Under Alternative A, the Little Mountain ACEC is available for locatable mineral entry, which would result in long-term adverse surface-disturbance impacts to the cultural, paleontological, and scenic values of concern for this area. As with all ACECs, the BLM has the ability to institute case-by-case withdrawals that may result in beneficial impacts to the values of concern by allowing for the protection of important sites. All cave and karst areas in the Planning Area also are withdrawn from appropriation under the mining laws, which would protect the Horsethief, Natural Trap, and other caves in the ACEC. Allowing locatable mineral entry would benefit this resource use, particularly where the potential for gypsum is moderate (3,154 acres).
Alternative A manages the ACEC as open to oil and gas leasing with an NSO restriction on the areas above these caves. Allowing mineral leasing with an NSO restriction would result in adverse impacts to mineral leasing in the ACEC by requiring directional drilling or other development techniques that may limit economically feasible recovery of these resources. NSO restrictions would benefit the values of concern in the ACEC by reducing their potential for destruction or degradation.
Under Alternative A, the Little Mountain ACEC is an ROW avoidance/mitigation area, which would result in adverse impacts to ROW authorizations. Managing the ACEC as an ROW avoidance/mitigation area and requiring intensive mitigation for new ROWs would benefit the values of concerns by reducing the impact of new ROWs on caves, cultural and paleontological resources, and scenic quality values of concern.
Under Alternative A, limiting motorized vehicle use to designated roads and trails would have adverse impacts on travel by limiting access and opportunities for travel. Travel management under Alternative A may result in beneficial impacts to the values of concern by eliminating routes that damage resources and limiting access to sensitive cultural, paleontological, and cave areas. Placing warnings signs around safety hazards in the Little Mountain ACEC to warn the public of health and safety hazards posed by radioactivity at uncovered mine entrances and adits would benefit visitor health and safety in the area.
Alternative B would expand the Little Mountain ACEC by 47,635 acres. Management and impacts described for Alternative A would apply to the expanded area unless otherwise noted. The larger size of the expanded ACEC, and the expansion of common management to include this area, would result in similar types of impacts, but to a greater extent than Alternative A.
Under Alternative B, restrictions on mineral development would result in adverse impacts to the use of these resources. The ACEC is withdrawn from appropriation under the mining laws and administratively unavailable for mineral leasing within the entire Little Mountain ACEC. Withdrawing the entire ACEC under Alternative B would have the greatest adverse impacts to locatable mineral development on the 16,867 acres with moderate-potential and the 745 acres with a high potential for gypsum. Withdrawal would eliminate the potential to develop locatable minerals because no new claims could be staked; valid existing mining claims represent valid existing rights and would not be affected by the withdrawal (see Section 4.2.1 Locatable Minerals). Adverse impacts to mineral development would be greater under Alternative B than under Alternative A, under which the BLM manages the expansion area as available for locatable mineral entry on 45,062 acres and would protect more area. Management of mineral leasing in the expansion area under Alternative B is more restrictive than under Alternative A. However, the development potential for oil and gas in the existing ACEC and expansion area ranges from very low to none, which may minimize the impact of this more restrictive management. Beneficial impacts to the values of concern as a result of restrictions on mineral development under Alternative B are greater than under Alternative A.
Managing the proposed ACEC expansion area as an ROW avoidance/mitigation area would result in greater adverse impacts to the authorization of ROWs because, unlike Alternative A, which manages a portion of the expansion areas as open to ROW authorizations (30,751 acres) and the remainder as an ROW avoidance/mitigation area, no areas would be open to ROWs. Managing the entire expansion area as an ROW avoidance/mitigation area would benefit the values of concern in the ACEC by limiting ROW development in the area or requiring mitigation to reduce adverse impacts.
Limiting motorized vehicle use in the ACEC to designated roads and trails would result in greater adverse impacts to motorized vehicle access and greater beneficial impacts to the values of concern than Alternative A in the Alternative B expansion area. Under Alternative A, the expansion area is limited to existing roads and trails.
Alternative C does not designate the Little Mountain area as an ACEC; the BLM would manage the area in accordance with multiple use principles consistent with other resource objectives.
Similar to Alternative D, only a small portion of the area under Alternative C (488 acres) is withdrawn from appropriation under the mining laws. This management may result in greater adverse impacts to the values of concern in the Little Mountain area than alternatives A and B by increasing mineral activity and associated surface disturbance.
Management of ROWs and motorized vehicle use under Alternative C would be similar to that under Alternative A. Applying standard guidelines related to surface disturbance for ROWs would result in a lower standard for the mitigation of surface disturbance compared to alternatives A and B, leading to greater potential for adverse impacts to the values of concern under Alternative C than the other alternatives.
Under Alternative D, the management of and impacts from the Little Mountain ACEC and the Craig Thomas Little Mountain SMA are the same as under Alternative B, except for authorizations for renewable energy development, locatable mineral entry, and mineral leasing in the SMA.
Under Alternative D, the Craig Thomas Little Mountain SMA is a renewable energy exclusion area. Excluding renewable energy would result in adverse impacts to the development of wind energy in the Little Mountain area, but would reduce the possibility of damage to the values of concern from surface disturbance and prevent adverse impacts from the introduction of new contrasting elements, such as wind turbines, on scenic qualities. Management of renewable energy is more restrictive than the other alternatives, which primarily manage the area as an open or avoidance/mitigation area for renewable energy.
The Little Mountain ACEC and the Craig Thomas Little Mountain SMA would be available for locatable mineral entry. As noted for Alternative A, the BLM has the ability to institute withdrawals for ACECs on a case-by-case basis and withdraws cave and karst resources from appropriation under the mining laws. Allowing locatable mineral entry would benefit the development of these resources, particularly in the 16,867 acres with a moderate the 745 acres with a high potential for gypsum, and the 2,195 acres with a high potential for bentonite. Allowing locatable mineral entry would result in long-term adverse surface-disturbance impacts to the values of concern for this area, particularly cultural and paleontological resources, scenic qualities, and wildlife and special status species habitat.
Under Alternative D, the restrictions on mineral leasing in the Craig Thomas Little Mountain SMA would result in adverse impacts to the use of these resources, particularly on the 50,981 acres managed as administratively unavailable. Management of mineral leasing in the Craig Thomas Little Mountain SMA under Alternative D is more restrictive than under alternatives A and C, but less restrictive than under Alternative B. As noted for Alterative B, the very low to no development potential for oil and gas in this area may minimize the impact of restrictive management to mineral development. Conversely, beneficial impacts to the values of concern as a result of restrictions on mineral development would be greater than under alternatives A and C, but less than under Alternative B.
Alternative A designates the Upper Owl Creek area as an ACEC (13,057 acres); Alternative B designates and expands the ACEC by 19,720 acres to become the Upper Owl Creek/Absaroka Front ACEC. Alternative C would not designate the Upper Owl Creek area as an ACEC. Management of this area would vary by alternative. Values of concern in the Upper Owl Creek area include cultural sites, fisheries habitat, recreational opportunities, scenic qualities, shallow soils, special status species and wildlife habitat, and important vegetation communities. Threats to the values of concern in the ACEC proposed under Alternative A include surface disturbance from mineral and ROW development. In the expansion area proposed under Alternative B, threats to the values of concern also would include timber extraction and land disposals.