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.-/ ¿¡feTT^/S'/'73 ;:i C^*i' 1 M ENVIRONMENTAL STUDY ■ -4 FOR THE M GILA RIVER M BELOW PAINTED ROCK DAM

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■ :s •J By '4 ■4 University of Arizona

■ it School of Earth Sciences Office of Arid Lands Studies

TD 194.56 .A6 P356 1970 |ii,t i,Bjp j i i | M I .....-rr/M m i1 r . w 1 1 IMI "" t I -"ai ion vtKv A d V

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ENVIRONMENTAL STUDY FOR THE GILA RIVER BELOW PAINTED ROCK DAM

Under Contract with Department of the Army Los Angeles District Corps of Engineers

Contract Number DACW09-70-C-0079

by

University of Arizona School of Earth Sciences Office of Arid Lands Studies

Y ¡11 October 1970

Bureau 01 Ru:!s; nc it! on Derwui, Uolorao10 The Gila River at the Dome Gaging Station. Photograph taken December 23, 1930 by U.S.G.S.

Matched photograph taken June 23, 1970 by Office of Arid Lands Studies. Significant changes include considerably more sur­ face water and heavy salt cedar growth, apparently a result of heavy irrigation runoff and perhaps the close proximity of bed­ rock to the surface. The line of young cottonwoods (center) has disappeared. CONTENTS

«»•«»»••»»•••si« -«-wit* ilij ■_ j o*> ' r ■ .. \ t > . ' P

FRONTISPIECE...... iSi

FIGURES ...... • * i*

TABLES ...... xi ABSTRACT ...... • • • xiii

INTRODUCTION...... 1

Location and Extent ...... 1

Authority ...... 1

Object and Scope of Study ....•••••«••••»••» 1 General Organization and Procedures ...... 2

SURVEY AND INVENTORY ...... 2 Geology, Landforms, and Surficial Deposits ...... 2

Structure, Earthquakes, and Economic Geology ...... 4

Channel Characteristics of the Lower Gila River ...... 4

Characteristics of the Major Tributary Washes...... 5

CLIMATE ...... 8

WATER FEATURES...... 9

Surface Water ...... 9

Irrigation...... »,« 10

Groundwater ...... 11

Hydrology...... 12

VEGETATION...... 13 Important Species ...... 13

v Page

Subunits ...... 16

Plant Communities ...... 17

/ ' Floodplain Plant C o m m u n i t i e s ...... 17

Plant Communities of the Floodplain as ;7-

.Designated for Impact Studies ...... 18

Description of Communities ...... 22

Successional Changes ...... 22

Upland Plant Communities ...... 23

Intermont Plains and Bajadas ...... 25

Sandy Plains and Dunes ...... 25

Malpais Fields and Volcanic Hills ...... 26

Older Volcanics...... 26

Granitic Mountains and Hills ...... 26

Successional Changes ...... 27

ANIMAL LIFE ...... 27

B i r d s ...... 27

Other Animals...... 29

Rare and Endangered Species ...... 30

Insect Population...... 31

ESTHETIC VALUES ...... 31

Contemporary Recreational Use ...... 31

Archaeologic and Historic Sites 32

LAND U S E ...... 33

Land Status ...... 33

Farmlands ...... 34

vi c

INTERRELATIONSHIPS ...... 36

EVALUATION OF ALTERNATE PROPOSALS ...... 38

CONCLUSIONS ...... 45

Impacts of No Program ...... 45

Impacts of Proposed Program ...... 47

Adverse Environmental Effects ...... 49

Alternatives to the Proposed Action ...... 50

Relationships between Long and Short-Term Uses 52

Irreversible and Irretrievable Commitments 53

APPENDICES

A. Individuals and Organizations Contacted * . . 55

B. Scientific and Common Names of Plants .... 57

C. Birds ...... 63

D. Other Animals ...... 67

E. Flood Control Plans ...... 69

F. Alternative Plans, 23 June 1970 ...... 77

6. Selected References ...... 81

H. Project Personnel ...... 89

I. General Organization and Procedures ...... 91

vii LIST OF FIGURES

Page

Frontispiece - Matched photographs of the Gila River at the Dome Gaging Station 1930 and 1970 iii

1. Drainage Àrea for the Gila River below Painted Rock D a m ...... following 2

2. Generalized Geologic Map ...... following 3

3. Histograms of Sediment Sample Size ...... following 4

4. Historic and Prehistoric sites ...... following 32

5. Interrelations in the Ecosystem ...... following 36

6. Map below 5th Street ...... following 41 7. Ponded Area 30th Avenue ...... following 41 8. Ponded Area 39th Avenue ...... following 41 9. Ponded Area 42nd Avenue ...... following 41

lx LIST OF TABLES

Page

1. Summary of Stratigraphy of the Lower Gila River Watershed...... 3

2. Analysis of Soil Samples taken from Watersheds below Painted Rock Dam ...... 6

3. Location of Soil Samples taken from Watersheds below Painted Rock Dam July 24, 1970 ...... 7

4. A Summary of the Soil Conditions as Indicated by the Principal Plant • Communities of the Southwestern Desert (After Shantz and Piemeisel, 1924) ...... 19

5. Acreage of Ecological Types and Communities ...... 20

6. Acreage of Ecological Types by L o c a t i o n ...... 21

7. Historic and Prehistoric Sites ...... 32a

8. Land Ownership Pattern, Yuma C o u n t y ...... 33

9. Farm Size Distribution Based on Irrigable Acres per Water Contract in 1960 ...... 35

10. Acreage of Vegetation under Various Alternatives ...... 40

i

xl ENVIRONMENTAL IMPACT STUDY ON THE GILA RIVER

BELOW PAINTED ROCK DAM c ABSTRACT

An environmental impact study of the proposed U. S. Army Corps of Engineers flood control project, on the Gila River in Arizona down­ stream from Painted Rock Reservoir, was conducted by the University of Arizona School of Earth Sciences. Utilizing consultants from several university departments, a survey and inventory of the following elements were made: geology, landforms, climate, water features including sur­ face water, irrigation and groundwater; vegetation, animal life, land use and esthetics, including recreation and archaeology.

For the purpose of this study three ecological subregions were recognized. These were: (1) farmland, (2) non-cultivated floodplain, and (3) upland.

The geology of the watershed is typically characteristic of the Basin and Range Physiographic Province. Sandy soils are characteristic of several contributing watersheds, resulting in a lack of heavy runoff in the last several decades. Other watersheds contributing considerably less area, have fairly high runoff characteristics.

There has been little use of the area for recreation other than hunting and significant archaeological sites have already been destroyed.

Seven floodplain and 5 upland plant communities were recognized. The most valuable wildlife habitat includes salt cedar/mesquite which provides for excellent dove nesting and cattail marsh which is particu­ larly rare in southern Arizona and provides nesting and food for a dozen or so species of birds and other animals. The bird survey and inventory of 142 species includes 53 species which were not previously listed for the area.

The impact of the authorized plan and several alternatives was evaluated. Although all flood control alternatives provide adequate flood protection, they vary in their detrimental effects on wildlife hab­ itat. If phreatophyte and cattail marsh habitats were maintained outside the proposed levees, the difference between alternatives is of somewhat less concern since almost two thirds of salt cedar/mesquite and over one half of cattail marsh habitat is outside the right-of-way; however, the wildlife habitats are not now preserved by any appropriate federal or state agency. The sale and clearing of several thousand acres of habitat, classified as irrigable lands and withdrawn for the original irrigation project, are planned in the near future.

xiii ENVIRONMENTAL IMPACT STUDY ON THE GILA RIVER BELOW PAINTED ROCK DAM

INTRODUCTION

Location and Extent

The project area under study lies between Texas Hill (river mile 68.5) and the Gila Siphon (river mile 8.4) in the Gila River Basin which in­ cludes most of the southern part of Arizona and a part of southwestern New Mexico. The drainage basin comprises about 58,200 square miles, 5,600 of which are in New Mexico; 51,500 in Arizona and 1,100 in Sonora, Mexico. The Gila River Basin downstream from Painted Rock Dam comprises about 7,300 square miles of which 2,700 square miles are between the dam and Texas Hill. Painted Rock Reservoir is an integral part of the flood control program, but at the time'this report was written, no flood con­ trol was contemplated between Painted Rock Dam and Texas Hill and hence, this evaluation is on alternative flood control proposals for the chan­ nel between Texas Hill and the Gila Siphon but recognizing that upstream flood control by Painted Rock Dam is an essential part of the program.

Authority

This ecological impact evaluation was initiated in compliance with Title I of Public Law 91-190 entitled National Environmental Policy Act of 1969. It was undertaken under Contract No. DACW09-70-C-0079 by the Department of the Army, Los Angeles District, Corps of Engineers, with the Board of Regents on behalf of the University of Arizona entered into the 15th day of May, 1970.

Object and Scope of Study

To relate an inventory of ecological factors to the existing and future environment of the area and to formulate an evaluation of the needs, im­ portance and rarity of the ecological features to man's urban and natural environment. The study was prepared on the basis of presenting an assess­ ment of the impact of no program or of structural and nonstructural alternative plans of improvement upon the environment, with a view to recommending the best plan to satisfy the greatest needs. The environ­ mental study includes a determination of all beneficial and detrimental impacts of the Corps' plans for resource development of the environmental resources of the area. The study was designed to provide data and evalu­ ations of the primary ecological and urban environmental parameters in the project area and affected adjacent areas.

1 The evaluation of impacts is based on predicted floods as outlined in the 1961 survey report wherein the assumption was made that all winter floods of any consequence originated above Painted Rock Dam. The Corps of Army Engineers are presently working on a revised flood frequency analysis for flooding below Painted Rock Dam. They have also revised downward the flood frequency curves on releases from Painted Rock Dam. These revisions were based on new inflow frequency studies. The full extent of the impact of these revised frequencies on the benefit-cost ratio is under study by the Corps and will be included in their design report.

Although the proposed project was authorized only for flood control, the impact on the environment by the proposed facility or alternatives can only be evaluated realistically on the basis of good overall water manage­ ment practices in the area. Water management, with regard to flood control, irrigation, drainage, maintenance of salt balance in the groundwater basin, water for recreation and to sustain wet and dry habitat, and to both quality and quantity of water required to satisfy international obligations, needs to be optimized for the entire area under study.

General Organization and Procedures

Field work included chartered plane flights over the area, followed by more detailed helicopter examinations and ground studies (see Appendix I). Contacts were made with representatives of public and private agencies and with interested and informed individuals. The major contacts are listed in Appendix I.

The data provided by the specialists (listed in Appendix H) were used as a basis for the sections on Survey and Inventory, Evaluations of Alternative Proposals and Conclusions. In the preparation of the last two, an effort was made to express the consensus of the group using differences in back­ ground and experience to provide a broad appraisal of favorable and unfavorable impacts.

-SURVEY AND INVENTORY

Geology, Landforms, and Surficial Deposits

The geology of the watershed of the Lower Gila River is typically characteristic of the Basin and Range Physiographic Province. The region in question consists of three sub-provinces; the dissected block mountains, the intermontane bajadas and alluvial surfaces, and the Gila River flood- plain (Fig. 1).

The Laguna, Gila, Muggins, Copper, and Mohawk Mountains are elongated bedrock ranges trending N. 35° W. They were uplifted by block faulting during the Tertiary, and they consist of Mesozoic granite, gneiss, and other metamorphics. Late Mesozoic elastics overlie the metamorphic basement rocks in the Gila, Laguna, and Muggins Mountains. The moun­ tain ranges are all strongly dissected; the slope angles are about 30°-35° on the average, but greater and lesser slope angles are also present.

2

The intermontane areas outside the m o d e m floodplain of the Gila River are dominated by Tertiary volcanics and terrestrial sediments, and Pleistocene lavas, fans, river terrace deposits, and playa sediments. Local dune sand and wash deposits are also present. Most of the slopes in this area are less than 15° and the area is only locally dissected. Small volcanic cones of late Quaternary age are also present.

The Gila floodplain varies in width from a mile at Texas Hill and two miles at Dome to four to five miles along most of its length in the study area. The floodplain contains the ephemeral and meandering Gila River with a gradient of about three feet per mile. Terraces on either side of the m o d e m floodplain attest to a complex geomorphic history of the Gila River since it became a through-flowing stream in the Pleisto­ cene.

The geological history of the area is summarized in the generalized stratigraphic section (Table 1), and the geologic map (Fig. 2) shows the spatial relationship of the main rock units.

TABLE 1.

Summary of Stratigraphy of the Lower Gila River Watershed

Quaternary - Sandy loamy soil. Alluvial mantle. Stream gravels and sands, floodplain deposits, valley fill, wind deposits.

. 100* Younger alluvial fill. Fine sand and silt. Upper 50 feet fine sediments, lower 50 feet coarse-grained sediments. Basalt-andesite.

. . 300-500' Older alluvial fill. Sand, gravel, silt, clay. Semi-consolidated conglomerate in dissected alluvial fans along mountain flanks. Terrace deposits.

Tert iary-Quat emary Lake beds.

Tertiary 500-1,000' Arkosic sandstones. Boulder conglomerate.

Early Tertiary 1,000' Volcanics: andesite, rhyolite, basalt, tuff and agglomerate.

Cretaceous Boulder conglomerate.

Mesozoic Schists, gneiss, marble, slate, quartzite, granites, pegmatite. Structure, Earthquakes, and Economic Geology • The major structural elements of the region are NW-SE trending faults, the surface traces of which are buried beneath alluvium. Movement along these faults has been recurrent from the Early Tertiary to Recent. Only two major h isto ric a l earthquakes are known for the area. Both may have been the result of movement along one or more of the faults already described. The November 9, 1852 earthquake was apparently centered north of Roll (33° N., 114° W.) and had an intensity of 8-9 on the Modified Mercalli Scale. The January 2, 1935 quake had an epicenter near Wellton and was rated at an intensity of 5-6. Geological deposits of economic value are insignificant in the area. Some placer gold was mined along the Gila until 1949. Sand and gravel is extracted from the floodplain for local use, and a bentonite deposit of unknown value is reported in the floodplain between Roll and Wellton. A thermal spring occurs at Radium Hot Springs with a water temperature of 140°F. Riprap rock material is available in the area, but rock outcrop­ pings from which it can be obtained are rare along the river channel, and the quality may be poor because of poor breaking properties, low density, and the possible content of montmorillonite in the volcanic rocks. Some mineralization in the Mesozoic rocks near Ligurta includes niobium, tanta­ lum, tungsten, and rare earths. None is of economic value. Channel Characteristics of the Lower Gila River - The Gila River below Painted Rock Dam is an aggradational surface. Prior to the construction of the dam, sediment was delivered to the main channel •by winter flows originating upstream of Painted Rock and by local ephem­ eral washes. Since the dam was built, the chief source of sediment has been the local washes. The pre-dam Gila below Painted Rock had a meander­ ing course as indicated by oxbow lakes and meander scars on the floodplain. Since the dam was completed, the channel has become braided and choked with sediments derived from the local washes, a condition which is intensified by the presence of dense phreatophyte growth in and along the channel. Under present conditions, the channel aggrades during summer runoff from local washes, and it tends toward scouring and meandering when the rela­ tively sediment-free waters are released from the Painted Rock Reservoir during the winter months. Eleven of the 26 samples of sediment from the channel of the Gila River were subjected to a mechanical analysis. All samples were separated into - 1, 2, 3, 4, and > 4 phi units () , and six samples were reduced to 0 ’ and 1 phi units. The 11 sample locations are shown on Figure 2 and the histograms are presented in Figure 3. The latter show very little uni­ formity, a relationship that is normal for an aggrading ephemeral river channel. The sand fraction of the samples is composed of sub-round to sub-angular quartz, feldspar, mica, and heavy minerals along with minor amounts of volcanic fragments.

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- f am M A i rS

r-..S

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//AÍÍa n t1 L0PC Upper t h i l l U n d lffer te rra ce lolie be Tertiary ee

rvJV^n ikrtlery * Cr V oleo a l FIGURE 2 I*'.'«'Ml M eeeiole o< Saetee GENERALIZED GEOLOGIC MAP EZ3 OF LOWER GILA RIVER, YUMA gnitTi • c M e i COUNTY, ARIZONA AFTER USGS. ARIZONA BUREAU OF MINES, AND W o wit US. BUREAU OF RECLAMATION. T e rr eoe «11« Kl*< Scot* • Location »f alluvium «e*

*7L>-r fi- H*vJv Conversion Table of Units to mm A mm Class -1 >2.00 pebbles 0 1.00 v.c. sand 1 0 3 0 coarse sand 2 0.25 med.sand

3 0.125 fine sand

4 0.625 v.f. sand

R 0.625 silt â clay -I 0 I 2 3 4 R -10 12 3 4 « -I 0 I 2 3 4 R

-I 0 I 2 3 4 R Figure 3. Histograms of grain sizes of Gila River Alluvium. Phi values along lower- margins. (See fig £ for location.) Characteristics of the Major Tributary Washes

The tributary washes to the Gila River below Painted Rock Dam are ephemeral and discharge both runoff and sediment to the Gila floodplain. The Mohawk, San Cristobal, and Tenmile (Rio Corner) washes drain watersheds south of the Gila, and constitute 3,931 square miles or about 54 percent of the total drainage area of 7,300 square miles downstream from Painted Rock Dam. Other major tributaries are the Kofa, Palomas, Ligurta, Castle Dome, and Coyote washes.

Many of these tributaries such as the Mohawk, Kofa, San Cristobal, and Tenmile (Rio Cornez) have poorly defined channels, and their tributaries disappear into alluvium. Sandy soils are characteristic of these water­ sheds and account for the apparent lack of heavy runoff in the last several decades. Two railroad culverts near the lower end of the San Cristobal Wash have cross-sections that appear to be more than adequate for any flows that have passed through them since their construction. Another railroad culvert built in 1904 on Tenmile (Rio Cornez) Wash has an estimated capacity of something over 10,000 cubic feet per second, but from the appearance of the approach channel and the culvert, it is doubtful whether more than one tenth of this discharge has ever passed through the culvert. These deductions are in accord with the general sandy condition of these watersheds. Other evidence for high infiltra­ tion rates and low surface runoff on the lower San Cristobal Wash exists in the form of numerous rodent holes that have not been destroyed by flood waters or drifting sand.

In contrast to the above, the Coyote and Ligurta Washes drain watersheds with fairly high runoff characteristics, which is explained by soils of higher clay content. Moreover, the secondary tributaries of the Ligurta and Coyote Washes are well integrated and show evidence of efficient run­ off during periods of high precipitation. Their combined areas, however, are considerably less than the tributary watersheds with low runoff char­ acteristics.

A further means of assessing runoff characteristics of the various tributary watersheds are the mechanical and other analyses on soil samples collected from the different watersheds. These are presented in Table 2 and their location and other pertinent comments appear in Table 3. The higher infiltration rates on the Kofa, and San Cristobal samples, and the high sand content of these and the sample from the Rio Cornez support the field observations that these watersheds have high loss rates and low runoff characteristics.

The ESP (exchangeable sodium percent) of the soils tested in the laboratory is also a significant factor in explaining the infiltration- runoff capacities of the watersheds. For example, the soils of the lower Coyote Watershed have lower silt and clay content than the Castle Dome Watershed. On this basis alone, the Coyote Watershed soils would be ex­ pected to have a much higher infiltration rate than the Castle Dome samples. The difference of 0.18 inches per minute (1.04 on the Coyote and 0.86 on Castle Dome 1, Table 2) is explained by the high ESP for Coyote as compared to Castle Dome 1.

5 TAflT.E 2. Analysis of Soil Samples Taken from Watersheds below Painted Rock Dam, July 24, 1970.

Mechanical Analysis Soluble Salts Exchangeable Inf iltrat ion** (percent) in Saturation Sodium rate after Sub Watershed* Sand Silt Clay Extract (ppm) (percent) 20 mins.

Castle Dome 1 21.8 60.2 18.0 5,411 19.6 0.86 Castle Dome 2 47.5 33.7 18.8 9,450 13.0 — Kofa 50.0 42.8 7.2 1,498 1.9 2.75 Palomas 75.2 17.2 7.6 212 1.0 — Ligurta 60.5 19.9 19.6 4,221 5.1 — Coyote 74.7 17.3 8.0 25,025 33.9 1.04 San Cristobal 86.5 9.1 4.4 2,436 6.4 +3.80*** Rio Cornez 58.0 38.2 3.8 1,365 1.1 —

*For locations see Table 3. **Infiltration rates were made on disturbed but recompacted samples with a rainfall simulator developed at the University of Arizona, which realistically simulates the momentum and kinetic energy of natural rainfall. Rate is in inches/hour. ***Infiltration rate exceeded applied rainfall rate of 3.80 inches/hour.

The sodium ions tend to disperse the clay and produce lower infiltration rates. The San Cristobal sample, on the other hand, has low clay and low ESP, so the infiltration rate is relatively high. The Kofa sample has relatively high clay and silt which would tend to make a low infiltration rate, but the relatively high rate of 2.75 inches per minute is apparently caused by an ESP of only 1.9 which is insufficient to disperse the clay fraction.

