The River The

' ' ., , A NATURAL MENACE BECOMES A NAT IO NA L R ESOU R CE

A Comprehensive Report on the Development of the Water Resources of the Colorado River Basin/or Irrigation, Power Production, and Other Beneficial Uses in , , Colorado,,, , and

By THE UNITED STATE ' DEPARTMENT OF T H E r l TEH I R

J. A . Krug, e retary

SPONSORED BY AND PREPARED U ; DER THE GENE R A L SUP EHVJSJO OF T H E BUREAU OF RECLAMATION

M ichael W. Straus, Commissioner

E. A. Moritz, Direc tor, Region 3; E. 0. Larso n, Direc tor, Region 4

MARCH 1946 HIS edition if THE COLORADO RIVER is issued in advance if its publication as a Congressional T Document in response to an urgent public demand for copies, many if them for qfjicial review . Y.he document has not been transmitted to the Congress for consideration, nor will it be, until certain States and Federal qfjicials who are now reviewing it have added their written comments to the text that appears here . When the report is published as a Con­ gressional 'Document these comments will be included, or will appear in a supplementary volume. Contents

Page PROPOSED REPORT OF THE SECRETARY OF THE Explora tions 46 INTERIOR Settlement . 48 Page Popula tion . 49 Letter of June 6, 1946, from the Acting Commissioner, Chapter III. D IVIDING T H E v\' A TER 53 Bureau of R eclam ation ...... 3 Virgin Conditions 55 REGIONAL DIRECTORS' REPORT Early D evelopment of the R iver . . 56 Summa ry of Conditions in the Early 1920's 59 M ap of Colorado River Basin Facing 9 Between the U pper and Lower Basins 59 Scope and Purpose . . . . . 9 Between U nited Sta tes and M exico 66 Authority for the R eport . . . 9 Chapter IV. D EVELOPI NG THE B ASIN 69 Cooperation and Acknowledgments 9 Description of Area . 10 Upper Basin . . . 72 72 Problems of the Basin 11 La bor Force 73 W ater Supply 12 Land Ownership and Use Div ision of W ater 13 Soils ...... 73 Fu ture Development of W a ter R esources 13 Agriculture . . . . . 73 T able I , Present and Potential Stream Depleti ons in M inerals and Mining 80 the Colorado River Basin ...... 14 Lumbering . . .. 85 Potential Projects ...... 14 M anufacturing . . . 86 T a b\e II, Potential Projects in the Colorado River Transporta tion and M arkets 86 Basin ...... 15 R ecreation 87 Table III, Poten tial Irrigation Development . . . 18 Lower Basin . 89 Table IV , Potential Power Development . . . . . 18 L and U se 89 Summary of Annual Benefi ts and Costs of Poten tial Agriculture 91 95 p~ ~~ ...... 18 Minerals and M ining Extended Benefits to the vV es t and to th e Na tion 18 11anufacturing and Other Industries 97 R eimbursement and Flood Control Alloca tion . 19 M a rkets and Transporta tion 98 Construction Program 20 Wholesale and R eta il Trade 99 Related Investigations 20 R ecreation . . . 100 Conclusions . . . 21 Summa ry-Colorado River Basin 101 21 Recommendations. . Chapter V. Usi NG T HE W ATER 105 SUBSTANTIATING MATERIAL Upper Basin ...... 107 Green Division ...... 109 FoREWORD . . 25 Present Development of W ater R esources 109 113 Chapter I. THE N AT UR AL SFTTING 29 Potential Development of Water Resources Grand Division 124 Physical Characteristics . . . 31 Present Development of Water R esources . 125 Geological History . . . . . 39 Potential Development of W ater R esources 130 Native Plant and Animal Life. 39 San .Juan Division ...... 139 Climate 41 Present Development of W a ter R esources . 140 Chapter II. CLAIMING THE BASIN 43 Potential Development of Water R esources 142 Primative Peoples . . . . 45 Summary-Upper Basin ...... 150 III IV THE COLORADO RIVER

Page Page Lower Basin . . 152 Forest Service 271 Little Colorado Division 152 National Forests and Reclamation in the Colorado Present Development of Water R esources 154 River Basin 2] 1 Potential Development of Water R esources 155 Federal Power Commission 273 Virgin Division ...... 157 Power Resources of the Upper Basin 273 Present Development of \!\Tater R esources 158 Power Resources of the Lower Basin 274 Potential Development of Water R esources 159 Boulder Division ...... 161 Appendixes Present Development of Water Resources 164 Appendix I. \!\Tater Supply, Colorado River 279 Potential Development of Water R esources 168 Index to Projects, Existing and Potential 287 G il a Division ...... 172 Index to R eservoirs and Reservoir Sites 291 Present Development of \Vater Resources 174 Appendix II. Eleven Maps 29 5 Potential Development of \ 1\T a ter R esources 179 Summary--Lower Basin . 183 Photographs Summary- Colorado River Basin 184 Frontispiece (, Arizona). Facing '3 Chapter VI. PowER FROM W ATER 187 Boulder D am 24 Upper Basin . 189 .Junction of the Green and Colorado Rivers 32 Present Power Development 190 Bow-Knot of the Colorado River 32 Power Market Survey and Load Trend 193 Black Canyon of the : 35 Potential Power Development 195 Goosenecks of the San Juan. 37 Summary 196 Long-range view, Grand Canyon 37 Lower Basin 197 Desert flora 40 Power Area 197 Desert scene 40 Present Power Development 198 Canyon country. 47 Power Market Survey and Load Trend 202 , an early reclamation development on Potential Power Development 204 Colorado River 57 Summary ...... 205 Near Lee Ferry, the dividing point 61 Summary- Colorado .River Basin 206 Herefords on the range near Moab, Utah 75 H ay harvest on Eden project, Wyoming . 75 Chapter VII. WEALTH FROM WATER 209 Peach orchard near Grand Junction, Colorado 77 Benefits to the West and to the Nation 213 Tomatoes from Grand Valley project 77 Summary of Costs, Benefits, and Repayment 218 Coal mine near Sunnyside, Utah 81 Lead-silver mine . 81 Chapter VIII. CooPERATING I NTERESTS IN TI-IE Gold mine .. 81 BASIN 221 Utah Oil Refining Company 82 Geological Survey 223 Outdoor life . 87 Quantity and Quality of Water 223 Rod and reel 88 U pper Basin . . . 224 Milch cows in irrigated pasture 90 Lower Basin 232 Irrigated sugar beets grown for seed 90 National Park Service 238 Winter vegetables for Eastern m arkets 92 Water Utilization Program 239 Skiing on Surveyor Peak . 101 Summary 249 Angler's pride 101 Fish and Wildlife Service . 250 Hives of bees in elate grove 102 Upper Colorado Basin 250 Attractive home on irrigated farm 102 Lower Colorado Basin 252 119 R ecomm endations 253 Main canal, Salt River project 119 Grazing Service 254 Colorado River Diversion Dam 127 Objectives and Functions 254 Grand Valley power plant . . 127 Grazing Districts in the Colorado River Basin 256 Grand Valley Canal 127 Bureau of Mines...... 258 Taylor Park Dam in Colorado 129 Program of Water Utilization . . . 258 Fishing at Green Lakes resort . 129 Low-cost Power and Mineral Development 259 Vallecito Dam . . 141 Office of Indian Affairs ...... 261 Vallecito Reservoir . . . . . 141 Indian Projects in the Colorado River Basin 261 and desilting basins on Colorado General Land Office ...... 268 River ...... 165 CONTENTS v

Page Page All-American Canal 165 Figure 15. Estimated trend, electric power load , A site is found . . 169 lower basin m arket area ...... 204 A d am is planned . . 169 Figure 16, river profil e showing reservoir and hy- Pumping ground wa ter 175 droelectric power plan ts . . . Faci.ng 206 Roosevelt Dam on Salt River . 177 M APS IN A P P ENDIX II Bartlett Dam on Verde River 177 Downtown Los Angeles . . . 199 W ater resources development, Colorado River Basin: Goodyear Tire and Rubber Company, Los A ngeles 199 Arizona Following 29 1 Citrus groves . . . 21 2 California Following 29 1 Yuma cantaloupes . 215 Colorado Following 29 1 Prize produce . . . 215 Nevada Foll owing 29 1 Cattle on mountain range 25 5 New M exico Foll owing 291 Irrigated hay field s . . . 255 U tah Following 291 Cottonwood Camp, Big Piney, Wyoming . 272 W yoming Following 29 1 H auling logs, Ashl ey National Park . 273 Principal power systems, existing and poten tial, Colorado River Basin . 291 M aps and Charts Conservation a reas and facilities, Colorado Rive r Basin ...... 291 Colorado River Basin ...... 9 Mineral resources, Colorado River Basin (two Divisions of the Colorado River Basin (map) 33 maps) ...... Following 29 1 Average annual precipitation (ma p) . Facing 41 Figure 1. Popula ti on growth, 1900- 40 . ·. . 50 TABLES Figure 2. Distribution of population, 1940 census . 50 I. \t\Tea ther records a t represen tative stations, Colo­ Colorado River Basin States (m ap) . . . . . 62 rado River Basin ...... 42 Figure 3. Trends in animal units, 1890- 1940, upper II. Popula tion growth in,.. the Colorado River Basin . 49 basin ...... 78 III. Estimated virgin flows in the Colorado River Figure 4. Number of farms, 188 0- 1940, u pper Basin ...... 55 basin ...... 78 IV. Irrigation development in the Colorado River Figure 5. Size of farms, 1890- 1940, u pper basin 78 Basin (1922) ...... 57 Figure 6. Value of fa rm property, 1939, upper V . Labor force in selec ted em ploymen t groups in basin ...... 78 u pper basin (1939) ...... 72 Figure 7. V alue of agricultural products, 1939, VI. Supplemen tal em ploymen t of farmers in upper upper basin ...... 78 basin (1939) ...... 72 Figure 8. Farm tenancy, 1890- 1940, upper basin 78 VII. Types of farms in upper basin (1939) . . . . 73 Figure 9. T ypes of farms, lower basin . . 93 V III. V alue of fa rm products so ld or traded in u pper Figure 10. Farm operation, 1940, lower basin 93 basin (1939) ...... 74 Figure 11. Estimated rese rves of copper in m ajor IX. Livestock in u pper basin (1939) 74 m ining d istricts ...... 96 X . Yields of major crops in upper basin (1939) 76 Figure 12. Copper production from principal mining XI. N umber of fa rms in the upper basin . . . 76 districts ...... 96 XII. Si zes of fa rms in upper basin (1939) 76 Figure 13. Mineral production, lower basin and X III. Farm land available in upper basin (1939) 79 southern California . • ...... 96 X l V. Value of farm property in upper basin (1939) 79 Irrigation developmen t, Colorado River Basin XV. Average income from farms in u pper basin (m ap) ...... 106 (1939) ...... 79 Green Division of the Col orado River Basin (map) . 108 XVI. Coal production in upper basin . . . . . 80 Grand Division of the Colorado River Basin (map). 125 XVII. Mineral p roduction in u pper basin . . . 83 San Juan Division of the Colorado River Basin X VIII. M anufacturing census data- upper basin 86 (m ap) ...... 139 XIX. Value of trade in upper basin (1939) 87 Little Colorado Division of the Colorado River Basin X X. Number and size of farms in lower basin 93 (m ap) ...... 153 XXI. I rrigated fa rm acreage in lower basin 94 Virgin Division of the Colorado R iver Basin (map) . 157 X X II. Value of farm lands and build ings in lower Boulder Division of the Colorado River Basin (m ap) . 162 basin ...... 94 Gila Division of the Colorado River Basin (map) . 174 X X III. V alue of agricultural products in lower Principal power systems, existing and potential . . 188 basin (1939) ...... 95 Figure 14. Estimated trend, electric power load, XXIV. Gross value of principal metals mined in upper basin ...... 195 lower basin 97 VI THE COLORADO RIVER

