TECHNICAL MEMORANDUM SUBJECT: Snake/Salt River Basin Plan Available Groundwater Determination PREPARED BY: Hinckley Consulting DATE: September 10, 2003 Table of Contents Introduction and Report Organization ..............................................3 Previous Studies...............................................................4 1964 - Wyoming Water Resources Inventory ..................................4 1967 - Wyoming Water Planning Program ....................................5 1975, 1976 - USGS Hydrologic Atlas .......................................6 1981 - WRRI Basin Studies ................................................8 1995/96 - USGS County Series ............................................9 1999 - Teton County Water Supply Master Plan ................................9 Other Relevant Reports ..................................................10 Hydrogeology................................................................11 Stratigraphy and Structure................................................12 Quaternary-age Deposits ...........................................12 Tertiary-age Deposits..............................................13 Older Bedrock Units ..............................................14 Groundwater Circulation .................................................14 Groundwater Development .....................................................17 Geology..............................................................17 Use Trends............................................................17 Groundwater Levels .....................................................21 Groundwater Quality ..........................................................22 Analytical Data ........................................................22 Groundwater Contamination ..............................................23 Geothermal Resources.........................................................27 Occurrence............................................................27 Development ..........................................................29 Groundwater Availability ......................................................30 Research Resources...........................................................32 Wyoming State Engineer’s Office (WSEO) ..................................32 United States Geological Survey (USGS)....................................33 Snake/Salt River Basin Plan Available Groundwater Determination Page 1 Wyoming Water Development Commission Groundwater Studies ................33 Wyoming Groundwater Vulnerability Study ..................................33 Wyoming Department of Environmental Quality (DEQ) - Subdivision Application Review Program........................................................34 Jackson Hole Environmental Restoration Study...............................34 Geologic Mapping......................................................35 Bibliography.................................................................35 Appendix A - Figures Appendix B - Lithologic and Water-Bearing Characteristics of Geologic Units in the Snake/Salt River Basin Appendix C - WSEO Snake/Salt River Basin Permits (electronic format only) Appendix D - USGS Snake/Salt River Basin Wells (electronic format only) List of Tables Table 1 - Municipal Groundwater Use in the Lincoln County Portion of the Snake/Salt River Basin - 1993 .................................................................11 Table 2 - Groundwater Consumption in the Snake/Salt River Basin - 2002 ................18 Table 3 - Snake/Salt River Basin Groundwater Permit Summary ........................18 Table 4 - Snake/Salt River Basin Groundwater Permit Summary - Teton and Lincoln Counties 19 Table 5 - Generalized Groundwater Quality (mg/l) - Snake/Salt River Basin ...............22 Table 6 - Groundwater Quality Standards ..........................................24 Snake/Salt River Basin Plan Available Groundwater Determination Page 2 Introduction and Report Organization This memorandum presents an investigation of the groundwater resources of the Snake/Salt River basin. It is one component of a comprehensive review of the water resources of the basin, completed as part of the River Basin Planning Program under the direction of the Wyoming Water Development Commission. As of this writing, similar groundwater memoranda have been completed for the Bear, Green, Powder/Tongue/ and Northeast Wyoming River basins as part of their respective Planning Program reports. We have followed the lead of our predecessors in terms of the general coverage and data compiled to inform future planning with respect to groundwater resources, while adapting to the specific circumstances of the Snake/Salt River basin and adding additional materials as we thought useful. The text of this memorandum provides general descriptions, summaries, and conclusions. The detailed data upon which these discussions are based are largely contained in the data tables and GIS products attached to the memorandum in its electronic form. We assume that future planners will primarily be addressing individual projects, for which the general discussions will provide reconnaissance-level guidance, but for which the more detailed data will likely be necessary to address unique, site-specific issues. This is by no means the first basin-wide review of groundwater resources in the Snake/Salt River basin. A history and summary results of previous investigations follows this introduction. Much of the material compiled in this report is drawn directly from previous studies, updated as appropriate for the intervening years, and we fully acknowledge the quality and contribution of those works. Following the review of previous investigations, we describe the geologic setting and hydrostratigraphy (the groundwater-bearing units beneath the surface) of the Snake/Salt River basin, then present a discussion of groundwater circulation within the basin. A discussion of groundwater quality, including considerations for the protection of groundwater supplies, completes the overview of the groundwater resource. The past and present level of groundwater development is reviewed, along with trends in groundwater use and changes over time in groundwater levels. The availability of groundwater for future development is also evaluated. The last two sections of the memorandum introduce the research tools developed for this project and the accompanying detailed datasets, and present a comprehensive bibliography of the literature pertinent to groundwater resources investigations in the Snake/Salt River basin. All report figures are included in Appendix A. Appendix B is a detailed table of lithologic and water-bearing characteristics of geologic units in the Snake/Salt River. Three other tables have been compiled in Microsoft Excel electronic spreadsheet form only, due to the size of the tables. The first of these three tables is Appendix C, a tabulation of 5,148 Wyoming State Engineer’s Office groundwater right permits as of the most recent postings to their electronic database (May 29, 2002). The other two tables are in Appendix D and are a compilation of data from the USGS. Snake/Salt River Basin Plan Available Groundwater Determination Page 3 The first spreadsheet in Appendix D, “general”, contains general information, e.g. use, static water level, discharge rate (gpm), etc., for 1,715 groundwater sites monitored by the USGS. The second spreadsheet in Appendix D, “chemistry”, contains data from chemical analyses for 894 wells. USGS groundwater data are current through August 30, 2002, although most of these data were collected under specific research programs of only a few years’ duration. Previous Studies This section presents a summary of the key publications addressing the groundwater resources of the Snake/Salt River basin. Relevant historical data (e.g. groundwater use estimates) are summarized here and these reports have contributed extensively to the data compilations detailed in later sections. The scope of our presentation is insufficient to duplicate all the information contained in previous reports, however. Those interested in specific aspects of the Snake/Salt River basin groundwater resource are encouraged to review these original documents as appropriate. Similarly, only previous investigations of a regional nature are presented, i.e. the antecedents for the present memorandum. An extensive bibliography is included as a final section of this memorandum to cover the extensive related literature of a more site- and topic- specific nature. 1964 - Wyoming Water Resources Inventory This program produced a report for each of Wyoming’s administrative Water Divisions. In the opinion of the Wyoming State Engineer at the time, “the broad picture on use and availability of water in Wyoming is probably more accurately reflected herein than in any previous publication” (p. ii). The Snake/Salt River basin was included in the report for Water Division Number 4 (Smith, 1965). Data deficiencies were identified throughout Wyoming by these reports, e.g. “Determinations of total irrigated acreage within some drainages indicate that there is a wide divergence between the figures used by various government agencies, the official records showing adjudicated water rights, and the evidence on the ground or as reflected on aerial photographs.” (p. ii). The groundwater section of the report for the Snake/Salt River basin reads, in its entirety: “Underground water at the present time is largely restricted to rural domestic and stock watering use.