been sampled. 4. Possible Water Uses Water from the storm drains would be difficult to control and should be allowed to flow and recharge along the stream channel. In addition, if the proposed waterway loop were developed, these waters would combine with the discharged water from the loop to help maintain a flowing channel for an unknown distance downstream. WATER SOURCE NO. 15- Speedway Boulevard Storm Sewer 1. Description of the Water Source Speedway Boulevard has a drainage channel and numerous storm sewers that drain the surrounding residential and coninercial area. The drainage channel and storm drain descriptions, obtained from the City of Tucson Engineering Division in January, 1976, are as follows: Direction of Structure Type of Entering the Location from Size Structure Santa Cruz River Speedway Boulevard 2 spanConcrete box East 1200 feet upstream 6 foot x culvert (Drainage channel from a 3 foot small residential area) 36 inchCorrugated East 500 feet upstream metal pipe

377 36 inchReinforced \Vest 30 feet upstream concrete pipe 36 inchCorrugated East 30 feet upstream metal pipe 36 inchCorrugated East 200 feet downstream metal pipe 2. Quantities of Water The effective watershed area of the storm tvater system. was not readily available and, there tine, volumes and peak (lows were not calculated. 3. Qualities of \Water -I ale chemical quality of storm water from this area has not been sampled. 4. Possible Water Uses Water from the storm drains would be difficult to control and should be allowed to flow and recharge along the stream channel. In addition, if the proposed walerw:lc ¡001) were developed, these "'tern would combine with the discharged % yater from the loop to help maintain a flowing channel for an unkmxynclist:nire downstream. \VATER SOURCE No. 16- Extended Silvereroft Wash 1.Description of the Area a. Overview The watershed of Extended Silyercroft Wash is located near the northwestern boundary o } -the city limits. and within the foothills and mountain range of the Tucson \}oumains. This watershed is composed of two sub - syateI,hCCls named Silvercroft Dash, 2.8 square miles. and Rifle Range Wash, (l.it square miles. General slope of the land is to the cast -northeast at about 100 feet per mile with an average elevation of 2400 feet above mean sea level. The watershed lias two defined channels with small rivulets extending over a small region. Surface drainage is fairly rapid from the steep, relatively impermeable hills, and moderate runoff occurs front the gently sloping foothills and valley. Slopes range from 0 to 3 percent in the alluvial bottom, to greater than 45 percent on the rock slopes or the foothills. In the middle reach of' the watershed, Pinta Community College and associated payed surfaces are drained by both ephemeral channels. In the lower reaches of the watershed, the channel has a moderate growth of riparian vegetation producing an areal spreading of floodwaters. A title variety of trees, shrubs. grasses, and cacti cover the watershed. Rock outcrops and shallow soils with a clayey horizon or caliche (.-tr;idc) over bedrock composes the -major portion of soil association in the watershed. The minor soil classification of the watershed is tìntisoit, primarily Fluvruts. Fitments are related to water transport of soil materials and exhibit no natural distinctive horizon or layers, except that their sub - surface usually exhibit stratifications of differently texture(} materials. The composite soil associations and geology in the watershed produces a complex drainage environment, whereby, low seasonal and annual runoff volumes are associated with long non-runoff periods. However, the small developed portion of the watershed has a considerable influence on the runoff volumes, flow- rates, and peak arrival tittles. As the potential rainfall intensity increases over the infiltration capacity, the potential peak flows become greater than peak flows front some urban watersheds, even though the Ilu%ent soils have greater infiltration rapacity than some of the other soil associations, which may reduce somewhat the summer storm peak flows. Itis obvious that any structural design should account for the skewed frequency distribution of peak flows. b. Drainage area = 3.3 square miles to just below West Speedway Boulevard Bridge crossing and the Silvercroft Wash Diversion Channel. c.Watershed composition by land use types. Desert area = 2. 7 square miles or $1.8 percent. -Composed of grassland, desert brush and cacti population. Urban area = 0.3 square miles or 0.1 percent.

378 -Composed of single and multi-family units on land parcels smaller than one acre including rooftops, paved and non - paved rights- of -w:ty, and vegetative cover. Suburban area _ O.1 square utile or 3.O percent. -Composed of single family units on land parcels greater than one acre, including rooftops, paved and non -paved rights -of -way, and vegetative cove-. _paved area = 0.2 square miles or 6.1 percent. -Composed of pared surface area, and large roof areas associated with cuttnercial or industrial facilities. 2. Quantities of \Water a.Water volumes for given frequencies in acre -feet. Sumniet, i ye :tr- 20 winter, I year- 10 Summer,er, 2 rear- 40 Winter, 2 year - 30 Summer,10 year -I00 Winter,10 year- 90 Summer, 25 year -160 \Winter,25 year -120 Sutnnter. 50 year -210 \Winter,50 'year-160 Summer, 100 year --270 winter. 100 year -2OO lt.Peak flows for given frequenciesin cubic feet per second. 2 year - 300 50 year -2900 I O year -ISOt) 100 yer -3300 25 scar -2600