Page Page XXV.Natural gas and petroleum produced in so uth­ LVI. Average annual stream fl ows in the San Juan ern California (1942) ...... 97 division ...... 140 XXVI. M anufacturing census data- Lower basin LVII. R eservoirs in San Jua n division ...... 142 and southern California (19 39) ...... 99 LVIII. Present irrigated areas in th e San .Juan divt­ XXVII. Wholesale and retail trade-Lower basin sion by Sta tes ...... 143 and southern California (1939) ...... 99 LIX. Estimated present average annual water c.on­ XXVIII. Expenditures in trade- Lower basin and . sumption San Juan division . . . . . 143 southern California (1939) ...... 100 LX. Estimated present average annual water im- XXIX. Average annual stream fl ows in the Green ports into San Juan division ...... 143 division ...... 109 LXI. Estimated present average annual water ex- XXX. Irrigation reservoirs in the Green division . 111 ports from San Juan division ...... 143 XXXI. Presen t irrigated areas in Green division by LXII. Potential projects in the San division 147 States ...... 112 LXIII. Potential reservoirs in San Juan division 148 XXXII. Estima ted present average annual water LXIV. Potential irrigation development in San consumption in Green division . . . . 112 .Juan division ...... 148 ·XXXIII. Estima ted present average annual water LXV. Potential irrigation developments in San .Juan exports from Green division ...... ' 11 2 division by States ...... 149 XXXIV. Potential projects in the Green division . 120 LXVI. Potential power development in Sa n Juan XXXV. Potential reservoirs in Green division . . 121 division ...... , ...... 149 XXXVI. Potential irrigation development in Green LXVII. Potential import diversions to San .Juan division ...... 122 division ...... 149 XXXVII. Potential irrigation development in Green LXVIII. Potential export diversions from San Juan division by Sta tes ...... 123 division ...... 149 X XXVIII. Potential power development in Green LXIX. Present a nd potential stream depletions in division ...... 123 San Juan division ...... 150 XXXIX. Potential export diversions from Green LXX. Present irrigated areas in upper basin . . . 150 division ...... 123 LXXI. Prese nt hydroelectric generating capacity X L. Presen t and potential stream depletions in in upper basin ...... 151 Green division ...... 124 LXXII. Potential development of water resources XLI. Average annual stream fl ows in the Grand in upper basin ...... 151 division ...... 124 LXXIII. Presen t and potential stream depletion in XLII. Irrigation reservo irs in the Grand division . 128 upper basin ...... 151 XLIII. Presen t irrigated areas in the Grand division LXXIV. Ave rage annual stream flows in the Little by States ...... 128 Colorado division ...... , 152 XLIV. Estimated present average annual water con­ LXXV. Existing reservoirsin Little Colorado divi- sumption in G rand division ...... 130 sion ...... 155 XLV. Estimated presen t average annual water ex- LXXVI. Present irrigated a reas in th e Littl e Colo- ports from Grand division ...... 130 rado division ...... 155 XLVI. Potential export diversions from Colorado LXXVII. Estim.ated present average annual deple­ River above Gunnison River ...... 132 tions in Little Colorado division ...... , . 155 XLVII. Potential export diversions from Gunnison LXXVIII. Potential p roj ects in ...... 133 division 15 6 XL VIII. Potential projects in the Grand division . 135 XLXXIX. Potential reservoirs in Little Colorado XLIX. Potential reservoirs in Grand division 136 division 156 L. Potential irrigation development in Grand divi- LXXX. Potential irrigation development in Little sion ...... 137 Colorado division ...... 156 LI. Potential irrigation developmen t in Grand divi- LXXXI. Present and potential stream depletions in sion by States ...... 137 Little Colorado division ...... 156 LII. Potential power development in Gra nd divi- LXXXII. Average annual stream flows in the Vir- sion ...... 138 gin division ...... 158 LIII. Potential diversions to San Juan division . 138 LXXXIII. Present irrigated areas in the Virgin LIV. Potential export diversions from Grand cl ivi- division 159 sion ...... 138 LXXXIV. Estimated present average annual de­ LV. Present and potential stream depletions in pletion in Virgin division ...... 159 Grand division ...... 138 LXXXV. Potential projects in th e Virgin division . 160 CONTENTS VII

Page Page LXXXVI. Potential reservoirs in Virgin division . 160 CX IX . Presen t hydroelectric generating capacity in LXXXVII. Potential irrigation development in Colorado R iver Basin ...... 184 Virgin d ivision ...... 160 CXX. Potentia l developmen t of water resources in LXXXVIII. Potential irrigation development in Colorado River Basin ...... 185 Virgin division by States ...... 161 CXXI. Present and potential stream depletion in LXXXIX. Potential power development in Virgin Colorado River Basin ...... 186 division ...... 161 CXXII. I nstalled generating capacity in u pper X C. Present and potential stream depletions in ba in (1943) ...... 19 1 Virgin division ...... 161 CXXIII. Energy generated a nd load requiremen t XCI. Average ann ual stream flows in the Boulder in upper basin (1943) ...... 192 division ...... 161 CXXI V. Electric energy load requirements in upper XCII. Levees and drains in the Boulder division . 166 ba in (1943) ...... 192 XCIII. Important dams in t he Boulder d ivision . 16 7 CXXV. Electric energy load requirements in R ocky X CIV. Irrigated and irrigable area under prese nt M ountain region (1943) ...... 193 developments (1943) ...... 167 CXXVI. E tima ted load growth in upper basin . . 195 XCV. Areas irrigated in Boulder d ivision by States CXXVII. Potential hydroelectric power p lan ts in (1943) ...... 167 upper basin ...... 196 X CVI. Estimated pre en t average annual stream CXXVIII. Installed generatino· capacity in lower depletions in Boulder division ...... 168 basin power a rea (1943) ...... 201 X CVII. Poten tial project in the Boulder d ivision . 171 CXXIX. E lectric energy load requirements in lower X CVIII. Potential reservoirs in Boulder division 172 basin power area (1943) ...... 202 X CIX. Potential irrigation development in Boulder CX XX. Estima ted load growth in lower basin power division ...... 172 a rea ...... 204 C. Potential irrigation developments in Boulder divi- CXXXI. Potential hydrocle tric power pla nts in sion by States ...... 172 lower basin ...... 205 CI . Potential power development in Bo ulder d ivision . 172 CX XXII. Pre ent power development in Colorado CII. Present and potential stream depletions, Boul- River Basin (1943)...... 206 der division ...... 172 CXXXIII. Estima ted cost of program, upper olo- CIII. Average annual stream flows in G ila d ivision. 173 raclo Rive r Basin ...... 225 C IV. Irrigated areas in independent ba_in . 178 CXXXI V. Estima ted cost of program, lower Colo- CV. Imported cl ams in the G ila d ivision . . . . . 179 rado River Basin ...... 232 CVI. Present irrigated a reas in G ila division . . . 179 CXXXV. Da ta based on U. S. Bu reau of Mine. CVII. Estimated presen t average annual stream exploration of mineral deposits in the Colorado depletion in G ila clivi ion ...... 179 River drainage bas in ...... 260 CVIII. Potential p roject in Gila division 181 CX XXVI. I ndian projects in the Colorado R iver CIX. Potential reservoirs in G ila division. 181 Basin ...... 267 CX . Potential irrigation developm ent in G il a d ivi- CXXX VII. R ecorded and estimated historical dis- sion ...... 182 charges, Colorado River a t Lee Ferry . . . . . 279 CXXXVIII. Acreage irrigated a bove Lee Ferry . 280 CXI. Potential irrigation developmen t in G ila d ivi- CXXXIX. Trammounta in d iversion abov Lee sion by States ...... 182 Ferry ...... 280 CXII. Poten tial power development in G ila d ivi- CXL. Estimated virgin flow Colorado River a t Lee sion ...... 182 Ferry ...... 281 CXIII. Presen t and potential stream depletions in XLI. Compariso n of average annual fl ow , long- G ila division ...... 182 time period with 1923- 43 perio:i . . . . . 281 CXIV .' Present irrigation development in lower CXLII. Precipitation and run-off near W illi ams basin ...... 183 River ...... 282 CX V. Presen t hyd roelectric generating capacity in CXLIII. ompari on of sections of Colorado R iver lower basin ...... 183 Vall ey above and below Topock ...... 283 CXVI. Poten tial developmen t of water resources in CXLI V. Past upstream irrigation depletion, G il a lower basin ...... 18 3 and Salt Rivers ...... 283 CXVII. Present and potential stream depletion in CXLV . G ila R iver cha nnel characteristics and lower basin ...... 184 climatological data . . . . . 284 CX VIII. Presen t irrigation development in Colora- CXL V I. Estimated virgin fl ow of G il a R iver at do R iver Basin ...... 184 mouth (1,000 acre-feet). . . . 285 172 THE COLORADO RIVER

