Ground-Water Resources of the San Luis Valley Colorado GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1379 Prepared in cooperation with the Colorado Water Conservation Board and the United States Bureau of Reclamation Ground-Water Resources of the San Luis Valley Colorado By WILLIAM J. POWELL With a section on An Inflow-Outflow Study of the Area By PHILIP B. MUTZ GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1379 Prepared in cooperation with the Colorado Water Conservation Board and the United States Bureau of Reclamation UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1958 UNITED STATES DEPARTMENT OF THE INTERIOR FRED A. SEATON, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.C. CONTENTS Page Abstract ______________________________________ 1 Introduction ____________________________________ 2 Location and extent of the area ____________________ 2 Purpose of the investigation _______________________ 2 The Closed Basin Committee and direction of the investigation_ 4 Previous investigations __________________________ 6 History and methods of investigation _________________ 6 Field work _______________________________ 6 Preparation of report _______________________ 8 Acknowledgments _____________________________ 8 Well-numbering system _________________________ 9 Geography ___________________________________ 10 Topography and drainage ________________________ 10 Climate ____________________________________ 13 Agriculture __________________________________ 13 Population _ _________________________ 15 Transportation ________________________________ 16 Geology _______________________________________ 16 General features ______________________________ 16 Tertiary deposits _____________________________ 18 Santa Fe formation _________________________ 18 Quaternary deposits ___________________________ 20 Alamosa formation _________________________ 20 Ground water __________________________________ 24 Artesian water ______________________________ 25 History of development _____________________ 26 Areas of flow _____________________________ 27 Pressure head ____________________________ 28 General features _______________________ 28 Fluctuations in pressure head ________________ 29 Piezometric surface ___?_______________________________ 30 Recharge _______________________________ 32 Discharge _____________________ 33 Discharge from wells ____________________ 33 Flowing wells _______________________ 33 Pumped wells _______________________ 36 Discharge from springs ____________________ 36 Mclntire Springs _______________ 37 Diamond Springs ____________________ 38 Russell Springs __________________^_ 38 Spring Creek __________________ _ 39 Hydrologic properties of artesian aquifers _____ 39 III IV CONTENTS Ground water Continued Pase Artesian water Continued Utilization of artesian water ____________________ 42 Domestic and stock supplies __________________ 43 Public supplies ______________ _ _ 43 Alamosa ___________________________ 43 Monte Vista _________________________ 44 Irrigation supplies _________ ___ - _ 45 Yields of wells _____________________-_ 46 Construction of small-diameter wells _________ 47 Construction of large-diameter wells ___ 48 Methods of lift _______________________ 50 Quantity of water discharged ______________ 50 Possibilities of additional development _ _ _ 51 Unconfined water ___________________________ 55 History of development ______________________- 56 Water table ______________________________ 57 Shape and slope _________________________ 58 Ground-water divide ______________________ 60 Fluctuations of water level ____________ _ _ 61 Recharge _________________________________ 62 Recharge from irrigation ___________________ 63 Recharge from precipitation ____________ _ _ 67 Recharge from artesian aquifers ___________ 68 Leakage from artesian aquifers _ _ 68 Contributions from flowing wells ____ _ _ 69 Recharge from streams and canals ________ _ 69 Discharge ________________________________ 70 Discharge by evapotranspiration ____________ _ 71 Discharge from wells ___________-__ - - 73 Discharge by drains and canals ________ _ 74 Hydrologic properties of the unconfined aquifer ________ 74 Permeability and transmissibility ___________ 74 Laboratory determinations ______-____ 75 Pumping-test determinations _____________ 75 Specific yield ___________________________ 80 Utilization of unconfined water _________________ 81 Domestic and stock supplies ______________ 81 Irrigation supplies ___________________ 82 Yields and drawdowns of wells _______ 82 Construction of wells _i____________ _ 84 Methods of lift _______________________ 85 Quantity of water discharged __ _ 86 Possbilities of additional development _______ 88 Quality of water _________________________________ 90 Chemical constituents in relation to use _____ _ _ 90 Dissolved solids ____________________ _ 90 Hardness ______________________ ___ _ 91 Chloride _________________________________ 93 Fluoride _________________________________ 93 Boron ____________________________________ 94 Sodium __________________________________ 94 CONTENTS Quality of water Continued Surface water _______________________________ 97 Lakes __________________________________ 97 Canals and laterals _________________________ 97 Drains _________________________________ 98 Ground water ________________________________ 99 Confined water ____________________________ 99 Unconfined water ____________________;______ 99 Quantity and quality of ground water available to proposed closed basin drain ___________________________________ 102 Quantity of ground water _________________________ 103 Method of investigation _______________________ 103 Evaluation of factors ______________________ 105 Salvage from transpiration and evaporation_____ 105 Coefficient of transmissibility ______________ 107 Drawdown at the drain __________________ 108 Results of investigation _______________________ 109 Quality of ground water _________________________ 110 Inflow and outflow of water in selected irrigated area _________ 118 Inflow-outflow study, by Philip B. Mutz ___________________ 120 Introduction to inflow-outflow study __________________ 120 Location ________________________________ 120 Period of study ____________________________ 122 Climate ________________________________ 122 Soils ___________________________________ 122 General cropping practices _____________________ 123 Methods of irrigation ______________________ 124 Drainage^ ________________________________ 124 Method of study ___________________________ 124 Inflow _______________________________________ 124 Surface-water inflow ____________________'._______ 124 Precipitation _____________________________ 124 Discharge of artesian wells _________________ 125 Outflow ____________________________________ 125 Surface-water outflow _______________________ 125 Shallow ground-water outflow _________________ 125 Evaporation _______________________ 127 Change in ground-water storage _______________-_ 127 Land use ___________________________________ 127 Results of study ______________________________ 128 Records _______________________________________ 129 Summary of method of presentation of data _____________ 129 Logs of wells and test holes _______________ 238 Selected bibliography __________________________ _ 280 Index ________________________________________ 283 VI CONTENTS ILLUSTRATIONS [All plates in pocket except as indicated] Page PLATE 1. Map of part of San Luis Valley, Colo., showing location of wells and springs. 2. Jetting observation wells ________ _ Facing 3. Log of well on Baca Grant. 4. Artesian wells. A, Well 43-8-31bc2 discharging at the rate of about 580 gallons a minute; B, mercury pressure gage used in measuring head of flowing well Facing 32 5. Reconnaissance piezometric map of part of San Luis Valley. 6. A, Parshall flume used in measuring discharges of large wells; B, discharge of Mclntire Springs Facing 40 7. Deep-well irrigation __________ Facing 41 8. Map of part of San Luis Valley, showing water-table contours, 1948-49. 9. Map of the sump area of San Luis Valley, showing con­ tours on the water table during the period September- November 1946. 10. Map of the sump area of San Luis Valley, showing con­ tours on the water table during the period May-June 1947. 11. Sections along and across proposed line of closed basin drain. 12. Classification of ground and surface water for irrigation. 13. Analyses of unconfined and confined ground water from indicated wells, showing the lowest, average, and high­ est concentration of dissolved solids. 14. Analyses of unconfined ground water in the closed basin, showing the average concentration of dissolved solids by land-survey ranges. 15. Maps of the area of inflow-outflow study, showing poly­ gons used for determining changes in ground-water storage. 16. Map of part of San Luis Valley, showing line of proposed closed basin drain, lines of cross sections, test holes, and test wells. FIGURE 1. Index map of Colorado, showing area described in this re­ port and areas on which ground-water reports are pub­ lished or are in preparation 3 2. Well-numbering system ______ _ 10 3. Profile of San Luis Valley from a point 0.2 mile east of Del Norte to a point 10 miles east of San Luis Lake___ 11 4. Normal monthly precipitation and mean monthly tempera­ tures at Monte Vista ______ _ _ ___ _ 13 5. Annual precipitation in San Luis Valley _ _________ 14 6. Geologic sketch map of San Luis Valley ___________ 17 7. Graph