3.\lean Water Qualities from WatershedArea* Summer Winter Units Storms Storms

a. Total dissolved solids = mg/1 180 150 b. Suspended solids = mg /1 3500 2000 c.Chemical oxygen demand = tag /1 200 125 d. Temperature = oC 25 13 e.lilt= 7.9 7.5 f.Bacterial density (1) Total conforms = #/100 nit 50 x 10' 70 x 102 (2) Fecal conforms = #1100 nil 20 x 10' 40 x 102 (3) Fecal streptococci = #1100 nil 15 x 10' 10 x 103 *.Assuming transposition of water quality data from .Atterbury Watershed (desert). 4. Possible \Water Uses Water from this source and Water Source No. 17 can be used for maintain - ing the West Side Park and about a three -acre recreational lake in the park. In years of excess water, beyond the \rater needed for maintenance of the lake and park, the storm runoff can be used as a supplemental supply for irrigation of the El Rio Golf Course, or maintenance of promising greenbelt areas along Silyercroft Wash between Grant Road and the confluence of the Silver-croft Wash Channel with the Santa Cruz River. WATER SOURCE NO. 17- Extended Anklani Wash I.Description of the Area a. Overview The watershed of Extended :\nklaui Wash is located near the northwestern boundary of the city limits and within the foothills and mountain range of the Tucson Nlountains. General slope of the land isto the north- northeast at about 120 feet per mile with an average elevation of 260( ft above the mean sea level. The tratershetl has a defined channel with small rivulets extending over a small region. Surf ice drainage is rapid from the steep. relatively impermeable hills. and moderate runoff occurs from the gently sloping foothills anti valley. Slopes range from O to 3 percent in the alluvial valley bottom, to greater than 45 percent on the rock slopes of the foothills. In the lower reaches of the watershed, the channel has a heavy growth of riparian vegetation producing an .n-eal spreading of floodwaters.. \tide variety of trees. shrubs, grasses, and cacti cover the watershed.

379 Rock outcrops and shallow soils with a clayey horizon or caliche (Argils) over bedrock composes the major portion of the soil association in the watershed. The composite soil association and geology in the watershed produces a complex drainage environment, whereby, low seasonal and annual runoff volumes are associated with long non -runoff periods. How- ever, as the potential rainfall intensity increases over tlic infiltration capacity, the potential peak flows become exceedingly large. itis obvious that any structural design should account for the skewed frequency distribution of peak flows. b. drainage area = 2.9 square miles to Silverbell Road. c.Watershed composition by land use types. Desert area = 2.7 square miles of 93.1 percent. -Composed of grassland, desert brush and a large cacti population. Suburban area = 0.1 square miles or 3.4 percent. -Composed of single family unhs on land parcels greater than one acre, including rooftops, paved and non -paved rights -of- way, and vegetative cover. Paved area = 0.1 square miles or 3.5 percent. -Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. 2. Quantities of 1Vater a.Water volumes for given frequencies in acre -feet. Summer, 1 year- 10 Winter, 1 year- 5 Sumner, 2 year- 20 Winter, 2 year- 15 Summer,10 year- 60 Winter,10 rear- 50 Summer, 25 year -100 Winter,25 year- 6U Sumner, 50 year -1-10 Winter, 50 year 9U Sumpter, 100 year -170 Winter, IOU year -i20 b. Peak flows for given frequenciesin cubic feet per second. 2 year- 200 50 year-4000 10 year -2300 I UI) year- 48(10 25 year -3500 3.Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg/1 180 150 b. Suspended solids = mg /I 3500 2000 c.Chemical oxygen demand = mg /1 200 125 d. Temperature = °C 25 13 e. pH= - 7.9 7.5 f.Bacterial density = (1) Total coliforms = # /100 ml 50 x 104 î0x 102 (2) Fecal coliforms = # 1100 oil 15 x 104 40 x 10" (3) Fecal streptococci = #1100 ml 15 x 104 10 x 10' *Assuming transposition of water quality data from Atterbury Water- shed (desert). 4. Possible Water Uses See description of possible water uses for this water sourcein the written narrative for Water Source No. 16.

WATER SOURCE NO. iS- University I- !eights Wash

1. Description of the Area a.Overview The watershed of University Heights Wash is located in the north-central portion of the City of Tucson, Arizona. General slope of the landis to the west at about 50 feet per mile with an average elevation of 24(10 feet above mean sea level. "Flic watershed has a well defined channel passing through and collecting runoff from the soil -vegetation surfaces, pavedand non - payed streets and building roufs. Storm runoff water froman urbanized