TABLE XCVIII.- Potential reservoiTS in the Boulder division

'rota! capacity Kame of site 1 Sour ce of water suppl y Project sen ·cd directl y (acre-feet) ------ ______Colorado River______Marble Canyon-K anab C reek ______500, 000 C oconino ______c ______Little Colorado River______Bridge Canyon ______1, tiOO, OOO Bridge Cany on ______Colorado River______do ______3, 720, 000 Alamo______Williams River______Alamo ______946,000 SentineL ______Gila River______Sentine l ______3, 000, 000

Total ______------9, 766, 000 1 1

1 All in Arizona.

TABLE XCJX.- Potential zrngation development m the TABLE C.- Potential irrigation develojJments in the Boulder Boulder division division by States Area to be bencfi tocl (acres) Area t b b~nc fi tcd (a res) Furnished -- Project 1 f;tatc New land supple- Total Sl ate· Furnished mental Xcw lund supplem ental Totul an•a watrr WOI('r Virgin Bay pumping _____ Nevada ___ 2, 800 0 2, 800 ------Las Vegas pumping______do ____ 20, 000 0 20, 000 Arizona ______Davi R eservoir pump- 0, 000 7, 00 7, 00 ing ______do ____ 2, 000 0 2, 000 C alifornia ______10, 000 0 16, 000 Big B end pumpiug ______do ____ 3, 700 0 3, 700 N c vada ______33, 600 0 33, 600 Fort Mojave ______do ____ 5, 100 0 5, 100 Mojave Valley ______Arizona ___ 10, 000 0 10, 000 T o tal ______129, 600 7, 00 137,400 Palo V erde Mesa ______California _ 16, 000 0 16, 000 Wellt on-Mohawk di v i- sion of Gila project_ ___ Arizona ___ 70, 000 7, 00 77, 00 TotaL______129, 600 7, 800 137, 400

1 All projects are in natural drai nage basiJ1 of the Colorado Ri ver.

TABLE CI.- PotentialjJower develo jmunt in the Boulder division , Installed ca pacity An nu al nrm ~e n c ro - Project 1 Name of power plant (kllowa LL ·J Li on (kilowatt-hour•) ------1------·------·----1------1------Marble Canyon-Kanab C reek ______{Marble Can yon ------o l ra cl o------22,000 164, 000, 000 Kanab C reek ______lo ______1, 250, 000 6, 570, 000, 000 Bridge Canyon ______Bridge Can yon ______do ______650,000 3, 440, 000, 000 TotaL ______- - __ __ ------·· ------1, !)22, 000 10, 174 , 000, 000

I All in Arizona.

TABLE Cll.- PTesent and potential st-ream dejJletions, Gila Division Boulder di vision

Estimated ave rage annual depletio n (acre-feet) The Gila clivi ion, con isting of the area drained by the above Sentinel and adja ent mall ind pend nt Existing or authorized State Ri ver projects drainage areas, mbra es 53,000 square miles, 47, 80 of Potential Total ul ti mate projects dc]lction which are in outh and central rizona, and 5,620 in Present Futuro depleti on in crease western New Mexi o. · ----- Arizona: Colorado River_ 205, 000 571, 000 340, 000 1, 122, 000 WATER R ES OURCES Williams River _ 3,400 0 0 3, 400 Surface water.- The flow of th ila River under SubtotaL ____ 208, 400 571 , 000 340, 000 1, 125, 400 California: virgin condition i e timat d at 1,752,000 a re-feet an­ Colorado River_ 2, 680, 000 2, 946, 000 176, 000 15, 02, 000 N evada: nually at Gillespie Dam and 1,270,000 a re-feet at Dome, Colorado River _ 20, 000 0 177, 000 197, 000 Ariz., near its mouth. Recorded stream fl ows in th Gila R eser voir losses ___ __ 713,000 66, 000 91 , 000 870, 000 division are shown in table ern. T otaL ______3, 021 , 40013, 583, 000 790, 000 7, 994, 400 Streams within the Gila Basin attain their maximum flows during late winter and early pring when mountain 1 Includes export of 5, 445,000 ac re-feet from the natural dramage basw of the Colorado River, made up of 2,535,000 acre-foot present, 2,798,000 acre-fee t future snows are melting. Precipitation on the water hed fall increase from existing or authorized projects, and 112,000 acre-feet from potential projects. mainly in late winter and late summer, the intervening USING THE WATER-GILA DIVISION 173

TABLE CJII.- A verage annual stream flows in the Gila ern Arizona are underlain with uncemented valley-fill division material, generally several hundred feet deep. This por­ ous material absorbs much of the flow of streams as they A veragc annual flow (a.-ft.) enter the valley areas, thus creating great underground SLatiou reservoirs. Irrigation seepage contributes substantial re­ For period For 1931-40 of record p riod charge to the reservoirs, but the scanty precipitation on valley lands adds little to the ground water supply. San Francisco River ncar Glenwood, Large quantities of water for irrigation and domestic N. Mex______1929- 43 51, 00 50, 000 'an Francisco River at lifton, Ariz_ 1914-43 172, 000 123, 000 u e are obtain d from ground water. Artesian wells of Gila River near Gila, . Mcx ______1929- 43 103, 000 93,400 in1p rtan e have b en drilled in the upper Gila Valley, Gi la River ncar ReI R ock, . M x_ 1910- 43 140, 000 127, 000 Gi la River below Blue reek near and mall arle ian fl ow have been encountered in the up­ Vird n , N . Mex ______192 - 43 137, 000 126, 000 p r an P dro and Santa ruz Valleys. Yield of indi­ Gila River ncar Clifton, Ariz ______1913- 4.3192, 000 112, 000 Gila River near Solomonsvill , Ariz. 1• 1915-43 302, 000 271, 000 vidual w Us within th clivi ion rang in di charge from ila Riv rat a lva, Ariz ______1 29- 4.3 24.6, 000 209, 000 .5 to 2,25 0 gallons a minute. Gila Riv r b low 'oolidg · D m, Ariz.2 ______1914.- 43 32 , 000 214 , 000 mall to mod rate-sized spring are scattered thr ugh Gila River at I lvin, Ariz.3 ______1911- 4.3 4.4.4, 000 299, 000 Lhe watersh d area. Only a mall amount of land i irri­ Gila Riv r b low Gillespi Dam, Ariz ______1922- 4.3 302, 000 149, 000 gat d dir tly from springs, but prings contribute a ub­ ila H.iver n ar Dom , Ariz ______1930- 4.3 4·, 600 57, 900 tanti al amount of wat r to the perennial fl ows of the an arlos River n ar P eridot, Ariz_ 1929- 4.3 45, 00 3 ' 300 San P dro River at harl ston, Ariz_ 1913- 43 50, 700 4.5, 900 larg r riv r . pring water i particularly valuabl in the anta ruz Riv r ncar rogal s, miarid outlying rang , wh re cr eks u ed for watering Ari z ______-- ______1930- 4.3 15, 4. 00 16, 900 a. nta. ruz Itiv rat Tucs n Ariz __ 1912- 43 15, 00 1",000 liv to k ar dry during larg part of th year. a. lt River n ar hrysotil , Ariz ____ 1 24.- 4. 493,000 4.79, 000 With f w epli n , ground water within the basin SaltRiv rn arRoo v lt,Ari z_ ___ l91 4.3721, 000 584, 000 h b n d v l p d b yond i onomi limit, and in all a.ltAriz Riv ______r at ranite R f Dam, 1, 060, 000 T nt r ck ncar R osovelt, Ariz ___ J 02- 4. 0 97, 00 85, 000 but a f w areas, ground-wat r withdrawals x ed Vrd IivrnarPin e,Ari z ______19' 5- 394.25, 000 31, 000 r pl ni hm nt. Verd H.iv r ab vo amp re k, ri z ______1 25- 434.33, 000 417, 000 ri z na la k Agua 1' ria River abov Lak PI as- ant, Ariz _------1933- 4.3 55, 300 "3, 500 IIa sayampa River at Box a.n yon dam sit , Ariz ______------41 , 400

' Includes Drown anal dl v rslons. ' F'low rogulntcd by oolldg l a m beginning J0 21l. w • Reg ulated art r 102 . tal Engineer an d clare any ar a with und rgr und wal r, th boundari s of wh.i h an b r a- During lh dry onably d l rmin d, to be an und rground water basin. Und rgr unci wal r within the area mu t then be appro­ prial d in mu h th am manner a that of surface lr am . Pr nt wal r us rs are thus prote ted, and exp n i n i p rmill d only wh r upplies are mor than ad qual for xisting developm nl . Quality of water.- urface waters of Gila River and merou r · rvoirs air ady tor its tribulari arry on id rabl quantiti s of dissolved and its tributari , whi h ar lid , chi fl y dium hl ride and the ulphate and hi- by xi Lin g irrigation proj · l . arb nat of sodi urn, cal ium, and magnesium; however, dry y ar th water availabl th p r nlag of s dium is r asonably low. Low flows of quate to me t the d mand. ila Ba in , th ref re, th ila River at Gille pie Dam in the lower part of the mu t look to other ba in for an additional supply of clivi ion arry over 6,000 parts per million total dissolved surfa e wat r. olid , while fl ood fl ows carry as little as 300 parts per Ground water.- T)l ere i no law in Arizona r gulating million. the development of percolating ground waters. In the The quality of the ground water obtained from artesian absence of 1 gal prot ction, development of ground water wells and prings varies with location. Some waters have resources for any purpose would be hazardous, and this less than 100 parts per million dissolved salts, while others factor should be recognized in planning future d velop­ range as high as 5,000 parts per million. The total hard­ ments. ness of these waters, expressed as calcium carbonate, Considerable portions of the broad basins of southwest- ranges from le s than 5 to over 700 parts per million. 174 THE COLORADO RIVER

0 .

