"< ._.!. Geology and Ground-Water ~ ~ ~ Conditions in the Gila Bend .....~ ~ Indian Reservation 00"' ~ ~., Maricopa County, Arizona t 00"' -;;; <.> "6'.o ~ GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1647-A f :;::i Prepared in cooperation with the ~z Bureau of Indian Affairs 0...... ~ ~ P'1 00 P'1 c:>:l WISCONSIN GEOlOGICAl :SURVEl' z ~ ~ ......z Geology and Ground-Water Conditions in the Gila Bend Indian Reservation Maricopa County, Arizona By L. A. HEINDL and C. A. ARMSTRONG WATER SUPPLY OF INDIAN RESERVATIONS-PAPAGO TRIBE GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1647-A Prepared in cooperation with the Bureau of Indian Affairs UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Prlntinl!, Office Washlnl!,ton 25, D.C. CONTENTS Page Abstract__________________________________________________________ Al Introduction______________________________________________________ 2 Previous investigations_____________________________________________ 4 GeologY---------------------------------------------------------- 6 Rocks and their water-bearing properties_ _ __ _ __ _ _ __ _ __ _ __ _ __ _ __ __ 7 Crystalline rocks__________________________________________ 7 Sil Murk formation________________________________________ 10 Sedimentary member__________________________________ 11 Volcanic member______________________________________ 15 Correlation, age, and origin_____________________________ 19 Tertiary and Quaternary alluvial deposits____________________ 21 Older alluvial filL_____________________________________ 22 Younger alluvial fill____________________________________ 23 Subsurface stratigraphy__ __ _ __ _ _ _ __ __ _ __ __ _ _ _ _ __ __ _ __ _ __ _ _ __ __ _ 23 ' Structure_____________________________________________________ 27 Geologio history__ _ __ _ __ __ _ __ _ _ _ __ _ __ _ _ __ _ __ _ _ _ _ __ __ __ _ _ _ __ _ __ _ 29 Water resources_----- _________ ,____________________________________ 31 Surfacewater_________________________________________________ 32 Groundwater_________________________________________________ 33 Valleyfill_________________________________________________ 33 Occurrence of ground water and slope of the water table____ 33 Recharge_____________________________________________ 36 Discharge____________________________________________ 36 Storage_______________________________________________ 36 Fluctuations__________________________________________ 38 Quality of water_______________________________________________ 40 Availability of ground water for future development__ __ _ __ _ __ _ __ _ _ 42 Summary and conclusions___ __ _ _ __ _ __ _ _ __ _ _ _ __ _ _ __ _ _ __ __ _ _ __ _ __ _ __ _ 44 References cited__ __ _ _ __ _ __ __ _ _ _ __ __ _ _ __ __ _ _ __ _ _ __ __ _ __ _ __ __ _ _ _ __ _ _ 45 Index____________________________________________________________ 47 III FIGURE.L .Index map of.. G~Ia Bend, Papagq, . Reservations ___ ~ ___ ~ ___ ~.:.~ __ ~--._ __ -~·~;.; ______ .. ___ --~ __ 2. Inde:X: map of Gila plain and adjacent mountains.... ~-~- 3. View of Gila Bend Moun1~airts_.:. 4. Geologic map showing of 5. Topographic relationships of the Sil Murk xurwablUil• 6. Thin-bedded red arkosic sandstone that forms the exposed part of the Sil Murk formation---------------.--- 7. Lower part of well-indurated fanglomerate of the Sil l\-furk formation _____________________ .. ____ .. ____ .. ___ .. ____ ~ ___ ~ 8. Weakly consolidated fanglomerate of the Sil Murk formation __ 9. Interbedded fanglomerate and gray conglomerate of the Sil Murk formation _____________________ ------_----------"" . 10. Diagrammatic section showing angular unconformity between fanglomerate and volcanic members of the Sil Murk forma- tion-------------------------------------------------~ 11. Contact between tuffaceous sandstone and ash bed of the volcanic member ______________________________ ----- __ _ 12. Dacitic welded tuff of the volcanic member ________________ _ 13. Generalized block diagram of Gila Bend Mountains a~d Gill!> Bend plain ________ ----------.. -----"-----'"--- .. .,. .. ------- 14. Annual ground-water pumpage and water-table fluctuations.;;~ . TABLES TABLE 1. Drillers' logs of selected wells in the vicinity of the Gila Bend . · Indian Reservation ________ .. ___ ...... _.... __ .......... ~-----_-~-~_ 2. Description of selected wells in the Gila Bend Indian.Reservation and vicinity ___________________ .. -----.-------------·.. --.