380 area is also drained by the channel. The urban area includes single and multiple family dwellings, several types of roofing materials, payed and unpaved -areas, and lawns. The developed area of the watershed has a major influence on runoff volumes, flow rates and peak arrival time. Pattern of the street arrangements will also affect the drainage performance. A major channel problem in certain reaches of the channel is the vegetation and debris clogging the channel bottom, thereby reducing channel capacity and increasing flood hazard in the surrounding urban areas. Overall, the watershed has a uniform urban drainage pattern which produces a simplified storm runoff h'drograpli. b. Drainage area = 1.1 square miles to Interstate I -10 c.Watershed composition by land use types. Desert area = O. I.square miles or 9.1 percent. -Composed of grassland, desert brush. cacti and low vegetative cover. Urban area = 0.9 square miles or 51.8 percent. -Composed of single and multi -family units on lanci parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Paved area = 0.1 square miles or 9.1 percent. -Coniposecl of payed surface area, and large roof areas associated with commercial or industrial facilities. 2Quantities of Water a. Water volumes for given frequencies in acre -feet. Summer, 1 year - 25 Winter, 1 year- 15 Summer, 2 year- 50 Winter, 2 year - 40 Summer,10 year -l00 Winter,10 year- 90 Summer,25 year -130 Winter,25 year -I20 Summer,50 year -180 Winter,50 year-170 Sumner, 100 year -230 Winter, I00 year -200 b. Peak flows for given frequenciesin cubic feet per second. 2 year- 500 50 year -1000 I O year - I I50 I00 year-1800 25 year -1400 3.\lean Water Qualities from WatershedArea* Sumpter Winter Units Storms Storms a. Total dissolved solids = mg/ I 200 190 b. Suspended solids = mg/ I 800 500 c.Chemical oxygen demand = mg /1 300 150 d. Temperature = °C 28 115 e. pH = - 7.3 6.9 f.Bacterial density = (1) Total conforms = #1100 ml 15 x 10' 12 x 104 (2)Fecal conforms = #11(1(1 ml I O x104 40 x IO' (3) Fecal streptococci = # /100 ml 60 x 103 35 x 10' *Assuming transposition of %vatcr quality data from High School Water- shed (urban). 4.Possible Water Uses This urban storm runoff could maintain a greenbelt area between In- terstate I -10 and the Santa Cruz. River. The storm runoff with appropriate storage facilities can supply irrigation water for vegetation maintenance consistently throughout the calendar year.

\\'.V1 ER SOURCE NO. 19 -Grant Road Storm Sewer 1.Description of the Water Source Grant Road has two storm sewers that drain the surrounding urbanized and commercial areas. The storm drain descriptions, obtained front the City of Tucson Engineering Division in January, I.176, are as follows:

381 Direction of Structure Entering the Location from Size Structure Santa Cruz River Grant Road 24 inch Reinforced East Upstream of concrete pipe bridge abutment 42 inch Tidal gate- East Downstream of reinforced bridge abutment concrete pipe 2. Quantities of Water The effective watershed of the storm water system in the urban area was not readily available, and, therefore, volumes and peak flows were not calculated. 3. Qualities of Water The chemical quality of storm water from the surrounding urbanized area has not been sampled. 4. Possible Water Uses See description of possible water uses for this water source in the written narrative for Water Source No. 20. WATER SOURCE NO. 20- Tucson Gas and Electric Company Plant at Grant Road (De \toss -Petrie Plant) .1.Description of the Water Source Blowdown effluent from the power plant cooling towers is discharged into an open ditch which crosses Interstate l -l0 via' a two -barrel culvert. Storm runoff water from a portion of the nearby urban- industrial area also discharges into the Tucson Gas and Electric Company ditch. The major portion of the industrial flow is intercepted by a diversion structure and transported through an 8 -inch asbestos -cement line to the Water Resources Research Center (\VRRC) Field Laboratory for artificial recharge studies. The remainder of the blowdown effluent flows into the Santa Cruz River by an open ditch. 2. Quantities of Water The industrial discharge is continuous, but flow rates vary with operational requirements of the plant. Discharge varies from 100 -200 gallons per minute with an estimated annual flow of about 250 acre -feet. No data available on the amount of storm runoff from the nearby industrial -urban area. 3. Qualities of \ Vater A complete chemical analysis of industrial discharge from the DeMoss- Penie Plant is given on Table 8. Values of pH, electrical conductivity, total dissolved solids, and chloride in effluent samples taken on various dates in 1973, 1974 and 1975' are reported in Table 9. River samples arc occasionally obtained near the WRRC Field Laboratory to determine chemical quality of storm runoff water. These samples and corresponding duality, represent a composite of water from upstream discharge points. Two representative analyses are reported on Table 10.

TaI,Ird. rhrnn.alt:har:crrrIt/ (:iug ltatrr F:lnurm (tem. due De\I,r..-Pruic 1'1,m S.mld4d.t Me 1t,1rr Rrvm,.a Hc.r.rtbtì,ncr 11,d,1m¢ I'nud.n,JrptruJxr.1, Cr7.1!1t',l..m,rtal. 11171.0. rh(/mal (,m.,Ì11,41,,% buio Hrpr wm.u.41',,mniunutrn.t'.lut, !mat Ih....I.r,1 x.,li.l. mg, 1 2:I5 1..14tIttlai(:m1.111411.,t.' "n" h.,t1,, 14 (..Li, n 1,,e:1 I!x 11a¢ur..um mg 1 a1 ....Mom mg, 1 'INI t:hhn Ilk- mp.1 :1a_

1..11..r ur'1 5 (:.nI., ,.Ir A, 1 ''tl 111a.t 1., ,.te ,nH,1 1:1 Hom ulr n,r.i

.\it,.lr . i.`+ 1)11 - t;,a N,nr- i hr rl!lucu, .I ihn lin,r .... .t r.,! ti.n1hr I'!.m1 am1 t,..1n4 ...utr u.r.l 1,r .l' S. n1,rr.0 1 Hn 1.numm u..ml.0 mt-, [war! r ti..,,, .