The various watersheds discharging to the lower Gila have variable runoff characteristics, but the watersheds characterized by high infiltration rates and low surface runoff have an area much greater than those where the reverse is true. This conclusion is based on field observations and laboratory analyses of soil samples.

6 TABLE 3. Location of Soil Samples Taken from Watersheds below Painted Rock Dam, July 24, 1970

Sub Watershed Location Remarks

Castle Dome 1 Sampled in R19W, T5S, near Sample representative of the Southwest c o m e r of large part of watershed. the Ko fa Game Refuge, near mountains.

Castle Dome 2 Sample taken in Sec. 12, Soil typical of large part R21W, T7S, near U.S. High­ of the lower watershed. way 95.

Kofa Sampled in Sec. 33, R16W, Representative of bottom T3S, approximately 20 land between stream chan­ miles above the conflu­ nels. ence with the Gila River.

Palomas Sampled in Sec. 11, R3W, Sample was representative T6S, located west of of fairly large area be­ Hoodo Wash. tween Palomas Wash area and Kofa Wash area. It is not representative of entire Palomas Wash area.

Ligurta Sample taken in Sec. 3, Representative of large R20W, T9S, about 200 yards area of the watershed. south of the new freeway.

Coyote Sample taken in Sec. 13 or Appeared to be represen­ 24 of R18W, T98, approxi­ tative of lower portion mately 3 miles south of of Coyote Wash area. highway.

San Cristobal Sample taken in Sec. 2, Appeared to be represen­ - Mohawk T9S, R13W, approximately tative of large area in 12 miles from the con­ the lower portion of San fluence with the Gila Cristobal and Mohawk River. Valleys.

Rio Cornez Sample taken in Sec. 34, Typical of large area in R6W, T9S, approximately upper Rio Cornez Wash. 16 miles south of Gila Bend near Highway 85.

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7 Bu;< '■ • ' n F ¡.'■üori CLIMATE

The area under study is the most arid part of Arizona with an average annual rainfall of about four inches. Rainfall for representative sta­ tions in the area is recorded in the Corps of Engineers report, Gila River and Tributaries, April, 1961. Biseasonal in distribution, the rainfall tends, with regard to amounts, to be slightly unbalanced in favor of winter (52 percent) (Hastings and Turner, 1965). The area is bone dry during the months of May and June receiving measurable amounts of rainfall in less than one year out of three; however, in October and November measurable amounts of rainfall have been received in three out of five years (Green and Sellers, 1964).

The area has unusually warm summers. In July and August the average daily temperature exceeds 90 degrees, with variations from middle 70's in the early morning to well over 100 degrees in the early afternoon. Readings above 110 degrees are quite common during the summer months.

Daytime temperatures in midwinter generally rise into the 60's and 70’s. Readings above 80 degrees have been recorded in all winter months. In December and January, freezing temperatures are not uncommon, however, with readings below 20 degrees occurring in about two of every three winters. Between mid-March and mid-November subfreezing nighttime tem­ peratures do not occur.

Summer rainfall in the area is sporadic and likely to occur at almost any hour. However most of the stations indicate a nighttime peak. The driest hours are frequently in the middle afternoon. The absence of rainfall and the attendant cloudiness during the day is one of the major causes of its extremely high afternoon temperatures, which have reached 120 degrees Fahrenheit during a 45-year period at Yuma.

While practically all of the moisture for Arizona’s summer rainfall is drawn into the state from the Gulf of Mexico and the Atlantic Ocean, this is not always the case. In fact, most of the record summer rains in the past century have been associated with deep surges of tropical air into Arizona from the Gulf of California and the Pacific Ocean. These storms, which occur most frequently in late August and September, usually origi­ nate as tropical hurricanes off the west coast of Mexico. As they move northward, they weaken considerably, sometimes to the point of disappear­ ing altogether. However, perhaps once every four or five summers, when conditions are right, a tropical storm may come rampaging through Arizona, accompanied by gale-force winds and flood-producing rains. What the "right conditions" are is not exactly clear. It has not even been defi­ nitely established that these storms always originate as tropical hurricanes, although in most cases they do. As a result of these storms, 61 percent of the rainfall stations in the area have experienced over three inches of rainfall in 24 hours. On September 30, 1921, for instance, Yuma recorded 3.63 inches (Green and Sellers, 1964).

8 WATER FEATURES

The writings of Father Kino, about 1700, one of the earliest and most enterprising of the Jesuit missionaries, contain numerous references to the river, some of which are here quoted. In regard to the Gila River near the present town of Wellton he writes: "This Rio Grande we named Rio de los Santos Apostóles. To this it may be added that all its inhab­ itants are fishermen and have many nets and other tackle with which they fish all the year, sustaining themselves with abundant fish and with their maize, beans, and calabashes." (Kino, 1948)

On November 17, 1846, when Emory was. perhaps somewhere between Agua Caliente and Palomas, he wrote: "The bottoms of the river are wide, rich, and thickly overgrown with willow and a tall aromatic weed and alive with flights of white brant, geese, and ducks, with many signs of deer and beaver." (Emory, 1848) In 1923, Ross wrote: "Thie bottoms in this por­ tion of the river at present are desolate wastes of sand and silt with clumps and thickets of arrowweed, which looks dry and almost dead during large portions of the year." (Ross, 1923)

At present along the Gila River from Texas Hill to the mouth, intermittent flows meander over the generally.flat bottom of a shallow channel about 1,000 to 3,000 feet wide. Most of the present channel bottom is covered with a heavy growth of phreatophytes sustained with excess surface and subsurface water from the Bureau of Reclamation’s 115,000-acre Gila Proj­ ect which, since 1952, has transformed the area from desert to highly productive farmland. The river-bottom growth has increased the aggrada­ tion of the channel and has restricted the channel to such an extent that flows in excess of about 2,500 cubic feet per second would overflow and inundate the adjoining cultivated area.

Surface Water

In describing the junction of the Gila and Colorado Rivers, Emory (1848) speaks of the "sea-green waters" of the Gila as contrasted with the "chrome-colored hue" of the Colorado. Ross (1923) wrote that by no stretch of the imagination could the present-day mud-laden water of the Gila be considered "sea-green."

With the completion of the Painted Rock Reservoir in 1959, flows in the lower Gila River were restricted to infrequent releases from the reser­ voir and storm runoff from rainfall over the 7,300 square mile watershed below Painted Rock Dam. The storage capacity of Painted Rock Reservoir is 2,492,000 acre feet and the facility is designed to take a maximum in­ flow of 300,000 cubic feet per second and to discharge a maximum outflow of 22,500 cubic feet per second.

The Gila River has a record of many large floods. The U.S. Geological Survey has maintained a gaging station at Gillespie Diversion Dam, near Gila Bend, since that dam was constructed in 1921, and another near the present site of McPhaul Bridge (Highway 95) since 1903. This latter is designated as "Gila River at Dome." y 9 The maximum flow at Gillespie Dam site was estimated at 280,000 cubic feet per second in February 1891. The maximum since installation of the gaging station was measured at 85,000 cubic feet per second on December 28, 1923. The maximum flow at Dome was estimated at 200,000 cubic feet per second on January 22, 1916. The big floods of the past were winter floods caused by prolonged general precipitation. These are now controlled for the most part by upstream dams and upstream depleted groundwater reservoirs. The upstream reservoir, however, cannot protect the Wellton-Mbhawk District from rainfall falling in the watershed below Painted Rock Dam. (Wellton- Mohawk Irrigation and Drainage District, 1965)

The principal tributaries that join the Gila River below Painted Rock Dam and their watershed areas are:

Palomas Wash 1,260 square miles San Cristobal Wash 1,810 square miles Kofa Wash 575 square miles Mohawk Wash (Snyder Ranch and Colfred) 710 square miles Coyote Wash 450 square miles Ligurta Wash 30 square miles Castle Dome Wash 410 square miles Fortuna Wash 45 square miles

Irrigation

The Wellton-Mohawk area has been an irrigated farming area for centuries. Ruins of ancient Pima Indian villages show that the people who inhabited them cultivated the soil, irrigated it by means of canals, and even built reservoirs to store water (Gordon, 1970) .

White settlement in the area started about 1860, and farming by means of irrigation by homesteaders in the Wellton Valley started by 1875. Canals and diversion dams were used to bring surface water to several hundred acres of farmland, but all these projects were ultimately destroyed by floods.

Dams and water resource development on the upper Gila River and its tributar­ ies had reduced the dependable surface flow to a negligible quantity by 1920.

Irrigation with pumped groundwater began about 1915 and several small irrigation districts were organized. Wells yielding up to 4,000 gallons per minute were drilled to about 100 feet in the Recent alluvial flood- plain. On the higher "terrace" lands, wells yielded 500 to 1,000 gallons per minute. By the early 1930's about 11,000 acres were being irrigated.

Wells began to fail because of the falling water table (about 18 feet in 20 years), and the buildup of salts caused by recirculation and évapo­ transpiration of the groundwater supply. Irrigated acreage had decreased to about 7,000 acres in 1945 when approximately 35,000 acre-feet were pumped. Water quality was poor, with total dissolved salts from 2,000 to 16,000 parts per million. Some wells had increased tenfold in salt content since 1927.

A new source of water had to be found if agriculture was to be maintained in the area, and that source was the Colorado River. On July 30, 1947, the Gila Project was reauthorized, and a canal leading off from Imperial Dam

y 10 was constructed to supply water.(811 ppm TDS, June 1968) to the Yuma Mesa Division, made up of the Mesa unit, and the South and North Gila Valley units, and in 1949, to the Wellton-Mohawk Division. The total area to be is 115,000 acres. In 1952, the first Colorado River water was applied through a system of more than 300 miles of lined canals and laterals. By 1957, no further groundwater was being pumped.

The Wellton-Mohawk Irrigation District consists of 75,000 acres, of which 60.000 acres are located in the long narrow valley of the Gila River and 15.000 acres on a mesa south of the valley. In 1968 a total of 60,758 acres were irrigated, 51,237 in the valley and 9,521 on the mesa. Besides the 75,000 acres, there are 15,000 acres of riverbed and wasteland inside the boundary of the Wellton-Mohawk Division.

In 1968, 471,884 acre—feet of water were diverted at Imperial Dam for the Wellton-Mohawk District; 219,760 acre-feet of drain water were returned to the Colorado River, and hence the final quantity of'Water charged against the District was 252,124 acre-feet (the total annual allotment is 300.000 acre-feet). Application rates were about 5 acre-feet per acre per year on the valley division, and 12 acre-feet per acre per year on the mesa. All irrigation is by flooding. Principal crops in the valley are alfalfa, cotton, small grain, Bermuda grass, pasture, and grain sorghum. The mesa is devoted entirely to citrus.

Groundwater

When the Gila Project was authorized, a drainage problem was anticipated because of the past history of the area, but water levels rose more quickly than expected. Excess water above consumptive use requirements was being applied partially to leach salts and partially because of the types of soil and irrigation methods used, and by 1958 a serious problem existed.

A concrete-lined main drainage channel was constructed in the center of the valley with a capacity (lower section) of 300 cubic feet per second. Drainage wells were selected as the principal method of removing excess water but approximately 8,000 acres of the tile drains were installed. They contribute about one percent of total drain flow.

In July 1961 drainage flow started from 62 wells, and by March 1964 the area with water level less than eight feet from the surface had been re­ duced from 26,000 acres to about 7,000 acres. The salinity of the drain flow was about 6,000 ppm and this, combined with decreased Colorado River flow to Mexico created the quality problem which was partially solved by drilling 25 additional wells and using them for selective pumping. Salt content of the water from individual wells is from 1,500 to 17,000 ppm, but drain flow (mixed) is now from 4,000 to 6,000 ppm. Some improvements in quality have been noted. In 1965, a channel was constructed to permit the Mexican Government to bypass the drain flow during periods of low flow in the Colorado.

There are more than 100 drainage wells in operation today, and pumpage in 1968 was 220,000 acre-feet. A total of more than two million acre-feet have been pumped into the drain since 1961.

11 system of drainage wells in the Wellton—Mohawk District can apparently maintain groundwater levels which will not interfere with agriculture in the valley; however, releases of water (64 ppm TDS) from Painted Rock Reservoir from January through March 1966 raised groundwater levels sufficiently to become a point of concern. Because of the growth of vegetation in the chan­ nel and resulting aggradation, the released water could not flow freely to the Colorado River, thereby permitting additional water to infiltrate into the channel and further aggravate the drainage problem. Of the total 254,740 acre-feet of water released from Painted Rock Reservoir, the U. S. Bureau of Reclamation estimated that 47,400 acre-feet infiltrated to the groundwater in the Wellton-Mohawk area carrying with it about 41,300 tons of dissolved salt. Just prior to the start of the release, about 12,000 acres of the area had water-table levels less than eight feet in depth; by April 1966 the area had increased to about 36,000 acres. By full capacity pumping, at the present time (June 1970) about 13,000 acres have water levels less than eight feet from the surface, but only 800 acres have levels less than four feet.

The quality of the drainage water released into the Colorado River is of international concern as Mexico is the last user of the River. If the drain water is discharged into the Colorado River above the point of diver­ sion to Mexico, it is considered to be part of the Mexican annual 1,500,000 acre—foot allotment. As the quality of the water being delivered has become a source of friction between the two countries, studies were directed by Congress to determine methods of alleviating the salinity problem. Part of the solution entails bypassing Morelos Dam with the drain water in winter when the Colorado River flow is low, and managing the well system at other times so that drain water being pumped provides suitable water with dilution at the diversion point. The two countries reached an agreement known as Minute No. 218, which is being reconsidered at the present time.

Although outside of the authorized project, it is recognized that water quality is an important part of the overall water regime that involves irri­ gation, drainage, and flood control, also that the application of irrigation water, especially in excess amounts, may have a deleterious effect, and that changes, as for example, a shift from flooding to sprinkler irrigation, could reduce drainage and salinity problems.

A report has been prepared by University of Arizona scientists on irrigation practices as related to quality of return flows. It will be released as a professional paper.

Hydrology

Evaluations in this report are based on the authorized plan as described in the 1961 review report and alternatives proposed by the Corps of Engineers (see Evaluation of Alternate Proposals p. 43). During the course of the present impact study, hydrologists at the University of Arizona made an independent analysis of flood frequencies and peak flows that might be ex­ pected in the reach of the Gila River between Texas Hill and the Gila Siphon. A part of this study was made together with Corps of Engineers hydrologists. The results of this analysis have been summarized in a docu­ ment submitted as a separate appendix. As this study and other recent data

12 acquired by the Corps resulted in new information relative to flood frequencies and potentials, the Corps is presently making a reanal­ ysis of the flood potential.

VEGETATION

A general inventory of the flora for the floodplain and upland has been made, based on field studies and a review of literature. The common plant species are listed in Appendix B by scientific and common names. The most important species as related to the flood control program are briefly described below. SALT CEDAR Tamarix pentandray sometimes listed as T. galZioa. Family Tamardoaoeae. Native from western Europe to Himalaya Mountains.. A large shrub or a small tree. It has extended its range throughout western United States and is especially adapted to the warmer areas subject to floods and high water tables. Prodigious seed producer, April to October. Germination depends . upon moist surface for four to six weeks. Favorable Characteristics G> A source of honey throughout the summer, animal cover j ;-r ; - - and nesting for birds, fence posts, erosion control. . ; ' ~ - Detrimental Characteristics A heavy water user, tends to clog channels and spread flood waters. May become established to the exclusion . of native species. PICKLEWEED OR IODINE BUSH Allenrolfea oeeidentalis. Family Chenopodiaceae. Native from Oregon to western Texas, Sonora and Baja California, Mexico. Somewhat fleshy plant, woody at the base, stems appearing jointed, leaves reduced to triangular scales. It produces a large tap root, is very salt tolerant, and restricted to areas with high water tables. Favorable Characteristics Animal cover, erosion control. Detrimental Characteristics Considered to be the cause of hay fever. SEEPWEED Suaeda tovveyana. Family Chenopodiaeeae. Native with range from Alberta or Oregon south to northern Mexico. A semi-woody plant reaching a height of 6 to 10 feet. » Occurs on saline soils with high water table.

13 Favorable Characteristics Animal cover and some browse, young plants and seeds 3 used as food, erosion control.

Detrimental Characteristics Water user, clogs channels and spreads flood water.

ARROWWEED Pluohea seriosa. F am ily Compositeze. Native with range from Texas to Utah, southern California and northern Mexico. Tall and slender, herbs or shrubs forming dense thickets. Usually found in association with Tamctrix on lighter soils with a high water table. Can tolerate moderate salinity and lowered water table. Flowers abundantly, seeds produced May to July.

Favorable Characteristics Browse plant, cover for animals, used for hut construe- tion, basketry and arrow shafts, source of honey, erosion c o n t r o l . '

Detrimental Characteristics A heavy water user, clogs channels and spreads flood w a te r .

BIG SALTBUSH Atriplex lentiformis. F am ily Chenopodiaoeae. N a tiv e with range from southern Utah and Nevada to Sonora and California. Scurfy shrub reaching height of 10 feet where water table is shallow. Can tolerate salinity.

Favorable Characteristics Browse plant and shelter for animals, erosion control.

Detrimental Characteristics - Water user.

MESQUITE Prosopis juli flora v a r . glandulosa. F am ily Legvmtnosae. Native shrub to small or large tree with range from southern Kansas to southeastern California, Mexico and South America. Trees may reach height of 30 feet or more with roots extending downward to more than 60 feet. It pan grow and thrive as a pnreatophyte or exist under dry upland conditions. Mesquite may flower in spring and again in summer. Seedlings are aggressive and become^ established rapidly.

Favorable Characteristics A good browse plant, source of honey, pods eaten by I Indians and browsing animals. Gum used as adhesive and dye, provides animal cover and nesting sites, fence posts, erosion control, firewood. M istletoe on mesquite is an -Important source of food for several species of birds.

Detrimental Characteristics High water user. I 14 BURSAGE Fransevia ctumosa. F am ily Compositae. A n a t i v e spinescent shrub up to 4 feet high with range extend­ ing from southeastern Utah to southeastern California and northwestern Mexico. Commonly associated with creosote bush on upland sites. Seeds germinate quickly after rains and make rapid aerial and root growth when young. Older plants are drought-enduring.

Favorable Characteristics Animal cover, favored browse plant, erosion control.

Detrimental Characteristics N one.

CREOSOTEBUSH Larvea tridentata , sometimes referred to as L. divaricaba. F am ily Zygophytlaoeae. A ubiquitous native with range from western Texas to southern Utah, Arizona, California - and northern Mexico, probably extending into South America. A much branched shrub to 12 feet with evergreen, thick, strong scented leaves. The most common and most widespread plant of the warmer North American deserts. Flowers and produces seed in rainy seasons, seed germi­ nates especially well following disturbance. A drought- enduring species that can stay alive for long dry . periods. Plants may attain an age of 100 years.

Favorable Characteristics Animal cover, erosion preventive, resin used in making mosaics and mending pottery.

Detrimental Characteristics N one.

FOUR-WING SALTBUSH (C ham iso) Atriplex canesoens. F am ily Chenopodiaaeae. A w id e ranging shrub from South Dakota to Oregon south to northern Mexico. Facultative phreatophyte shrub up to 6 feet high, tolerates some salinity, but considered as indicator of land suitable for crops. Flowers from June to August, produces abundant palatable seeds. Seedlings often scarce because of consumption of seeds and seedlings by herbivores.

Favorable Characteristics Excellent browse plant and fruits are eaten by wild • and domestic animals. Used for erosion control.

Detrimental Characteristics N one.

SCREWBEAN - Prosopis pvbesoens. F am ily Legwninosae. Native shrub or small tree up to 20 feet high occurring from western Texas to southern California and northern Mexico.

15 Growth habits are similar to those of mesquite, but screwbean is largely restricted to .floodplains. Favorable Characteristics A good browse plant, pods a food source for Indians and animals, source of honey, fence posts and tool handles, animal cover and nesting sites, firewood, erosion control. Detrimental Characteristics None. CATTAIL Typha domingensis. Family Typhaoeae. Native semiaquatic marsh plant in southern United States to southern South America. It usually indicates surface water of good • quality or a very shallow water table. •• -• Favorable Characteristics * Food source for people, spike used in home decoration. - ' r : Detrimental Characteristics Clogs channels. Subunits The study area can be divided conveniently into three subregions. 1. The non—cultivated floodplain. 2. The upland including mesas, bajadas, and mountainous areas.* 3. Farmland (an ecological unit dominated by man's activities). The non-cultivated floodplain represents an ecological unit with consider­ able diversity of plant and animal life. With the exception of the cattail marsh type, the units are intermingled and their distribution is subject in part to fortuitous circumstances and in part to minor differences in habitat. The various plant species tend to form pure colonies or mixtures of two or three species. They are all more or less phreatophytic. The upland', while not directly involved in the proposed action, is important as a major part of the local watershed and even though plant life is sparse and animal life scattered, there is a definite relationship with watershed conditions. Plants, especially along drainageways, retard runoff and stabi­ lize highly erodible and sandy areas. Animals, particularly burrowing animals, increase infiltration. Time did not permit mapping these areas, but sufficient information was obtained to appraise their relationship to the project area. The farmland aside from its economic importance has some major ecological implications, the most important of which for this study relate to wildlife relationships. Farmland is a major source of food for some species of animal life which find shelter and reproductive habitats in the vegetation dominated by salt cedar. If either agricultural crops or habitat were elim­ inated, there would be great reduction in animal life. If grain crops were

16 drastically reduced, a reduction in animal life would follow. On the other hand, a large stand of salt cedar would support only a small animal population in the absence of grain crops.