LOC ATIO N MAP

r· ·- ·-·l i j oPotogor io . • : · - · S A Ill T A C R U l '~ '"'" "'b OlLE'P 0, SOW ILESlfl "F ...... _ .. ~ o qole s J' ' I e - ..______CLJ..:... ,V!'.ll..I.R ~~ -- - w EX I CO •Dou glas Gila Division of the Colorado R iver Basin

Ground waters of unsuitable quality for either irrigation or domestic use are found in wells in the upper Gila Valley, lower Salt River Valley, and in the Casa Grande and General Coolidge districts. Ground waters of the division are generally unsuitable for industrial use. The surfa e and ground-water supplie of the Gila Some of the surface water in the smaller tributaries and division are the basis for practi ally all its agri ultural much of the ground water in the basin contain fl uorides development, and stream flow, through the generation in such high quantities that it is quite often difficult to of hydroelectric energy, makes possible many of the obtain a satisfactory domestic water supply. area's industries. urface water , with the exception of USING THE WATER- GILA DIVISION 175

PUMPI G GRO D W TER O verdraft of underground supplies in Arizona is serious th1·e-at to aariculture. Thousands of acres may be abandoned unless more irrigation water is supplied 176 THE COLORADO RIVER a few small tributary flows, are almost completely uti­ The San Carlos R eservoir, with a capacity of 1,200,000 lized by lands now under irrigation; and an estimated acre-feet formed by Coolidge Dam (Office of Indian Af­ 1,600,000 acre-feet of ground water is pumped annually fairs ), store water u ed for irrigation on everal down­ for irrigation and domestic use. Ground-water pumping streams projects. T he San Carlos project, largest of these greatly increases during dry years when reservoirs are low, irrigation developments, serves 100,500 acres, about half throwing a tremendous strain on generating facilities al­ of which is farmed by Indians. Project lands require ready curtailed by low water conditions. The output of more water than is uppli d to th m by exi. ting irriga­ power plants in the division has been augmented recently tion development on the Gila Riv r. by energy from Parker Dam on the Colorado River. Oth r down tr am developments in lude tho e made Rivers of the area transport large quantities of silt each by the Bu ckey W ater Con ervation and Drainage Dis­ year. Although river flows in dry weather are fairly tri t, Arlington anal o., Gill pi Land & Irrigation clear, a load of sand constantly is being moved along the Co., and other . Th se land obtain mu h of their wat r river bed even during the lowest river stages. High dis­ supply by pumping from underground our At the charges, resulting from torrential rains and rapid run-off, pre ent tim ground-wat r d pl tions ex eed r charges to carry in suspension heavy loads of fin e silt and lay in a considerable d gr e, and unl r pla m nt wat r is addition to enormously increa ed bed loads. upplied, orne land mu t b taken out of ultivation within The fine material carried in u pen ion pre ents no a few year . . problem in canal maintenance, except when fl o.w arc ex­ an Pedro Rivet.- bout 2,600 a r of land ar irri­ ceptionally low. Coar er bed-load material, however, gated in the B n on- t. David ar a of th upp r . an settles in canals and ditches and must be removed to main­ P dro River wat r h d and a few hundr d a r s ar dry­ tain the capacity of the conduits. Both bed loads and farm d. o urfa wal r torag i vail bl nd irri­ suspended loads settle in storage reservoirs. This accum­ gation upplie l pend on th exlr m ly variabl !low of ulation is important in determining the length of lif of a the riv r, th output of ev ral mall !lowing w ll , and a reservoir. R ecords of the alt River Valley Water U r ' limited amount of pumping fr m gr und water. Association show a total silt accumulation of 108,000 a re­ 11 of lh d p ndabl urf wal r uppl y I lh an feet in Roosevelt R eservoir on alt River during the p riod P dro i now clivid d am ng irrigator in th an P clr 1905 to 1934, inclusive. Other treams in the basin Vall y and in the ila River Vall y d wn lr am from th notably the Gila, are known to carry gr ater proportions confiu enc of the two tr am . T h only po ibility of of silt than Salt River, so this fi gure i lower than the irrigating additional land in th an P dro Vall y i average to be expected. through th importation of water to the The suspended material found in the waters of the Gila that an Pedro Riv r wal r now u d th River and its tributaries contains con iderable organi 1 as d for u e in lh an P dr all y. m atter and but little coloidal clay. When applied to an P clro Riv r ar not fully d - sandy land, this material gives body to the soil and is veloped, and in r a d pumping would yi ld valu bl beneficial. When spread on tight land, however, it log but limit d uppl m ntal wal r uppli . the pores of the oil, reducing its permeability and making alt and Verde Rivets.- Div r ion of irrigati n w l r its cultivation more difficult. In municipal water works, from alt Riv r w r fir t mad by whit ttl r in 18 7. it clogs intakes and makes water clarifi ation co tly. B au e of rrali riv r fl ow and la k of storag fa iliti , The only practicable solution of the ilt problem lies water uppli during dry year were in ad qual to uppl in providing adequate silt storage capa ity in reservoir on the demands of the land in ultivali n. T h Bur au f major streams contributing ilt and in limiting erosion by R eclamation on lru t d R oo v It Dam and pow r plant better watershed control. to provid torage and regulation of alt River. Div r­ sion work , anal , lateral , and other pow r plant w r Irrigation also built by the Bur au b fore turning th proj t v r Gila River.- Irrigated area along the Gila River and to the alt Riv r Valley Wat r rs' o 1at10n in its tributaries, San Francisco River, San Simon Creek, 1917, subj t to payment of th unpaid balan e of con­ Queen Creek, and Centennial Wash, total 213,400 acres. struction harge . During lh y ar betw n 1922 and Irrigation projects located above Coolidge Dam h ave 1930, the a.Sso iation con tru ted the H or M a, Mor­ no water-storage facilities and must depend on diversions mon Flat, and tewart M untain Dam for irrigation from the unregulated flow of the Gila River supplemented and power, and the Cave re k Dam for flood control. by pumping from ground water for their irrigation sup­ The Bureau of R eclamation, during th 1936- 39 period, plies. These upstream projects cover an area of ap­ built Bartlett Dam on the Verde River, principal tributary proximately 51,000 acres and require additional water of Salt River. to irrigate adequately all project lands. Large areas of fertile land surrounding the Salt River U ING THE WATER- GILA DIVISION 177

BARTLETT DAM ON VERDE RIVER Another R eclamation dam to irrigate Arizona's thirsty lands 178 THE COLORADO RIVER project are irrigated with water wholly or partly supplied As no electrical energy is generated in the area, all energy by pumping from wells. The Salt River project also used is purchased from power plants located in other supplements its surface-water supplies with ground water. regions. Ground-water pumping should be reduced and, Approximately 336,000 acres of land were irrigated in if possible, replaced by surface water. the Salt River and Verde River Valley region in 1939. Some 500 acres of land lying near the Hassayampa This included 14,000 acres of Indian land, not all of River is presently irrigated. Much fertile land in the val­ which is irrigated at the present time. The Office of ley would be very productive if adequately supplied with Indian Affairs contemplates ultimate development of the irrigation water. full acreage. Of the total area 240,000 acres were irri­ Independent drainage basins.- Approximately 10,400 gated principally with surface water and the remainder acres of irrigated farm land in the Gila division are in with water from wells. small independent drainage basins or in basins draining Pumping from underground storage exceeds recharges into M exico. These lands derive their water suppli and unless ground-water supplies are supplemented, the principally from artesian or pumped well , although ur­ amount of land under cultivation will have to be reduced. face fl ows are used when available. An earth and rock-fill dam is at present being con­ structed at the Horseshoe site on the Verde River by the TABLE CIV.- l nigated area in indejJendent basin Phelps Dodge Corporation in cooperation with Defense Plant Corporation. Under the terms of an agreement be­ Area Basin ount y and tate Drainag irrigated tween these corporations and the Salt River Valley Water (acres) Users' Association, water conserved by this dam will be Sulphur pr tng Val- ochisc, Ariz _ _ Ind pendent_ __ 3, 000 exchanged for water diverted from Black River, another lev. tributary of Salt River, for use at the Morenci Mine and Whit water Draw ______do ______Yaqui lliv r _ 2, 000 Vamori______Pima, Ari z _____ Ind p nd nt I 5, 200 Reduction Works, owned by the Phelps Dodge Corpora­ Animas Valley ______Hidalgo, r. ·- _____ do ____ _ 200 tion. The Horseshoe Dam will conserve a part of th TotaL ______. __ _ Verde River flood water for use on the lands of 10, 400 the association, and in return the association will 1 Indian lands. permit Phelps Dodge and Defense Plant Corpora­ tion to divert from Black River an amount of water Po wer equal to that conserved by Horseshoe Dam, but not in ex­ cess of 14,000 acre-feet a year, nor in exce of 250,000 Power plant upplying lectri al energy to th Gil a acre-feet total. division fall into two cla e : ( 1) tho e whi h n rat The reservoir formed by Horseshoe Dam will have -a energy for ale, and ( 2 ) those whi h wer on tru t d storage capacity of 60,000 acre-feet, but the dam will be for the ole purpose of furni hing n rgy to om nearby so constructed that it may be enlarged ultimately to in­ industrial development. Both publicly and privat ly crease the reservoir capacity to 300,000 acre-feet. owned plant are located in th ar a. Those own d Santa Cruz River.- Wells furnish practically all of the privately have by far the great r install d apa ity and water used by the 115,400 acres of irrigated land in the have been on tructed mainly to upply the nergy de­ Santa Cruz River Valley. Electric energy for pumping mands of min , mill , and m lters. 1 he t tal in tal led purposes is imported from the Salt River Valley and capacity of pow r plant in the divi i n i about 27,000 Parker Dam power plants. kilowatts. Because of the high fertility of the lands in this region . The Bureau of R eclamation's power plant at Park r the acreage under cultivation has increased greatly with Dam upplies large amounts of nergy to power-marketing a consequent increase in the amount of ground water agen ies located at Phoenix, Coolidge, and Tu on, ri z. pumped for irrigation use. Ground-water withdrawals The e agencies in turn distribute this energy over a wid exceed replenishments and unless additional water be­ area. comes available, much land must go out of cultivation Power plants of the Gila division are hydroel ctri , within a few year . steam, or int mal combustion. team plants pre- Agua Fria and H assayampa Rivers.- Approximately dominate. 48,700 acres of land are irrigated in and adjacent to the Agua Fria River Valley through the utilization of both Drainage surface and ground-water supplies. Surface waters arc stored in a 178,000-acre-foot reservoir formed by Lake Soils and topography within the Gila division are Pleasant Dam, and ground water is made available by such that drainage under irrigation i generally adequate means of numerous deep-well, electrically-driven pumps. and in some cases excessive. Subsurface drainage is USING THE WATER- GILA DIVISION 179 usually good because of the open, permeable subsoils Flood control found through most of the region. Some areas of the Cave Creek Dam, situated just north of Phoenix, Ariz., Salt River Valley are drained by pumping from wells. is the only dam constructed for flood control in the Not only does this re ult benefi cially in lowering the region. Its reservoir capacity is 14,000 acre-feet. Al­ ground-water level but also makes available a dependable though other storage dams were constructed primarily upply of irrigation water. for irrigation and power development, they offer some everal farming di tri ts urrounding th alt River degree of protection. on iderable damage, however, projec t are wholl y d pendent upon this drainage water till results from fl ash fl ood . for their irrigation supply. The drainage sy tern com­ pri e about 190 w 11 . Ele tri ally operated pump lift th wat r about 86 feet to distributing anal , where it Summary fl ow by gravity to th irrigat d land . orne 240,000 Imp rtant dam , irrigated acre , and the net effe tiv a res are thus drained and about 95,000 acr f thi area tream d pletion du to pr ent irrigation development arc irrigat d by pump d wat r. ar ummariz d in the f llowing tabl s :

