Prohibiting surface-disturbing activities on slopes of more than 7 percent would result in adverse impacts on the ability to construct range improvements, explore and develop certain minerals, authorize ROWs, and perform other activities. These restrictions would reduce surface-disturbing activities, which would benefit fragile soils, alpine tundra, crucial winter range, and the control of invasive species that could degrade the vegetation and wildlife values of concern in the ACEC. Areas with steep slopes are particularly prone to erosion and can be difficult to reclaim following surface disturbance.
Managing the Carter Mountain ACEC as available for mineral entry, open to minerals leasing, and open to mineral materials disposal would result in adverse impacts to the values of concern by increasing the potential for surface-disturbing activities that could degrade soils and disturb vegetation and wildlife resources. The low potential for all the mineral resources in the ACEC would minimize adverse impacts to the values of concern. Managing the ACEC as primarily open to mineral development would benefit the use of these resources. There would be major constraints on oil and gas development across most of the ACEC (9,954 acres), with smaller areas of closure and moderate constraints across the remainder.
Acquiring 840 acres in the Carter Mountain ACEC under Alternative A would result in long-term beneficial impacts in the ACEC by improving the effectiveness and consistency of management for the area’s watershed and habitat values through consolidation of land ownership.
Under Alternative A, managing the Carter Mountain ACEC as an ROW avoidance/mitigation area applies restrictions to ROW authorizations and would result in adverse impacts to ROW authorizations by limiting these authorizations or requiring specific lease stipulations. These restrictions would benefit the values of concern by reducing development and increasing impact mitigation measures. Requiring intensive mitigation for new ROWs would further benefit the values of concern by reducing the impacts of any new ROWs on vegetation, crucial winter range, and wildlife using the area.
Under Alternative A, limiting motorized vehicle use to designated roads and trails in the Carter Mountain ACEC, with a seasonal closure from November 15 to June 15 or later if weather or road conditions are unfavorable, would result in adverse impacts to motorized vehicle use. Adverse impacts to travel may be minimized because the BLM commits to maintaining existing public access and pursuing additional access opportunities under this alternative. Seasonal restrictions and limiting travel to designated roads and trails would benefit the values of concern by protecting fragile soils and alpine tundra and eliminating disturbances to big game habitat during sensitive periods. Requiring approval before snow is removed from BLM-administered roads in big game crucial winter range would further help minimize disturbance to wildlife.
Prohibiting the construction of new recreational sites and restricting the use of heavy equipment in the Carter Mountain ACEC would result in adverse impacts to recreation and fire and fuels management. Under this alternative, restrictions on recreational facility development may affect the BLM’s ability to provide desired recreation experiences in the area. Heavy equipment restrictions may result in difficulties controlling or suppressing wildland fires in the ACEC, although the use of prescribed fire to control fuels is allowed. Restrictions on recreation and fire and fuels management would benefit the values of concern. These restrictions would prevent surface-disturbing activities that could affect wildlife and vegetation to protect fragile soils and alpine tundra.
Managing the Carter Mountain ACEC as VRM Class II would result in adverse impacts to resource uses by limiting certain activities in the ACEC. Activities such as range improvement projects and oil and gas facility development would be adversely affected because no activity would be allowed to attract the attention of the casual observer; therefore additional mitigation or design consideration may be required. Management as VRM Class II would benefit vegetation and wildlife habitat values of concern by limiting the size and types of development and surface disturbance that would be allowed, and potentially increasing mitigation for activities that did occur.
Under Alternative B, the BLM would expand the Carter Mountain ACEC by 5,706 acres. Management and impacts described for Alternative A, except for mineral and recreational facilities, 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 means that the impacts from such management would be comparatively larger under Alternative B than under 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, administratively unavailable for mineral leasing, and closed to mineral materials disposal. The potential for gypsum and bentonite in the ACEC is low; therefore, adverse impacts to the use of these resources would be minimal. Managing the ACEC as administratively unavailable to oil and gas development would result in the greatest impact in the 1,780 acres with moderate development potential for oil and gas; the remainder of the ACEC has very low development potential. Likewise, closure to mineral materials would result in the greatest adverse impacts on the 1,872 acres with high-potential for sand and gravel in the ACEC. Minerals management under Alternative B is more restrictive than under Alternative A and would result in greater adverse impacts to mineral resources by further limiting development. Restrictions on minerals development would benefit the values of concern. Under Alternative A, the area proposed for expansion under Alternative B is available for locatable mineral entry and open to mineral leasing. Under Alternative B, more restrictive management limiting surface disturbance from minerals development would result in greater beneficial impacts, compared to Alternative A, in the existing and expansion areas on the vegetation, soils, big game crucial winter range, and cultural and recreational values of concern for these areas.
Managing the Carter Mountain ACEC expansion area as an ROW avoidance/mitigation area, limiting motorized vehicle use to designated roads and trails, and managing the area as VRM Class II would result in more restrictive management than under Alternative A. Under Alternative A, the area proposed for expansion under Alternative B is managed as an ROW avoidance/mitigation area. Under Alternative B, increasing resource use restrictions would result in greater adverse impacts to ROW authorizations, travel, and development activities compared to Alternative A. Managing the expansion area as VRM Class II places additional stipulations on the types and locations of activities that would be allowed in the ACEC compared to Alternative A. Under Alternative A, the BLM manages the area proposed for expansion under Alternative B as VRM Class IV (4,348 acres) or Class II (1,358 acres). Managing the existing and expansion areas as VRM Class II under Alternative B would maintain the visual environment more than Alternative A and provide the greatest benefits to recreational and other uses compared to the other alternatives.