Plant Communities ’

The two natural subregions, floodplain and upland, have been discussed in a number of publications. The more pertinent of these have been reviewed to augment field surveys as a basis for designating and describ­ ing ecological communities.

Floodplain Plant Communities

Marks (1950) made a very detailed study of plant communities in the lower Gila area. His floodplain communities included the following:

Arrowweed-Salt Cedar Community: (Vluchea seriaea-Tamarix pentandra) lowest bottomlands paralleling channels dropping into old oxbows. Both dominants are dependent upon underground water and v irtu a lly independent of s o il texture. Never found on upper terraces or where the water table is much below the surface. Other species include screwbean (Bvosopis pubesoens) , seep willow (Baaoharis glutinosa), big saltbush (Atriplex lentifovmis), and spiny aster (Aster spinosus) . Along river channels are cottonwood (Populus fremontii) and black willow (Salix gooddingii) . Soils mostly non­ salin e but dominants can tolerate some sa lin ity .

Prosopis Community: Dominated by honey mesquite (P. g u liflo ra var. glandulosa) . Orchard-like groves are scattered less extensively than formerly. Other species: seepweed (Suaeda toweyana), desert saltbush (Atriplex polycarpa) . Seepweed lands are more saline than saltbush. Soils medium textured with unrestricted drainage, favorable for crop production.

Saline Communities: Two d istin ct faciatio n s, namely seepweed, moderately saline, and pickleweed (Allenrolfea oacidentalis) , with salinity throughout the profile. The latter is invariably an indicator of heavy-textured deep soil, ranging from the heavier silt loams to the clays. Seepweed in dense stands indicates mod­ erate salinity and medium to heavy-textured soils. Seepweed may occur alone or with desert thorn (Lyciwn andersonii) , or linear leaf four-wing saltbush (Atriplex linearis).

Lowe (1964) recognized desert riparian communities in "dry" arroyos and washes. The dominant species are blue paloverde (Ceraidium floridum) , mesquite, catclaw acacia (Acacia greggii) , smoketree (Dalea spinosa) , desert willow (Chilopsis linearis) , jumping bean (Sapium biloculare) , and net leaf hackberry (Celtis reticulata). He states (p. 26): "Such desert riparian associations are nearly as prevalent among the creosote bush as well as the paloverde communities, and in the Yuma area even saguaros, fo o th ill paloverdes and ironwoods are found in such arroyo h ab itats."

y 17 Desert saltbush communities dominated by Atriplex polycarpa are found in periodically flooded bottomlands with fine textured and more or less alka­ line soils. The Sonoran Desert Mesquite Community formerly grew along the Gila and other drainages forming forest-like stands called mesquite bosques. Individual trees reached heights of 40 to 50 feet and trunk diameters of 2 to 3 feet. Lowe includes a description of the desert marsh community (p. 30): "There were extensive marshes, swamps and floodplains with cattail (Typha dorrrin- gensis), bulrush (Scirpus olneyi) , giant reed (Arundo donax) , common reed (PhragnrLtes communis'), arrowweed (Pluchea sericea), and many trees. The dense vegetation of these well-developed riparian communities often stood ten to fifteen feet high and supported a tremendous quantity and variety of wildlife...tamarix (Tamarix) is an increasingly abundant foreign intro­ duction in some of these riparian situations and may become locally undesirable. Shantz and Piemeisel (1924) covered both floodplain and upland communities. The most pertinent contribution to the present project is their discussion of plants as indicators of soil conditions. Their results are summarized in Table 4. Plant Communities of the Floodplain as Designated for Impact Studies, The U. S. Geological Survey photographed the floodplain area, and provided a set of 9 x 9 inch ektachrome transparencies which were mounted individu­ ally in clear plastic envelopes. Vegetation types were delineated as an •fnlr overlay on the plastic envelopes utilizing a binocular microscope and light table. The mapped areas were checked in the field, on the ground, and by low-level helicopter flights; corrections were made, and finally xerox copies were used to determine areas by cutting and weighing the indi­ vidually mapped units which included 16 ecological types plus cattail marsh. The types were divided between low cover (0 to 50 percent) and high cover (50 to 100 percent) where appropriate, and were combined into seven commu­ nities. Tables 5 and 6 show acreage by ecological type/community and ecological type/location respectively. On the basis of the literature reviewed and ground and aerial studies, the following general breakdown of communities in the floodplain has been made: 1. Cattail - Marsh, includes open water (Typha dorrtingensis) 2. Salt Cedar - Arrowweed (Tamarix pentandra) (Pluchea sericea) 3. Big Saltbush (Atriplex lentiforrrrLs) 4. Mesquite (Prosopis juliflora var. glandulosa) 5. Mixed Saltbush (Atriplex polycarpa, A. linearis)

18 \ TABLE 4# A summary of the soil conditions as indicated by the prlnoip&l plant communities of tho Southwestern Desert after Sh&ntz and Plemelsel (1924)

Kind of Soil Moisture Salinity Types cf Vegetation Vegetation Surface foot Subsoil Surface foot Subsoil Surface foot Subsoil

Creosote buih Good growth Sandy loam Sandy loam Moist after rains only hoist after rains only Nonsaline Nonsaline Poor growth Often stony or if Hardpan or rock Do Apt to be dry due to above (see under layer more lack of penetration subsoil) rarely alkali

Desert saltbush Good growth Pine sandy loam Fine sandy loam Do { Moist after rains only Do Nonsaline Poor growth Do Hardpan or Do Apt to te dry due tc Do Saline alk ali lack of penetration L ' ; j : Mesquite and Sand : and Do j j Moist after rains only Do Nonsal im chamiso i . 1 ! ' I v Chand so Sand Sand Do j Do Do Do

Seepweed Rank growth Pine sandy loam Fine sandy loam Moist in spring Moist most of the year Saline Saline Rains and high water High water table table Poor grovrth Do Do Moist after rains only Moist part of the year Do Do Rains and high water t&ole

Eig Saltbush and Loam Fine sandy loam Moist most of the year Moist a ll the year Strongly saline Moderately arrowweed with sand High water table High water table saline layers

Piokleweed Fine sandy loam Do Moist a ll the year Wet all the year Do Strongly to loam High water table High water table saline

Mesquite thioket Clay loam Clay loam Moist after rains only Moist a ll the year Slightly saline Do High water table

Cig Saltbush Heavy olay loam Heavy clay loam Wet most of the year Wet a ll the year Saline Saline High water table High water table TABLE 5. ACREAGE OF ECOLOGICAL TYPES AND COMMUNITIES

Ecological type numbers with an A represent 0-50Z cover; others represent 50-100Z cover.

C a t t a i l S a l t c e d a r B i g M i x e d S e e p w e e d M e s q u i t e Creosote bush N o t , Type Number and Name M a r s h A r r o w w e e d S a l t b u s h S a l t b u s h P i c k l e w e e d M e s q u i t e A p p l i c a b l i

1 Salt cedar — . 2 7 7 — ...... ______1A 6 6 ---- — — — 2 — — ...... ______Essentially no vegetation ...... — . —— — — ... 8 5 1 3. Mesquite ...... ------3A 2 7 ... 7 8 9 — ------. .. 4. Seepweed I— — M ““ “■'*** — — — — 4A -— 2 1 1 .... — — —* —— — —- 1 4 4 5. Essentially open water . 1 1 9 | ä — — 6. Polypogon (grass) —— 7. Mixed saltbush 7 ------— ——— ... 7A I 5 2 7 — — . . . | N> 8 Cleared areas, etc. 2 , 0 8 9 . —— — — — O ------9. Creosote bush/mesquite 1 , 4 3 9 ——— — — . 9A 8 0 «... — “T*— — ‘ 10 Big saltbush 6 7 0 j . —— 3 6 0 — — ....

10A — ■“*— 1 5 1 — — .... ______i . Creosote bush 11 — — — ■ ------— — ______: 11A 8 i — ~ — — — ... 4 9 ! 12. Arrowweed — l —— 1 , 0 5 3 — —. ... 12A 5 2 1 — — — 13. Saltbush/Creosote bush — 1 4 14. S eepweed/pickleweed i — — — — 2 3 1 | | 14A — — -— 1 1 8 3 « . . . i 15. Salt cedar/arrowweed/mesquite — 2 , 4 0 6 — ■ ______i ______; 15A ' — ----- 3 , 5 4 4 — — -— 16. ... Salt cedar/arrowweed/saltbush ——* 1 , 2 0 4 — — 16A —— ...... 1 , 4 8 6 X. — ! Cattail marsh 1 4 2 — — — --- Total acreage 261 10,557 511 816 2,630 769 Total vegetation acreage 16,358 807 2,297 Total phreatophyte acreage 15,290

u TABLE 6. ACREAGE OF ECOLOGICAL TYPES BY LOCATION Ecological type numbers with an A represent 0-50% cover; others represent 50-100% cover

Gila Siphon 5th St. 22nd Ave 29th Ave 35th Ave 43rd Ave 50th Ave to to to to to to to 55*5 Ave Type Number and Name 5th St. 22nd Ave 29th Ave 35th Ave 43rd Ave 50th Ave 22 15 57 126 1 Salt cedar 39 14 4 . 4 41 1A 16 1 1 — 3 2 Essentially no . 325 vegetation 32 142 171 56 77 48 — — — 2 3. Mesquite 1 12 12 21 32 5 3A 20 25 584 102 — — 29 Seepweed 83 25 16 58 4. — — 4A 15 9 118 2 ■“ 5. Essentially open 7 1 water 49 5 2 12 43 — ; 6 Polypogcm (grass) 7 -- — — . 121 81 65 7. Mixed saltbush 4 44 212 281 — 7A mmmm 291 723 794 235 102 444 323 56 to 8. Cleared areas, etc. 73 206 — — 3 9. Creosote bush/mesquite 21 48 — 8 — —— * 9A 397 239 34 — 3 10. Big saltbush 27 44 92 63 114 17 17 8 " 10A 8 25 80 13 — — — — —— Creosote bush 8 — — 11. — — — — 11A 36 7 6 211 75 Arrowweed 31 26 126 283 , 301 12. 141 62 12A 7 37 139 101 34 — — — 14 — 13. Saltbush/creosote bush — — 83 14. Seepweed/pickleweed 24 8 115 1 — — — 45 14A 25 • 57 45 11 15. Salt cedar/arrowweed/ 354 . mesquite 437 393 249 229 345 399 748 1,547 15A 221 501 112 75 340 16. Salt cedar/arrowweed/ — — saltbush __ 100 344 605 155 — — 16A 142 432 336 576 21 X. Cattail marsh______18 18 — 4 81 Total Vegetation 1,490 1,740 2,846 2,852 2,968 2,021 2,441 6. Seepweed - Pickleweed (Suaeda torreyana) (Allenrolfea oooidentalis) 7. Creosotebush - Mesquite (Larrea tridentata) (Prosopis juli flora v ar. glandulosa) Description of Communities Cattail Marsh: found primarily in low areas in the main channel, particularly a stretch of several miles just upstream from Gila Siphon and the area adjacent to Antelope Hill. Also found outside the main channel in some areas with surface water. This community is characterized by cattails, open water and some sedges. Salt Cedar — Arrowweed: found primarily in the lowest bottomlandsi on soils of undifferentiated alluvium and varying periods of surface water» Less abundant species include screwbean and big saltbush. Occasional species are cottonwood, seepwillow, black willow, and athel tree (Taxnarix aphylla). Big Saltbush: found primarily on low, saline moist bottomlands, often forming a mosaic with the Salt Cedar - Arrowweed Community. Mesquite: found primarily above the lowest bottomlands in non-saline or only slightly saline soils. Where salinity increases, seepweed also occurs. Mixed Saltbush (desert saltbush, narrow leaf saltbush): found primarily on drier upper terraces, interspersed with or outward from the Mesquite Community. Soils are non-saline or slightly saline and may have a hardpan layer. Other species may include four-wing saltbush (A* canes certs) and desertthom (Lycium andersonii) . Where th e com­ munity grades into drier, lighter soils, mesquite or creosote bush may be found, while seepweed indicates more salinity. Seepweed - Pickleweed: found primarily on moderately to strongly saline, moist and somewhat heavier soils. Seepweed may occur under less moist conditions than pickleweed, particularly as growth on cleared or abandoned land, while the latter is found in the most strongly saline soils. Creosote Bush - Mesquite: found primarily in a non-saline transition region between valley and mesa regions on relatively dry and light or stony soils, often with a hardpan layer. Desert, narrowleaf, or four-wing saltbush are also frequently encountered. Successional Changes Past plant successions have little meaning for the floodplain area because of the changes that have taken place in recent years as a result of man's occupancy of the area. The succession has been backward or in the term of some ecologists retrogressive succession. Mesquite bosques have been deci­ mated and much of the original area placed under cultivation. Cottonwoods and willows have almost disappeared. The hydrophytic habitats have been

22 almost eliminated, and while the drying up of marshes under natural conditions may be considered as normal succession, the drying up because of disturbance, sedimentation and other influences of man cannot be con­ sidered as a progressive change.

The original cottonwood, willow, mesquite and arrowweed communities were once climax, but it is unlikely that similar climax conditions w ill again be reached because of disturbance created by man. The salt cedar stands may be a temporary or permanent replacement for the original climax spe­ cies, but because salt cedar is an alien, it could not be classed as a natural climax. Other than that resulting from the invasion of salt cedar, there is little evidence of successional change taking place at the present time.

The introduction and spread of salt cedar occurred generally after 1900, a relatively short time ago in terms of most ecological successions. Therefore, an accurate prediction of the role of salt cedar in succes­ sional development is difficult, although it appears that the species may have a significant role.

Long periods of surface water such as occurred in the spring of 1966 favor germination and establishment of salt cedar, since great quantities of viable seed may be produced for several months. The removal of com­ peting phreatophyte vegetation during and subsequent to 1958 (Frost and Hamilton, 1960) also favored rapid growth of salt cedar. The plants may flower the first year after establishment whereas species such as willow, cottonwood, and mesquite may require several years to flower.

It seems likely that the lack of a long occurring and quantitatively large and viable seed source may limit the establishment of willow and cotton­ wood. Seedlings of cottonwood and willow several years old were observed in the floodplain although most of the plants were not yet of flowering age. Whether a subsequent climax might include significant numbers of willow and cottonwood if phreatophyte vegetation is not removed, is a .moot point. Limited data from other areas indicate that salt cedar had a difficult time establishing itself in mature mesquite and cottonwood com­ munities although it does establish well in disturbed areas such as those resulting from vegetation removal or the natural creation of new meanders in river beds. Limited data from other areas indicate that salt cedar is somewhat intolerant of shade such as that resulting from large cottonwoods. The artificial and unpredictably fluctuating groundwater table in the study area further complicates meaningful predictions of the pattern for ecological succession and climax.

Upland Plant Communities

Marks (1950) described four upland communities:

Mesa Communities: The mesas adjacent to the floodplain support several types of mostly small communities. These include (1) a Creosote Bush Saltb u sh T ra n sitio n a l Community (2) Creosote Bush-White Bursage (association) most extensive of all communities in the lower Colorado Desert which is subdivided into gravelly mesa types, sandy mesa types and heavy soil mesa types.

✓ 23 Creosote Bush-Desert Saltbush Community: Mixture of desert saltbush, mesquite with creosote bush, white bursage. Mixed medium to light soils with salinity are typical.

Creosote Bush-White Bursage Community: This is the typical and most extensive plant community in the Lower Colorado Desert. It is made up of scattered individuals of the two dominants, with many ephem— in the rainy season. The typical community may vary toward gravelly washes, blow sand or heavier soils. Changes in the sub- ®^ra*:a are marked by the intrusion of other species. The sub types are described by Marks but are not included at this time since the classification by Shreve appears to fit our needs better.

Bajada Communities: No marked change from mesas; creosote bush and white bursage persist but are more widely scattered. Big galleta grass ([Hilaxia rn.gi.da) is abundant in washy parts and cacti appear including holycross cactus (0. ramosissima) , Christmas cholla (0. leptooaulis), and bisnaga (Eohinocactus aaanthodes). Ocotillo (Fonquievia sptendens) is found throughout, indicating a gravelly soil with considerable cementation and some fine materials among the coarse. Desert holly (Atviplex hymenelytra), desert marigold (Baileya pauaivadiata) and white brittle bush (Enoelia facvnosa) are found on the most gravelly areas.

Lowe (1964) classified the vegetation of the lower Gila area as the creosote bush associations of the Southwestern Desert Scrub Formation. He also discusses the vegetation under "Arizona Life-Zones" as a part of the Lower Sonoran Life-Zone.

Creosote busn-bursage plant-animal communities characterize valleys, mesas and shelving plains in the Lower Colorado Desert section of the Sonoran Desert (the so-called Colorado Desert). They are composed of shrubs and dwarf shrubs with creosote bush, and white bursage dominants growing together or alone.

Lowe also describes a paloverde-saguaro community in the Arizona upland desert section (e.g.t between Ajo and Tucson) but does not identify it with the lower Gila area.

Shreve (1964) recognized five upland communities, which we found to be satisfactory as a basis for our breakdown into subunits as follows:

1. Interment plains and bajadas — creosote bush — white bursage (Larvea tridentata - Fransevia dumosa) . '

2. Sandy plains and dunes - big galleta grass (Hilccria vigida) .

3. Malpais fields and volcanic hills - mesquite, ironwood and oco­ tillo (Pvosopis sp., Olneya tesota and Fouquieria sptendens).

4. Older volcanics - tanglehead (Heteropogon contortus).

5. Granitic mountains and hills - paloverde, ironwood, saguaro (Ceroidium miorophyllian, Olneya tesota, Camegiea gigantea). 24 Interment Plains and Bajadas

Creosote bush and white bursage constitute 90 to 100 percent of the intermont plains and lower bajadas. Creosote bush is rather uniformly distributed although varying in size with variations in soil conditions. White bursage is most abundant on sandy loam soils of the plains, and less abundant on gravelly bajadas.

The remaining small percentage is made up of other shrubs, cacti and a few perennial herbs.

Outside of drainageways small trees or shrubs of mesquite and paloverde are rare, ocotillo is infrequent and its presence usually indicates thin or stony soil. Four-wing saltbush is infrequent and big galleta grass is largely restricted to sandy soils.

Drainageways of two types are common .in the area and each has its characteristic vegetation. One is the dendritic type, in which the floodwaters are gathered into increasingly larger streamways with drainageways usually emptying into the Gila River unless blocked off. In some cases these drainageways fan out on the flat land outside of the floodplain without directly contributing floodwaters to the Gila River. In dendritic drainages the vegetation is larger and more closely placed than are the plain or bajada vegetation and forms a definite pattern when seen from above. The most abundant woody plants along the larger drain­ ageways are velvet and honey mesquite, blue paloverde, and smoketree. The size of these trees is proportional to the size of the drainageways. Along smaller washes they may be absent, or occur as scattered small ■individuals along with burrobrush, seepwillow, desert thorn and catclaw acacia.

The reticulate type in which the drainageways anastomose, the water courses increase very little in size as they progress downslope, forming a network of rills which have no external drainage. The plants do .not form continuous belts along the shallow washes, but often appear to be a part of the uniform community over the entire drainage.

The stand of plants becomes thicker, the stature greater in ascending the bajadas from base to top. Ironwood, blue and little leaf paloverde are found away from streambeds, saguaro appears and ocotillo, barrel cactus, and acacia become more abundant. Creosote bush is present but not predomi­ nant. White bursage tends to become larger, but in some localities is replaced by triangular leaf bursage. The upper bajada streanways support a more numerous and larger stand of trees, but some of the commoner plants of the lower bajadas are missing. These include smoketree, seepwillow, desert willow and burrobrush.

Sandy Plains and Dunes

While dunes are present at various locations in the lower Gila River Basin, most of the.sandy area is relatively level and has a stabilized surface. Under such conditions there is little evidence of surface drainage. Much of the area within the basin is occupied by gravelly plains, with moving sand accumulating in depressions or forming small dunes. Similar deposits

25 are found in malpais areas where the black rock surfaces stand out conspicuously when viewed from above.

Sand accumulates at the windward base of h ills, and elsewhere local dune areas occur. In areas of moving sand, vegetation is sparse or absent. Big galleta grass is the chief stabilizing plant, becoming less abundant on stabilized plains. Plants found on partially stabilized sandy areas include creosote bush, longleaf ephedra, Emory dalea, four-wing saltbush, white bursage, Palmer coldenia, desert eriogonum and Thurber sandpaper p la n t.