T ADLE V.- l mjJor tant dams in the ila division

Nom :or dam lllvor l' urposo ------Trrigali n div r i n ------lrri ga li n, fl d onlr I, p w r __ ------l , 200, 000 ------Irrigali n d iv rs io n ______do ______------__ d ------Tr ri gati n, pow ~' ------•• 1, 400,000 P ow "------__ 245, 000 ___ __d ------57, 00 ____ d ------7~ 000 ·------Jrrigali n d iv rsion ___ ------_ ------Trrigali o, fl d conlr !______------1 2, 600 F l d con lroL ______:14, 000

rI' ri ga Li n------17 I 000 . d o_ ------·-·· ------60, 000 T otal_ ___ _ 3, 407, 400

ABLE V I.- Present inigated areas in the p TE TIAL D EVEL PM ENT F W ATER R E UR 'ES

A c r ~ s l rrl ~ntcd water upply of ila clivi ion i inad quat to trenm bos iu m t the r quir m nt of land now irrigat d. round­ N ow Arlzo uo M exico Total wat r uppli ar b ing xhau t d, and urfa suppli s ar in ad quat In g n ral , th rea i uff ring fr m a ila lliv "------­ 10, 00 2 13, 400 contin ual wat r hortag . T h nly our c of wat r for an P d r :Ri v "----- _ 0 2, 600 alt and V rd :Ri v r _ 0 336, 000 uppl m ntal, rcpla m nt, r additi nal u e is th olo- ] 15, 400 a ola r·u z :Ri v r______----- 0 rado Riv r. Ag ua Fria :Ri v "------0 4 ' 700 lias ayarnpa R iv. r ______----- 0 500 Central Arizona fJ roject.- v ral plans hav b n ad- 200 10, 400 Jnd 1 ndc n t B a rn .------v n d f r div rting l rado Riv r wat r to entral T taL ______7 16 , 000 11 , 0 0 727, 000 rizona. Pr liminary inve ligation by the tate of Ari­ zona and by the Bureau of R lamation h av reduced

T ABLE CVII.- Estimated present average annual stream the numb r of alt rnativcs on idered to thr ; these thrc depletion in the Gila division are receiving study at the time this r port i b ing pr pared to det rmin whi h plan shall receiv the detail d investi­ Dept tion (acrc·fcct) gation n essary for proj ct report. Division New All plans would serve the purpose of delivering olo­ Arizona 'J'otnl M exico rado R iver water to Granite R eef Dam, on the alt River at the nominal head of irrigation. Brief descriptions of G il a d iv ision ______, 1, 135, 000 16, 000 1, 151, 000 these routes follow: ( 1) M arble Canyon route (grav- 180 THE COLORADO RIVER ity) -Colorado River water would be diverted from the Verde River into a 64-mile canal would permit utilization potential Marble Canyon Reservoir, the dam site for of Verde River water on 85,000 acres of land in this unit which is about 320 miles upstream from Boulder Dam, north of Phoenix. through 143 miles of continuous tunnel, to discharge into The San Carlos unit c9uld divert water through a short the Verde River 95 miles upstream from its confluence tunnel from the Saguaro Reservoir (formed by Stewart with the Salt River. A series of reservoirs and power Mountain Dam ) on Salt River and through a canal ex­ plants on the Verde River would regulate the diverted tending over 100 miles to 15 7,400 acre of irrigated land water, as well as Verde River water, for irrigation use, and in the an Carlos Irrigation Distri t and pumping de­ develop power through the head available. In common velopment in the Gila River Valley. Ground-wat r with the other alternative routes, water imported from pumping could thereby be deer a ed to the a£ yield of the Colorado River would be delivered finally at Granite the ground-water basin. R duction in en rgy generation Reef Dam on the Salt River. (2) Bridge Canyon route at Stewart Mountain Dam, a a r ult of u h a div r ion, (gra vity ) - Colorado River water would be diverted from would be offset by energy g nerated at th propo d new the potential Bridge Canyon Re ervoir, the dam site for plant at H ors shoe Dam. which is located 118 miles upstream from Boulder Dam. A dam at th Buttes site on th Gila River b low an The diverted water would flow by gravity through a 78.5- Carl os R rvoir could b on tructed to form a re rvoir mile continuous tunnel south to the Big andy River, with a apacity of 400,000 acre-f t. This torag would thence by 235 miles of aqueduct and through 11 shorter regulate nood from tributari s ntering the main tr am tunnels totaling 13.7 miles, into the potential McDowell below San arlo Re ervoir and thu provid prote tion Reservoir, which would be located on the Salt River im­ for irrigated lands down tr am. The tor d wat r ould mediately upstream from Granite Reef Dam. ( 3) Parker be released a r -quired by down trean1 u rs. n annual route (pumping )-Vnder this plan Colorado River average of 17, 000,000 kilowatt-hours of power ould b water would be pumped from Hava u Lake through a generated at a plant at the Butt s ite with an in tall d series of four pumping lifts totaling 985 feet, and thence capa ity of 5,800 kilowatt . Thi plant would op rat would flow by gravity through 235 miles of aqueduct to only when wat r i requir d f r irrigation purp Th Granite Reef Dam. energy thus gen rat-d, while not firm, would b availabl For simplicity in pre enting the potentialities pf the for irrigati n pumping and could b u ed for that purp . . , it has been necessary to limit With demand of the an Carl unit ati fi d, irrigat r discussion to one alternative plan. That employing the on the upper Gila and tributarie could in r as th ir di­ Bridge Canyon route has been selected arbitrarily for that version beyond any pr ent legal limitation. In many discussion; likewise, an annual diversion by the project of a s, h wever, r gul ation of stream n w would b n s­ 2,000,000 acre-feet has been assumed arbitrarily. Esti­ sary to make uch div rsion physi ally p ibl . mates of co t and of power potentialities are consistent The Charleston unit would involve n truction of a with these assumptions. The plan finally elected may dam at the Charleston it on San P dro River and a 70- differ materially from that assumed herein, both as to mile pipe line to deliver 12,000 a r -f t of wat r annually route and as to quantity of water diverted, and it should to the city of Tu on. With a af our e of supply thus not be assumed that the plan selected arbitrarily for dis­ provided, the city ould di continue or d r a it pr nt cussion herein has been shown to have the greatest merit. pumping fr m a dimini hing underground upply. The Salt River unit would utilize Colorado River water re ervoir with a capa ity of 240,000 a r -fe t f rm d by delivered to Granite Reef Dam by diver ion at points Charleston Dam would provide sufficient storage to pro- · along the Salt and Gila Rivers through existing facilities. teet downstream irrigator from noocl damage. uppl - Supplemental water could be supplied to approximately mental irrigation water uld b furni hed to 2,600 acres 384,900 acres now inadequately irrigated in this area and of land lying below the dam site. to 20,000 acres of new land lying within the boundaries The Safford Valley unit, through con tructi n of a of existing irrigation di tricts. dam at the. Elliott sit on th Gila River, on -fourth of a The Paradise Valley unit would utilize Verde River mile below the mouth of San Franci co River to provide water now required by the Phoenix area, that area receiv­ a re ervoir of 70,000 acre-feet capacity would upply sup­ ing Colorado River water instead. Enlargement of plem ntal water to 32,460 a res of land in Safford Valley. Horseshoe Dam on the Verde River to increase the reser­ Although the reservoir would be operat d primarily for voir capacity to 300,000 acre-feet would provide ad­ irrigation, it would serve also to control fl oods. ditional regulation of this stream. Installation of a The San Francisco unit would furnish additional up­ 10,000-kilowatt power plant at this site would provide plemental water to the Safford Valley unit by regulation replacement power for the Stewart Mountain power plant of the San Francisco River. Storage could be obtained on Salt River. Diversion at the Bartlett Dam on the by the construction of a system of small reservoirs, the USING THE WATER- GILA DIVISION 181 number, location, and capacity of which have not been furnished an additional supply by concrete lining an exist­ determined. By distributing the e reservoir in the upper ing canal leading from the diversion points on Granite reaches of the basin, regulated fl ows could also be utilized and Willow Creeks to the project lands and by making to supplement supplies to approximately 2,500 acres of certain other improvements to reduce water conveyance land now irrigated in the San Francisco unit. In addi­ losses. No new lands ould be brought under cultivation, tion, approximately 2,000 a r -s of new land could be and a full supply co uld not be furnished to the entire brought under irrigation. Although con idered a a part project area. H owever, d istre s occa ioned by recurrent of the Central Arizona proje t, it i po sible that this unit water shortage ould b alleviated. ould b - d veloped independently on a modified ale. H assayamjJa project.- By con tru ti on of a dam at the The Duncan-Virden Valley and ew M exico units Box Canyon it on H a a yampa River a storage re ervoir w uld provide storage at th H oker it on Gila Riv r f 210,000 acre-f et capa ity ould provid uffi i nt !iff, N. Mex., to provid upplemen tal water and water t irrigate 8,800 a res f de ert land we t of Witt­ om n od- ntrol prole lion f r 13, 00 a r of Janel man, Ariz. T his reservoir al o would h lp to control now irrigated n ar Dun an, ri z. A ,000-kil walt a­ fl oods in th ar a. pa ity pow r plant at H o k r D am could suppl m nt entinel f;roj ect.- Although th reservoir which would available electri nergy in th ar a. A permanent lak b form d by a fl o d- ontr 1 dam n ar entin 1, ri z., in thi vi inity w uld furni. h valuabl r acti onal oppor- w uld xlencl int the Gila clivi ion, the dam site and tu niti s. pre nt d this dam would b an int gr l proj ct land ar in th Bould r division. Th proje t, part [ th · ntral riz na pr j t. hould lorado th ref re, i di u cl unci r th at clivi i n. Riv r water n t b div rl d l l ummary [ th Gila clivi i n ar urn-