382 Table 9. Chemical Character nl Gaoling Warr H fluent Irian the De Moss-Petrie Plain Sampled at the Kater Resources Kesse/ h Critter 110111ing l'..nd pp Various D.os l Wilson. a :d. 1976).

Electrical Total Dissolved (7omlut[kits Salid. (1111.11C Date p)I ,,unuwun) ong /l) 1 mg' 1) 212773 6.58 2.93 2022 400 75;73 6.83 330 2415 463 719/73 980 3 98 2530 4911 8/11973 6.88 3.43 2397 4911 II/3773 6.93 2.49 1718 313 11.29973 9.90 3.14 2101 4414 12/7172 6.84 3.59 2177 469 1/28/74 9.95 3310 2759 510 51.98/14 9.88 3.189 2546 436 7i 16.'74 7.04 3.20 2208 440 8/6/74 7.01 3.311 2277 4214 WI 1/74 7.411 3.51 2422 441 !918774 7..52 3.30 2277 4111 9126/74 7.99 2_-12 1670 295 1.2174 7.73 410 2790 039 0104 7.30 2.91 20114 399 2,'11974 7.82 3.2)1 22014 404 2,18'74 737 I.70 117'. 301 2'23/74 7.99 2.15 1483 3311 7.57 2.78 I918 375 ,9;75 7.74 3)í14 2071) 405 72'975 7.7it 3 D 2139 4112 /31/73 7.31 2.511 1725 3113 2'20.'75 7.62 2.61 I8'28 397 3/17/75 7.75 2.31 1921 319 3/2475 6.81 2.98 1819 399 Notr: Thr rIllurnt:mh,-.e tia8. ...is at nulls .t .l n..Ue, Dom hMint :nUl tooling w:urr used lor HUI Vat. 01 His I.in.atn.0 u misfit. .ner in.."r t1.1.1111,

'I..hle f0. Krpr rs, m:uis-e l:henti..il :\11.11..,....1 Smtn. Kn....11 IIno. the S.1111.11(:10/ Kiser nn "(wo tetrad tt'i1w,.,. et al. 9,104).

Dates Chemisai Constituents Cnl1: 2;12/69 8:14.98 Total Dissolved S..IiAs mg,I 397 hi'I Hi, u Couduclistts nnni,nvc m 0.45 11.22 C:,kiu u1g/1 51 ?lagnesiunt mg,1 Stadium mg'1 94 17 CLlnride iog7I 52 12 Soltate mg/ I 91 :.6 l :,rlw.nate u.g1 II 0 Rita i 1.0ute mg, 1 131 45 Nitrate mg%I U 1.3 prl fi.8 7.1

4. Possible Water Uses The volume of industrial water and storm runoff from Water Source No. 20 are adequate and continuous enough to maintain a one -half utile greenbelt area and a landscaped lake between Interstate I -10 and the Santa Cruz. River. Such an area would provide an excellent demonstration of the use of cooling iyater and storni runoff for landscape irrigation. Surplus water could be used for artificial ground-water recharge either on the greenbelt area or at the nearby WRTRC Field Laboratory. Incidentally, guidelines for the design and manageaient of the greenbelt recharge facilities could he based on the results of more than 10 year of experimentation at the Field Laboratory (Wilson, 1971a, 1971 h, and 1976). )PATER SOURCE NO. 21- Treated Sewage Effluent on the Southern and Eastern Irrigated Fields, City of Tuc- son Farm 1. Description of the )Water Source and Area of Use "Treated sewage effluent can be delivered to the head of the southern and eastern fields, 2.10 acres, Of the City of "Tucson Farms by an 15 -inch pipeline. The principal crops grown are wheat and maize. 2. Quantities of Water The line can deliver effluent at a maximum flow rate of approximately six cubic feet per second at this point. 3. Qualities of )Pater The duality Of the treated sewage effluent with regard to chemical constituents stakes the effluent ideal for use in landscape irrigation. Chemical quality of sewage effluent data from the City of Tucson Wastewater Treatment Plant are shown in Table II.