Malpais Fields and Volcanic Hills

In the lower Gila River Basin there are many areas whose surfaces are occupied by volcanic eruptives, either of recent origin, or with little erosion or degradation. Often these are in the form of gently tilted mesas ending in a scarp at the high end and along one or both sides.

On the edges of these volcanic areas the vegetation differs little from the surrounding plains, but toward the center creosote bush and white bursage become less abundant and smaller. Small ironwood and mesquite trees occur in depressions and single plants of ocotillo appear from place to place. In general there is a lack of uniformity in the plant cover. Shrubs and semi-shrubs may grow abundantly or may be scarce. The vegeta­ tion is usually denser at the base of a hill than on the upper slopes and the plants taller in the shallow canyons and waterways.

Older Volcanics

Under this term are included mountains and hills of rhyolite, andesite, basaltic conglomerate and all other volcanics except Recent basalt. All are highly eroded, usually with bare summits and narrow lateral ridges. The surface is either bare or with a poor soil development. When viewed from a distance the volcanic ranges appear bare but closer examination shows-a very scattered and irregular cover of small perennials and grasses.

The most typical plant is tanglehead, a straw-colored to reddish coarse grass. Under the most favorable conditions, ocotillo and white brittlebush are found. The only cacti are of the barrel and cushion types.

Granitic Mountains and Hills

These are conspicuous features throughout the basin. They are made up of crystalline rocks with granite and gneiss preponderant along with smaller areas of schist. They vary in topographic features and amount of weather­ ing. The surface soil is coarse but weathers to loam or finer texture below the surface. The boulder-strewn surface and porous surface tend to lessen runoff and erosion.

The vegetation of these mountains includes the same plants as the volcanic ranges, but they are more numerous.

26 Successional Changes

In the upland area plant succession in the same sense as succession in humid climate is minimal or lacking. The plants that invade bare soil often remain as constituents of the climatic climax. Because growth conditions are so rigorous and successional changes in the environment are so small, there is little difference in the vegetation over periods of time, except those resulting from the local accumulation of favorable conditions such as the accumulation of fine materials in small basins or other events which may improve the moisture relations either by provid­ ing additional amounts or by decreasing losses through shading.

The primary actions favorable for plant growth are stabilization, e , g . t sand dunes, and the reduction of losses through erosion and runoff.

In summary, under natural conditions the major desert plant communities change little through time, but there is a great deal of internal change because of local improvement or deterioration of the habitat.

Desert communities are very fragile, and disturbances, as for example grazing, fire, clearing, road or trail development, can bring about very great changes. Even driving a vehicle across a desert area will leave marks for many years and may result in local vegetation changes.

ANIMAL LIFE

The zoological survey is in two sections: (1) birds, and (2) other animals including mammals, fish, amphibians, and reptiles. (See Appendix C and D.)

Terminology follows Lowe (1964) , Vertebrates of Arizona.

‘ Birds of the Gila River Basin below Painted Rock Dam

Phillips, Marshall, and Monson in their Birds of Arizona (1964) , list 89 species of birds from the lower Gila River channel area. The list includes a number of records from the surveys of the 1840's but none made after 1960. The list is short; few persons worked the area during the 1900's and there are almost no references to birds in the area after the completion of the Wellton-Mohawk Irrigation Project.

The only known recent observations on non-game birds were made in March, April, and May 1970 by Dick Todd and Robert Hembrode of the Arizona Game and Fish Department. Their records constitute Column 3 of Appen­ dix C. On June 10 and 11, 1970, R. Roy Johnson and Stephen M. Russell surveyed the area intensively; a summary of their observations consti­ tutes Column 4.

The list of-birds prepared from the Birds of Arizona was increased by 53 species as the result of the few 1970 observations. Almost nothing is available on use of the area in winter, or during the migration season.

27 The most conspicuous and unique feature of the avifauna of the lower Gila concerns the proportion of birds associated with the cattail marshes and associated open water. Nineteen species of marsh birds have been recorded; thirteen species probably nest in the marshes. Twelve of the thirteen species are not known to have nested in this area previously, although they may have done so when the Gila River was a permanently flowing stream. The following species of birds nest (or presumably nest) in the cattail marshes

Pied—billed Grebe Green Heron Black-crowned Night Heron Least Bittern Common G allin u le American Coot Virginia Rail (Yuma) Clapper R a il T raill's Flycatcher Long-billed Marsh Wren Yellow-throat Yellow-headed Blackbird Blue Grosbeak

The marshes are undoubtedly the indirect result of the agricultural devel­ opment in the area; only the green heron on this list is believed to have nested in the area prior to the formation of the marshes after 1952.

Relatively few ducks and geese are known to use the area. It is probable that waterfowl do utilize the marshes and other open water areas, but docu­ mentation is not available. The phreatophytes are known to be favorite nesting sites for doves.

It has been difficult to obtain specific information on the w ildlife resource. The following statement by consultant Hungerford is the best we have found:

Davis (1967) reported Arizona hunters spent $5,812,965 for small game hunting in 1965. The most popular species pursued were quail, mourning dove, white-winged dove, and cottontail rabbit in this order. Over 1.1 million quail were harvested and 669,000 white-winged doves. White-winged doves are harvested in great numbers in the Salt, Gila and Santa Cruz drainages near irrigated agriculture and near the larger cities of Yuma, Phoenix and Tucson. Banding studies, hunter questionnaires, and bag checks revealed that most of the white—wing hunting pressure is on birds raised in "colony type" nesting areas (Western Migratory Upland Game Bird Committee, 1970). It is difficult, perhaps impossible, with data presently available to determine what portion of the Arizona white—winged dove population and yearly production results from specific areas of habitat. The Gila area has long been an important hunting and production area. Arnold (1942) states: "The section of the river bottomland along the Gila River from Gillespie Dam to Yuma is considered one of the best white-wing hunting areas of the state." He also states (p. 98) in regard to colonial nesting: "The two factors appearing paramount in hinder­ ing the normal activities of the birds nesting in these sections are the continued cutting of the trees that form the breeding areas and continued human disturbance within the concentrated breeding areas'during the breeding season."

28 Shaw (1961) reported the increasing importance of salt cedar as nesting habitat along the Gila. Shaw and Jett (1959) found be­ tween Gillespie Dam and the confluence of'the Salt and Gila 400,000 nesting white-wings on 2,500 acres of mature salt cedar in July of 1959. These breeding birds combined with their poten­ tial production yielded a total population of over a million b ird s. Published information emphasizes the importance of cultivated agriculture in attracting and supporting white-winged dove breeding populations. The fortunate combination of irrigated agriculture, available water, and suitable colonial nesting habitat is stressed in Shaw (1961), Arnold (1942), and Cottam and Trefethan (1968). Potholes created by runoff water along the Gila below Painted Rock are recognized as areas used by migratory waterfowl of several species. Primary uses of these sites- are for refuge and resting areas in the late fall and winter. They are valu­ able for ducks because they are not often disturbed there by human activity. Waterfowl hunting occurs along the Gila but it is not one of the more popular areas. ; Brush and weeds are not compatible with irrigated agriculture in Arizona. Ditch banks are kept clean by several methods, most of the field borders are not fenced, and most land is cultivated. When agriculture adjoins desert land or stream channels with heavy vegetation, an edge is created that is un­ usually suited to wildlife. The fertile land and its food- producing plants attract quail, rabbits, doves, and many other forms. In Arizona the "farm game" is often restricted to such places. While range and forest lands produce game species, the recognized farm game are especially abundant near agricul­ ture if stream channels or open desert is immediately adjacent •to it. An "edge effect" is recognized and indeed hunting may be desired to protect the farmer from an over-abundance of rabbits or crop depredation can result. Small game such as Gambel quail and cottontail rabbits are hunted in the Painted Rock area and several other places along the Gila to the west. Animals of the Gila River Basin below Painted Rock Dam River bottoms are known to be very important areas for a wide variety of animals. The river bottom provides cover for nesting, water for 'living and a concentrating effect which may be important for reproduction. In arid regions, where water is a scarce commodity, river bottoms are even more important as refuge for animals from the desiccating effects of the environment. The area along the Gila River is an important refugium in western Arizona. Two kinds of habitat which seem the most important from the standpoint of animal life are the phreatophyte thickets and the cattail marshes and open water areas along the river. The phreatophyte thickets provide

29 ■ important nesting areas for mourning doves and white-winged doves as well “ as cover and protection for a wide variety of other birds and mammals.

I The cattail marshes are very interesting and quite unique areas along the M lower Gila. The total amount of open water and marshes in the study area probably totals about eight to ten linear miles of channel. The animals ■ supported in this area include amphibians, mammals, birds, reptiles, fish. I Species of particular interest include beaver, muskrat, bullfrogs, and a wide variety of aquatic birds (see Appendix D).

I The list of mammals was obtained from personal observations, observations of Arizona Fish and Game personnel, reports of personnel of the Bureau of Sport Fisheries and Wildlife, and from published range maps of Arizona I mammals.

Undoubtedly, an extensive trapping program would reveal additional mammals ■ not on the list, particularly among the small rodents. However, it is j l believed that the most important species are included in the list. Two animals, the mountain lion and the bighorn were included in the list am because they have been seen and reported in the area. However, they are I not residents, but rather are transients passing through from one moun­ tain range to the other. In 1969 four bighorn rams were found drowned in the canal at the northern end of the Mohawk Mountains. Apparently they ■ were moving from one mountain range to the next, fell into the canal and ™ were unable to get out. Mountain lions have been reported periodically in the study area.

I Muskrats are present and probably abundant in many areas holding permanent water along the Gila, especially those with cattails and rushes. At pres- ■ ent muskrat pelts do not have much value. Style changes in the future ■ could easily bring back an economic importance to this animal. At present its pelt is not valuable and it can even be a nuisance by its digging in _ unlined irrigation canals.

“ ' "Predator calling" is a significant sport in Arizona. Davis (1967) reported $735,000 spent by hunters in 1965 for predator and non-game animal hunting. I River channels form natural travel ways for fox, coyote, and bobcat. The ■ Gila is a popular area for this type of hunting, but no figures are avail­ able on the extent to which these lands are used for this sport.

I Rare and Endangered Species

_ The Yuma Clapper Rail is an endangered species (U. S. Bureau of Sport I Fisheries and Wildlife 1968) with a habitat localized along the lower * * Colorado River in alkaline cattail marshes and probably in the vicinity of the Salton Sea. The species also occurs and probably nests in the ■ cattail marshes of the lower Gila River. Channelization of the Colorado ■ River, flooding or draining of marshes in construction of reservoirs and increasing salinity or vegetation removal in the area of the Salton Sea I have resulted in a loss of habitat and a decline in the population. Pro- | tected areas have been set aside in the Cibola, Havasu Lake, and Imperial A I National Wildlife Refuges on the Colorado River. Elimination of cattail ■ marshes will be deleterious to this species.

30 The 8potted bat is a rare species (U, S. Bureau of Sport Fisheries and Wildlife 1968) and may be America’s rarest mammal. It is known in Arizona from only four specimens collected in Yuma and Maricopa counties (Lowe 1964). Extremely little is known about this species, but there is no evidence to indicate that the Corps of Engineers flood control proj­ ect will be deleterious.

Insect Populations ±

Time and resources did not allow an analysis of the insect populations which may be dependent upon the phreatophyte communities although a large population of cicadas did occur in areas of salt cedar in early August.

Domestic beehives are numerous in areas of phreatophytes adjacent to farmland and the flowering season of up to six months for salt cedar is conducive to honey production.

■<■' . ESTHETIC VALUES

Contemporary Recreational Use

The Gila River from Texas Hill to Gila Siphon contains at present no important recreational resources aside from hunting. Except for some fishing and picnicking by local residents, especially those from the lower socio-economic levels, use is limited to hunting almost exclusively

Fishing - There are several pools, according to local informants, that can be expected to contain water throughout the year. The pools are in a marshy environment and find their greatest current use as fishing holes for local residents. Carp and sunfish are found in these pools.

Hunting - The utilization of thickets for the production of doves which then provides recreational hunting for a large number of persons, some of whom come from some distance to hunt these doves, is a major potential use of the habitat. This is an important economic resource which is really unique in the United States. Additional sport hunting is obtained from the quail and cottontail rabbits abundant in the area. Waterfowl hunting is also important and could be made more so by habitat improve­ ment. .

Picnicking - At present, there are no formal picnicking areas directly associated with the Gila channel. Local informants suggest that there is some use of channel areas for picnicking by local residents in the spring and fall.

Education - With the great interest in environmental problems now current one of the important emphases is concerned with acquainting students with various facets of the environment. The habitats such as the cattail marshes could be made available to schools as outdoor biological labora­ tories. There are at least three high schools within easy reach of these areas. They are Yuma High School, Kofa High School, and Antelope Valley High School. Arizona Western College is also within easy reach of these areas. 31 Esthetics - Rivers which flow through arid areas are landscape features appreciated by both local residents and transients. Unfortunately, the lower Gila has little to recommend it in its current state. The predom­ inant vegetation type is salt cedar and arrowweed. These plants do not contribute to the riparian lushness that generally attracts people to rivers in the Southwest. Areas of standing water are, without exception, sluggish and offer little except modest opportunities for fishing or the chance to view birds and other wildlife including beaver and muskrat.

Archaeologic and Historic Sites

Investigation of archaeological resources that might be endangered by Gila River channel improvement plans of the U. S. A m y Corps of Engineers was first made in 1964. At that time the archaeological survey was extend­ ed east beyond Texas Hill to the Painted Rock Dam. Four conclusions were drawn from the results of this survey: 1) very few sites remained in the region between the Gila Siphon and Texas Hill, 2) site density was more than four times as great in the region east of Texas Hill, 3) none of the sites in the Gila Siphon - Texas Hill region would be directly endangered by the channel improvement project, and 4) site loss in the lower Gila Valley could be attributed almost exclusively to clearing land for culti­ vation.

Subsequent checking of archaeological remains in the lower 60 miles of the Gila River (including a visit made by the Environmental Impact Studies Group in June 1970) have reaffirmed the above conclusions. The most recent loss of a site (the Antelope Stage Station) appears to have been the result of quarrying operations.

The present lower Gila channel improvement project proposed by the Corps of Engineers will not directly endanger archaeological or historical remains. This may be attributed in part to the fact that channel improvement is de­ signed primarily for the channel area itself where few sites would exist. More important, however, is the fact that few sites remain in this area, a circumstance resulting from extensive cultivation.

Important historic and prehistoric sites between Texas Hill and the Gila Siphon are shown in Figure 4 and Table 7.

32 I I I TABLE 7

■ Historic and Prehistoric Sites

B Site or Type of Site ASM Number

m Gila City (historic Anglo town) Ariz. X:3:3

I Historic Anglo Refuse Dump Ariz. X:3:2

^ Historic Stage Stations

Antelope Ariz. X:8:6 ■ ■ Mohawk Ariz. X:l:2

g Historic Papago Villages Ariz. X:3:4 Ariz. X:8:5

Prehistoric Yuman Campsites Ariz. X;7:2 Ariz. X:8:l Ariz. X:5:3 Ariz. X:2:l A" Jm Petroglyph Sites Ariz. X:8:2 Ariz. X:8:3 Ariz. X:8:4 (Radium Hot Springs) Ariz. X:8:7 (Antelope Hill) f Ariz. X:2:2 (Texas Hill) I See following maps for location. I I I I I 32a 1 • FIGURE +

Historic and Prehistoric Sites

0 t g 3 4 Scot« tnmitt

ARIZ X:7 AR!Z X:8

Map of the Lower Gila River from Dome to Antelope Hill showing site locations in quadrangles Arizona X:3, X:7, and X:8.

From VIVIAN , 1968 LAND USE

Land Status

Much of the lower Gila River Basin north of the river lies within the Kofa Game Range which includes some 1,000 square miles in Yuma County. The area is administered by the Bureau of Sport Fisheries and W ildlife, U. S. Fish and W ildlife Service in cooperation with the Bureau of Land Management. The bighorn sheep population of the game range is estimated to be approxi­ mately 300. There is some grazing by domestic stock, but primary emphasis is on production of food for w ildlife, such as desert mule deer, many sm aller mammals, and b ir d s , includin g q u a il and doves. Palm Canyon, the habitat for native palm trees, along with other portions of the Kofa Moun­ tains offer spectacular scenery.

The remaining public domain lands along the Gila River downstream from the Phoenix metropolitan area, including the public domain bottomlands between Liberty and Texas H ill, have been classified for multiple use management by the Bureau of Land Management.

The land in the lower Gila River Basin is predominantly under public ownership. At this time figures were not available for the basin, but the following table for Yuma County shows the general ownership pattern (after Holland, 1967):

TABLE 8

Landownership Pattern, Yuma County

Designation Area Sq. Miles Percent of Total

Game Refuge 1,500 15.0 M ilitary 2,880 28.8 BLM 3,800 38.7 Indian 360 3.6 Other ___ 80 0 .9 All Federal 8,620 87.0 State of Arizona 650 6.3 P riv a te 715 6 .7 T otal 9,985 100.0

Except for the Yuma Metropolitan area and some Arizona State land bordering the floodplain, most of the land south of the Gila River is included in the Luke-Williams Air Force Range. The southwestern portion is included within the Cabeza Prieta Game Range which is closed to grazing by domestic livestock. The Air Force Range is subject to some grazing.

33 The area north of the Gila River not included in the Kofa Game Range lies within the Yuma Proving Ground of the U. S. Department of Defense. This area is closed to grazing but some of the testing underway results in land disturbances that might influence runoff and erosion. The principal community in the project area is Wellton, with a 1967 population of 600. Small trading centers exist at Roll, Tacna, Mohawk, and Dome. The area is traversed by the Gila and Phoenix branches of the Southern Pacific Railroad and by U. S. Highway 80-Interstate 8. Farmlands Yuma County farmers enjoy the highest income per farm in the nation. The climate of the area favors the growth of high-return specialty crops such as citrus, melons, and winter vegetables; short, mild winters and long, hot summers are conducive to high yields of cotton and alfalfa. Average gross return (1960) per cropland acre in Yuma County was $335; and the 1964-68 average for the Wellton-Mohawk Irrigation District was $300; com­ pared with this is $226 for Arizona and $123 for the United States. Although the area averages less than four inches of rainfall per year, water for irrigation is available from the Colorado River at low cost. Due to the advantage of a large pool of unskilled labor (largely immobile Mexican-American workers), farm labor costs are low compared to other areas of the United States. Yuma County farmers are in a very strong competitive position with other areas, and hence, are able to earn net returns which are among the highest in the nation. The bulk of farm income in Yuma County is derived from the sale of crops. The 1964 census of Agriculture reports that 77 percent of the $76.5 mil­ lion gross farm income for the county was due to the sale of crops and the remainder, or 23 percent, was due to the production and sale of livestock and livestock products. Principal field crops in descending order of acreage (1967) are alfalfa, short staple cotton, lettuce, cantaloupe and other melons, grain sorghum, barley, Bermuda grass seed, and wheat. Other field crops grown in lesser amounts are Sudan grass and other miscellaneous hays and grasses for pasture, and various winter vegetables. Some seed crops such as lettuce, beets, onions, sugarbeets and carrots are also grown. Safflower, long staple cotton, and flax have also been grown. Due to the mild winters and the rapid maturity of crops, there is considerable double-cropping and occasionally triple-cropping from the same land in the area. Barley, wheat, grain sorghum, lettuce and canta­ loupe are often double—cropped. Along with field crops, a substantial quantity of citrus is harvested annually within the area. Most of the citrus has been developed within the past nine or ten years. It was estimated that in 1965 there were about 24,000 acres of citrus in Yuma County as a whole.

34 Most of the faros in the District were established following the organization of the D istrict. Although farming in the District dates back well into history, irrigation water problems, flood problems, and other factors retarded the general development of the area. By 1940, 68 farm operators had organized the Mohawk Municipal Water Conservation D istrict. The Conservation District functioned until 1951 when it was taken over by the present Wellton-Mohawk Irrigation and Drainage D istrict.

In 1959 there were 168 full-time and 18 part-time farmers in the D istrict. Cropped acreage per farm ranged from 60 to 6,000 acres. Harvested crop­ land and pasture totaled 51,835 acres. The 1960 size distribution of farms based upon water contracts is shown in Table 9.

TABLE 9

Farm Size Distribution Based on Irrigable Acres Per Water Contract in 1960

Wellton-Mohawk Irrigation and Drainage D istrict

Acres No. of Contracts % of Total Farms

0 - 7 9 53 23 39 . 8 0 - 1 5 9 87

160 - 239 29 13 9 240 - 319 20

320 - 639 22 10

Over 640 13 6

Source: Luke B. Wishart and Aaron G. Nelson, Farm Adjustment Possibilities to Increase Income in the Wellton- Mohawk D istrict of Yuma County. Report No. 218, Agricultural Experiment Station, University of Arizona, Tucson, Arizona, 1963.

As indicated, climatic conditions are such that a variety of crops can be profitably grown in the D istrict. In general, however, alfalfa, cotton, barley, wheat and Bermuda grass seed are the principal crops and occupy the majority of the acreage. Specialty crops and citrus take up lesser acreage.

