Environmental Assessment Red Desert Complex Herd Management Area Gather DOI-BLM-WY-030-EA15-63 September 2017 Prepared by: U.S. Bureau of Land Management U.S. Bureau of Land Management High Desert District Wind River Big Horn Basin District Office Rawlins Field Office Lander Field Office 1300 North Third Street 1335 Main Street Rawlins, Wyoming 82301 Lander, Wyoming 83520 Mission Statement To sustain the health, diversity, and productivity of the public lands for the use and enjoyment of present and future generations. DOI-BLM-WY-030-EA15-63 Table of Contents ......................................................................................................................................................... 1 1.0 INTRODUCTION .............................................................................................................. 1 1.1 Purpose and Need ............................................................................................................... 3 1.2 Decision to be made ............................................................................................................ 3 1.3 Scoping ............................................................................................................................... 4 2.0 ALTERNATIVES CONSIDERED .................................................................................... 5 2.1 Actions Common to Alternative 1 and Alternative 2: Proposed Action ............................ 5 2.2 Alternative 1: Remove all wild horses outside of HMA boundaries and utilize fertility control on mares to be released back to the HMA ...................................................................... 7 2.3 Alternative 2: Proposed Action—Remove to low AML and utilize fertility control ........ 8 2.4 Alternative 3: No Action--No Gather or Removal and no fertility control ..................... 10 2.5 Alternatives Considered But Eliminated From Further Analysis ..................................... 11 2.5.1 Use of Bait and/or Water Trapping ........................................................................... 11 2.5.2 Other Alternative Capture Techniques ..................................................................... 11 2.5.3 Remove or Reduce Livestock within the HMAs ...................................................... 12 2.5.4 Change the Current Established AMLs .................................................................... 13 2.5.5 The Use of Surgical or Chemical Sterilization to Reduce Population Growth......... 13 2.5.6 Control of Wild Horse Numbers by Natural Means ................................................. 13 2.5.7 Genetic Testing Before Decision about Which Animals to Turn Back .................... 13 2.6 Conformance with Existing Land Use Plans (LUPs) ....................................................... 14 2.7 Relationship to Statutes, Regulations, or Other Plans ...................................................... 15 3.0 AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES .......... 16 3.1 Wild Horses ...................................................................................................................... 16 3.1.1 Affected Environment ............................................................................................... 16 3.1.2 Environmental Consequences ................................................................................... 19 3.2 Wildlife, Threatened and Endangered Species, Special Status Species, and Migratory Birds........................................................................................................................................... 36 3.2.1 Affected Environment ............................................................................................... 36 3.2.2 Environmental Consequences ................................................................................... 38 3.3 Soils, and Watershed ......................................................................................................... 41 3.3.1 Affected Environment ............................................................................................... 41 3.3.2 Environmental Consequences ................................................................................... 42 3.4 Vegetation, Special Status Plants ...................................................................................... 43 3.4.1 Affected Environment ............................................................................................... 43 3.4.2 Environmental Consequences ................................................................................... 47 3.5 Recreation ......................................................................................................................... 51 3.5.1 Affected Environment ............................................................................................... 51 3.5.2 Environmental Consequences ................................................................................... 51 3.6 Livestock Grazing ............................................................................................................. 52 3.6.1 Affected Environment ............................................................................................... 52 3.6.2 Environmental Consequences ................................................................................... 57 3.7 Cultural Resources ............................................................................................................ 61 3.7.1 Affected Environment ............................................................................................... 61 3.7.2 Environmental Consequences ................................................................................... 61 4.0 CUMULATIVE IMPACTS .............................................................................................. 62 Past, Present, and Reasonably Foreseeable Actions .................................................................. 62 Effect of Past, Present, and Reasonably Foreseeable Future Actions ....................................... 63 4.1 Wild Horses ...................................................................................................................... 63 4.2 Wildlife, Threatened and Endangered Species, Special Status Species, and Migratory Birds........................................................................................................................................... 64 4.3 Livestock Grazing, Vegetation, Soils and Watershed ...................................................... 65 4.4 Recreation ......................................................................................................................... 66 5.0 MITIGATION MEASURES AND SUGGESTED MONITORING ............................... 66 6.0 RESIDUAL IMPACTS .................................................................................................... 67 7.0 TRIBES, INDIVIDUALS, ORGANIZATIONS, OR AGENCIES CONSULTED ......... 67 List of Preparers......................................................................................................................... 68 8.0 REFERENCES ................................................................................................................. 69 APPENDIX 1 Standard Operating Procedures for Wild Horse Gathers ................................... 77 APPENDIX 2 Historical Gather Environmental Analyses and Tables ..................................... 85 APPENDIX 3 Genetic Diversity and Variability ...................................................................... 90 APPENDIX 4 Standard Operating Procedures for Application of Fertility Control ................. 99 APPENDIX 5 Population Model Overview ............................................................................ 101 APPENDIX 6 Population Estimate and Methods ..................................................................... 113 APPENDIX 7 Individuals, Organizations, Tribes or Agencies consulted ............................... 125 APPENDIX 8 Summary of Scoping and Public Comments..................................................... 128 APPENDIX 9 Summary of Public Comments on Revised May 2017 EA Document ............. 137 1.0 INTRODUCTION This Environmental Assessment (EA) has been prepared to analyze the Bureau of Land Management’s (BLM) High Desert District, Rawlins Field Office (RFO), and Wind River – Big Horn Basin District, Lander Field Office (LFO), proposal to conduct a wild horse gather in the Lost Creek, Stewart Creek, Green Mountain, Crooks Mountain and Antelope Hills Herd Management Areas (HMAs) – collectively called Red Desert Complex. The “gather area” includes the five HMAs and areas outside of the HMAs where wild horses reside (See Map 1). These HMAs are analyzed as a Complex since the HMAs are adjacent, but not necessarily contiguous, and have animal interchange. The BLM has determined that excess wild horses are present in the Red Desert Complex. The terms “horse” and “wild horse” are used synonymously throughout this document. The EA contains a site-specific analysis of potential impacts that could result from implementation of any one of three alternatives. It assists the BLM in project planning and ensuring compliance with the National Environmental Policy Act (NEPA), and in making a determination as to whether any “significant” impacts to the human environment could result from the analyzed actions. “Significance” is defined by NEPA and is found in regulation 40 CFR 1508.27. An