- 3. Chemical analyses of water from selected wells in the vicinity of the Gila Bend Indian Reservation------------·----"~~~- WATER SUPPLY OF INDIAN RESERVAT ONS-PAPAGO TRIBE GEOLOGY AND GROUND-WAT R CONDITIONS IN THE GILA BEND INDIAN ESERVATION, MARICOPA COUNTY, RIZONA I I By L.A. HEINDL and c. A. rSTRONG ABSTRACT I The Gila Bend Indian Reservation, Maricopa;County, Ariz., comprises an area of 16 square miles about 3 miles north of Gil Bend, Ariz. The Gila River flows across the reservation at an altitude of abo t 620 feet, and the Gila Bend Mountains, which form the northwestern partt of the reservation, rise to an altitude of about 2,000 feet. · The reservation is underlain by crystalline rock~ of possible Precambrian and Mesozoic ages, red sandstone, fanglomerate, collltlomerate, and volcanic rocks of probable Tertiary age, an older alluvial fill of tt'ertiary and Quaternary age, and channel and flood-plain deposits of Quaternao/ age. The Gila Bend Moun­ tains are composed of granitic, metamorphic, and Ivolcanic rocks, and older ter­ restrial deposits and appear to be a fault block th~t has been tilted to the west. The older alluvium and the channel and flood-plain !deposits were laid down on an eroded surface of the tilted block. The fiood-pl*n deposits are about 80 feet thick and are underlain by older alluvium, whicl in this area is about 300 to 500 feet thick. The sandstone, fanglomerate, andt volcanic rocks are more than 1,500 feet thick. · The principal aquifer is in the valley fill, which !comprises hydraulically inter­ connected parts of the older and younger alluvi~l deposits and the sandstone, fanglomerate, and conglomerate of Tertiary age. i This aquifer yields water in large quantities. The crystalline rocks are virtlially not water-bearing. The principal recharge to the alluvial deposits is byin!filtration from the Gila River. Large quantities of water are in storage in these de~osits. The concentration of dissolved solids of most pf the ground water obtained from the valley fill ranges from about 1,000 to 3~500 ppm. The water is high in sodium, chloride, boron, and fiuorid~. The sutface water of the Gila River during periods of low flow contains more than 5,poo ppm of dissolved solids-­ chiefly sodium, calcium, magnesium, and chloride. t, Painted Rock Dam, now being constructed acr s the Gila River for flood­ control purposes about 11 miles downstream fro the reservation, will have a spillway at an altitude of 660 feet. When the Iieservoir behind the dam fills to the level of the spillway, all the reservation, tcept for the part in the Gila Bend Mountains, will be inundated. However, 1 ng-term effects of inundation by high water likely will be unimportant beca se the reservoir will receive . water only from infrequent maximum floods, and ,the water will not be retained permanently in the reservoir. 1 Al A2 WATER SUPPLY OF INDIAN RESERVATIONS-PAPAGO TRIBE INTRODUCT ION The study of ground-water resources of the Gila Bend Indian Res­ ervation is part of an investigation of the ground water available to the Papago Indian Tribe. The study was made by the Geological Survey in cooperation with the Bureau of Indian Affairs. The Bureau of Indian Affairs requested data regarding the possibilities of develop­ ing water supplies for bot~1 range and irrigation purposes, and an opinion regarding the possible effects of Painted Rock Dam being constructed about 10 miles downstream and west of the reservation (fig.l). ;;: .~-{~~#l#tttt~~S~A@N tX A V lER~lt="N:::;Dl;::AN'-j---- -· RESERVATION -........._ - ~Nogal~ _ 111 0 110° 109 50 50 tOO Miles FIGURE 1..---.lndex map of Arizona showing Gila Bend, Papago, and San Xavier Indian Reservations. GROUND WATER, GILA BEND INDIAN RESERVAT ION A3 The Gila Bend Indian Reservation, the smallest of three Papago Indian Reservations, is 16 square mij es in area, and is in the Sonoran Desert section of the Basin and Range province (Fenneman, 1931) . It is 3 miles north of Gila Bend, Ariz., at the north end of a large gently northward-sloping intermontane basin called the Gila Bend plain, and at the south end of the Gila Bend Mountains (fig. 2) . Im­ mediately east of the Gila Bend Indian Reservation the Gila River bends from south to west to give the region its name. The reserva­ tion is divided by the Gila River, which here marks the boundary between the Gi la Bend plain and the Gila Bend Mountains. E XPL A NATION R . 5W. R.4W. CJ CJ Bedrock Surface deposits on Gi la Ben<! -~~~nee­ R .3W. plain except for inner flood plain and channels of Gila Ri ver, whi ch are separate­ r. ly marked T . Older Gila River 3 flood plain Outline of area mapped s in this report R.7W. PAINTED ROCK DAMSITE ~ _ _. -... *- <>' \.. ,./ T . 5 s P l A I N N 1 0 l 2 3 4 5 MI LES T. 8 s . FIGURE 2.-Index map of Gila Bend pl•aln and a djacent mountains, Rhowing outline of hard-rock outcrops. After Babcock and others (1948, pl.. 1) . A4 WATER SUPPLY OF INDIAN RESER'VATIONIS--PAPAGO TRIBE The altitude of the Gila River