Analyses of the productivity of land resources indicate that current prices of agricultural real estate are in line with the earning capacity

35 of land resources. Large operators earn returns large enough to permit them to pay from $1,500 to $2,000 per acre for land. This price exceeds the capitalized income value which small farmers might expect on the basis of their returns. Since the price which expanding landowners are offering is above the earning power of land for small farmers, an active and viable land market prevails. The historical trend towards increased farm size through consolidation of existing farms, or through additions to present holdings may be expected to continue.

Transfer of land resources from small farmers to larger operators, either permanently or on a temporary basis only, would not result in increased farm revenues for the region as a whole. However, were such shifts in landownership to take place there would probably be no important changes in the gross value of farm output. The most important impact would be to reduce the number of farms in the area and to increase the average farm size.

Given present price ratios and levels of technology, and the limited opportunities for expansion of irrigated acreage because of limits on diversions from the Colorado it can be expected that irrigated agricul­ ture in western Yuma County will continue to yield attractive profits. Expansion of agriculture at the extensive margin, however, will be limited unless firm water supplies are increased.

Under present restrictions on diversions, reallocation of existing water supplies at the intensive margin may shift the cropping pattern from alfalfa to barley-sorghum (or conversely). However, as indicated, little change is to be expected in the gross value of agricultural output. To the extent that crops now limited by institutional factors or market con­ straints are not increased, or unless new high income enterprises enter the cropping program, the growth of irrigated agriculture in western Yuma County will be limited. Conversion of agricultural land into urban and suburban development is not to be foreseen within the near future. The future of the agricultural development hinges to a large extent upon mar­ ket conditions for the respective crops, and upon agricultural and farm policy programs administered by the Federal Government. Subsidy payment limitations and other trends in the direction of unsupported agriculture will play a significant role in the future development of the area.

INTERRELATIONSHIPS

Figure 5 shows an orthodox diagram of interrelations in the ecosystem with some additions that are often overlooked, but may be implied in an ecosystem as it relates to man. The ecosystem approach which relates all organisms to the environment in a reciprocal way, and in modern usage a quantitative way, offers the best basis for the evaluation of any impact on the environment. In a simple form the general relations within the ecosystem are shown in the following diagram:

36 FIGURE 5 INTERRELATIONS IN THE ECOSYSTEM I I Shlü I 3 P ESCAPE FROM BROUGHT INTO

ECOSYSTEM ECOSYSTEM IMPORTS L WATER IRRIGATION £ O. ki § ------> O r ^ ^ I I ^ I I ENVIROMENTAL Iran RESOURCES l S | ACCUMULATED -» SOLAR ENERGY WATER, MINERALS COjjOt ,HS0 a MINERALS AND SOLID WASTE 1I £53 I— _ j

CONSUMERS PRODUCERS PARASITES, HERBIVORES -* PHOTOSYNTHETIC AND CARNIVORES ORGANISMS

DECOMPOSERS SAPROPHYTES a SCAVENGERS Aerial Factors A

Plants Animals t Edaphic Factors

Any change in any of these factors will have an effect, direct or remote, on the other factors.

The ecosystem approach has been a powerful force tending to unify what is undoubtedly one of the most complex and diversified fields of science. . The ecosystem approach can be applied to small communities or area up to the earth itself with its atmosphere and all biological organisms. It can be used for stable units or those that are in a process of changing. It may be used in a specific kind of landscape unit or to express the abstract concept of relatedness (Daubenmire 1968).

In this approach man is as much a part of the ecosystem as any other organism, and the more he can be treated as a unit in the environmental complex, the more nearly will objective conclusions be reached as to the impact of various manipulations on the environment.

Man must be considered as a variable force that can be exerted in many different ways. To understand the interplay it is necessary to catalog all the ways in which man may affect or be affected by the environment. This means that for the lower Gila area we must consider man in relation to all water, whether it be water used for irrigation, flood water, or groundwater; the source of water imported or locally obtained; and the agreements for use of water locally, river basin-wide, or internationally. Flood water cannot be considered by itself, because it is only one item in the ecosystem and its effect on the environment is subject to its rela­ tionships to all other sources of water and the disposition of the water from these sources.

Actually, we are dealing with four "subspecies" of man: (1) The man who farms the land and attempts to control a segment of the ecosystem with some success, but causes mis-adjustments which he tries to offset by use of "imported" forces, e.g., pesticides, which may result in upsetting the ecosystem. (2) The man who changes the physical environment. He is the engineer who brings water to land that in the original ecosystem had little or no water; he also removes water that may have had its place in the pristine ecosystem, but does not fit in with man's attempt to modify the ecosystem. This may be surface or underground water. (3) The man who has carried the hunter instinct into the modern ecosystem. He may at the same time be a farmer, an engineer or an urban dweller, but what­ ever his occupation, he desires to push back the ecosystem to a state wherein wildlife would find a place. There are two recognizable varie­ ties, (a) the shooter, and (b) the man who provides the target for the shooter. And finally there is (4) the subspecies of man who has looked at the ecosystems of the past and found them good. He would like to

37 bring worldwide ecosystems back to where they were before they were warped by man, but failing in this he would like to preserve pieces of ecosystems in what he terms a "natural state."

The problem of ecological impacts is not one of an ecosystem without man, but rather one that must meet the various impacts of the "subspecies" on the ecosystem.

Man as a part of the ecosystem is predictable in many ways. He is looking out for his individual interests and finds it difficult to understand the viewpoint of others who would manipulate the ecosystem to their interest which might run counter to his. Hence we can be sure that there will be forces working in many directions.

It is impossible for our scientists to be competent in all field? represented in an environment. Even leaving out the physical sciences, the field is too broad for the individual scientist, and because it is impossible to obtain this competency and because we are products of envi­ ronment and heredity, we are prone to color our conclusions with a personal bias. Because of this, few biologists ever attain the breadth of the ideal ecosystem ecologist, and we therefore have to weigh their conclusions in light of their training, interests, and the personal quotient which is a rather complex thing.

EVALUATION OF ALTERNATE PROPOSALS

The Corps of Engineers report Gila River and Tributaries Downstream from Painted Rock Reservoir, Arizona, dated April 1, 1961, the material Scope of Work and Suggested Approach, dated April 16, 1970, the letter from the Chief of Engineering Division, dated 24 June 1970, and the memorandum from the Project Manager, Corps of Engineers, dated 23 June 1970, to the Direc­ tor of the School of Earth Sciences, University of Arizona, provide information regarding the authorized plan and alternatives and suggest an approach for evaluating the ecological impacts due to the proposed plans. (Copies in Appendix F.) All of these were supplemented by material pre­ sented at the 10 September meeting in Los Angeles. The alternatives were 'combined into seven plans with additional choices combining plans B and F .

A. Authorized plan 1961 report: 1,025 foot right-of-way, 750 feet between 18 foot high levees with 100 foot strip of vegetation permitted to regrow.

B. Modified authorized plan 23 June 1970 memorandum: 990 foot right-of-way, 750 feet between 18.5 foot high levees with 100 foot strips of undis­ turbed growth inside levees.

C. Modified plan: 1,000 foot right-of-way, 750 feet between 18.5 foot high levees, with 100 foot strips of undisturbed growth and marsh areas included inside and outside of levees.

U. Modified plan: *1,070 foot right-of-way, 750 feet between 22.5 foot high levees, with 215 foot strips of undisturbed vegetation inside each levee.

38 E. Modified plan: cleared floodway with 720 foot right-of-way and 450 foot floodway between 20 foot high levees.

F. Undisturbed growth with a 1,500 foot right-of-way and 1,200 feet between 20 foot high levees.

G. Concrete-lined channel and levees with 400 foot right-of-way and 250 feet between levees.

H. 23 June a lte r n a tiv e s : 1. Plan B entire length. 2. Plan B Texas Hill to 5th St. and plan F 5th St. to Gila Siphon 3. Ponded areas

Sketches illustrating plans A to G are included in Appendix E.

The alternatives would differ in their impact on agriculture to the extent of acreage taken out for right-of-way, and amount of ponded areas and phreatophytes retained outside of the levees. Plan F with a 1,500 foot right-of-way would take out the most land and plan G the least. If phre- atophyte areas were maintained outside of the levees, there would be little difference among the various alternatives. As shown in Table 10, 5,749 acres of salt cedar and mesquite, 66.5 acres of open water and 81 acres of cattails lie outside of a 1,000 foot right-of-way. It is not certain to what extent these w ildlife areas would be retained in competition with agriculture, after the flood control program gives protection to lands not now farmed because of flood danger.

These plans would have the following advantages:

I. Farmland and irrigation and drainage works would be protected from flood damage.

2. From the infrequent larger releases from Painted Rock Reservoir and flood runoff from the lower tributaries to the Gila River, a larger quantity of good quality streamflow will reach the Colorado River which would help alleviate the international water problem.

3. Less infiltration will result which would help alleviate the ground- water problem.

4. Controlling floods could protect and stabilize wildlife habitats.

Possible disadvantages would be:

1. Habitat will be reduced due to clearing of the phreatophytes.

2. Removal of phreatophytes will result in less transpiration and hence the increase in groundwater may more than nullify the decrease due to less infiltration because of the cleared channel.

With regard to Scheme C, the marsh area o u tsid e the lev ees would be very valuable for habitat. This area could be fostered by either lining or

39 TABLE 10 i » • • • • i Acreage of salt cedar/mesquite, open water and cattail marsh in ; the floodplains, outside a 1,000 foot right-of-way, and remain- 1 ing between levees under various flood control alternatives.

Salt cedar/Mesquite Open Water Cattail Marsh 5th St. to Texas Hill 5th St. to Texas Hill 5th St. to Texas Hill Total Total Total to 5th St. Gila Siphon to 5th St. Gila Siphon to 5th St. Gila Siphon

Present in 18.0 142.0 floodplain 8,269 714 8,983 70.0 49.0 119.0 124.0

Outside 1,000 foot right-of- 73.0 8.0 81.0 way 5,397 352 5,749 47.0 19.5 66.5

Plan A, B, . 11.0 2.5 13.5 and C 594 71 665 6.5 4.0 10.5 16.0 3.0 19.0 Plan D 1,248 159 1,407 13.0 13.5 26.5 None None Plan E and G None None None None None None None 57.0 11.5 68.5 Plan F 3,396 417 3,813 26.5 33.0 59.5 excavating below the water table. Plastic lining could be used for smaller ponds and the result would be a natural looking lake filled with a marsh-type vegetation.

Plan G would certainly alleviate the problem with regard to the rise in the groundwater table with releases of water from Painted Rock Reser­ voir. The plan would also assure the largest quantity of good quality streamflow reaching the Colorado River. However, a lined channel would be overly expensive, and certainly not acceptable to conservation groups.

Because nearly two thirds of the salt cedar and mesquite acreage lies outside of a 1,000 foot right-of-way, the variation between alternatives becomes of less importance as far as effects on vegetation are concerned. Itl addition, over half the open water and cattail areas are outside of. a 1*000 foot right-of-way. The impact on vegetation and animal life will still vary to some extent as shown in Table 10.

Communities with salt cedar and mesquite or cattail marsh are of primary concern because of the wildlife they support. An analysis of vegetation maps indicates that about 714 acres of salt cedar and mesquite, 49 acres of open water, and 18 acres of cattail marsh are found in the floodplain from 5th St. to the Gila Siphon (Figure 6).

Plans A, B, and C would include between the levees only about 71 acres of what is presently salt cedar and mesquite, 4 acres of open water, and 2.5 acres of cattail marsh. Plan C would provide additional marsh area outside the levees. Plan D would include about 159 acres of salt cedar and mesquite, 13.5 acres of open water, and 3 acres of cattail marsh. Even under plan F, a considerable amount of habitat, including about 16 acres of open water and 6.5 acres of cattail marsh, would be left outside of the levees or eliminated because of the 300 foot width of levees; however, about 417 acres of salt cedar and mesquite, 33 acres of open water and 11.5 acres of cattail marsh would be included under plan F. Plans E and G include none of these habitats.

Host of the ponded area in the vicinity of 30th Avenue would fall within the proposed levees under all plans except plan G (Figure 7); therefore, evaluation as an outside ponded area is inappropriate. Under plans A, B, and C, about 22 acres of salt cedar and mesquite, 4 acres of open water, and 1 acre of cattail marsh would be included between levees. Under plan D the acreage would be about 42.5, 8.5, and 1.5 respectively. In the vicinity of 39th and 42nd Avenue, all present ponded areas fall outside the proposed levees under all plans except for a small amount of cattail marsh near 42nd Avenue (Figures 8 and 9).

The floodplain from Texas Hill to 5th St. includes about 8,269 acres of salt cedar and mesquite, 70 acres of open water and 124 acres of cattails at the present time. Plans A, B, and C would include between levees about 594, 6.5, and 11 acres, while plan D would include about 1,248, 13, and 16 acres respectively. Plan F would include about 3,396 acres of salt cedar and mesquite, 26.5 acres of open water, and 57 acres of cattails with much of the remaining marsh area contained outside the proposed levees in ponded areas at 39th and 42nd Avenue.

41 Although cattail marsh and open water may be saved in strips under various flood control plans, changes in surface water levels because of channeli­ 0 zation may significantly alter or virtually eliminate these habitats. Because the construction expense may be relatively low, consideration should be given to excavating occasional pockets with a gradient above and below the water table where borrow is removed from the channel; cattail marshes will thrive in water less than one foot deep. Although silting may eventually modify such excavations, some pockets may persist as they do under present conditions. Extensive flooding might temporarily elimi­ nate some cattails, but the plants have repeatedly survived similar flooding under natural conditions. Creation of additional cattail marshes could actually improve present wildlife habitat conditions. The acreage of salt cedar and mesquite between 5th St. and the Gila Siphon is relatively small, but the salt cedar thickets are mostly dense. There is a question however if enough would be gained as far as white-winged dove habitat is concerned to warrant the extra cost for right-of-way under plan H. There are open water and cattail marshes of importance to aquatic birds and mammals which should be preserved if possible under one plan or another. A major problem that cannot be answered at present is how much land the farmers in the Wellton-Mohawk area are willing to allot to wildlife, and what agencies, if any, will maintain wildlife areas? It has been assumed that as soon as flood control levees were constructed the farmers would crop the land as close as possible to the levees. Some of this land is not suitable for cultivation and there might not be much of a problem. It is believed however that there will be a conflict of interests that will have to be resolved by agreement between the farmers and the wildlife in te re s ts . A possibility to offset the reduction of salt cedar, open water, and cattail marshes due to the flood control program would be to develop off­ setting habitats in the area between Painted Rock Dam and Texas Hill. At least' this should be given serious consideration in any wildlife manage­ ment plan for the reach of the Gila River below Painted Rock Dam. Plan E would have the advantage that herbicides could be used with less danger of killing other vegetation by drift, and it should be easier to maintain a clear channel because invasion would be impeded by levees. Because of the narrow rights-of-way requirements for plan E (720') and plan G (400'), a greater opportunity would be offered under these alterna­ tives for a comprehensive wildlife program outside of the levees through the combined cooperation of federal, state, and project agencies. This same opportunity is offered by the other alternatives, but to a lesser degree. Maintaining a clear channel may be rather expensive. The cost will vary with the quantity of plants and the composition of the stand. It will also vary with water table levels. If surface water stands for a month or six weeks, or if the water table is close enough to the surface so that the surface is constantly wet, conditions will be ideal for germination and

42 LEGEND

E3 CATTAIL MARSH COMMUNITY

□ SALTCEDAR - ARROWWEED COMMUNITY

P UNDIFFERENTIATED 0 1000 1000 1 __ I______I SCALE IN FEET

FIGURE & ■ GILA RIVER BETWEEN THE GILA SIPHON AND 5TH STREET LEGEND

0 CATTAIL MARSH COMMUNITY

D 8ALTCEDAR - ARROSWEED COMMUNITY 30 TH AVE. I □ UNDIFFERENTIATED

PROPOSED CHANNEL CENTER LINE

FIGURE 7

PROPOSED PONDED AREA, 30TH AVE. 39TH AVE.

PROPOSED CHANNEL CENTER LINE

FIGURE 8

PROPOSED PONDED AREA, 39TH AVE.

*

LEGEND

H CATTAIL MARSH COMMUNITY

11 SALTCEDAR -ARROWWEED COMMUNITY

□ UNDIFFERENTIATED

0 IOOO 2000 1 ------1______i SCALE IN FEET LEGEND

13 CATTAIL MARSH COMMUNITY

B SALTCEDAR -ARROWWSED N COMMUNITY

r □ UNDIFFERENTIATED

0 IOOO 2000 1 ______I______I SCALE IN FEET

42N D AVE.

41ST AVE 4

r PROPOSED CHANNEL CENTER LINE

FIGURE 9

PROPOSED PONDED AREA, 42ND AVE. establishment of seedlings. With a shallow water table vegetative propagation following mowing or cutting is more vigorous. This does not appear to be feasible on the Gila, below Texas Hill. But control of the water table at intermediate depths will influence the vigor of the stand; germination and establishment of seedlings and possible substitutes such as grass may help control the regrowth of woody phre— atophytes. The lowering of the water table will create a problem for fish and wildlife habitats. A high water table is essential for the maintenance of existing ponds. Because of the porous substrata it would be impossi­ ble to maintain ponds unless an impervious bottom were provided. In 1958 a 55 mile, 400 foot strip was cleared in the Gila River floodplain below Texas Hill (Frost and Hamilton 1960). Costs for undercutting ranged from $6 to $30 per acre depending on the amount of vegetation present. Raking and stacking added $7 to $16 more. The cost of burning was insig­ nificant. This control resulted in a 99 percent reduction in areal cover and 88 percent reduction in density. After one year the reduction in areal cover was 92 percent and density 72 percent. The areas with the highest initial cover produced the most regrowth. There was no relation­ ship between salt cedar control and soil type. The cost of undercutting mesquite is greater than for salt cedar. There are no data for other phreatophytes, but it is believed that the costs would be less than for salt cedar. In this area there was no reinvasion by any woody or bushy species other than salt cedar and arrowweed. Lowry (1966) reported on extensive studies for control of salt cedar in the Rio Grande Basin. His tests showed that salt cedar could be con­ trolled by mowing followed immediately with a spray application of eight pounds of silvex ester per acre in diesel oil. Stands were reduced as much as 83 percent. The use of herbicides is questionable in the lower Gila area because of the drift of herbicides from the channel area onto the strips that are to be maintained inside the levees. Lowry found that the most effective equipment for complete eradication of salt cedar was the root plow. Costs with this type of equipment ranged from $7 to $9.50 per acre. It would be easier to use herbicides with plan E because the levees would help control the drift. A rotary brush cutter was found to be effective for control of regrowth. This equipment when combined with revegetation with grasses may provide some utility as well as control (Powers and Hamilton 1961) . The impact of changes in bird habitats can be summarized as follows: 1. Any change in the existing habitats will modify the avifaunal composition and density. 2. The "most valuable" habitats now present are the cattail marshes, and salt cedar-arrowweed communities. Marshes are valuable because they contain an assemblage of birds unique in Southern Arizona (and marshes are diminishing in extent throughout the Southwest) . The tamarisk thickets support high densities of nesting doves, especially

43 white-winged doves. Doves are popular game birds and if their habitat is reduced elsewhere in the state the prime nesting habitat in the Lower Gila becomes more important. 3. The other five habitat types in the project area are not considered to be so important with respect to nesting birds. The species char­ acterizing them are not particularly unique and are found in adjacent areas or are widespread throughout southern Arizona. It should be emphasized, however, that these studies are based mainly on summer field work and we can only guess at the vise made of the area by tran­ sients or wintering birds. Many transients utilize the region, mostly thickets near water. Certainly some waterfowl winter here. Evaluation of the project's effect on these birds (transients and wintering) is difficult but as long as some thickets and water remain, the adverse effects will be minimal. 4. If the cattail marshes are destroyed, but are replaced by other cattail marshes, it is likely that the same nesting species would occur again in the area after a few years. It is very important, whatever the steps taken by the Corps, to insure the presence of some cattail marshes. One species, the Yuma Clapper Rail, is listed as an endangered species be­ cause of the reduction of marsh habitat. Other species could become rare also! Cattail marshes are very limited in extent anywhere in A rizona. 5. Little information is available on the specific characteristics that make a salt cedar grove suitable for colonially nesting doves. It is certain they must be over 15 feet tall but some thickets may have hun­ dreds of doves and other apparently suitable sites lack nesting doves. It is apparent that reduction of groves will reduce dove numbers. On the other hand, it is believed that if salt cedar thickets in the proj­ ect area are destroyed, the doves would use other thickets i_f they were available nearby. 6. No reliable quantitative information has been found as to what reduc­ tion in nesting of w’nite-wings would result from reduction in nesting area. There appears to be considerable variation in density of nest­ ing. Cottam and Trefethan (1968) report ranges in density of nesting in salt cedar stands on the Gila west of Phoenix from 16 to over 200 nests per acre. It is not known if the present nesting density repre­ sents the maximum for the area under consideration. The same authorities note that in Texas, citrus trees supply major nesting h a b ita ts. The impacts of the flood control program on people can be summed up as follow s: 1. The area holds little short-run or even intermediate-run potential for recreation (consumptive and non-consumptive users of wildlife excepted). a. The area is -esthetically unappealing. b. The local (include Yuma) demand for recreation areas is relatively modest. 44 c. Near term demands for recreation can be met by the Colorado River. Although the Colorado may be crowded during periods of peak use, there are still long stretches of river that are lightly used and await development. There is some need for camping areas, especially those catering to campers and travel trailers on Interstate 8. While Corps areas could be used, the needs of these transient campers could be met by a park in the town of Tacna or an overnight roadside r e s t . Overuse of ponded areas by tourists and recreationists would most likely destroy them. a. If developed for fishing the natural plant-animal relationships will be destroyed and a "fish farm" environment will be developed. b. If artificial ponds are created it should be done to facilitate good water management; recreation could be a fringe benefit. The original project was only authorized for flood control; however, recent changes in authorization require consideration of all phases of water management with regard to flood control, irrigation, drainage, maintenance of salt balance in the groundwater basin; the use of water for recreation and to sustain wet and dry habitats; and water require­ ments of international obligations both as to quality and quantity. The impact of the flood control program on the environment must take these aspects into consideration and the alternatives evaluated as to their relative impacts on the basis of good overall water management.

