UPPER HENRY’S FORK SUBBASIN ASSESSMENT Final December 1998 Prepared by Sheryl Hill Christopher Mebane Idaho Department of Health and Welfare Division of Environmental Quality Idaho Falls Regional Office 900 N. Skyline, Suite B Idaho Falls, ID 83402 (208) 528-2650 Table Of Contents Introduction ................................................................................................................................. 1 Nomenclature: Henrys or Henry’s? .................................................................................... 2 Authorization and Purpose.................................................................................................. 2 Acknowledgments............................................................................................................... 5 Physical Characteristics of the Upper Henry’s Fork Subbasin....................................................... 6 Climate................................................................................................................................ 6 Geology............................................................................................................................... 9 Topography....................................................................................................................... 18 Hydrography and Hydrology ............................................................................................ 22 Soils................................................................................................................................... 25 Biological Characteristics of the Upper Henry’s Fork Subbasin.................................................. 33 Cultural Characteristics of the Upper Henry’s Fork Subbasin ..................................................... 36 Land Ownership and Land Use......................................................................................... 36 Population Distribution..................................................................................................... 36 Planning ............................................................................................................................ 41 Watershed Advisory Group .............................................................................................. 42 Water Quality Concerns and Status .............................................................................................. 47 Water Quality Standards................................................................................................... 47 Designated Uses ..................................................................................................... 47 Water Quality Criteria............................................................................................ 51 Antidegradation Policy........................................................................................... 51 Water Quality-Limited Segments ..................................................................................... 51 Summary and Analysis of Existing Water Quality Data .............................................................. 55 Henry’s Lake..................................................................................................................... 55 Henry’s Fork: Buffalo River to Riverside Reach ............................................................. 66 Sheridan Creek.................................................................................................................. 77 Assessment of Remaining Waterbodies............................................................................ 81 Henry’s Lake Watershed................................................................................................... 82 Lower Henry’s Fork Watershed........................................................................................ 87 Island Park Reservoir Watershed...................................................................................... 88 Sheridan Reservoir Watershed.......................................................................................... 90 Thirsty Creek, Buffalo River, Warm River, and Robinson Creek Watersheds ................ 91 Conclusions and Recommendations ............................................................................................. 95 i Citations ............................................................................................................................... 97 Appendix A. Section 303(d) of the Federal Water Pollution Control Act (Clean Water Act) as amended, 33 U.S.C. § 1251 et seq...................................................................... 105 Appendix B. Background information regarding development of the Idaho TMDL Schedule ............................................................................................................................. 107 Appendix C. Names of 7.5 minute quadrangle maps............................................................... 109 Appendix D. USDA soil survey information ........................................................................... 111 Appendix E. Water quality criteria .......................................................................................... 129 Appendix F. Additional sources of data and information for the upper Henry’s Fork s subbasin............................................................................................................... 131 Appendix G. Draft Upper Henry’s Fork Subbasin Assessment: Responses to public comments ............................................................................................................ 141 List of Tables Table 1. Summary of climate data collected from February 1, 1937 to June 30, 1997 at Island Park1 and from August 1, 1948 to June 30, 1997 at Ashton2 . 7 Table 2. Length of growing season: probabilities of the number of days at Island Park and Ashton that will exceed minimum temperatures of 24°F, 28°F, and 32°F.1 . .8 Table 3. Length of growing season: probabilities that the last freezing temperature in spring and first freezing temperature in fall will occur later or earlier than a particular date in Island Park and Ashton.1. 8 Table 4. Descriptions of generalized geologic units in the Upper Henry’s Fork subbasin and their water-bearing characteristics (after Whitehead (1978) and Christiansen and Embree (1987)) . 13 Table 5. Wetland sites in the Upper Henry’s Fork subbasin that have been categorized by the Idaho Conservation Data Center (after Jankovsky-Jones 1996) . .35 Table 6. Excerpt of “Designated Uses Within Upper Snake Hydrologic Basin” (IDAPA 16.01.02.150.01), showing designated uses of waterbodies in the Upper Henry’s Fork subbasin . 49 Table 7. Excerpt of the 1994 § 303(d) list showing water quality-impaired waterbodies in the Upper Henry’s Fork subbasin . 52 Table 8. Excerpt of the draft 1998 § 303(d) list showing water quality-impaired waterbodies in the Upper Henry’s Fork subbasin . 54 Table 9. Henry’s Lake total phosphorus budgets for 1992 through 19941. 59 Table 10. Recommendations for improving the water quality of Henry’s Lake and its tributaries, and expected reductions in phosphorus load due to implementation of each recommended action . 62 Table 11. Percentages of Henry’s Lake shoreline and tributary streambanks classified by the Henry’s Lake SA WQP Final Planning Report/Environmental Assessment (YSCD 1995) as slightly, moderatelt, or severely eroding . 64 Table 12. Examples of water quality and habitat enhancement projects implemented at Henry’s Lake since 1991 . 65 iii List of Tables, Continued Table 13. Change in the macroinvertebrate community at Riverside, as indicated by changes in biological metric scores from 1992 to 1997. 72 Table 14. Idaho River Index (IRI) scores for sites on the Henry’s Fork between Buffalo River and Riverside Reach. Scores greater than 16 are indicative of good to excellent water qualty . 73 Table 15. Macroinvertebrate biotic index (MBI) scores for sites sampled in the Henry’s Lake watershed by the Division of Environmental Quality (DEQ) and the Henry’s Fork Foundation (HFF) . 84 Table 16. Macroinvertebrate biotic index (MBI) scores for sites sampled in the Lower Henry’s Fork watershed by the Henry’s Fork Foundation (HFF) . 88 Table 17. Macroinvertebrate biotic index (MBI) scores for sites sampled in the Island Park Reservoir watershed by the Division of Environmental Quality (DEQ) and the Henry’s Fork Foundation (HFF) . 89 Table 18. Macroinvertebrate biotic index (MBI) scores for sites sampled in the Sheridan Reservoir watershed by the Idaho Division of Environmental Quality (DEQ) and the Henry’s Fork Foundation (HFF) . 90 Table 19. Macroinvertebrate biotic index (MBI) scores for sites sampled in the Thirsty Creek watershed by the Division of Environmental Quality (DEQ) and the Henry’s Fork Foundation (HFF) . 92 Table 20. Macroinvertebrate biotic index (MBI) scores for sites sampled in the Buffalo River1 watershed by the Division of Environmental Quality (DEQ) and the Henry’s Fork Foundation (HFF) . 92 Table 21. Macro invertebrate biotic index (MBI) scores for sites sampled in the Warm River watershed by the Division of Environmental Quality (DEQ) and the Henry’s Fork Foundation (HFF) . 93 Table 22. Macroinvertebrate biotic index (MBI) scores for sites sampled in the Robinson Creek watershed by the Division of Environmental Quality (DEQ) and the Henry’s Fork Foundation (1-IFF) . 94 iv List of Figures Figure 1. Location of the Upper Henry’s Fork subbasin,