Restricting travel to designated roads and trails in this area provides more protection than Alternative A for fragile soils, vegetation communities, wildlife habitat, watershed functions, and cultural resources. Under Alternative A, the BLM limits motorized vehicle use in the area proposed for expansion under Alternative B to existing roads and trails (5,135 acres), and limits the remainder to designated roads and trails (571 acres).
Alternative B allows the construction of recreational facilities to address visitor health and safety, use and user conflicts, and resource protection, which would result in greater beneficial impacts to recreational values than under Alternative A. This management may also increase surface disturbance and visitation to sensitive areas compared to Alternative A, which may result in adverse impacts to the non-recreational values of concern.
Under Alternative C, the BLM would not designate the Carter Mountain as an ACEC, and would manage it in accordance with multiple use principles consistent with other resource objectives.
Management under Alternative C would result in the least impact to the development of oil and gas resources and ROW authorizations. Similar to Alternative A, the area would be available for locatable mineral entry, open to mineral leasing, and open to mineral materials disposal. Constraints on oil and gas development would be lowest under this alternative, because there would be moderate constraints on oil and gas development on most of the area (15,563 acres), with major constraints on the remainder. Under Alternative C, the BLM would manage the Carter Mountain area as open to ROW authorizations. Standard guidelines related to surface disturbance would apply. These resource uses would result in additional surface disturbance in the area compared to alternatives A and B, leading to potential damage to the identified values of concern.
Applying only the standard guidelines for surface-disturbing activities under Alternative C would reduce the beneficial impacts on the protection of fragile soils, scenic quality, vegetation communities, wildlife habitat, watershed functions, and cultural resources compared to the other alternatives.
Managing motorized vehicle use as limited to designated roads and trails (5,135 acres) or with seasonal restrictions (11,438 acres) would result in impacts similar to those under Alternative A for the existing ACEC. Travel management in the proposed expansion area under alternatives B and D is more restrictive than under Alternative C and, therefore, Alternative C would result in fewer adverse impacts to travel. Compared to Alternative A, management of motorized vehicle use under Alternative C would result in fewer adverse impacts to the values of concern.
Under Alternative C, the BLM would manage the Carter Mountain area as VRM Class II, and impacts would be the similar to those under Alternative B.
Management of and impacts from the Carter Mountain ACEC under Alternative D are the same as under Alternative A, with the exceptions described below.
Management of and impacts to travel in the ACEC and the area proposed for expansion under Alternative D is the same as under Alternative B. Unlike alternatives A and B, this alternative does not pursue additional public access to the area, which may reduce the beneficial impacts to public access described for Alternative A.
In addition to the 840 acres identified for acquisition in Alternative A, Alternative D would consider the acquisition of other parcels from willing sellers in the Carter Mountain area. Such acquisitions may result in additional long-term beneficial impacts to management for the area’s watershed and habitat values compared to Alternative A.
Under Alternative D, the BLM would manage ROW authorizations in the Carter Mountain ACEC and the expansion area proposed under Alternative B the same as under Alternative B. However, unlike alternatives A and B, intensive mitigation is not required for additional ROW authorizations, and associated adverse impacts to ROW authorizations and beneficial impacts to habitat and sensitive wildlife from this mitigation would not occur. Alternative D would allow surface-disturbing activities throughout the ACEC if the effects on alpine tundra could be avoided or mitigated based on site-specific analysis. Compared to alternatives A and B, allowing the construction of range improvements and other surface-disturbing activities throughout the ACEC would reduce adverse restrictions to these resource uses and would reduce the benefits of prohibiting these activities in habitat and alpine tundra on steep slope.
Impacts from the construction of recreational facilities would the same as under Alternative B.
Under Alternative D, the management of mineral resources would generally be more restrictive than alternatives A and C, but less than Alternative B. Alternative D withdraws a smaller portion of the ACEC from locatable mineral entry (5,064 acres) than Alternative B, but, similar to Alternative B, the BLM would manage the entire area as administratively unavailable for oil and gas leasing. Similar to alternatives A and C, the entire area is available for mineral materials disposal.
VRM classifications and associated impacts in the Carter Mountain ACEC and the expansion area proposed under Alternative D are the same as under Alternative B.
The BLM would designate the Five Springs Falls area as an ACEC under alternatives A and D (163 acres) and designate and expand it by 1,646 acres under Alternative B. The BLM would not designate the Five Springs Falls ACEC or its expansion area as an ACEC under Alternative C. Management of this area would vary by alternative. The values of concern in the Five Springs Falls ACEC include special status species plants and scenic and recreational features. In addition, the proposed expansion area contains geologic features and would be managed to improve public awareness of natural geologic hazards in the area. Threats in the area of the ACEC proposed under alternatives A and D include damage to rare and endemic plants caused by recreation. Threats to the expansion area proposed under Alternative B include surface disturbance from mineral and ROW development.