383 4. Possible \\'titer Uses The present pipeline could, of course, continue to irrigate land from this point down gradient to the City of Tucson Wastewater Treatment Plant. Since treated sewage effluent is not the limiting factor, a new enlarged pipeline can be extended to the south and effluent can be used for irrigating lands on both sides of the Santa Cruz River. With extension of the enlarged pipeline to the south, treated sewage effluent can he used con - junctively with storm runoff for irrigation of the El Rio Golf Course, the \\'est Side Park, and possibly the proposed golf course and park development along the River near the center of the City. Further, greenbelt areas designed for nutrient removal from sewage effluent can be constructed in selected locations along the Santa Cruz River. WATER SOURCE NO. 22- Extended Flowing Wells Wash 1.Description of the Area a.Overview The watershed of Extended Flowing \\-ells Wash is located in the north - central portion of the City of Tucson. General slope of the land is to the west -northwest at about 25 feet per mile with an average elevation of 2350 feet above mean sea level. The watershed has a well defined channel passing through and collecting runoff from the soil -vegetation surfaces, paved and non -paned streets and building roofs. Storm runoff water from an urbanized area is also drained by the channel. The urban area includes single and multiple family dwellings, several types of roofing materials, paved and unpaved areas, and lawns. The developed area of the watershed has a primary influence on runoff volumes, flow rates, and peak arrival time, whereas the grassy area of the cemetery has a moderating influence on the runoff hydrograph. Pattern of the streets trill affect the drainage performance. A major structural asset of the watershed is the uniform concrete -lined channel which permits larger potential channel flows and decreasing flood hazards in the surrounding urban areas. Overall, the watershed has a fairly uniform type of urban water flow pattern which produces a uniform storm runoff hydrograph. b. Drainage area = 4.2 square miles to Interstate I -10. c.Watershed composition by land use types. Desert area = 0.2 square miles or 4.8 percent. -Composed of grassland, desert brush, cacti and low vegetative cover. Urban area = 3.0 square miles or 71.4 percent. -Composed of single and multi -family units on land parcels smaller than one acre including rooftops, paved and non - paved rights -of -way, and vegetative cover. Suburban area = 0.1 square miles or 2.4 percent. -Composed of single fancily units on land parcels greater than one acre. including rooftops, paved and nun -paved rights -of- way, and vegetative cover. Paved area = 0.5 square miles or 11.9 percent. Composed of paved surface area, and large roof areas associated with commercial or industrial facilities. Parks or grassed areas = 0.4 square miles or 9.5 percent. -Composed of high density vegetative cover with essentially no exposed soil areas.

2.Quantities of Water a.Water volumes for given frequencies in acre -feet. Summer, I year- 60 Winter. 1 year- 50 Summer, 2 year-170 Winter, 2 year -160 Summer,10 year -3.10 Winter,10 year -3311 Summer,25 year -470 Winter,25 year -450 Summer,50 year -650 Winter.50 year -630 Summer. 100 year -790 Winter, 100 year -740 b. Peak flows for given frequencies in cubic feet per second.

384 2 year- 950 50 year -2600 IO year -1850 100 year -3100 25 year -2300 3.Mean Water Qualities from WatershedArea* Summer Winter Units Storms Storms a.Total dissolved solids = mg/ 1 200 190 b. Suspended solids = mg /1 800 500 c.Chemical oxygen demand = mg/1 300 150 d. Temperature = °C 28 16 e. pH = 7.3 7.0 f.Bacterial density = (1) Total coliforms = # /100inl 15x104 12x104 (2) Fecal coliforms = #/100 ml 10 x 104 40 x 103 (3) Fecal streptococci = #/100 ml 60 x 10' 35 x 10' *Assuming transposition of waterquality data frone High School Water- shed (urban). 4. Possible 4Vater Uses Storm runoff from this source warrants consideratiòn for use in the proposed City park and golf course development in this area. Because of the characteristics of the storm runoff, storage and treatment., either grass and /or grass -soil filtration and chlorination would be needed. %VATER SOURCE NO. 23- Treated Sewage Effluent on Western Irrigated Field, City of Tucson Farm

Table 1 I. Lualfts III a Compo nite Sample ol'Treated Sewage !.(Ilucnt at City o('1'ur.s.tt Wastewater Ti l'lam (:\II s a.a uulli4r:111s par lilt r exrgd pf I)

Chemical Tussoit ('.uL,.ite Constituents fir wage Elllurnt Total Dissolved Stalas Calf inns Magna-sun" S,,,lto Chloride Sulfate lit ait),.nalt (:ofd,ute !'lottar la' N \os -S NÇh-N N l'.Totalal l'at.u.uuu saha Iron cou pli

'9 ...lignite weighted ef fluent sample nuns; asrra4e 1.1111 anrh.tr 4n It urn 1971-72.1/at., pula,sled hr Ike I l'171f. Separatgm.l sodium atta y.rass,um was mude I: um samples taken b. the lFUer I(e..uvras Ra.earah Center.