CONCLUSIONS

Im pacts o f No Program The environmental impacts of no program will be greatest for enterprises and activities related to agriculture and the occupancy and use of land to support rural and urban economies, and least for conservation of wild­ life and esthetic uses. Without flood control of any kind, the agricultural land in the floodplain is subject to inundation resulting in crop loss and damages through silta- tion. Bridges, roads, canals, buildings, and other improvements are also subject to damage. It was estimated by the Corps of Engineers (1969) that the proposed flood control project would prevent damages of $23,500,000 if a project design flood should occur. With uncertainties relating to flood protection, potential cropland in the lower portions of the floodplain is being held out of production. Because of high investment per acre within the Wellton- Mohawk Project, it is not economically feasible to produce low value crops

45 in vulnerable areas, and hence any damage will have to be borne by relatively high value crops. The capitalized income value of land is from $1,500 to $2,000 per acza (p. 36) with an average annual crop value of $300 per acre (p. 3 4 ).1 Without flood control, drainage problems are increased. In 1966 (p. 12), releases from Painted Rock Reservoir raised water levels sufficiently to become a point of concern. This was attributable partly to the growth of vegetation in the channel and resulting aggradation that retarded the flow to the Colorado River. Less infiltration would result from a clear channel. As pointed out in the Corps of Engineers Review Report (1961), the emergency costs and business losses resulting from small floods might be proportion­ ately larger than losses from floods of greater magnitude in some cases. The Wellton-Mohawk Irrigation and Drainage District Report (1965) estimated that a flow of 2,500 cfs along the Gila withip the district could rupture irrigation and drainage facilities that could disrupt irrigation in the entire district. There are also intangible losses including the loss of life, delay in the shipment of perishable products, isolation of a community, interruption of home life and other community activities, inconvenience caused by inter­ ruption of public utility services, diminishing property values because of fear of floods, and general lowering of community moral. There would be no immediate impact on wildlife since the lack of a flood control program would maintain the status quo. There could be future im­ pacts, however, because of flood damage to habitats. On the other hand, phreatophytes would benefit from high water tables resulting from retarded flows, and salt cedar thickets would probably become more extensive. At the same time, the average height of existing stands would increase and the cover would become more dense, thus providing more and better condi­ tions for nesting doves. Even if no program is initiated, changes will take place in the ecosystem. Because of clogging by phreatophytes, the channel will aggrade (p. 4), and unless the pumping program is accelerated, accumulation of salts will favor a change in vegetation toward more salt tolerant species (Table 4). The flood control program of the Corps of Engineers is only one of several potential force'' that may result in environmental changes that can alter the ecosystem, responsive as it is to total inputs, outputs and accumula­ tion of water, minerals, and solid waste (Fig. 5). The watershed below Painted Rock Dam will have some ecological influencé regardless of whether or not a program is initiated. The local drainage areas play an important role in floods and resulting siltation, and pro­ vide the major flood potential below Painted Rock Dam, which controls upstream floods. Because of the general pervious nature of the plains lPage numbers refer to this report unless otherwise identified.

46 and bajadas, however, the watershed can take the impacts of rainstorms with a minimum of disturbance to the upland ecosystem (p. 5) . Although the vegetation is sparse it does exert some stabilizing influence, so that if it were destroyed, siltation problems in the floodplain would be augmented.

Under no program, the aquatic habitats would be sustained subject to some management that would insure the maintenance of local high water tables and protection from human destruction. The principal endangered species in this area, the Yuma Clapper Rail (p. 30) and the dozen or more marsh species of birds, would be provided with a suitable habitat (p. 28).

This forecast is, of course, predicated on no or little change in present drainage practices within the Wellton-Mohawk District. A lowering of the water table, for example, could eliminate many of the present marsh and open water areas.

Impacts of Proposed Program

The impacts of the suggested program may have wide effects. There is first, the effect on floods, the primary justification for the program, the effect of flood control on the environment including the agricultural and urban economy, improvements of various kinds including farm struc­ tures and transportation facilities; the effect on the quantity and quality of the water supply, the water table, and underground storage; the effect on the channel in relation to its hydrological characteristics. The alternatives may increase or decrease vegetation or change its compo­ sition. Wildlife may be favorably or adversely affected, and even areas outside of the project may feel the effects economically or socially; and finally, there would be international implications in the flood control program.

Impacts cannot be measured in dollars alone. Social, psychological, and esthetic values enter into the picture very markedly. The impact also extends outward like waves caused by dropping a pebble in a still pond, with effects some hundreds of miles beyond the project area. Because of this, a major problem in evaluating local impacts is lack of ecological knowledge elsewhere. For example, how well are endangered species pro­ vided for outside the area, and what is the statewide or nationwide situation as to the present status and future of white-winged dove habi­ tats? It is known that white-winged dove habitats are being reduced elsewhere, but should this be taken into consideration in this area or should each area stand on its own merits? Because of lack of information we can evaluate impacts only in terms of the project area.

Another problem in evaluation is the positive and negative relationships. Phreatophytes are tremendous water users, depleting water supplies but providing the principal nesting habitat of white-winged doves; however, the bird population would be low if it were not for the grain crops, which are reduced by dove feeding. Salt cedar requires a high water table for its existence, yet it lowers the water table because of trans­ piration.

A7 Although the proposed project is only, concerned with flood control, the Impact on the environment by the proposed facility or its alternatives 0 can be evaluated realistically only on the basis of good overall water management practices in the area. Water management, with respect to flood control, irrigation, drainage, maintenance of salt balance in the groundwater basin, water for recreation, the ability to sustain wet and dry habitat, and to both quality and quantity of water required to satis­ fy international obligations needs to be optimized for the entire area under study.

For the purpose of discussion of the environmental impact of the proposed action, the original plan presented in the 1961 review report will serve as a general pattern. The alternatives discussed in this report differ mostly in degree rather than in major design changes.

The 1961 authorized plan provides for two compacted earth fill levees, the one on the right bank 49 miles and the left bank 50 miles in length with an average height of 18 feet. The channel width would be 750 feet with a cleared floodway of 500 feet. In the authorized plan, phreato- phytes would be allowed to regrow in a 100-foot strip inside each levee (alternatives would leave strips of undisturbed phreatophytes).

Since the project is designed to give full protection to land and improvements, it would have a favorable impact on both rural and urban communities. It should be pointed out that a very great advantage of a construction program would be in the control of fire, which has been one of the major problems in maintaining salt cedar stands (J. S. Horton, personal communication). In addition to protecting property, the progi'am would enable the Wellton-Mohawk Irrigation and Drainage District to make final allocation of land within the project.

From the standpoint of wildlife and particularly game birds, the proposed project would result in reduction of habitat area. The most valuable habitats are the cattail marshes and salt cedar-arrowweed thickets (p. 20- 22, 43) The extent of impact would be reduced by the portion of the floodplain ecological communities lying outside of the right-of-way. Based on a hypothetical 1,000-foot right-of-way, 64 percent of the salt cedar/mesquite communities, 56 percent of the open water and 57 percent of the cattail marsh would lie outside of the right-of-way. However, data released by the District (Thane Baldwin, personal communication) show 8,000 acres of non-allocated state and federal land in the channel area, much of it irrigable. This land could be sold and developed when the flood control program is consummated. This might be to the detriment of the wildlife, since there would be a tendency for farmers to occupy all land outside of the levees, thus reducing existing wildlife habitats. The greatest unfavorable impacts will be those to the native flora and fauna. The project plan would result in the clearing of some 800 feet within the right-of-way or almost 5,000 acres in a 50-mile stretch of the channel. This acreage is about one third of the "river bed and wasteland" within the Wellton-Mohawk Irrigation and Drainage District (p. 11). Some of this, however, is-presently bare ground; hence, the acreage of destroyed phreatophytes would be somewhat less than this amount. According to our ecological type inventory, the total phreatophyte acreage in the floodplain I

is 15,290 (Table 5, p. 20) and of this, 8,983 acres (Table 10, p. 40) have f c a salt cedar/mesquite cover of which 5,749 acres would lie outside a 1,000- foot right-of-way and 665 acres would remain in the 100-foot strips within the levees. This means a net loss of 2,569 acres or about 29%. It is not known what effect this reduction in white-winged dove nesting area would have on the dove population since the present number of nests per acre is unknown, but it is believed that the density of nesting might be increased (p. 44) if the food supply continues to be available.

A possible major impact would result if all or most of the land outside the right-of-way were cleared, thus removing up to two thirds of the salt cedar cover. This impact could be avoided if the land now occupied, by phreatophytes outside the right-of-way were set aside for wildlife use. This can be accomplished by joint action of the Corps of Engineers, the Bureau of Reclamation, the Wellton-Mohawk Irrigation and Drainage Dis­ trict, the Bureau of Land Management, the Arizona State Land Department, the U. S. Bureau of Sport Fisheries and Wildlife, and Arizona State Game and Fish Department, and interested groups and individuals.

On the basis of our ecological surveys it does not appear that there is much opportunity to increase the acreage of phreatophytes in the flood- plain outside the right-of-way, but it is possible that the salt cedar stands would be enhanced through management by providing habitats favor­ ing this aggressive species. This is largely a matter of manipulation of the water table and control of excess soil salts which might accumu­ late if river flows no longer flush them out.

Of the fauna, the white-winged dove is considered to be the most important because of the great numbers nesting in the salt cedar thickets. The importance of this habitat has been increased in recent years because of the reduction of suitable habitats elsewhere in Arizona (p. 32).

The impacts on the human population will vary with the needs and desires of those who might be affected by the proposed program (pp. 37-38). These would include the farmers and builders who would benefit by the program, and those using the area for enjoyment, recreation or game pro­ duction who might face problems of maintaining suitable conditions for their needs.

Any Adverse Environmental Effects Which Cannot Be Avoided Should the Proposal Be Implemented

The unavoidable adverse environmental effects are a result of the removal of nearly one third of the floodplain ecosystem, by the construction of 99 miles of levees and about 50 miles of cleared channel (both of these are reduced under proposed alternatives). The levees are sterile habitats with a potential for very little vegetation and little use by animal life. The channel will be maintained as free of vegetation as possible and hence will have a very reduced habitat value.

Some mitigation is possible through reduction in width and length of levees (there are some areas where levees may not be essential for flood control purposes) and through reduction in width of the cleared channel (suggested under alternatives D, E, and G).

49 Some mitigation can be achieved through the development of a comprehensive wildlife enhancement program outside the levees and through modification of channelization to provide ponded areas, either by excavation or cross dikes. Marshes and open water areas falling within the right-of-way could be replaced outside of the right-of-way by utilizing old oxbows and other low-lying areas (p. 41 and Figs. 6-9). It is believed that nesting species would move to these new habitats (p. 44) . Small basins could be lined to maintain water habitats if necessary.

An advantage to the hunter and the bird watcher would be the improvement in accessibility if roadways are maintained on the crest of, or adjacent to the levees. The cleared channels could also provide access for dune buggies.

Some mitigation may result from management of flows from Painted Rock Reservoir. It is possible to regulate to some extent the flow of rela­ tively clear water of low salt content in the area below Texas Hill in order to flush and recharge ponded areas, and also to manage the water regime above Texas Hill in order to provide offsetting habitats for white­ winged doves and aquatic species of birds and mammals.

In considering the adverse environmental effects, it should be kept in mind that substitution is possible within the floodplain ecosystem. The construction of levees and channels is not the only activity that reduces natural habitats; clearing and cultivation are also responsible for reduc­ tion,' while fire or drainage may alter local habitats. For a rational solution to the optimum management for the greatest good, it is necessary to consider all aspects of the ecosystem and to make adjustments that will achieve the greatest benefits in terms of production and satisfaction of human desires.

Alternatives to the Proposed Action

The alternatives under consideration include:

1. No comprehensive flood control program involving major structures.

2. The recommended proposal in the 1961 Review Report of the District Engineer for Flood Control, comprising levee and channel improvements along the Gila River from Texas Hill to the Gila Siphon. The plan provides for 99 miles of compacted earth fill, revetted levee, 49 miles on the right bank and 50 miles on the left bank. The channel would have a width of 750 feet, contained within a 1,000-foot right- of-way. A fringe of river bottom growth about 100 feet in width would be allowed to grow on the river side of the levees. (Plan A)

3. Alternatives proposed in the 23 June 1970 memorandum (copy in Appendix F) provided for two construction schemes:

Scheme A with construction of levees only (Plan F), and Scheme B, a modified plan with an excavated channel (Plan B).

y 50 The proposed alternatives are:

a. Scheme A for the entire reach of the project, Texas Hill to the Gila Siphon.

b. Scheme B for the reach of the project from Texas Hill to about 5th Street, and scheme A from 5th Street to the Gila Siphon.

c. In addition, three ponded areas outside the proposed levees to provide wildlife mitigation were mentioned, these to be located in the vicinity of 30th Avenue, 39th Avenue, and 42nd Avenue. Alternate conditions for ponded areas to be considered include:

1) Leave in natural state.

2) Create ponds by artificial water replenishment and lining to prevent infiltration.

• • 3) Provide public access to the areas for picnicking, etc.

4. At the 10 September conference a set of seven plans was presented. These include plans A, B, and F mentioned above and four additional alternatives:

C. Phreatophyte and marsh areas maintained within a 1,000-foot right-of-way and provision for marsh areas outside.

D. Strips of vegetation 215 feet wide left on the inside of levees with a 320-foot floodway and 1,070-foot right-of-way.

E. Cleared 450-foot floodway within a 720-foot right-of-way.

G. Two hundred fifty foot concrete-lined floodway within a 400-foot right-of-way.

These alternatives are discussed in some detail under Evaluation of Alternate Proposals (pp. 38-45).

Of the alternatives, those offering the least removal of vegetation appear to be most desirable ecologically, but they may not be economi­ cally feasible (p. 40). Plan B is an improvement over Plan A because the vegetation between the levees and the channel is not disturbed. Plan C adds additional wildlife habitat. Plan F provides for the least dis­ turbance of vegetation, but would require a right-of-way one and one half times as wide as that of the modified authorized plan. This raises the cost greatly and would decrease the amount of land available for crop production. Plan G with a concrete-lined floodway is also very costly, but it would have minimum requirements for right-of-way and would provide maximum efficiency for transporting floodwaters to the Colorado River without increasing groundwater problems. Very little would be gained by Plan H, which combines Plans B and F, except to maintain aquatic habitats below 5th Street, rather than replacing disturbed areas as might be done under the other alternatives.

51 These various plans Indicate a desire on the part of the design engineers to reduce undesirable impacts of the flood control program to the mini­ mum. Considering that much of the natural habitat lies outside of the right-of-way and that all plans include substantailly the same area of levees, there is not a great difference among the various alternatives; however, it is important that the minimum disturbance compatible with adequate flood control and costs should be the major aim of the program. The Relationship between Local Short-Term Uses of Man’s Environment and Maintenance and Enhancement of Long-Term Productivity Although projected growth for Yuma is one and one half times the present population, it is not expected to expand toward the east. None of the small towns within the Weliton-Mohawk Project is expected to expand mate­ rially nor is any great rural development anticipated. On the basis of present knowledge there will be little if an^ reduction in acreage of farms and hence the longtime use within the área is expected to follow the present pattern with possibly an expansion of recreational uses and the development of trailer courts and homes for winter occupance. The hunting pressure will increase as other game production areas are reduced or eliminated. Greater use will be made of the area by student biologists, amateur naturalists, and lovers of sunshine and open spaces. As water for irrigation becomes more limited because of demands for agriculture, domestic, and recreational use, the value of cropland with an assured water supply and adequate flood protection will become greater. The WeiIton-Mohawk Project area will be a highly considered area for agricultural production. Because of the future needs, the short-term use of the area should be geared to the maintenance and enhancement of long-term productivity of the entire ecosystem and its major ecological communities, the non- cultivated floodplain, the upland and the farmland (p. 16). The combined communities making up the overall ecosystems should be considered together, with each taking its proper place in providing the maximum benefits to mankind. This means that, as far as possible, wildlife and agricultural activity should be integrated so that neither prospers at the expense of the other. Flood control is essential for urban and agricultural stabili­ zation, but this should not be accomplished without consideration of the other needs of man. The Gila River below Painted Rock Dam offers an outstanding opportunity for the practice of ecology. Here is a place where cooperation, under­ standing, and mutual consideration can be used to reconcile what at fir’st glance may appear to be completely conflicting interests. The solution of the problems will require a complete ecosystem approach based on natural laws rather than subjective bias. In the long run, it will involve more than flood control, since all land and water uses are closely related (pp. 38-39). The proposed project should provide both short- and long-term enhancement of the complex social, economic, and international factors related to agricultural productivity in the community. There will be a short- and long-term negative impact on floodplain biological communities insofar 52 as wildlife productivity and related hunting recreation is concerned, even though these communities are only partially wild and natural. However, maintenance and enhancement of wildlife habitat outside the proposed right-of-way would significantly reduce the long-term negative impact on hunting recreation and partially replace the lost area which might provide for nature appreciation and other forms of recreation over the long term.

Any Irreversible or Irretrievable Commitments of Resources Which Would Be Involved in the Proposed Action Should It Be Implemented

The major irreversible and irreturnable commitments of resources have already occurred.

The present composition of the ecosystem has been greatly modified by man (p* 9). The river has changed to an intermittent flood-fed stream, and the floodplain has been altered from a natural riparian environment to a dry watercourse community. The original stands of cottonwood, willow, and mesquite have been destroyed and their place taken by shrubby natives and an exotic invader - the salt cedar. Successionally the vegetation has been reduced from a riparian climax to a displacement community which under present conditions appears to be relatively stable.

The important archaeological and historical sites have already been destroyed. Transportation systems have been located outside the project area» and there are few improvements that would have to be replaced.

The proposed flood control program will not worsen the situation materially, because the existing habitats that may be lost can be replaced. Some open water and marshland will be destroyed and the total acreage of salt cedar decreased, but these losses can be offset by re­ placements outside of the flood control structures. Even the replacement of cottonwoods, willows and mesquites is attainable under a comprehensive plan of management. The biggest irreversible item may be the opinions of those who think these things might not be done.

