Under Alternative A, limiting or prohibiting surface-disturbing activities in the Upper Owl Creek ACEC would restrict the ability to perform activities such as geophysical exploration and road construction. Restricting surface-disturbing activities would protect fragile soils, alpine tundra, important wildlife habitat, and scenic values of concern. Additional protection for these values would be provided by requiring a detailed activity plan before approval of any proposal for a major surface-disturbing activity.
Under Alternative A, restrictions on mineral development would result in minimal adverse impacts to these resources in the ACEC. Alternative A includes a withdrawal from appropriation under the mining laws for the Upper Owl Creek ACEC. The potential for gypsum and bentonite in the ACEC is low. Therefore, development and potential impacts would be low. The Upper Owl Creek ACEC is open to oil and gas leasing with an NSO restriction; however, the development potential for oil and gas in the ACEC is very low and there would be minimal adverse impacts from this management. Restrictions on minerals development would benefit the values of concern by reducing surface disturbance that could decrease the recreational setting, fragment or disturb special status species and wildlife habitat and vegetation communities, and reduce the potential for erosion and disturbance to shallow soils.
Managing the Upper Owl Creek ACEC as open for future ROW authorizations would result in adverse impacts to the values of concern by allowing development and disturbance associated with ROWs. There may be some impacts to fragile soils, vegetation, and wildlife habitat from ROW surface disturbance, although prohibiting and limiting surface-disturbing activities in this ACEC would minimize adverse impacts. Allowing ROW authorizations in this ACEC would benefit ROWs.
Restricting motorized travel to designated roads and trails would limit the roads and trails available for travel and would result in adverse impacts to travel and motorized recreational use. This designation may benefit the values of concern in the area by reducing the number roads and trails and closing routes that damage soils and vegetation; impact scenic quality; alter the desired primitive RSCC, experiences, and benefits; and impact wildlife habitat values of concern.
Encouraging coordination between the BLM and local stakeholders in landscape management may provide opportunities to improve wildlife habitat, decrease the fragmentation of vegetation communities, maintain or enhance the visual qualities, and provide for exceptional primitive type recreational opportunities, experiences, and benefits across jurisdictional boundaries within the mixed land ownership pattern of the ACEC.
Alternative B would expand the Upper Owl Creek ACEC by 19,720 acres and rename it the Upper Owl Creek/Absaroka Front ACEC. Management and impacts described for Alternative A would apply unless otherwise noted. The larger size of the expanded ACEC, and the expansion of common management to include this area, would result in similar, but comparatively greater impacts, to those under Alternative A.
Under Alternative B, expanding restrictions on mineral development would result in minimal adverse impacts to the use of these resources. The area withdrawn from appropriation under the mining laws is larger under Alternative B (13,238 acres). The proposed expansion area has low-potential for bentonite and gypsum. Therefore, the withdrawal is expected to result in minimal adverse impacts to locatable mineral development in the area. In addition, making the ACEC administratively unavailable for oil and gas leasing would be more restrictive than under Alternative A, which manages the area as open, although the low to very low development potential for oil and gas in the area may minimize adverse impacts to mineral leasing. Management that restricts mineral development would benefit the values of concern by reducing the potential for surface disturbance associated with mineral development.
Expanding the ROW avoidance/mitigation area to include the expansion area would result in greater adverse impacts to the authorization of ROWs under Alternative B compared to Alternative A, which manages the expansion area as open to ROW authorizations. This management also would increase protection for the values of concern compared to the other alternatives.
Impacts to and from travel management would be similar to Alternative A, because most of the area under both alternatives is limited to designated roads and trails. Alternative A limits motorized vehicle use in the expansion area primarily to designated roads and trails (18,080 acres) with a smaller area limited to existing roads and trails (1,640 acres).
Alternative C does not designate the Upper Owl Creek area as an ACEC; the BLM would manage it in accordance with multiple use principles consistent with other resource objectives.
The area would be available for locatable mineral entry under Alternative C, but adverse and beneficial impacts would be minimal because the potential for gypsum and bentonite is low. Due to the low to no development potential for oil and gas in the area, impacts would be low and similar to Alternative A.
Alternative C manages the Upper Owl Creek area as open to ROW authorizations (29,743 acres) and as an ROW avoidance/mitigation area (3,034 acres). ROW management under Alternative C is more restrictive than under Alternative A, and the adverse impacts to ROW authorizations would be greater under Alternative C than under alternatives B and D. Beneficial impacts to the values of concern from ROW authorizations would be greater than under Alternative A due to increased area excluded and avoided to ROW authorizations. Only standard guidelines related to surface disturbance would apply, so the impacts from the additional restrictions on surface disturbance realized under alternatives A and B would not occur.
Under Alternative C, managing motorized vehicle use as limited to existing (19,720 acres) and limited to designated (13,057 acres) roads and trails would result in the greatest adverse impacts from motorized travel to the values of concern by increasing access and opportunities for travel that could degrade or damage resources. This alternative would place the fewest restrictions on motorized travel of any alternative.
Under Alternative D, management of and impacts from the Upper Owl Creek ACEC are the same as under Alternative A, except for ROW authorizations, locatable mineral entry, and mineral leasing. However, under Alternative D, management of the area proposed for expansion under Alternative B differs from management under Alternative A.
Under Alternative D, management to limit or prohibit surface-disturbing activities in the existing ACEC would result in impacts as described for Alterative A. In the proposed Alternative B expansion area, only standard guidelines related to surface disturbance would apply. Therefore, the impacts from the additional restrictions on surface disturbance realized under Alternative B would not occur under Alternative D.
Unlike Alternative A, Alternative D manages the Upper Owl Creek ACEC as available for locatable mineral entry, administratively unavailable for oil and gas leasing, and as an ROW avoidance/mitigation area, which would result in adverse impacts to mineral leasing and ROW authorizations. Alternative D manages the area of the existing ACEC as administratively unavailable for oil and gas leasing and the area proposed for expansion under Alternative B as open with primarily moderate constraints (16,719 acres). This management would result in greater adverse impacts to mineral leasing and greater beneficial impacts to the values of concern than alternatives A and C, but less than Alternative B. Unlike alternatives A and C, this alternative does not withdraw the existing ACEC or the Alternative B expansion area, and impacts to and from locatable mineral entry would therefore be similar to Alternative C. However, 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 in the existing ACEC by allowing for the protection of important sites.
Managing the existing ACEC as an ROW avoidance/mitigation area and open to ROW authorizations in the expansion area proposed under Alternative B would result in impacts to the authorization of ROWs and the values of concern similar to those for Alternative A, and fewer adverse impacts to ROW authorization and beneficial impacts to the values of concern than under Alternative B.
As under alternatives A and B, the existing area of the Upper Owl Creek ACEC and the expansion area proposed under Alternative B are limited to designated roads and trails under Alternative D. Impacts from this management would be the same as for the other alternatives.
Alternative B would designate the Chapman Bench area as an ACEC (23,326 acres), but alternatives A and C would not. Although not proposed as an ACEC under Alternative D, the BLM manages a portion of this area as the Chapman Bench Management Area. Values of concern in the proposed Chapman Bench ACEC are special status bird species, vegetation, and wildlife habitat. Threats to this area include potential mining interests when this reserved land is opened to all public land laws, which would affect special status bird species (e.g., long billed curlew, mountain plover, and greater sage-grouse) in the area.