385 4. Possible Water Uses The present pipeline could continue to irrigate land from this point to the north. Since treated sewage effluent is not the limiting factor, a new, enlarged pipeline can he used for irrigating lands on the western side of the Santa Cruz River. Further, a demonstration greenbelt area for nutrient removal from sewage effluent by grasses can be developed along the Santa Cruz River. WATER SOURCE NO. 24 -City of Tucson Wastewater Treatment Plant 1.Description of the Water Source and Area of Use The city -county sewage collection system carries most of the composite domestic -industrial sewage load of greater Tucson to the City treatment plant. The City of Tucson Wastewater Treatment Facility is composed of three treatment plants summarized as follows: Plant 1is a 12 million gallons per day (45,500 cubic meters per clay or 18.6 cubic feet per second) standard activated sludge plant with tapered aeration; Plant 2 is a.12 million gallon per day high -rate trickling filter plant: and Plant 3 is a 12.9 million gallon per day (48,900 cubic meters per day or 20.0 cubic feet per second) activated sludge plant with step aeration. Ilot%'evcr, Plant 3is presently being operated as a conventional activated- sludge plant. 2. Quantities of Water Two 36 -inch pipelines discharge sewage effluent into the Santa Cruz River. The average daily flow is 50 cubic feet per second with sinusoidal variations of 28 cubic feet per second at low flow and 70 cubic feet per second at high flow. Average effluent discharges from the three treatment facilities are shown in Table 12.

Tattle 12. Ayer.,ge St, agr F711urm Dí. kit-gm h,no Mains L Y Anti :I. Ott nl l'ucwm l5aarwvter rreaunem l'I:un, 1971.1773.

1'ra,lt t0, h. Avr,agr 51unthl\ IN.. hat g,. Ayr, age Dain Inst hargn as rr1 n"t Bllr-Irrt att r.lrr

Plant 1 I.21 x 101 1.111 s IIN :1.31 s III' Ihaut! 0.10 S t11' 11.75x IIN 2.17 x l0' Plant 3 1.321 s 1111 1.10s1'P 3.77x III' "1-ut:a 3.19x IU 2.71 x 10, 9.55 x 10.

Dye (1975).

3. Qualities of \ Vater The quality of treated sewage effluent makes it ideal with regard to chemical constituents for use in landscape irrigation. Water quality of sewage influent and effluent data from the City of Tucson Wastewater Treatment Plant are shown in Table 13. Extensive studies regarding biophysico- chemical transformations of sewage effluent as it flows down the Santa Cruz River are also available from theses by Sebenik (1975a, 1975b), University of Arizona. 4. Possible Water Uses The volumes of treated sewage effluent from the Tucson Wastewater Treatment Plant are such that, the amount of water is probably not the limiting factor. Possible water uses are discussed in the previous sections. However, sewage effluent uses should be restrictive, if the biochemical quality effects of effluent to the environment are unknown. WATER SOURCE NO. 25-City of Tucson. El Camino l)el Cerro I Inkling Pond 1.Description of the Water Source and Area of Use Treated sewage effluent is stored in a 42 -acre holding pond from which effluent discharges can be regulated. A portion of the flows from flail 3 of the City of Tucson \Wastetoater Treatment Plant is diverted down a concrete lined ditch into the pond. Eutrophie nutrients such as nitrogen :nul phosphorus are constantly being added to the pond water. 2. Quantities of Water "l'he pond contains approximately 380 acre -feet of sewage effluent and the effluent overflow is released to the Santa Cruz River through a concrete drop -inlet structure and culvert.

386 3. Qualities of Water The quality of treated sewage effluent in the pond is summarized in Table 14. 4. Possible Water Uses The pond, of course, provides storage for treated sewage effluent for any of the possible uses discussed for the effluent in the previous sections. Under proper wastewater management techniques, the Camino del Cerro Holding Pond provides a tertiary treatment to the effluent by removing nitrogen in the form of ammonia (NH3) through the utilization of the photosynthetic action of algae. Pennington (1970) suggests that rock -lined shallow basins with a depth of two feet and gentle side slopes would pro - vide best design for ammonia nitrogen removal. Basins could be baffled so that detention times of one day could he attained with maximum ammonia removals of greater than 60 percent.

(-able 13. Quality of Influent and Ffflornt Sewage Flows at .M.00 nl tin wn R'astewater Treatment flaut. 1974- 1975.

Wastewater El Ilurtn

Chrnlwal Gnoliulenss LJlurnt l'I.un 1 Plain 2 19..n1't -totallhvsohnlS,hds.Fvalwuansn(111í'C) 920 6411 689 6541 Susprndsd Solids 249 2 34 :ui Dissolved Solids 1171 liIa 613 17:1) fixed krstlut 1110 467 301 469 tbl.mteReaulue 310 173 11gt 187 Total Alkalinity 1C=tCbrl 294 294 28I 2 ' lialAtidhsll:.l(:0d 23 19 IR :'ll 911 7.6 7.6 7.7 7.6 801) 233 36 8:1 2S C:()I) 295 48 98 fiR kll)AS 5.4 11.5 2.4 0.4 Crease 41 li 12 6

N111-N 19.7 17.5 199 18.9 \(),-\ - 0.1 I) 1 0.2 \(),N (L O 11.1 11.1) 0sgsniN 14.8 7.6 9.7 8.2 Total-N 32.5 25.2 29.8 27.3