53 APPENDICES APPENDIX A

INDIVIDUALS AND ORGANIZATIONS CONTACTED

Thane Baldwin Wellton-Mohawk Irrigation and Drainage D istrict, W ellton, Arizona

Edward L. Brazeel Yuma County Highway Engineer, Yuma

Bud Bristow Arizona Game and Fish Department, Phoenix

Captain Alan Chapman Corps of Engineers, Phoenix

Chuck Christianson Phoenix Parks Director, Phoenix

Tom C la rk Interstate Stream Commission

Victor B. Cotton U. S. Weather Bureau, Yuma International Airport

Angelo Dalcerro U. S. Geological Survey, Yuma

Dennis Davis Economic Planning and Development

Richard Fisher U. S. Bureau of W ildlife and Sport Fisheries, P h o e n ix

Riley Foreman U. S. Bureau of Land Management, Arizona State Office, Phoenix

Howard Gillmore Maricopa County Parks Department

Robert Grounds County Agricultural Extension Service Office, Yuma

Robert Hembrode Arizona Game and Fish Department, Yuma

Jerome S. Horton U. S. Forest Service Hydrology Laboratory, Rocky Mountain Forest and Range Experiment Station, Tempe

Don Howell County Agricultural Extension Service Office, Yuma

Jerald Hutchins U. S. Forest Service, Tonto National Forest

Paul C. Kangeiser U. S. Weather Bureau, Phoenix Office

D. L. Krull U. S. Bureau of Reclamation, Yuma

Jim Lenert-z Biology Department, Arizona Western College, Yuma I John C. Lowry Flood Control D istrict, Phoenix I 55 Dennis Lunn U. S. Forest Service, Tonto National Forest 3 Ted Moser U. S. Bureau of Reclamation, Yuma

Dennis McCarthy Director, Arizona State Parks, Phoenix

F. J. McDonald Commission on Arizona Beauty, Phoenix

Ronald McKinstry U. S. Bureau of Wildlife and Sport Fisheries, Phoenix

Frank Pritchard University of Arizona Agricultural Experiment Station, Yuma

Hud Reynolds U. S. Forest Service Hydrology Laboratory, Rocky Mountain Forest and Range Experiment Station, Tempe

Ab Romeo U. S. Bureau of Land Management, Yuma

Marvin Skousen Soil Conservation Service, Phoenix

Cliff Tabor Wellton-Mohawk Irrigation and Drainage District, Wellton, Arizona

Gene Warren U. S. Bureau of Land Management, Arizona State Office, Phoenix

Ï.O-)

3

y 56 APPENDIX B

PLANTS FOR THE GILA RIVER BASIN BELOW PAINTED ROCK DAM BASED ON LITERATURE AND FIELD SURVEYS

(Alphabetically by Scientific Names)

Acacia greggii (1)* catclaw acacia Agave deserti desert agave AÍlenrolfea occidentalis (1) pickleweed (iodine bush) Amaranthus sp . careless weed Anisacanthus thurberi desert honeysuckle Aplopappus laridfolius turpentine brush Arundo donax (2) giant reed Aster spinosus (l) spiny aster Atriplex canescens (1)* four-wing saltbush (chamiso) Atriplex hymenelytra desert holly Atriplex lentifomris big saltbush (quail bush) Atriplex linearis (1)* linear leaf four-wing saltbush Atriplex poly carpa (1)* desert saltbush Atriplex semibaccata (1) Australian saltbush Baccharis emoryi (1) Emory baccharis Baccharis glutinosa (1) seepwillow Baccharis sarothroides (1) desert broom Baileya pauciradiata desert marigold Bebbia júncea var. aspera sweet rush bebbia Bouteloua aristidoides and B. barbata six weeks grama Brickellia atractyloides brickellia Bursera microphylla elephant tree Carnegiea gigantea saguaro Celtis pallida desert hackberry Celtis reticulata (1)* net leaf hackberry Cerddium floridum (1) blue paloverde Cercidium microphyllun little leaf paloverde Chilopsis linearis (1)* desert willow Coldenia paimeri Palmer coldenia Coldenia plicata desert mat coldenia Condalia lycioides graythorn Cucurbita palmata coyote melon Cynodon dactylon (1)* Bermuda grass Balea emoryi Emory dalea Balea schottii mesa dalea Balea spinosa (1)* smoketree Batura meteloides sacred datura

♦Terminology of both scientific and common names follows Kearney and Peebles (1960).

57 Dicoria canescens dicoria Dyssodia porophylloides dogweed Echinocereus engelmannii hedgehog cactus Echinomastus johnsoni beehive cactus Encelia farinosa white brittlebush Encelia frutescens bush encelia Ephedra trifu rca longleaf ephedra (Mormon tea) Ephedra v ir id is green ephedra Erio goman sp. wild buckwheat Ferocactus acanthodes bisnaga Fouquieria splendens o co tillo Franseria ambrosioides (1)* ambrosia bursage Franseria deltoidea triangular leaf bursage Franseria dumosa white bursage Gatium stellatum bedstraw Heliotropium curassavi aum (1) quail plant Heteropogon contortus tanglehead Hilaria rigida big galleta grass Hymenoclea monogyra (1) burrobrush Hymenoxys odorata (1) fragrant bitterweed Hyptis ernoryi Emory bushmint (desert lavender) Jatropha cuneata sangre-de-drago Krameria grayi white ratany Larrea tridentata creosote bush Lemaireoceveus thurberi organ pipe cactus Lycium andersonii desert thorn (Anderson wolfberry) Medicago sativa a lfa lfa Niaotiana clevelandii (1) tobacco Nicotiana glauca (1) tree tobacco Nicotiana trigonophyIla (1) desert tobacco Nolina bigelovii bear grass Olneya tesota ironwood Opuntia acanthocarpa buckhom cholla Opuntia basilaris beavertail prickly pear Opuntia bigelovii teddy bear cactus (jumping cholla) Opuntia echinocarpa strawtop prickly pear Opuntia kunzei Kunze cholla Opuntia leptocaulis Christmas cholla Opuntia ramosissima holycross cactus Palafoxia linearis palafoxia P ectis papposa chinchweed Petalonyx thurberi Thurber sandpaper plant Petunia parviflora (1) small flowered petunia Peucephyllum schottii pigmy cedar (Schotts sprucebush) Pragmites communis (2) common reed Pluchea sericea (1) arrowweed Polygonum argyrocoleon silversheath knotweed Polypogon sp. rabbit foot grass Populus fremontii (1) Fremont cottonwood Porophyllum gracile slender poreleaf Prosopis juliflora var. glandulosa (1) honey mesquite Prosopis juliflora var. velutina (1) velvet mesquite Prosopis pubescens (1) screwbean

58 Sàlix gooddingii (1) black willow Salsola kali Russian thistle Sapium bi.locu.lare jumping bean Sclrpus olneyi (2) bulrush Simnondsia ohinensis jojoba (coffee berry) Sphaeralcea emoryi desert hollyhock Suaeda torreyana (1) Torrey seepweed or inkweed Tamarix aphylla (1)* * athel Tamarix pentandra (gallica) (1) tamarisk (fivestamen) Tetraooccus hallii Hall fourpod spurge Teucrium cúbense var. depressum (1) germander Tidestromia lanuginosa tidestromia Trixis oalifomica trixis Typha domingensis (2) cattail Washingtonia filifera fan palm

(1) phreatophytes (2) hydrophytes * may not always occur as a phreatophyte

59 r. (Plants Listed Alphabetically by Common Name) alfalfa Medioago sativa arrowweed Pluohea sericea (1) athel Tamarix aphylla (1)* bear grass Nolina bigelovii bedstraw Galium stellatimi Bermuda grass Cynodon daotylon (1)* big galleta grass Hilaria rigida bisnaga Ferocactus aoanthodes black willow Salix gooddingii (1) brickellia Brickellia atractyloides bulrush Scirpus olneyi (2) burrobrush Hymenoclea monogyra ( l) bursage, ambrosia Franseria ambrosioid.es (1)* bursage, triangular leaf Franseria deltoidea bursage, white Franseria dumosa bush encelia Encelia frutescens cactus, beehive Echinomastus johnsoni cactus, hedgehog Echinocereus engelmannii cactus, holycross Opvntia ramosissima cactus, organ pipe Lemaireocereus thurberi careless weed Amaranthus sp. catclaw acacia Acacia greggii (l)* cattail Typha domingensis ( 2) chinchweed Pectis- papposa cholla, buckhorn Opuntia acanthocarpa cholla, Christinas Opuntia leptocaulis cholla, jumping (teddy bear cactus) Opuntia bigelovii cholla, Kunze Opuntia kunzei coldenia, desert mat Coldenia plicata coldenia, Palmer Coldenia paimeri common reed Pragmites communis (2) coyote melon Cucurbita palmata creosote bush Larrea tridentata dalea, Emory Balea emoryi dalea, mesa Dalea schottii desert agave Agave deserti desert broom Baccharis sarothroides (1) desert holly Atriplex hymenelytra desert hollyhock Sphaeralcea emoryi desert honeysuckle Anisacanthus thurberi desert marigold Baileya paucirodiata desert thorn (Anderson wolfberry) Lycium andersonii desert willow Chilopsis linearis (1)* dicoria Dicoria canescens dogweed Dyssodia porophylloides elephant tree Bursera microphylla Emory baccharis Baccharis emoryi (1) Emory bushmint, (desert lavender) Hyptis emoryi ephedra, green Ephedra viridis ephedra, longleaf-(Mormon tea) Ephedra trifurca

60 fan palm Washingtonia f i l i fera fragrant bitterweed Hymenoxys odorata (1) Fremont cottonwood Populus fremontii (1) germander Teucrium cubense var. depression (1) giant reed Arando donas (2) gray t h o m Condalia lyoioides hackberry, desert Celtis pallida hackberry, net leaf Celtis reticulata (1)* Hall fourpod spurge Tetraoooous h a llii ironwood Olneya tesota Jojoba (coffee berry) Simmondsia ohinensis jumping bean Sapium biloculare mesquite, honey Prosopis ju li flora var. glandulosa (1) mesquite, velvet Prosopis juliflora var. velutina (1) ocotillo Fouquieria splendens palafoxia Palafoxia linearis paloverde, blue Cercidium floridum (1) paloverde, little leaf Cercidiim miorophyllum petunia, small flowered Petunia parviflora (1) pickleweed (iodine bush) Allenrolfea oooidentalis (1) pigmy cedar (Schotts sprucebush) Peuoephyllum sohottii prickly pear, beavertail Opuntia basilaris prickly pear, strawtop Opuntia echinocarpa quail plant Seliotropium auras savi cum (1) rabbit foot grass Polypogon sp. Russian thistle Salsola kali sacred datura Datura meteloides saguaro Camegiea gigantea saltbush, Australian Atriplex semibaoaata (1) saltbush, big (quail bush) Atriplex lentiformis saltbush, desert Atriplex polycarpa (1)* saltbush, four-wing (chamiso) Atriplex canèscens (1)* saltbush, linear leaf four-wing Atriplex linearis ( 1) * sangre-de-drago Jatropina cuneata screwbean Prosopis pubesoens (1) seepwillow Baccharis glutinosa (1) silversheath knotweed Polygonum argyroooleon six weeks grama Bouteloua aristidoides and B. barbata slender poreleaf Porophyllum gracile smoketree Dalea spinosa (1)* spiny aster Aster spinosus (1) sweet rush bebbia Bebbia juncea var. aspera tamarisk (fivestamen) Tamarix pentandra (gallica) (1) tanglehead Heteropogon contortus Thurber sandpaper plant Petalonyx thurberi tidestromia Tidestromia lanuginosa tobacco Nicotiana clevelandii (1) tobacco, desert Nicotiana trigonophylla (1) tobacco, tree Nicotiana glauca (1) Torrey seepweed or inkweed Succeda torrey ana (1) trixis Trixis cali fornica turpentine brush Aplopappus la ricifolius

61 white brittlebush Encelia favinosa white ratany Krameria grayi wild buckwheat Eriogonum sp.

(1) phreatophytes (2) hydrophytes * may not always occur as a phreatophyte

62' APPENDIX C

BIRDS OF THE GILA RIVER AREA BELOW PAINTED ROCK DAM*

1. Positive record, Birds of Arizona 2. Implied, Birds of Arizona 3. Recorded by R. Todd or R. Hembrode in March, April, or May 1970 4» Recorded by S. M. Russell and R. R. Johnson, June 1970

Species 1 2 3 4 Comments

Grebe, Pied-billed* X X Nesting, June 1970

Heron, Great Blue* X X Green* X X X Probably nesting, June 1970 Egret, Common* X Snowy* X Night-Heron, Black-cm.* X Probably nesting Bittern, Least* X X Territorial and probably nest' Ibis, Wood* X ing, June 1971 White-faced* X

Swan, Whistling X 1846 Goose, Canada X Recorded in the 1840's Snow X 1840's White-fronted X Tree Duck, Fulvons X .. ~ ; C V “

Teal, Blue-winged X Cinnamon X Redhead X Bufflehead X Found dead Duck, Ruddy X Widgeon, American X

Vulture, Black X Turkey X X

Hawk, Ferruginous X Red-tailed X X Swainson's X X?

*Marsh birds Species 1 2 3 4 Comments

Hawk, Sharp-shinned X - Cooper's X Harris' X Marsh X Osprey X Falcon, Prairie X Hawk, Pigeon X • Sparrow X X

Quail, Gambel's x X X Nesting, June 1970

Sora* X X Rail, Clapper (Yuma)* X X Probably nesting, 1970 Virginia* X X Nesting abundantly, 1970 Gallinule, Common* X X Probably nesting, June 1970 Coot* X X Probably nesting, June 1970

Killdeer X X Nesting Plover, Mountain X t ■ Snipe, Common X ' • • . ' .V Curlew, Long-billed X Sandpiper, Spotted X X ■ ' ' l't •_ / Yellowlegs, Greater X . . r : • • Sandpiper, Least X Western X Avocet X Stilt, Black-necked X X Possibly nesting Gull, Sabine's X 1960 > Tern, Least X

Dove, White-winged X X X Nesting abundantly Mourning X X X Nesting abundantly Ground X X X Nesting abundantly Roadrunner X X

Owl, Elf X Short-eared X Common Screech X Ferruginous X Burrowing X X X • -

Poor-will X Nighthawk, Lesser X X X Species 1 2 3 4 Comments

Swift» White-throated X Vaux's X Hummingbird, Black-chinned X i U Costa's X Anna's X Rufous X Flicker, Gilded X Woodpecker, Gila X Lewis' X - . r' ' Ladder-b acked X X ’ • Kingbird, Western X X X Flycatcher, Ash-throated X X X Phoebe, Say's X X Flycatcher, Traill's* X Territorial, probably nesting, Gray X Tacna oxbow Pewee, Western Wood ‘ X X

Lark, Homed X X Swallow, Violet-green X . " ... Tree X X Roush-winged X X X .• :' Bam X C liff X X Nesting under bridges Bank X X Nesting Verdin X X X Nesting Wren, Bewlckis X Cactus X X Long-billed Marsh* X X Nesting Rock X Mockingbird X X X Thrasher, Bendire's X X Crissal X X X Curve-billed X ! , LeConte's X X Gnatcatcher, Blue-gray X Black-tailed X X X Kinglet, Ruby-crowned X Pipit, Water X

Phainopepla X X X Shrike, Loggerhead X X X

65 Species 1 2 3 4 Comments

Starling X X

Vireo, Bells X

Warbler, Orange-crowned X Nashville X Yellow X - »■ Audubon's X X %

Black-throated Gray X ' Townsend's X X Lucy's X

Mac Gillivray's X X ■ '* • ' - Yellow-throat* X X - Warbler, Wilson's X Chat, Yellow-breasted X ...... _ • ......

Sparrow, House X X - , •

Meadowlark, Western X X Blackbird, Yellow-headed* X X Nesting ; i v Red-winged X X X Oriole, Scott's X Hooded X Bullock's X Grackle, Boat-tailed X Cowbird, Brown-headed X X

Tanager, Western X X

Pyrrhuloxia X Grosbeck, Black-headed X Nesting marsh edges Grosbeck, Blue* X X

Finch, House X X X Goldfinch, Lesser X X X Lawrence's X Towhee, Green-tailed X X Towhee, Abert's X X Bunting, Lark X Sparrow, Vesper X Lark X Sage X Brewer's X White-crowned X Black-throated X Song X X X Nesting

66 :• •;.! >2 bse: y -r ‘ ■ '■ ~ ■' •' - V - •APPENDIX D . .... v.yi- ^

MAMMALS, FISH, AMPHIBIANS AND REPTILES FOR THE GILA RIVER AREA BELOW PAINTED ROCK DAM

Mammals

Order Chiroptera: Bats

Macrotus californieus , California leaf-nosed bat Myotis velifery cave myotis Myotis calif'om icus , C a lifo rn ia myotis Pipistrellus hesperus, western pipistrelle Euderma maculata, spotted bat ...... Eumops p e r o t is , greater mastiff bat

Order Lagomorpha: Hares and Rabbits

Lepus calif'om icus , black-tailed jack rabbit Sylvilagus audubonii, desert cottontail

Order Rodentiax Rodents , .1 .

Citellus karristiiy Harris antelope squirrel Citellus tereticaudus, round-tailed ground squirrel Thorrvmys b o tta ey valley pocket gopher ■ Perognathus arizonensis, pocket mouse Perognathus anrplus jackson i Perognathus baileyi domensis Perognathus penicillatus , desert pocket mouse Perognathus intermedius, rock pocket mouse Dipodomys m erriam iy Merriam's kangaroo rat Dipodomys d e s e r t i, desert kangaroo rat Castor canadensis, beaver Onychomys to rrid u s, southern grasshopper mouse Reithrodontomys megalotis, western harvest mouse Peromyscus eremicusy cactus mouse Peromyscus maniculatus, deer mouse Neotoma a lb ig u la , white-throated wood rat Ondatra zibethicusy muskrat Erethizon dorsatnm couesiy porcupine

Order C arnivora: Carnivores

Canis latrans, coyote Vulpes microtis, k it fox Urocyon dnereoargenteus, gray fox Bas saris cus as tutus yumanensis, r in g t a il Procyon lotory raccoon Taxidea taxust badger Spilogale putorius, spotted skunk y 67 Mephitis mephitis, striped skunk Lynx rufus, bobcat Feiis concolor, mountain lion

Order Artiodactyla:

Odocoileus herrtionus, mule deer 0vi8 canadensis, bighorn

Fish

Micropterus salmcides, largemouth bass Lepomis macroahirus, bluegill Lepomis microlophus, redear sunfish Cyprinus carpio, carp

Amphibians and Reptiles

Scaphiopus couchi, Couch’s spadefoot toad Bu/o cognatus, Great Plains toad Bu/b pvnctatus, red-spotted toad Bu/b alvarins, Colorado River toad Bona pipiensy leopard frog Bana catesbeiana, bullfrog Terrapene omata, western box turtle Trionyx spp., softshelled turtle (spiny) Gopherus agassizi, desert tortoise Coteonyx variegatus, desert banded gecko Catiisaurus draconoides, zebra-tailed lizard Holbrookia texana, southwestern earless lizard Sauromalus obesus, chuckwalla Dipsosaurus dorsalis, desert iguana Crotaphytus wisiizev.i, leopard lizard Crotaphytus coltaris, collared lizard Sceloporus magister, desert spiny lizard Urosaurus ornatus, tree lizard Uta stansbvriana, side-blotched lizard Urosaurus graciosus, western brush lizard Phrynosoma platyrhinos, desert horned lizard Cnemidophorus tigris, western whiptail Leptotyphlops hiunilis, western blind snake Phyltorhynohus deourtatus, spotted leaf-nosed snake Masticophis flagellum, red racer Salvadora hexalepis, western patch-nosed snake Pituophis■melanoleucus, gopher snake (Sonora) Arizona elegans, glossy snake Lampropeltis getulus, Yuma kingsnake Rhinocheilus lecontei, western long-nosed snake Sonora semiannulata, western ground snake Chionactis occipitalis, Colorado desert shovel-nosed snake Hypsi’glena torquata, spotted night snake Crotalus atroxt western diamondback rattlesnake Crotalus cerastes, sidewinder Crotalus scutulatus, Mohave rattlesnake

68 APPENDIX E

FLOOD CONTROL PLANS A - G \

AUTHORIZED PLAN

i ...... J A A*«rê3 * M 10 fc«t R/W 990' i

loo ' iMJiSturfaJ c^rovJ^H «G- 550' Inair\ta.in. a.S cleared -floodu>a.y

T 5' 1 av«r

MODIFIED AUTHORIZED PLAN

B

\ \ \ \

R/W lOOO’i

! OO1 ______5 5 û !______loo1 M ainfdiA ¿is cleared T i D o d u J Q y Marsh a x e a M arsh a re a , /fi------H

T

: •/ f “1 5 1 c I average v w /

c R/W 1070- t **\ R/W 7 i

450 ‘ fc'laú'vWr' «.5 c le a re d Fvoootiüoy

i ' > ' f

51 average' s- ■ WWW E \ \ /

r /W 1500* *

I 100 '

Existing -ê h 5 4 r la m b e d

u ■g Aa/ 4-00*Ì

G APPENDIX F

ALTERNATIVE PLANS, 23 JUNE 1970 -CÓPY-

DEPARTMENT OF THE ARMY LOS ANGELES DISTRICT, CORPS OF ENGINEERS P O* BOX 2711 los An g e l e s ’, c a l i f o r n i a 90053

in reply refer to SPLED-RE 24 June 1970

Director, School of Earth Science Geology Building, Room 120 University of Arizona Tucson, Arizona 85721

Dear Sir:

In reference to the scope of work for the Gila River below Painted Rock Dam Project (Contract No. DAGV09-70-C-0079), the alternative flood control improvements and specific areas that the Corps is considering for wildlife mitigation are provided for your use on the attached SPLED-DD memorandum of 23 June 1970 (Incl 1) and sketches "A" and "B" (Incls 2 and .3).

Overlays for the photographic mosaic (1"=2000' scale) showing the proposed channel alignment of the centerline are also provided (Incl 4, S sheets).

If you desire additional information, please contact Mr. Robert Joe or Lt. Torok, telephone 688-5459.

