Subsurface Flow to Eagle Valley from Vicee, Ash, and Kings Canyons, Carson City, Nevada, Estimated from Darcy's Law and the Chloride-Balance Method By DOUGLAS K. MAURER, DAVID L BERGER, and DAVID E. PRUDIC U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 96-4088 Prepared in cooperation with the CARSON CITY UTILITIES DEPARTMENT Carson City, Nevada 1996 OCT 30 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY GORDON P. EATON, Director Any use of trade names in this publication is for descriptive purposes only and does not constitute endorsement by the U.S. Government For additional information Copies of this report can be write to: purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Branch of Information Services 333 West Nye Lane, Room 203 Box 25286 Carson City, NV 89706-0866 Denver, CO 80225-0286 CONTENTS Abstract .................................................................................................................^ 1 Introduction ........................................................................................................................................................................... 2 Purpose and Scope .................................................................................................................................................... 4 Acknowledgments ..................................................................................................................................................... 4 Description of Eagle Valley .................................................................................................................................................. 4 Location and Geography ........................................................................................................................................... 4 Vegetation ..........................................................................................................................^^ 4 Precipitation .............................................................................................................................................................. 5 Streams ...................................................................................................................................................................... 5 Geology ..................................................................................................................................................................... 5 Ground Water ............................................................................................................................................................ 7 Previous Recharge Estimates ................................................................................................................................................ 9 Subsurface Flow Beneath Vicee, Ash, and Kings Canyons ................................................................................................. 10 Estimates of Subsurface Flow Using Darcy's Law ................................................................................................... 10 Direction of Subsurface Flow and Hydraulic Gradients ................................................................................ 13 Vicee Canyon ..................................................................................................................................... 13 Ash Canyon ........................................................................................................................................ 16 Kings Canyon ..................................................................................................................................... 16 Distribution of Basin-Fill Sediments and Weathered and Fractured Bedrock .............................................. 16 Vicee Canyon ..................................................................................................................................... 19 Ash Canyon ........................................................................................................................................ 19 Kings Canyon ..................................................................................................................................... 19 Hydraulic Conductivity of Basin-Fill Sediments and Weathered and Fractured Bedrock .................................................................................................................................... 20 Estimates from Slug Tests .................................................................................................................. 20 Estimates from Resistivity Logs ........................................................................................................ 22 Lithologic Units Determined from Hydraulic Conductivity .............................................................. 27 Geometric-Mean Hydraulic Conductivity of Lithologic Units .......................................................... 27 Estimates of Subsurface Flow Across Hydrogeologic Sections .................................................................... 29 Estimates of Subsurface Flow Using Chloride-Balance Method .............................................................................. 29 Comparison of Flow Estimates with Recharge Estimated from Maxey-Eakin Method ...................................................... 32 Estimates of Water Yield ...................................................................................................................................................... 34 Summary and Conclusions ................................................................................................................................................... 35 References Cited ................................................................................................................................................................... 37 Appendix 1. Borehole geophysical and lithologic data...................................................................................................... 41 Appendix 2. Well location, construction, and water-level data ......................................................................................... 49 Appendix 3. Slug test and detailed well-construction data................................................................................................. 53 CONTENTS III FIGURES 1-2. Maps of Vicee, Ash, and Kings Canyons, Carson City, Nevada, showing: 1. Geographic features, Eagle Valley hydrographic area, and study area........................................................... 3 2. Surficial geology and location of streamflow gaging stations and hydrogeologic sections ........................... 6 3. Schematic three-dimensional diagram illustrating flow into and out of basin-fill aquifer in Eagle Valley........... 8 4-5. Maps of Vicee, Ash, and Kings Canyons, showing: 4. Location of geophysical surveys and test holes used in calculating subsurface flow..................................... 12 5. Water levels at shallow wells in winter 1994 and near gaining stream reach in spring 1994 in Vicee Canyon, and direction of subsurface flow and downslope water-table gradient.............................. 14 6. Idealized hydrogeologic section along direction of subsurface flow at test hole in Vicee Canyon, showing expected difference in water levels between shallow and deep wells..................................................... 15 7. Hydrogeologic sections across Vicee, Ash, and Kings Canyons, showing distribution of saturated and unsaturated basin-fill sediments and bedrock.................................................................................................. 18 8-9. Graph showing: 8. Relation between hydraulic conductivity determined from slug tests of wells and formation factor determined from resistivity of basin-fill sediments, bedrock, and ground water in test holes in Vicee and Kings Canyons.................................................................................................................. 24 9. Distribution of hydraulic conductivity calculated from long-normal resistivity logs for tests holes in Vicee, Ash, and Kings Canyons........................................................................................................ 24 TABLES 1. Previous estimates of recharge to basin-fill aquifer in Eagle Valley, Carson City, Nevada................................... 9 2. Results of slug tests in wells in Vicee, Ash, and Kings Canyons, November 1994.............................................. 21 3. Comparison of formation factor determined from resistivity of basin-fill sediments, bedrock, and ground water to average hydraulic conductivity determined from slug tests of wells in Vicee, Ash, and Kings Canyons........................................................................................................................................ 23 4-5. Geometric-mean hydraulic conductivity beneath Vicee, Ash, and Kings Canyons of: 4. Lithologic units of basin-fill sediments .......................................................................................................... 27 5. Bedrock units.................................................................................................................................................. 29 6-7. Estimates of subsurface flow beneath Vicee, Ash, and Kings Canyons using: 6. Darcy's law....................................................................................................................................................