Silica (S101) 51 40 42 42 Alu,mna,,. 1t I run I A60, 4 Fe:0,) 29 25 23 23 Tot.t fr oat ()aeromal 1).5 0.3 0.3 11.4 Cak ion, 74 74 611 till Magnet 19 111 17 17 li:oollsa s((ìr /('a4 16 16 17 16

Chloride 98 93 92 92 Carbonate 0 0 1) 0 ó,tarbnobate 359 - 346 343 339 Flu nplute.Ord. 21 15 28 18 Sullste 131 155 147 146 Sodium X Potassium (\AffiK') 117 113 IR 116

.All data from .Annual Ripons .,f the t(aterwater Division. \t- ttopo6tan l'Iihti.-a llao..ytt, -,t Agen. t hs t)sr.1975 All Jte mgi lrvtrpt p) In noted. Moils I .uni ate _Ill .u.d sludgy unis..11111 11.101 2 Is (ling filter unit. 6un,:11e.! t out presto.o et f uen . ujhldata.

l'aMr 14.Quah ollTratrd Sew-agr Effluent n H ( Del Cerro 11 Mating l'ood nr.,r Tut w,n..Arinsns

Rrpo 1nt.nrn Average

t.manuru Cos oltalh luo. D,swlvrol)hsgrn fogli ti :1 pl1 - 7K tC.te, Trntprr.lture 'C Iv

Cldornlrs mg' I , ,1 It.. 11V111111.11 t)s, Krn I)r11utd lug- I 111 1,,,..):(Ildlltin ((.,(.+,I mg .1 ":111 (:(111 :ng! 1 I110 \I i,-\' mw I 14. 1) \ I),- \' log. 1 \'l ),. \ ,t,g I 0og.,ow\ n,g I it

-Iin.,l-\ ntg 1 Itata ...00hed is by E. JTI uel4,..). t 11)741. (:henst, (t,,, f la, «o ttanrw.trr 71,-am,ru, PI ou .,ud un(e.bh.hrd 41.11.1 )n l'1:. klw-,1111274) Lta,rr Res... n R.Iear il ):role,. du,ing ....us ...piing 1w ,t+l. 1 1171 t, 117)

387 REFERENCES CITED Arizona Slate Departmentent of Ilralah Senices. Rules and Regulations for Seuugr S,.tr.0 and Treatment Work, :1t Anna State Depart mens ul Health. Phoenix, Arizona. Chapter 2. Article 2. Part 3, August 17, 1962. Arizona Stase Department of Health Services. !Loser Quahn Standards far Surface Rum en drimnt, Arizona State Department of Health. Phoenix. Arizona, Article 6. l'an :June 18. 1968. A unnsa Suse Depanuwms ofI Irahh Srovwes, Ruff. and /trps/anuns fur Rerlasnnl IBs,tn, Arizona State Department of I fralsh, Phoenix. Arizolu. Article 6. Pan -4. 1972. Aulenbach, D. B.. T. P. Glavin and J. A. R. Rojas. "Protracted Recharge of Treated Sewage into Sad, Parr 1- Quality Changes in S'enw al Transport Tbro ogl she Sand." Vol. 11 No. 3, (,.un I Man, Slav -Jane. 1974. Barfield. B. J.. D.I. V. Kau, and E. W. - Follner, "Analysis of the Sediment Filtering Action) of Grassed Slydia; University of Kentucky Water Rnourres Institute. Research Repon No. 90, December. 1973. Buu.er. II., J. C. laine. and SI. S. Riggs. 'l ligh -Rase Lind Treatment II: Water Quality. and F'rmonic Aspens of she Flushing Meadows Project: fwtme/.4 Water PollutmaCuntrd Eet/mutton, Vol. 46, No.5, Stay. 1974. ISM lisant. D. E..Ikplet Ant of Strrandlon lo bdilitamon in the %tam Channels of she Tucson Basin. Southeastern Arizona: U. S. Geol. Sunny %LaterStipplç Paper 1939 -B, 1970. California Stale Water Pollution Itmn!.-Waste \\rater Rn Lunation in Relation to (Atwood Water l'ollwi.n." Puhliaiio No. 0. Beclsley: Sanitary Eng. Research lab.. 1' ni, ersiw of (410ornia, 1953. Daniel. W. H.. -Purr-Wick Rootznne System for Turf," .ltu/ary Turf .Veux and Research, Department of Agromony, Purdue Unitet.ily, Repart No 411, March, 1974. DeCowl, K. J.. -Economic Feasibility of Selectite Adjustments in Use of Salvageable ll'aters in the Tucson Region. Arizom: Ph.D. Dissertation, University of Arizona, 1970. Ihtgan. G. 1_, R. IL F. 1 "using. L. S. lass. P C. Flerss and P. C. S.I oh. land Disioaal sot Wastewater inI lawafi, "fount /mf IPntn I'd/lawn Control Enlnnnun, Vol. 47, No. B. August. 1973. Dye. E. O.. Depan meat of Water and Severs, Wastewater Division. Annual Report 1971 -197'2. City o( 'Fut soon. 1972. lise. E. U., Department of 1Sater and Sewers. ll'astewaier Division. Annual Report 1971 -1975. City of Fur son. 11175. Federal Water Pollution Control Administration, "Belons tap the Committee on Water Quality Co menas,. U. S. Drptn mein of the bsseriur. W.101%111 0011. U. C.. 11644. Greene, G. S. and Associates.' Sluter Plan for the Santa Cruz Linear Park," Proposal Submitted to the City of Tucson, September 2, 1975. Kasper. I). R.. -Organic Qsulisv s,f (doundwater Annual Report No. 12. ( Illise of parer Retoatrh anti lesh,wh,gv Isrnjeit No. .A.1867 -A R12, August i, 1970. Lebow o. G. S., "Soil and Grass Filtration of Dmnntk Sewage tannent for the Removal of Trite Element," Ph.D. Dissertation, L'miytrsitr of Ancona. 1968. Matlock. W. G., P R. Davis and R. L. Roth. -Sewage Effluent Pollution nIa Gr.nutdwaser Aquifer; Annarn Somers of Agnndtura/ Eugrntm, Winter Sleeting. Chicago. Illitwis. December 11.15. 1972.

