Environmental Assessment
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Environmental Assessment Wild Horse Gather to Appropriate Management Levels on the Adobe Town, Salt Wells Creek, Great Divide Basin, White Mountain and Little Colorado Herd Management Areas The BLM’s multiple-use mission is to sustain the health and productivity of the public lands for the use and enjoyment of present and future generations. The Bureau accomplishes this by managing such activities as outdoor recreation, livestock grazing, mineral development, and energy production, and by conserving natural, historical, cultural, and other resources on public lands. DOI-BLM-WY-D040-2020-0005-EA Environmental Assessment for a Wild Horse Gather to Appropriate Management Levels on the Adobe Town, Salt Wells Creek, Great Divide Basin, White Mountain and Little Colorado Herd Management Areas Bureau of Land Management Rock Springs Field Office & Rawlins Field Office Wyoming DOI-BLM-WY-D040-2020-0005-EA March 2021 Wild Horse Gather to Appropriate Management Levels on the Adobe Town, Salt Wells Creek, Great Divide Basin, White Mountain and Little Colorado Herd Management Areas. Environmental Assessment DOI-BLM-WY-D040-2020-0005-EA Table of Contents 1.0 INTRODUCTION.......................................................................................................................... 2 1.1 Background ......................................................................................................................................... 2 1.2 Purpose and Need for the Proposed Action ........................................................................................ 5 1.3 Relationship to Statutes, Regulations, Land Use Plans, Agreements, and Policies ............................ 5 1.4 Scoping and Public Involvement ........................................................................................................ 6 1.5 Issues Identified for Analysis ............................................................................................................. 7 1.6 Issues not Analyzed in Detail ............................................................................................................. 8 2.0 PROPOSED ACTION AND ALTERNATIVES ......................................................................... 9 2.1 Alternative I – No Action Alternative .............................................................................................. 11 2.2 Alternative II – Proposed Action – Gather to Low End of AML and use Non-permanent Fertility Control .................................................................................................................................................... 11 2.3 Alternative III – Gather and Removal ............................................................................................. 13 2.4 Alternative IV – Gather and Removal with Permanent Sterilization, Fertility Control and Mare to Stud Ratio Skewing ................................................................................................................................ 13 2.5 Alternatives Considered but not Analyzed in Detail ....................................................................... 15 3.0 AFFECTED ENVIRONMENT & ENVIRONMENTAL EFFECTS ...................................... 18 3.1 Issue 1: How would the proposed population growth suppression activities affect wild horses? .... 19 3.1.1 Affected Environment ............................................................................................................... 19 3.1.2 Environmental Effects ............................................................................................................... 19 3.1.3 Cumulative Effects: ................................................................................................................... 31 3.2 Issue 2: How would gather operations affect wild horses? .............................................................. 33 3.2.1 Affected Environment ............................................................................................................... 33 3.2.2 Environmental Effects ............................................................................................................... 33 3.2.3 Cumulative Effects .................................................................................................................... 40 3.3 Issue 3: How would the proposed action affect the genetic diversity of the herd? How would it affect the herds ability to maintain a self-sustaining population? .......................................................... 41 3.3.1 Affected Environment ............................................................................................................... 41 3.3.2 Environmental Effects ............................................................................................................... 44 3.3.3 Cumulative Effects .................................................................................................................... 46 3.4 Issue 4: How would the proposed action affect livestock operations within these HMAs? .......... 47 3.4.1 Affected Environment ............................................................................................................... 47 3.4.2 Environmental Effects ............................................................................................................... 49 3.4.3 Cumulative Effects .................................................................................................................... 50 3.5 Issue 5: How would the concentration of wild horses at trap sites affect vegetation, special status plants, and soils? ..................................................................................................................................... 51 3.5.1 Affected Environment ............................................................................................................... 51 3.5.2 Environmental Effects ............................................................................................................... 52 3.5.3 Cumulative Effects .................................................................................................................... 54 3.6 Issue 6: How would the proposed action affect rangeland health? ................................................ 55 3.6.1 Affected Environment ............................................................................................................... 55 3.6.2 Environmental Effects ............................................................................................................... 56 3.6.3 Cumulative Effects .................................................................................................................... 57 3.7 Issue 7: How would gather operations impact big game habitat on crucial winter range? ............ 58 3.7.1 Affected Environment ............................................................................................................... 58 3.7.2 Environmental Effects ............................................................................................................... 58 3.7.3 Cumulative Effects .................................................................................................................... 59 3.7.4 Mitigation .................................................................................................................................. 60 3.8 Issue 8: How would the removal of wild horses affect sage-grouse habitat in PHMA? ................ 60 Wild Horse Gather to Appropriate Management Levels on the Adobe Town, Salt Wells Creek, Great Divide Basin, White Mountain and Little Colorado Herd Management Areas. Environmental Assessment DOI-BLM-WY-D040-2020-0005-EA 3.8.1 Affected Environment ............................................................................................................... 60 3.8.2 Environmental Effects ............................................................................................................... 61 3.8.3 Cumulative Effects .................................................................................................................... 62 3.8.4 Mitigation .................................................................................................................................. 62 3.9 Issue 9: How would gather operations affect raptors and migratory birds that are present within these HMAs? .......................................................................................................................................... 62 3.9.1 Affected Environment ............................................................................................................... 63 3.9.2 Environmental Effects ............................................................................................................... 63 3.9.3 Cumulative Effects .................................................................................................................... 64 3.9.4 Mitigation .................................................................................................................................. 64 3.10 Issue 10: How would the removal of wild horses affect recreational wild horse viewing?......... 64 3.10.1 Affected Environment. ............................................................................................................ 64 3.10.2 Environmental Effects ............................................................................................................. 65 3.10.3