Geology and Ground­ Water Resource·s of the Douglas Basin Arizona By D. R. COATES and R. L. CUSHMAN With a section on CHEMICAL QUALI1'Y OF THE GROUND \VATER By J. L. HATCHETT GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1354 Prepared in cooperation with Arizona State Land Department UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1955 • UNITED STATES DEPARTMENT OF THE INTERIOR Douglas McKay, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price $1.50 (paper cover) CONTENTS Page ~~~~~~tti~~~:::·:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ::: : ~ Purpose and scope of the investigation............................................................................ 2 Acknowledgments................................................................................................................ 2 Location and extent of the area........................................................................................ 3 Climate................................................................................................................................ 4 History of development ........................... ~.......................................................................... 5 Previous investigations.................................................................................................... 5 Methods of investigation................................................................................................... 6 Well-numbering system...................................................................................................... 6 Geology and its relation to ground water............................................................................ 8 Geomorphology.................................................................................................................... 8 History and water-bearing characteristics of rock units.............................................. 11 Schist............................................................................................................................ .. .. 11 Sedimentary rocks.......................................................................................................... 13 Granite............................................................................................................................... 13 Volcanic rocks................................................................................................................ 14 Valley fill........................................................................................................................ 15 Basalt.............................................................................................................................. 17 Gypsum............................................................................................................................ 18 Structural geology.............................................................................................................. 18 Ground-water resources ...................................... ;................................................................... 20 Occurrence.......................................................................................................................... 20 Unconfined water............................................................................................................ 20 Water in valley fill...................................................................................................... 20 Water in hard rocks.................................................................................................... 22 Confined water................................................................................................................ 23 Springs .............................................................................................................................. · 24 Origin..................................................................................... .............................................. 25 Movement.............................................................................................................................. 27 Recharge.............................................................................................................................. 28 Precipitation in mountain areas.................................................................................... 28 Precipitation on valley floor........................................................................................ 29 Seepage from irrigation.................................................................................................. 29 Discharge............................................................................................................................ 29 Evapotranspiration.......................................................................................................... 29 Flow out of basin............................................................................................................ 30 Pumping from wells........................................................................................................ 31 Springs.............................................................................................................................. 32 Summation of recharge and discharge............................................................................. 33 Fluctuations of the water table........................................................................................ 33 Quality of water, by J. L. Hatchett...................................................................................... 37 Chemical character of the ground water.......................................................................... 37 Wells.......................................... .. .................................................................................... 37 Springs ................................ :............................................................................................. 37 Dissolved-solids content of the ground water................................................................ 38 Source of dissolved solids............................................................................................ 38 Discharge of dissolved solids...................................................................................... 39 Comparison of recent analyses with those of earlier years.......................................... 39 Relation of quality of water to use.................................................................................. 39 Irrigation......................................................................................................................... 39 Domestic.......................................................................................................................... 40 Literature cited..................................................................................................................... 41 Index........................................................................... .............................................................. 55 III IV CONTENTS ILLUSTRATIONS [All plates in pocket] Plate 1. Map of Douglas basin showing geology and depth to water table in ' spring 1952. 2. Map of Douglas basin showing contours of the water table, spring 1952. 3. Map of Douglas basin showing decline of the water table, spring 1947-52. 4. Map of part of Douglas basin showing irrigation wells and irrigated areas. 5. Map of Douglas basin showing dissolved-solids content of the ground water. Page Figure 1. Map of Arizona showing location of Douglas basin.............. ........................... 3 2. Sketch showing well-numbering system in Arizona. ........................................ 7 3. Columnar section showing relation of rock types and geologic names......... 12 4. Diagrammatic cross section of representative valley-fill conditions in Douglas basin................................................................................................... 16 5. Graphs showing fluctuation of water levels in observation wells and pumpage in Douglas basin. ............................................................................. .. 35 TABLES Page Table 1. Climatological data, Douglas basin.................................................................... 43 2. Records of representative wells and springs in Douglas basin...................... 44 3. Logs of representative wells in Douglas basin................................................ 48 4. Analyses of water from selected wells and springs in Douglas basin.......... 51 GEOLOGY AND GROUND-WATER RESOURCES OF THE DOUGLAS BASIN, ARIZONA By D. R. CoATES and R. L. CusHMAN ABSTRACT The Douglas basin is part of a large northwest-trending intermontane valley, known as the Sulphur Spring Valley, which lies in southeastern Arizona, and extends into north­ eastern Sonora, Mexico. Maturely dissected mountains rise abruptly from long alluvial slopes and culminate in peaks 3,000 to 4,000 feet above the valley floor, Bedrock in the mountain areas confines drainage on the east and west, and an arc of low hills to the north separates the basin from the Willcox basin of the Sulphur Spring Valley. Drainage of the 1,200 square miles in the Douglas basin is southward