SIC P. H. and R. B. Krone. "Soil Scande as a Wastewater Treatment System; University of California. Rn Leper. Sanitary Engineering Research Ldnorau,n -. December, 1967. McKee.). E.. and H. W. Wolf. "Water Quality Criteria:' The Resources Agency of C'alifonna, State Water Control Board Publica- tion No. 3 -A, 1963. Urlob. C. T.. and R. C. Butler. "An Intrssigwmu of Sewage Spreading on Five Gdifnrnia Soils; let h. Bulletin No. 12. IER Series 37. Berkeley: Sanitary Engineering Research lab.. University of California, June. 1955. l' g , J. C.. "Amon mica Dissipation During 1'Iwunvns hrsis of .Algae.' Si. S. 'phew. University of Ann na. 11470. Popkin, IS. Y., "Faret of Mixed-Grass Cover and Natice -Soil Filter on Urban Runoff Quality; M.S. Thesis. University of Arizona. 1973. Purges. Rsoul G. J.I lopkits, 'Broad Field Disposal of Beet Sugar 1S'astn; Souvge and hsdutnnd linon, Vol. 27. No. 10. p. 11611 1170. 1955. Searle. S. S.. "The Cet of Grass Filtration Arras for Sewage Purification; Paper presented tu the 12th Annual Conference of Sewage Engineers and Operausrs. 1949. Sebenik. P. C... " Physpachemical Transb,rnsatbnu of Sewage Emu..ut Rrlcssrs in an Ephemeral Stream (3cancel. 51.5. Thesis. Cnivrrsiv ml Arturo, 1975a. Srbenik. P. G.. "Relationships of Dissolved Oxygen and Bitchenical Oxygen Demand in Sewage EDbmni Releases," MS. Thesis, University 14 .s. 19751. Sidle. R. C.. and G. V. Johnson. "Evaluation of a Turfgrass -Suit System to Utilize and Purify Municipal Warne W'ater;' Prweerhnp q'thr A mimes Water Rewurus .loo(ntwn and ehr.natta Amadous of Science, Prescott. Arizona. Vol. 2, 1972.

S . R. and W. F. Garber. "Sewage Reclamation ltv Spreading Basin Infiltration.- Prurorhrtg. Amerman Sonora Cird Elsgtn rn, Vol. 77,September. 1951. U.S. Public Health h Servis r,' l'ubli I pr.dsh Service Dt inking tEanrr Standards," Public I lralth Service Puldi anon. No. 956, 1962. Wilson. L. G.. "Uhservat son on Water Content Changes in Strasilicd Sediment, Dining Pit Res hay gr. -Gonna Meer, 913), pp. 29-40, 1971a. Wilson. L. l:.- "hsntig:oi no on nbe Std,.u1 lase Disposal tap Waste Elliott,. at Inland 5iin,' U. S. Ikparumnm of tarte Interior. Office of Saline Water, Research and Development Progress Report No. 650. 1071h. Wilson, 1_ C.., and G. S. Lehman, "Crass Filtratism of Sewage Effluent for Quality Imps ovnneel Prior to Artificial Recharge. Anerunn S.nns Jappes ultued Ertb arm, Paper No. 6&710. 11406. Wilson, L. G., U. O'Donnell and W. O. Rasmussen. "Feasibility of Modeling the Influences of Po Ret harpe on Groundwater levels ares) Qualit in Alluvial Basins,' C otplctis0 Report. Project No. A- 056 -A RIZ, Water Rem wren Research Center, July. 1976. W'ilon. L G., P. S. ()Absn'« and D. J. Percisus. "Dilution of an Industrial Waste Effluent with Roer Wafer in the Vaduse Region During Pit Recharge." .lnniran Sworn of Ag.wltnral Esgsnrm, Winter Sleeting, Chicago. Illinois. Paper No. 68-727. Dec12. 19t1í.

388