Prepared in cooperation with the Oglala Sioux Tribe Water Quality of Selected Springs and Public-Supply Wells, Pine Ridge Indian Reservation, South Dakota, 1992-97 Water-Resources Investigations Report 99-4063 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior U.S. Geological Survey Water Quality of Selected Springs and Public-Supply Wells, Pine Ridge Indian Reservation, South Dakota, 1992-97 By Allen J. Heakin Water-Resources Investigations Report 99-4063 Prepared in cooperation with the Oglala Sioux Tribe U.S. Department of the Interior Bruce Babbitt, Secretary U.S. Geological Survey Charles G. Groat, Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. Rapid City, South Dakota: 2000 For additional information write to: District Chief U.S. Geological Survey 1608 Mt. View Road Rapid City, SD 57702 Copies of this report can be purchased from: U.S. Geological Survey Branch of Information Services Box 25286 Denver, CO 80225-0286 CONTENTS Abstract.................................................................................................................................................................................. 1 Introduction ........................................................................................................................................................................... 2 Purpose and Scope....................................................................................................................................................... 4 Previous Investigations ................................................................................................................................................ 4 Description of Study Area ........................................................................................................................................... 4 Physiography and Climate................................................................................................................................. 4 Geology ............................................................................................................................................................. 5 Hydrology.......................................................................................................................................................... 5 Public Water-Supply Systems............................................................................................................................ 9 Water-Quality Sampling Locations and Methods.................................................................................................................. 9 Location of Springs and Wells..................................................................................................................................... 9 Sampling Methods....................................................................................................................................................... 13 Quality Assurance........................................................................................................................................................ 15 Blank Samples ................................................................................................................................................... 15 Duplicate Samples ............................................................................................................................................. 17 Standard Reference Samples ............................................................................................................................. 21 Summary of Quality-Assurance Data................................................................................................................ 21 Water-Quality Data And Analysis for Selected Springs and Wells....................................................................................... 23 Springs......................................................................................................................................................................... 23 Public-Supply Wells .................................................................................................................................................... 35 Summary and Conclusions .................................................................................................................................................... 39 References ............................................................................................................................................................................. 40 Supplemental Data................................................................................................................................................................. 43 ILLUSTRATIONS 1. Map showing location of study area ........................................................................................................................... 3 2. Map showing generalized geology of the study area.................................................................................................. 8 3. Map showing location of springs and public-supply wells sampled for this study .................................................... 11 4. Site-location diagram.................................................................................................................................................. 14 5. Hydrographs for selected springs ............................................................................................................................... 30 6. Trilinear diagrams showing proportional concentrations of major ions in ground-water samples from selected springs and wells .................................................................................................................... 32 TABLES 1. Generalized stratigraphic column showing selected geologic units and characteristics......................................... 6 2. Spring sites for which data are presented................................................................................................................ 10 3. Public-supply wells for which data are presented................................................................................................... 12 4. Quality-assurance results of blank samples ............................................................................................................ 16 5. Chemical and radionuclide analyses of duplicate field samples for springs and public-supply wells.................... 18 6. Precision of chemical analyses of duplicate field samples for springs and public-supply wells ............................ 20 7. Quality-assurance results for standard reference samples M-116 and T-99 submitted during public-supply well sampling program..................................................................................................................... 22 8. Water-quality criteria, standards, or recommended limits for selected properties or constituents ......................... 24 9. Statistical summary of chemical analyses of spring-water samples collected September 1992 through March 1997................................................................................................................................................ 28 10. Comparison of water-quality data for selected springs to U.S. Environmental Protection Agency drinking-water standards......................................................................................................................................... 33 Contents III TABLES—Continued 11. Tritium and pesticide analyses for selected springs................................................................................................ 34 12. Comparison of water-quality data for selected public-supply wells to U.S. Environmental Protection Agency drinking-water standards.......................................................................................................... 36 13. Spring water-quality data........................................................................................................................................ 45 14. Public-supply well water-quality data .................................................................................................................... 53 ABBREVIATED UNITS USED IN THIS REPORT AND VERTICAL DATUM mi2 square miles ft feet mi miles in. inches ft3/s cubic feet per second gal/min gallons per minute gal/d gallons per day gal/hr gallons per hour ° F degrees Fahrenheit µg/L micrograms per liter mg/L milligrams per liter µS/cm microsiemens per centimeter at 25 degrees Celsius mL milliliters col/100 mL colonies per 100 milliliters pCi/L picocuries per liter Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)—a geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929. IV Contents Water Quality of Selected Springs and Public-Supply Wells, Pine Ridge Indian Reservation, South Dakota, 1992-97 By Allen J. Heakin ABSTRACT Nine of the springs with better water quality were sampled repeatedly; however, only minor This report presents results of a water- variability in water quality was identified. Six of quality study for