VIII.- Potential fJ1'oj ects in the Gila divi ion

Estimat d construe· Project and un it Location or projrrt , ourcc or watrr supflly Purpose to he sen· d 1 tion cost'

'enLral ri zona ______Ari zo na______;olorado Hi v ~' ------J, F, P, :\[, $432, 00, 000 alt H.iv r Paradi e Valley an arl os had sLo n a ff ord Valley , an Franci co ] u1 can-Virden Valley r w Mexic hino Vall ey ______------____ do______rani Le and \\"il l w reeks ______T__ ------___ 150, 000 liassayampa ______------Ifassayampa Hiver ____ _ ------I, Jo'______6, 650, 000 ToLaL ______- ____ - __ - _- _------439, 600, 000

I Symbols:uscd: ! = irrigation, F - nood co ntrol, P=powcr, 1= municipnl, U =und rground waterdischnrgo. ' Proliminnryostimntes bas J on eo nstruetloo costs or Jnn. l, 19 10

TABLE IX.- Potential reservoirs in the Gila division

Total capacity Name or sito Sourc or water supply Project son ·ed (acre-rcet) l------1------l------'en Lral Ari ?.o na: 1IeDowelL ______alt River ______a l t Jli ver u niL ______250, 000 IIors shoe Enlargement______V rd Riv 1' ------­ Para I ise Valley u ni L ______300, 000 ButLes ______ila River______San arlo unit______400, 000 harte ton ______an P edro lli ver ______Charl esLon unit______240, 000 Elli LL ______Gita R iver ______afl'ord Vall y u niL ______70,000 IIo kcr_•______do ______cw Mexico uniL ______150,000 Miscellaneous ______San Francisco Riv rand Lributaries ___ _ 'an Franci co unit______(') Box Canyon ______------____ Ha ssa ~' ampa Riv r______Hassayampa___ _ ------210, 000

TotaL ______2 1, 620, 000

1 Not determined. 'Exclusi,-e or potential reservoirs in San Francisco unit. 182 THE COLORADO RIVER

TABLE CX.- Potential irrigation development m the Gila division

Area to be benefited (acres) Project and unit State Furnished supple- Nowland mental water Total ------·-·l-----1------Central Arizona: Salt River______Arizona ______20, 000 3 4, 900 404, 900 Paradise Valley ______do ______85,000 0 805, 000 San Carlos ______do ______0 157, 400 157, 400 Charleston ______do ______0 2, 600 2, 600 Safford Valley______do ______0 32, 460 32, 460 San Francisco ______r ew Mexico ______. __ 2, 000 2, 500 4, 500 Duncan-Virden Valley ______Arizona- Jew M exico ______0 ' 100 ' 100 New Mexico ______ew Mexico ______0 5, 500 5, 500 Subtotal ______------_ ------107, 000 593, 460 700, 460 Chino Valley ______Ari zo na ______------0 2, 540 2, 540 I!assayarnpa ______do ______00 ' 0 ' 00 TotaL ______115, 00 596,000 711 , 00

TABLE CXI.- Potential irrigation development in the Gila division by States

Area to bo benentrd (acres)

State Furnished Tow land supplemental •rolnl water

Arizona ______New Mexico------Total ______

TABLE CXII.- Potential power development in the Gila di vision

Power plant P roject and unit Nam e or power plant Stream instnlle I ca po - Annual nrm genera­ ity (ki lowatts) tion (kw. -hrs.) --·------·------·------1------ll ------Central Arizona: Paradise Valley ______I!orseshoe ______V rde Riv r ______I 10, 000 I 37, 000, 000 San Carl os ______Buttes -- - --~------______Gila River ______5, 00 ' 000, 000 New Mexico ______I!ooker ______. do ~- -- ______3, 000 8, 000, 000 TotaL ______18, 00 2 43, 000, 000

I Replacement power ro r Stewart Mountain power plant. 'Net annual firm generation wo uld bo 16,000,000 kilowatt-hours.

TABLE CXIII.- Present and potential stream depletions in TABLE CXIII.- Present and potential stream depletions in the Gila division the Gila division- Con tinu d

Estimated average annual depletion (acre- Estimated avomgo annual depletion (acre- feet) feet) State and ri ver State and ri ver T otal Potential T otal Present Potential ultimate Present ultimate depletion increase depletion depletion increase depleti on

Arizona· New Mex ico: Gila River ______1, 135,000 20,000 1, 155, 000 Gila River ______16,000 ------16, 000 Colorado River______' 000 8, 000 Colorado River______------1, 588,000 1, 588, 000 ------SubtotaL ______16, 000 8,000 24, 000 SubtotaL ______1,135,000 1, 608, 000 2, 743,000 TotaL ______1, 151, 000 1,616, 000 2, 767, 000 USING THE WATER-SUMMARY- LOWER BASIN 183

Summary of Present and Potential Development in the Lower Basin T he following tables summ arize in th'e lower basin resources with estimated con truction costs, and present present irrigated areas, potential development of water and potential stream depletions.

TABLE CXIV.- Present irrigation development in the lower basin 1

Acres irrigated ·ni viRion Arizo na Cali fo rni a Nevada New Mex ico Utah Total

LiUie Colorado. ______Virgin ______39, 230 '770 48, 000 2, 00 9' 800 ------23' 500 36, 100 2 BGiolua l__d ___ r ______------______I 244, 00 03, 000 l ' 200 ------1, 049, 000 716, 000 11 , 000 727, 000 T tal ______l , 002, 30 3 03, 000 11 , 000 19, 770 23, 500 3 1, 60, 100

' Includes I fi6,900 nc r ~s not yet i rr i g at~d under cxisl ing projects. • In c l ud~ s 416,400 acres irri gated and 296,600 acres not yet irrigRtcd under the Ail­ ' Includes 342.100 acres yet to be irrigated under existing projects. American Canal sy ~ tc m outEidc the olorado Ri ve r natural drainage ba.'in

TABLE CXV.- Present hydroelectric ge nerating capacity in TABLE CXV.- Present hydroelectric generating capacity in the lower basin the lowe1· basin- Continued

Prescot Authorized P resent Authorized installed or plaon d Total capacity insta ll ed or plano d T otal capacity tate and division capacity capacity (kilowatts) State and division capacity capacity (kilowatts) (kilowatts) (kil watts) (kilowatts) (kilowatts) ---- Ari zona: Ari zona-Nevada: LiLLi e olorado ______40 40 Bould r _____ - l ' 030, 000 512, 500 1, 542, 500 ~ 7, 950 7, 950 alif rnia: oila ------Boulder. ______-- -- 16, 600 6 ' 000 84, 600 ubL LaL ______ULah: 7, 990 7, 990 Virgin ______------3, 440 ------3, 440 Arizon a-California: T LaL ____ ------1, 25 ' 030 5 0, 500 1, 838, 530 Boulder. ___ _ l 20, 000 -- . ------120, 000

T.<\BLE CXVI.- Potential development of water resources m the lower basin 1

A eros to be irrigated ' Power plants Estimated State and division construction Furnished sup­ lnstailed capac- Annual Orm ~e n cra­ cost • N w land plemental water ity (kilowa tts) tion (kil owatt-hours)' ------·----·------l-----1------l------l------Ari zona: Li Ltle Colorado______32, 250 600 ------'24, 700, 000 Virgin ______------3,000 1, 000 ------2, ooo, roo Boulder ______0, 000 7, 800 1, 922, 000 10,174, 000, 000 563, 200, 000 Gila______113, 800 585, 200 15, 800 ' 000, 000 425, 500, 000 Subtotal ______------229, 050 594, 600 l , 937, 00 JO , l 2, 000, 000 l , 01 5,400, 000 California: Boulder- ---- _----______16, 000 ______3, 100, 000 Nevada: Virgin _- ______9, 500 4, 500 ______4, 00, 000 Boulder______33,600 ------11, 700, 000 -----1---- -1------1------SubtoLaL ______43,100 4, 500 ------16,500, 000 ew Mexico: Gila. ------______2, 000 10, 800 3, 000 8, 000, 000 14, 100, 000 Utah: 9, 100, 000 Rive~i;~~~fi~~t;~;; -~~d-co-n"t-r~i ~======- -- ~~~ ~~~ ------~ ~ ~~~ ------~~- ~~~ ------~ ~·- ~ ~~·- ~~~ - 5, 000, 000 TransJnissio n grid ______192, 100, 000 TotaL ______303, 150 618, 100 1,945,400 10, 205, 000, 000 1,255,300,000