Sincerely

4 Incls EDWARD KOEHM as stated Chief, Engineering Division s/S. F. Cramer for Edward Koehm

77 -COPY-

DEPARTMENT OF THE ARMY LOS ANGELES DISTRICT, CORPS OF ENGINEERS P.O. BOX 2711 LOS ANGELES, CALIFORNIA 90053

1n reply refer to SPLED-DD - 23 June 1970

MEMORANDUM. FOR ENVIRONMENTAL SECTION - PLANNING UNIT

SUBJECT: Lower Gila River Ecology Studies

1. In accordance with an oral request the following schemes aTe furnished for ecological consideration. They represent two possible methods for satisfying wildlife mitigation. The considerations will be an objective determination as to the ecological impact of each on the project area. The schemes are designated as Scheme A and Scheme B. Typical sections illustrating these are attached.

a. Scheme A represents construction of levees only, with no channel excavation. Materials for construction of the levees would be obtained from sources outside of the levees.

b. Scheme B represents a modified plan with an excavated channel. The excavated material would be used for construction of the levees and possibly supplemented with borrow material fTom outside the levees.

2. Hie evaluations should be based on the following, as applied to the typical sections:

a. Evaluate Scheme B for the entire reach of the project - Texas Hill to Gila Siphon.

b. Evaluate Scheme B for the reach of the project from Texas Hill to about 5th Street. From 5th Street to the Gila Siphon, use Scheme A.

3. Evaluate three ponded areas that will provide wildlife mitigation for areas outside the limits of the proposed levees at three locations in the vicinity of: 30th Avenue; 39th Avenue and 42nd Avenue.

a. The three ponded areas should be evaluated as follows:

(1) Leave in natural state. (2) Create ponds by artificial water replenishment (pumps) and lining to prevent infiltration. (3) Providing public access to the areas fOT picnicking, etc.

' 79 -COPY-

SPLED-DD 23 June 1970 SUBJECT: Lower Gila River Ecology Studies

b. The ponded areas will require additional rights-of-way and therefore will add to the cost of the project.

4. Evaluate provision for ponded areas in the floodway (low flow channel). These could be provided by low dikes, 3 feet + high at locations to be recommended by the ecologist on the basis of critical needs. These ponds could be constructed by the Government during initial construction, however, they would be subject to loss by even minor flood flows. Replacement of the low dikes would be by someone other than the Federal Government.

JOHN AUMDNT, P. E. Project Manager

2 80 APPENDIX G

SELECTED REFERENCES

Arizona Bureau of Mines 1969 Mineral and water resources of Arizona. Arizona Bureau of Mines, Bulletin 180.

Arnold, W. 1942 The Western White-winged Dove in Arizona. Arizona Game and Fish Department Bulletin. 103 p.

Babcock, H., S. C. Brown, and J. Hem 1947 Geology and groundwater resources of the We lit on-Mohawk area, Yuma County, Arizona. U. S. Geological Survey, open-file report.

Babcock, H., A. Sourday 1948 Wellton-Mohawk area, Yuma County, Arizona. U. S. Geo­ logical Survey, open-file report.

Baum, B. 1966 Monographic revision of the genus Tamarix. Final Research Representative for the U. S. Department of Agriculture, Project A10-FS-9. Hebrew University, Jerusalem, Department of Botany. 193 p.

Brown, R. H., H. E. Thomas, J. W.. Harshbarger 1956 Analysis of basic data concerning groundwater in the Yuma area, Arizona. U< S. Geological Survey open-file report. 117 p.

Bryan, K. 1925 The Papago country, Arizona - a geographic, geologic, and hydrologic reconnaissance, with a guide to desert watering places. U. S. Geological Survey, Water-Supply Paper 499. 436 p.

Campbell, C. J. and W. A. Dick-Peddie 1964 Comparison of phreatophyte communities on the Rio Gran'de in New Mexico. Ecology 45:492-502.

Campbell, C. J. and W. Green 1968 Perpetual succession of stream-channel vegetation in a semiarid region. Arizona Academy of Science, Journal 5(2):86-98.

Cords, H. P. and Badiei 1964 Root reserves and susceptibility to systematic herbicides in two phreatophytes. Weeds 12(4):299.

81 I

Cot tant, C. and J. B. Trefethan (ed.) 1968 Whitewings. D. Van Nostrand Co. 348 p.

Culler» R. C., ei at 1970 Objectives, methods, and environment - Gila River Phreatophyte Project, Graham County, Arizona. U. S. Geological Survey, Professional Paper 655-A. 25 p.

Darton» N. H. 1933 Guidebook of the Western U. S. F:The Southern Pacific Lines, New Orleans to Los Angeles. U. S. Geological Survey, Bulletin 845.

Daubenmire , R. F. 1959 A canopy-coverage method of vegetation analysis. Northwest Science 33:43-64.

Daubenmire , R. F. 1968 Plant communities. Harper and Row, New York. 300 p.

Davis » C . 1967 Value of hunting and fishing in Arizona 1965. University of Arizona, College of Business and Public Administration Bulletin. 91 p.

Emory, W. m 18 A 8 Notes of a military reconnaissance from Fort Leavenworth in Missouri to San Diego in California. 30th Congress, 1st Sess., Senate Doc. 167.

Fletcher, . E. and G. L. Bender, eds. 1965 Ecology of groundwater in the southwestern United States - a symposium. AAAS, Southwestern and Rocky Mountain Division, Committee on Desert and Arid Zone Research, Contribution 5. Arizona State University, Tempe. 74 p.

Frost, K. R. and K. C. Hamilton 1960. Report on the Wellton-Mohawk salt cedar clearing studies. Arizona Agricultural Experiment Station, Report 193. 54 p.

Gary, H. L • i 1963 Root distribution of five-stamen tamarisk, seepwillow, and arrowweed. Forest Science 9(3):311-314.

Gary, H. Li • 1965 Some site relations in three floodplain communities in central Arizona. Arizona Academy of Science, Journal 3(4):209-212.

Gatewood, J. S., et at 1950 Use of water by bottomland vegetation in lower Safford Valley Arizona. U. S. Geological Survey, Water-Supply Paper 1103. 210 p.

82 Gordon, Y. 1970 Water management alternations for the Colorado River below Imperial Dam. University of Arizona (Ph.D. dissertation).

Gorsuch, D . M. 1934 Life history of the Gambel quail in Arizona. University of Arizona, Biological Science Bulletin 2. 89 p.

Green, C. R. and W. D. Sellers 1964 Arizona climate. University of Arizona Press, Tucson,

Halpenny, b. C . sf c£l* 1952 Groundwater in the Gila River Basin and adjacent areas, Arizona: A summary. U.- S. Geological Survey open-file report. 224 p.

Harris, D. R. 1966 Recent plant invasions in the arid and semiarid Southwest of the United States. Annals of the Association of American Geographers 56(3):408-422.

Hastings, .J. R. and R. M. Turner 1965 The changing mile. University of Arizona Press, Tucson. 317 p.

Heck, N. H . and R. A. Eppley 1958 Earthquake history of the U. S. I: Continental U. S., and Alaska. U. S. Department of Commerce, Coast and Geodetic Survey.

Helndl, L. and C. Armstrong 1963 Geology and groundwater conditions in the Gila Bend Indian Reservation, Maricopa County, Arizona. U. S. Geological Survey, Water Supply Paper 1647-A.

Holland, J • 1967 Yuma County 1985 comprehensive plan: Land use report. Prepared for Yuma County Planning Commission. Phoenix.

Horton, J. S. 1959 The problem of phreatophytes. Symposium of Hannoversch- Munden. International Association of Scientific Hydrology, Publication 48(1):76-83.

Horton, J. S. 1966 Problems of land management in the various phreatophyte zones. In Vegetation management on floodplains and riparian lands, p. 1-6. Phreatophyte Symposium 66-3 Meeting of Pacific Southwest Inter-Agency Committee. Albuquerque, New Mexico.

Horton, J. S.,-F. C. Mounts, and J. M. Kraft 1960 Seed germination and seedling establishment of phreatophyte species. U. S. Department of Agriculture, Rocky Mountain Forest and Range Experiment Station, Paper 48. 25 p.

83 í

Horton, J. ., T. W. Robinson, and H. R. McDonald 1964 Guide for surveying phreatophyte vegetation. U. S. Department of Agriculture, Handbook 266. 37 p. Hughes, E. 1965 Basal and stump sprays for control of salt cedar. Weeds 13:338-340. Hughes, E. 1966 Research in chemical control of various phreatophytes. In Vegetation management on floodplains and riparian lands, p. 19-23. Phreatophyte Symposium 66-3 Meeting of Pacific Southwest Inter-Agency Committee,. Albuquerque, New Mexico. Hughes, E. 1966 Single and combination mowing and spraying treatm ents for control of salt cedar (Tamarix pentandm P a ll). Weeds 14:276-278. Israelson, i. W. and V. E. Hansen 1962 Irrigation principles and practices. Wiley and Sons, New York. Kearney, T. H., R. H. Peebles, and collaborators 1960 Arizona flora. 2nd ed. University of California Press, Berkeley. Kino, E. F. 1948 Historical memoir of Pimeria Alta. Ed. by H. E. Bolton. University of California Press, Berkeley. Lewis, D. D 1963 Desert floods. Arizona State Land Department, Water Research Report 13. Ligner, J. J . , et d l 1969 Water resources. In Mineral and water resources of Arizona p. 471-580. Arizona Bureau of Mines, Bulletin 180. Lowe, C. H. , ed. 1964 The vertebrates of Arizona. University of Arizona Press, Tucson.

Lowry, 0. J • 1966 Establishment, operation and maintenance of phreatophyte control projects. In_ Vegetation management on floodplains and riparian lands, p. 26-36. Phreatophyte Symposium 66-3 Meeting of Pacific Southwest Inter-Agency Committee, Albuquerque, New Mexico. MacDougal, D. Tr 1904 Delta and desert vegetation. Botanical Gazette 38:44-63.

84 Marks, J. 1950 Vegetation and soil relations in the lower Colorado Desert. Ecology 31(2):176-193.

McDonald, . C. and G. H. Hughes 1968 Studies of consumptive use of water by phreatophytes and hydrophytes near Yuma, Arizona. U. S. Geological Survey, Professional Paper 486-F. 24 p.

Mainzer, 0 E. 1927 Plants as indicators of groundwater. U. S. Geological Survey, Water Supply Paper 577. 95 p.

Merkel, D. L. and H. H. Hopkins 1957 Life History of salt cedar (Tamax-ix gaZZica L.). Kansas Academy of Science, Transactions 60(4):360-369.

Monson, G. and A. R. Phillips 1964 Species of birds in Arizona. In C. H. Lowe, ed., The Vertebrates of Arizona, p. 175-248. University of Arizona Press, Tucson.

Moss, E. H 1938 Longevity of seed and establishment of seedlings in species of Populus• Botanical Gazette 99:529-542.

Parish, S. B. 1913 Plants introduced into a desert valley as a result of irrigation. Plant World 16:275-280.

Phillips, A. R., J. Marshall, and G. Monson 1964 The birds of Arizona. University of Arizona Press, Tucson. 212 p.

Powers, B. and K. C. Hamilton 1961 Revegetation of a cleared section of a floodway. Arizona Agricultural Experiment Station, Report 198. 23 p.

Robinson, T. W. 1958 Phreatophytes. U. S. Geological Survey, Water Supply Paper 1423. 84 p.

Robinson, T. W. 1965 Introduction, spread and areal extent of salt cedar (tamarix) in the Western States. U. S. Geological Survey, Professional Paper 491-A. 12 p.

Robinson, T. W. 1966 Evapotranspiration losses - the status of research and problems of measurement. In Vegetation management on floodplains and riparian lands, p. 7-18. Phreatophyte „ Symposium 66-3 Meeting of Pacific Southwest Inter-Agency Committee. Albuquerque, New Mexico.

85 (

Robinson, 1969 Areal extent of phreatophytes and hydrophytes in the Western States. U. S. Geological Survey, open-file report. 47 p.

Ross, C. P 1923 The lower Gila region, Arizona - a geographic, geologic, and hydrologic reconnaissance, with a guide to desert watering places. U. S. Geological Survey, Water-Supply Paper 498. 237 p.

Ross, P. 1921 Geology of the lower Gila region, Arizona: Shorter contributions to general geology. U. S. Geological Survey, Professional Paper 129-H.

Shantz, H. L. and R. L. Piemeisel 1924 Indicator significance of thé natural vegetation of the southwestern desert region. Journal of Agricultural Research 28:721-802.

Shaw, H. 1961 Influence of salt cedar on white-winged doves in Gila Valley. Arizona Fish Department, Game Management Division Special Representative. In Arizona Small Game Investiga­ tions, 1960-61-62. 9 p.

Shaw, H. . and J. Jett 1959 Dove nesting populations in the Gila Valley between Gillespie Dam and the junction of the Salt and Gila Rivers. Arizona Game and Fish Department Report.

Shreve, F. 1964 Vegetation of the Sonoran Desert. In F. Shreve and I. L. Wiggins, Vegetation and flora of the Sonoran Desert, vol. 1. Stanford University Press. 2 vols.

Smith, W. and W. L. Heckler 1955 Compilation of flood data in Arizona, 1862-1953. U. S. Geological Survey, open-file report. 113 p.

Sykes, G. 1937 Delta, estuary and lower portion of the channel of the Colorado River. Carnegie Institution of Washington, Publication 480. 70 p.

Sykes, G. 1937 The Colorado Delta. Carnegie Institution of Washington, Publication 460. 193 p.

Thomas, H 1962 The meteorologic phenomenon of drought in the Southwest. U. S. Geological Survey, Professional Paper 372-A. 43 p.

86 Turner, P. M. 1965 Annual report of phreatophyte activities. U. S. Bureau of Reclamation, Water Conservation Branch, Report WC-22. 39 p.

Turner, S. F. and H. E. Skibitzke 1952 Use of water by phreatophytes in 2,000 foot channel between Granite Reef and Gillespie Dams, Maricopa County, Arizona. Phreatophyte Symposium. American Geophysical Union, Trans- > actions 33:66-72.

U. S. Army Corps of Engineers South Pacific Division 1969 Water resources development in Arizona. San Francisco, California. 50 p.

U. S. Army Engineers District, Los Angeles, Corps of Engineers 1961 Review report for flood control, Gila River and tributaries downstream from Painted Rock Reservoir, Arizona, April 1, 1961. Los Angeles, California.

U. S. Bureau of Reclamation, Region 3 1963 Special studies: Delivery of water to Mexico. U. S. Department of the Interior. February 1963.

U. S. Bureau of Sport Fisheries and Wildlife 1968 Rare and endangered fish and wildlife of the U. S. Bureau of Sport Fisheries and Wildlife Resource Pub. 34. 130 p. van Hylckama, T. E. A. 1960 Measuring water use by salt cedar. 4th Annual Arizona Watershed Symposium, 4th, 1960, Proceedings, p. 22-26.

Vivian, R. G. 1965 An archaeological survey of the Lower Gila River, Arizona. Kiva 30(4):95-146.

Wellton-Mohawk Irrigation and Drainage District 1965 The proposed Gila River channelization. A Corps of Engineers flood control project sponsored by Yuma County and Wellton-Mohawk Irrigation and Drainage District. 7 p ., map.

Western Migratory Upland Game Bird Committee 1970 Report of the Western Migratory Upland Game Bird Committee No. 9. June 1970. 62 p.

Wilson, E. D. 1933 Geology and mineral deposits of southern Yuma County, Arizona. Arizona Bureau of Mines, Bulletin 132. 236 p.

Wilson, E. D. 1960 Geologic map of Yuma County, Arizona (scale 1:375,000) . - Arizona Bureau of Mines.

87 Wilson, E. 1961 Gold placers and placering in Arizona. 6th ed., rev. Arizona Bureau of Mines, Bulletin 168. 124 p.

Wilson, E. 1962 A resume of the geology of Arizona. Arizona Bureau of Mines, Bulletin 171. 140 p.

Wlshart, L. B. and A. G. Nelson 1963 Farm adjustment possibilities to increase income in the Wellton-Mohawk District of Yuma County. Arizona Agricultural Experiment Station Report 218. 26 p.

Youngs, F. »., et al 1929 Soil survey of the Yuma-Wellton area, Arizona-Califomia. U. S. Department of Agriculture, Bureau of Chemistry and Soils, ser. 1929, no. 20. 37 *p.

88 APPENDIX H

PROJECT PERSONNEL FOR ENVIRONMENTAL IMPACT STUDIES ON GILA RIVER BELOW PAINTED ROCK DAM

Stephen Bahre Reference Librarian Cartography

«*» Gordon Bender Professor Zoology, A.S.U. Animal Ecology - Recreation

William B. Bull Associate Professor Geology Geomorphology - Sedimentation

Brent Cluff Associate Hydrologist Hydrology Water Resource Research

• Gerald A. Cole Professor Zoology, A.S.U. Zoology

John C. Day Assistant Professor Land Use - Agricultural Economics Economic Impact

Lay James Gibson Assistant Professor Geography Recreation

Edward F. Haase Assistant Arid Land Ecologist Ecology

Paul Handverger Consulting Geologist Geology and Soils

John Harshbarger Professor Geology Hydrology - Inter­ national Relations

Charles R. Hungerford Professor Biological Sciences Animal Ecology

R. Roy Johnson Associate Professor Zoology Bird Population Prescott College

William G. Matlock Associate Professor Water Use - Percolation Agricultural Engineering

William G. McGinnies Arid Land Ecologist Ecology - Project Leader

Sol Resnick Associate Director of Hydrology - Water Resources Research Project Manager

Stephen M. Russell Associate Professor Bird Ecology Biological Sciences

Richard G. Vivian Assistant Archaeologist Archaeology - Antiquities

James H. Zumberge Director, School of Project Advisor Earth Sciences

8? 3 ADVISORS OF ENVIRONMENTAL IMPACT STUDIES ON GILA RIVER BELOW PAINTED ROCK DAM (WITHOUT COMPENSATION)

Bryant Bannister Director Tree-Ring Dendrochronology Laboratory

James R. Hastings Associate Professor Climatology - Atmospheric Sciences Ecology

J. S. Horton United States Forest Phreatophytes Service - A.S.U.,Tempe

David Thorud Professor Watershed . Watershed Management Management

Raymond M. Turner Ecologist - U. S. Plant Ecology Geological Survey

1

90 APPENDIX I

ORGANIZATIONS AND PROCEDURES

The program was set up under the auspices of the Office of Arid Lands Studies in the School of Earth Sciences under general supervision of James H. Zumberge, Director, School of Earth Sciences. Sol Resnick, Associate Director of Water Resources Research Center, was designated Project Manager for the entire study and Leader for the Phoenix Project. William G. McGinnies, Arid Land Ecologist in the Office of Arid Lands Studies, was designated Leader for the Gila Project and senior ecologist for both projects.

Consultants and advisors were selected from various disciplines within the University of Arizona, Arizona State University and Prescott College, and from various federal organizations. A complete list is appended.

A general outline for the study was prepared and a meeting was held at the University on May 18, to acquaint the participants in the program. Each was furnished background material and a schedule.

Scheduled flights of chartered planes were arranged for three groups of five each. In each case the plane flew at a low altitude from Painted Rock Dam to Yuma where a car was rented and a ground tour was made through the project area to Texas Hill and return to Yuma. On the return trip, the plane flew along the Gila River to Texas Hill. The groups included:

May 27: Raymond M. Turner, Sol D. Resnick, W. G. Matlock, Edward F. Haase and W. G. McGinnies

June 3: John Day, Brent Cluff, Valmore C. LaMarche, Stephen Russell, and Edward F. Haase

June 12: William Bull, Paul Handverger, John Harshbarger, Richard Vivian and Brent Cluff

For trips 2, Haase, and 3, Cluff served as trip managers and coordinators. In addition to these trips, Resnick, Haase, and McGinnies spent June 4th and 5th in the area consulting with local agency representatives. Gordon Bender and Lay Gibson spent June 3 and 4 in the area on zoology and rec­ reation. Russell and Roy Johnson spent June 10 to 12 checking on bird populations with special attention to those found in water habitats. Haase spent June 23 to 26 in the area collecting representative plants, photographing habitat sites, conducting ground checks for analysis of vegetation, and consulting with local agency representatives. Handverger spent two days in the field and additional time in the laboratory on geol- ogy and sedimentation. Gibson spent July 13 to 16 in Phoenix, partly for Gila River consultations. Cluff spent July 21 to 25 in Boulder City,

91 v- \ Nevada and Yuma to obtain watershed information for the drainages entering the Gila River below Painted Rock Dam; July 22 to 24 and July 31 to August 1 in the Yuma area collecting records and examining watersheds by helicopter. Haase made a ground and helicopter check on vegetation JulJ 22 to 24 and August 3 and 4. People and organizations contacted are listed in Appendix A.

A progress report (Phase I) was prepared and mailed to the Corps of Engineers 11 July 1970. This was discussed in Los Angeles 27 July 1970 by Besnick, Cluff, and McGinnies. It was revised and additional matter added including preliminary evaluations and resubmitted 21 August 1970 (Phase II Report). This was reviewed in Los Angeles 10 September 1970 with Zumberge, Resnick, Cluff and McGinnies representing the contractor. Following this meeting, extensive revisions have been made, the evalu­ ations augmented and conclusions were added for the final draft (Phase III).

This was reviewed 6 October 1970 in Los Angeles by personnel of the Corps of Engineers with McGinnies representing the University of Arizona. Following this review a final draft was prepared and submitted 23 October 1970.