1 In addition to irrigation and power production, many potential projects would have value for nood control, silt retention, recreation. and fish and wildlife conservation and recharge lor underground water supplies. 2 Does not include irrigable lands under constructed or authorized projects. • Net firm generation, exclusive of replacement power. • Preliminary estimates based on construction costs ol Jan. 1, 1940. 184 THE COLORADO RIVER

TABLE CXVII.-Present and potential stream depletion in the lo wer basin

E stimated average annual depletion (acre-feet)

Existing or authorized projects Potential projects SLate and division Present depletions Future increase Total ultimate depletion Consumed in Exported Consumed in Consum ed in basin basin Exported basin Exported ------·------1------1-----1------1------l------Arizoua: Little Colorado ______5 ' 700 4 ' 700 ------107,400 Virginia ______5, 100 12, 700 ------17, 00 Boulder ______208,400 571, ooo · ______346, 000 ------1' 12.') , 400 Gila ______1,135, 000 1, 608, 000 2, 743, 000 ~----1------·---1------SubtotaL______1, 407,200 ------571 , 000 ------2, 01 5,400 3, 993,600 California: Boulder______._ . _._ 145, 000 2, 535, 000 148, 000 2, 798, 000 64, 000 112, 000 5, 02, 000 Nevada: Virgin ______23,800 36, 000 59, 00 Boulder ______20, 000 177, 000 197, 000 SubtotaL ______43, 800 ______213, 000 ______. 25G, 00 New Mexico: Little Colorado ______Gila ______13, 000 ------13, 000 16, 000 ------' 000 ------24' uoo ------1------1------1-----·- SubtotaL ______29, 000 ------' 000 ------37,000 Utah: Virgin ______45, 000 56,300 10 I , 300 R eservoir losses ______713, 000 66, 000 9l,OUO 70, 000 TotaL______2, 383, 000 2, 535, 000 785, 000 2, 79 , 000 2,447, 700 112, 000 11,060, 700

SUMMARY OF PRESE T A D POTENTIAL T ABLE XIX.-Present hydroelectric generating capacity in DEVELOPME T I COLORADO RIV ER the Colorado R iver Basin BASIN Prrscnt in- A uthorizcd tate and division stollcd capac- or plann d Total ity (kilowatts) (k il owatts) The following tables summarize present and potential (k il owatts) development of water resources in the entire Colorado Colorado: Green ______200 200 River Basin. Grand ______------49, 667 ------49, 667 Table CXXI shows that the "total ultimate depletion , · San Juan ______4, 650 ---·------4, 650 are over 20,000,000 acre-feet annually. The long time Sub to taL ______54, 517 ------5<1, .517 average annual undepleted flow of the Colorado River at New Mexico: an Juan . .. ___ 280 ------280 the International Boundary is estimated at 17,720,000 Utah:Green ______2, 050 ..... ------2, 050 acre-feet. (See appendix I, Water Supply, Colorado Grand ______50 ------50 San J uan ______170 ------170 ubtotaL ______2, 270 2, 270 TABLE CXVIII.- Present irrigation develoj;ment in the ------Colorado River Basin Wyoming: Green ______150 ------150 T otal, upper basin ___ 57, 217 57,217 Upper basin Lower bas in ------Arizona: State 'l'otal (acres) Little oloraclo ______40 40 Irrigated Irrigable 1 Irrigated Irrigablc 1 G i Ia ______------(acres) (acres) (acres) (acres) 87, 950 ------87, 950 u b to taL ______87, 990 ------87, 990 Arizona ______6, 000 835, 930 166, 900 1, 006, 30 Arizona-California: ------Boulder ______California ____ ------460, 900 342, 100 2 03, 000 120, 000 ------120, 000 Colorado _____ 770, 170 32, 670 02, 40 Arizona- evacla: ------Boulder. ______Nevada ______------11, 000 ------11, 000 1, 030, 000 512, 500 1, 542, 500 New Mexico __ ------38, 000 19, 770 57, 770 California: ------Boulder. ______Utah ______274, 20 ------23, 500 ------298, 320 16, 600 6 '000 4, 600 Wyoming _____ 236, 070 11 , 470 ------247, 540 Utah: Virgin ______-,- ______3, 440 ------3,440 TotaL_ 1, 325, 060 44, 140 1, 351, 100 509, 00013, 229, 300 Total, lower basin ___ 1, 258, 030 580, 500 1, 838, 530 Total, olorado River I Land that will be irrigated under present development._ Basin ______1, 315, 247 580, 500 1, 895, 747 ' Includes 713,000 acres outside the natural Colorado Rive r drainage area. USING THE WATER- SUMMARY- COLORADO RIVER BASIN 185

River. ) The required delivery to Mexico, assuming It is evident that the list of potential projects selected for ratification by Mexico of the pending treaty, with ultimate actual development will need to be modified to conform development in the i estimated to average to the available water upply. A plan of modification is 1,500,000 acre-feet annu ally, which would leave an aver­ not suggested in this report. Final selection of projects age annual fl ow to be used in the United States of about will depend upon their relative merits, the final alloca­ 16,220,000 acre-feet, or about 80 percent of the sum of tions of water among the States, the desires of each State the present and potential development pos ibilities li ted as to alternative possibiliti , and the finding of future in the report. inve tigations.

TABLE XX.- Potential develojnnent of water resources in the Colorado R iver Basin

Acres to be lrrlga t d • Pow r plants Esiimat d State and division Furnished Installed construction N ow land supplemental capacity Annual firm gono ra· cos t 1 wat r (k ilowatts) Li on (kil owatt-hours)

Arizona : Sa n Juan ___ _ 1 '6 0 6, 000 400, 000 2, l ' 000, 000 65,62 , 000 Lit,lle 'oloracl 32, 250 600 ------24, 700, 000 V irgi ••------3, 000 1, 000 ------2,000, 000 B ulcler ______80, 000 7, 800 l ' 022, 000 10, 174, 000, 000 563, 200, 000 Gila ______. 11 3, 00 5 5, 200 15, 00 ' 000 , 000 4.25, 500, 000 ub LoLa l ___ _ 247, 730 600, 600 2, 337, 00 J 2, 370, 000, 000 ===1=====1--== alifornia : B oulde r __ 16,000 3, 100, 000 ol •·ado : U r n ____ _ 1!)7, 00 30, 360 17U, 500 944, 000, 000 06, 300, 000 , rand __ 13!), 300 1!) ' 270 ' 000 453, 000, 000 57, 232, 000 an Juan __ _ _ 11 0, 060 37, 920 67, 000 264 , 000, 000 69, 227, 000 ubLoLaL __ _ 444., 0 0 226, 550 325, 500 1, 661, 000, 000 222, 759, 000

Nevada : V irgin ____ _ 9, 500 4., 500 4., 00, 000 Boulder_ _ 33, GOO 11 , 700, 000 1-----1------SubLoLaL __ _ 4.3, 100 1, 500

New M exico: , an Juan ___ _ 224., 9 0 15, 100 76, 2, 000 ila __ _ 2, 000 10, 00 3, 000 14. , 100, 000 . --- ·------SubL La l ___ _ 226, 960 25, 900 3, 000 8, 000, 000 90, 9 2, 000 ======1~~====,1======; 1 ======Lah: r en ___ _ 150, 520 145, 010 2 ' 000 l , 579, 000, 0 0 11 6, 500, 000 Grand __ '700 1, 950 200,000 J ' 141' 00 ' 000 0, 975, 000 San Juan ___ _ 12,560 l4, 200 40 , 000 2 063 000 000 150,298, 000 V irgin ___ _ 13,000 '200 4., 600 ' 15: ooo: 000 9, 100, 000 ----1-----1------SubL Ln. l ___ _ 264 , 7 0 109, 360 990, 600 5, 39 , 000, 000 356,873, 000

W yoming : Gr en __ _ _ 291, 330 95, 360 1, 500 ' 000, 000 4.7, 100, 000 Tii vcr r cc lificaLion and conLroL __ _ 5, 000,000 T ransmis ion grid ______362,100,000 ------1---- T ota!______------1, 533,960 1, 122,270 3, 65 , 4.00 19, 4.4.6, 000, 000 2, 185, 44.2, 000

' Does not inr-lud r irriga hlo land s under 'ist ing or aut hori zo cl projects. 1 P reliminary os ti matcs based on construciion cost; or Jan. 1, 1g10.

70D 515--4G----13 186 THE COLORADO RIVER

TABLE CXXI.-Present and potential stream depletion in the Colorado River Basin

Estimated average annual depletion (acre-feet)

Existing or authorized projects Potential projects

State and division Total ultl· Present depletion Future increase mate deple­ tion Consumed in basin Exported

Arizona: San Juan______10,200 ------______39, 000 49, 200 Little Colorado______58, 700 ______4 , 700 107,400 Virgin______5,100 ------12,700 17, 00 Boulder______208,400 ------571 , 000 ------346, 000 1, 125, 400 Gila ______1, 135,000 ------1, 60 , 000 2, 743, 000 ------·------1------SubtotaL ______1, 417,400 ------571, 000 ------2, 054,400 ------4, 042,800 1======1======1======1======1======1======1======California: Boulder ______145,000 2,535,000 148, 000 2, 798, 000 64, 000 112, 000 5, 02, 000 Colorado: Green ______115, 000 324, 000 75, 000 514, 000 Grand ______776, 000 98, 300 05, 000 421, 000 295,000 1,492, 000 3, 147, 300 SanJuan ______------238,000 4, 000 21, 000 251, 000 85, 000 599,000 ------1-----1------·-- SubtotaL ______1, 129, 000 102, 300 65, 000 442, 000 70, 000 1, 652, 000 4, 2 0, 300 Nevada: V~g in ______23,800 36, 000 59, 800 Boulder ______20,000 177,000 197,000 ------1----11----1- Subtotal ______43,800 213,000 256, 00 New Mexico: San Juan ______68,400 450, 000 518,400 Little Colorado ______. _____ . ___ __ . ___ _ Gila ______18, 000 13, 000 16, 000 8, 000 . ------24,000 ------1·---·------Subtotal ______97,400 458, 000 555,400

Utah: Green ______c______358,000 81,500 ------32,000 264,000 975,700 1, 711, 200 Grand______13, 000 ------______186,000 ______. 199, 000 San Juan______63,400 ______------30,000 7, 000 100,400 Virgin ______. ______. _. __ .. -- 45, 000 ___ . ______. _. ___ . __ . ______56, 300 ______. . . 101, 300 ------1----1-- Subtotal ______479, 400 81, 500 32,000 536, 300 982, 700 2, 111, 900

WyomiGreenng: ______374, 000 17, 000 ------

T ABL E CXLIII.- omj;a riso n of sections of olora do R ivf'r Valley above and below 'J"o j;o k

A r(IU "' HllO\ 'l' 'Ptipm·k Bt•tw(l(' ll Bou1 d,•r IJ t' IWI't'll 'Pn[HH'k nud In pP r· F ~a tur o I> HIIl nncl T opock ] A\I.UIIll\ I>U IIl t• ut nr !H' (' I\.'~ ht•IO\\ ' l'opo<·k

Ht r e am chann r l I I ,000 acrrs _ 25, 000 IH'I"('H II a rea.1 ws : Val ley fl oor a rea 1 __ 1-! 0,000 a r r~ _ 250,000 n< ' l" (' ~ :) 2 Irrigated a rea ____ _ l'\() 11 (' :3 5, 000 ll (' I"PH 0 Tributari es enter ing 1 in o r washes '\ illi a m ~ lli v< •r T A IILJ·; 'X L I Pa.1l ujHtu ·am tll tt.: ation d cjJlclion, ita ol raclo Hiver. n n d ~< 111 a II and, 'till R ivt'l.\ W!l Hh C':<.

Olin Hh ••r Hull HIH'I n iHJ\'t' um (IU'It' r1 •11t)

IH\l!l 12, 000 12, 000 I!IO!l !i, 000 12, 000 J!l22 77, ()(() 12, ()() 1\l:l:l 7! ), ()()() 12, 000 1\ll:l 7!1, 000 12, ()()()

(c)

Virgin fiow ) Colorado R iver at L aauna The average annu. I virgin n v f th I r c t Laguna Dam ( ab v m ulh ( as f How : A rrr Jrt•l irgin fl ow, Colo rado River at Bou ld r D am ___ _ 17 33 0, 000 Plus tributary inflow, Bould r D am to m uth of il a 15 ' 0 () L ' SS natural channel losses_ __ - · ------' · 03 ' 0 Virgin flow, Colorado Ri v r at Laguna am (above Gila Ri ver ) ------I , 45 , 0 0

Virgin fiow) Gila R iver at Yuma Throughout the Gila Riv r Ba in stream-flow record i mad cl ifTi ull by vi nl fl d , shifting channels, and and and il t. Ex pt in lh Phoenix area, where ext n ive irrigation dev 1 pment has been made, there are no r liabl long- tim r ords of the ar a mpare with th ila River and its tributa ri es . sing the available rec- Gille pie Dam as hown in the following table: 284 T H E CO LO RADO RIVER

TABLE CXLV.- Gila River Channel characteristics and climatological data

Area between Gillespie Dam and mo uth PbocnLx area

Length of river channel: Gila River ______145 .------Above alt River ______go miles B elow al t River______35 miles Salt River______40 miles

T otaL ______------145 m il es ______1 165 m il s Average river gradient: Gila R iver ______4 feet per mil ______G fe L 1 r mile. Salt River ______9 ~ feeL p r mile.

Average ______- _____ -_ 4 fe t per mil 7 fee L p er mile. Climatological data: Average annual precip itation ______5 inches ______69 in h s. Average annual temperature ______72 degrees ______9 l g r e ·.

1 In addition to Gi la and Salt Ri ve r ct1annels, water will be lost from tributary chru m Is such as Jl gua :F ira, J tassayampa, and Qul'cn rl'e ks.

(d) Using concurrent records of Gila River di charge availabl in[ rm a ti n n lr am fl ows. at Gillespie Dam and at the mouth (Dome, Ariz. ) f r of this stu dy the av rag virgin f1 w at th the period August 1921 to December 1934, and making ila Riv r ha b n r und d t 1 27 0 due allowances for the mall irrigation usc in this ar a annuall y. and for the fact that fl ows at Gille pie Dam wer largely controlled by storage during the period of concurr nt record, a curve was defined which hows the r lation hip Virgin fio w olorado R iv r at I nt rnational between annual (unregulated ) dis harge at ill pi Boundary Dam and annual channel losses b lwe n Gill pi Dam and the mouth of the Gila River. The curve was appli d to the entire p riod to determine channel 1 The channel losses, thus determin d, ubtra t d fr m the computed natural (or virgin ) fl ows at illc pi Dam, l i CI' '·{ct't Av rag a nnual virgin fl w, \orad Riv -r a t La una give the virgin fl ows of the Gila River at it mouth. Th Da m J 4 0, 00 basic computation are ummarized in tabl LVI. Av rag annual virgin flow, ila Riv r a t mouth J, 27 0, 00 While these c timatcd virgin fl ows may not b ntir ly vcragc a nnual virgin flow, ol rado Riv I' a t I nt r- dependable, they are the best that could be made from na ti onal b undarY------··- _ ------17, 720, 000

TABLE CXLVI. - Estimated virgin flo w of ila R iver at mouth (thousand acre-feet)

Natural toss or Natural now n1 F low of J!'Jow of Unmeasured 'f otal nntural Natural loss I Natural now of ill spl!' n am lo Year alt Riv rat Gila River at natural inflow to Inflow to in Ph n ix ita Hi ve r at ilu J lvr•· at (l il a tllwr o L Granite Reel Kelvin Phoe nix area l' hoenix area ar a Olllespte Dam mouth lliOUth ----- 1897 ______-- I 1, 2 9 605 23 1 2, 125 5"0 501 1, 74 1898 ______I 53 7 401 97 1, 035 372 302 3 ' I 1899 ------. -- 514 302 9 914 345 272 207 1900 ______269 274 52 595 262 193 140 1901 ______765 352 136 1, 253 4.15 34. 49 1902 ______44 2 223 99 764 302 240 222 1903 ______436 266 9 00 314 2'1 23 1904 ______527 336 121 9 4 355 2 0 330 1905 ______5, 542 I 1, 5 2 21 7, 945 904 00 6, 141 2, 396 I 68 360 3,44.4. 690 6"9 2, 095 1907190"6 --_____----__- -_-_-___-- -_-_-_ 2, 021 I 1, 013 337 3, 371 6 5 650 2, 03 1908 ______1, 828 I 4 3 270 2, 5 1 610 5 4. 1, 407 1909 ______1, 736 395 262 2, 393 5 54 0 1, 265 1910 ______206 216 ] '352 416 376 560 1911 ______930 I 2, 143 521 326 2, 990 650 612 l , 72 1912 ______I 1, 041 535 1 7 ], 763 502 443 1 1913 ______888 310 160 1, 358 430 37'.1. 554 1914 ______1, 350 1, 342 167 2, 59 65 1 59 l, 610 1915 ______2, 490 1, 487 306 4, 2 3 760 72 2, 795 1916 ______5, 301 1, 716 435 7, 452 901 5 5, 666 1917 ______------~ 2, 819 420 384 3, 623 702 673 2, 24 1918 ______1, 018 250 258 1, 526 444 408 674

1 Basic run-off record estimated in whole or part. WATER SUPPLY 285

TAB L E CXLVI. -Estimated virgin fl ow of Gila River at mouth (thousand acre-feet) - Continued

Flow of N aturalloss of Salt R iver at Flow of Unm easured Total natural Natural loss Natural fl ow of Gillespie Dam to Natural flow of Year Granite Reef Gila River at natural inflow to inflow to in Phoe nix Gila R ive r at Gil a River at Gila River at Kelvin Phoenix area P hoenix area area Gill spie Dam mouth mouth 1919 ______1920 ______2, 201 949 375 3, 525 697 2, 28 666 2, 16 2 1921 ______2,478 627 440 3, 545 691 2, 854 670 2, 18 4 1922 ______1, 826 536 170 2, 532 616 1, 916 558 1, 35 8 1923 ______1, 569 189 339 2, 097 534 1, 563 501 1, 062 1924 ______1, 754 575 325 2, 654 610 2, 044 573 1, 471 1925 ______967 299 140 1, 406 443 963 3 0 583 1926 ______693 303 143 1, 139 3 751 330 421 1927 ______1, 334 493 241 2, 06 546 1, 522 '.192 1, 030 1928 ______1, 927 366 417 2, 710 607 2, 103 5 2 1, 521 643 214 153 1, 010 353 657 300 35 7 1929 ______1, 025 338 188 1, 55 1 462 1, 0 9 409 6 0 1930 ______420 6o r-: 1931 ______857 15 1,435 446 9 9 3 4 0 1932 ______1,360 577 224 2, 161 560 1, 601 507 1, 09 4 1933 ______2, 045 534 390 2, 969 635 2,334 610 1, 72 4 701 304 107 1, 112 390 722 31" 40 7 1934 ______372 256 712 2 r. 7 1935 ______84 427 220 20 1936 ______1, 516 4 1 255 2, 252 560 1, 692 520 1, 1.7 2 1937 ______l , 109 32 146 1, 5 3 472 ] ' 11 l 410 701 1938 ______2, 101 511 40 3, 020 4.0 2, 3 0 011' J, 7 )5 1939 ______971 232 222 1, 425 414 l, Ol l 3 5 02 1940 ______749 263 136 1, 14 410 73 320 41 1, 070 462 126 1, 65 490 1' 1 515 r. 3 1941 ______3, 491 1, 250 557 5,29 1942 ______0 4, 490 790 3, 70 0 8 4 2 147 1,319 '127 !)2 35" 1)3 7 1943 ______974 288 143 1, 405 44 0 905 3 5 F ------Average ____ _ 1, 50 527. 244 2, 279 527 l, 7"2 4 0 ] '27 2

v