Alternative A does not designate the area as an ACEC; the BLM manages the area in accordance with multiple use principles consistent with other resource objectives.
The area would be open to locatable mineral entry except on 560 acres, open to mineral leasing (with primarily major constraints on 18,943 acres and moderate constraints on the remaining 6,210 acres), and open to mineral materials disposal on 24,574 acres and closed on 579 acres. Allowing mineral development in areas open to minerals would result in beneficial impacts to these resource uses. Mineral development would result in surface disturbance and habitat fragmentation that would result in adverse impacts to vegetation and big game wildlife habitat values in the area.
The Sheep Mountain area is managed as open to ROW authorizations (19,475 acres) or as an ROW avoidance/mitigation area (5,607 acres). Standard guidelines related to surface disturbance would apply. Alternative A limits motorized vehicle use primarily to designated roads and trails (22,926 acres), and limits motorized vehicle use in a smaller area to existing roads and trails (2,227 acres).
Standard guidelines related to surface disturbance would apply and may reduce the severity of impacts to the values of concern from surface disturbance. There would still be adverse impacts if surface-disturbing activities are authorized.
Under Alternative B, prohibiting surface-disturbing activities in the Sheep Mountain ACEC would restrict such activities as geophysical exploration and road construction, but would benefit vegetation communities, sensitive plants, and big game habitat by limiting the potential for fragmentation or invasive species infestations that would degrade vegetation and habitat.
Under Alternative B, restrictions on mineral development would result in adverse impacts to the use of these resources or beneficial impacts to the values of concern by reducing surface-disturbing activities and disruptions. The ACEC is withdrawn from appropriation under the mining laws and closed to mineral materials disposal. Adverse impacts to mineral resources would be greatest in areas of high-potential for gypsum and bentonite (2,809 acres and 1,953 acres, respectively) or sand and gravel (13,648 acres). The ACEC is administratively unavailable for mineral leasing, but the development potential for oil and gas is very low to low and adverse impacts would be minimal.
Under Alternative B, the Sheep Mountain ACEC is an ROW and renewable energy avoidance/mitigation area. Of all the alternatives, this management is the most restrictive to future ROW authorizations and the most restrictive to ROW-related surface disturbance and disruption that would adversely affect the wildlife and vegetation values of concern. Therefore, management of ROWs and renewable energy would result in the greatest beneficial impacts to the values of concern in the ACEC compared to the other alternatives.
A portion (13,023 acres) of the Sheep Mountain ACEC is seasonally restricted and the remainder (11,905 acres) is limited to designated roads and trails for motorized and mechanized vehicle use. Limiting or closing the ACEC to motorized vehicle use would result in adverse impacts to travel and access and beneficial impacts on the values of concern. Closing this area would eliminate disruption from motorized vehicles to wildlife and may reduce disturbance of vegetation and sensitive plants. Management under this alternative would be the most restrictive to motorized vehicle travel, but would result in the greatest beneficial impacts to the values of concern in the area compared to the other alternatives.
Seasonally stipulating, where feasible, vegetative/silviculture treatments, invasive/nonnative pest species control, fuels management, and maintenance of existing facilities in the Sheep Mountain ACEC would protect wildlife during sensitive times of the year, while still allowing maintenance and treatments to occur.
Alternative C does not designate the area as an ACEC; the BLM manages the area in accordance with multiple use principles consistent with other resource objectives.
The area would be open to locatable mineral entry except on 560 acres, open to mineral leasing (with primarily moderate constraints on 24,011 acres, major constraints on 976 acres, and standard stipulations on 166 acres), and entirely open to mineral materials disposal. Management of minerals would allow for the greatest level of mineral development in the area and would result in the greatest adverse impacts to the values of concern compared to the other alternatives.
ROW management in the Sheep Mountain area is open to ROW authorizations (19,865 acres), with a smaller portion managed as avoidance/mitigation for ROW (5,288 acres). Standard guidelines related to surface disturbance would apply; however, the additional restrictions under Alternative B would not. Alternative C is less restrictive to ROW authorizations than Alternative A. Management of ROWs under Alternative C would result in the greatest adverse impacts to the values of concern in the area compared to the other alternatives.
Alternative C limits motorized vehicle use primarily to designated roads and trails (11,630 acres) or imposes seasonal restrictions (13,248 acres), and limits a smaller area to existing roads and trails (275 acres). Impacts to motorized travel are generally expected to be similar to Alternative A.
Standard guidelines related to surface disturbance would apply and could result in additional surface disturbance in the area compared to alternatives A and B, leading to potential increased degradation of the values of concern in the area.
Surface-disturbing activities are allowed in the Sheep Mountain ACEC and the larger area managed as an ACEC under Alternative B, reducing the potential for adverse impacts to activities such as ROWs and range improvement projects compared to Alternative B. Allowing these activities would result in adverse impacts to the values of concern similar to Alternative A, although these impacts would be reduced in the ACEC under Alternative D. Surface-disturbing activities in the ACEC are limited to slopes of 15 percent or less, except where needed to improve watershed function, wildlife habitat, or land health.
Alternative D does not pursue a withdrawal for the Sheep Mountain ACEC, and only a small portion of the larger area proposed under Alternative B (54 acres) is withdrawn to meet other resource objectives. Management of and impacts from locatable mineral entry under this alternative would be similar to Alternative A, and the adverse impacts to mineral uses and beneficial impacts to habitat identified under Alternative B would not occur.
As under Alternative B, the Sheep Mountain ACEC is closed to mineral materials disposal and administratively unavailable for mineral leasing; however, the larger area designated as an ACEC under Alternative B is available for locatable mineral entry, open to mineral materials disposal, and only managed as administratively unavailable to oil and gas leasing on a portion (6,085 acres) under this alternative. Impacts in the Alternative D ACEC would be the same as under Alternative B; impacts in the larger area managed as an ACEC under Alternative B would be less adverse to the use of mineral resources. The less restrictive management of mineral uses under this alternative would reduce the beneficial impacts to the values of concern compared to Alternative B. As noted for Alternative B, the very low to low development potential for oil and gas would minimize both adverse impacts to leasing and the benefit of leasing restrictions on the values of concern under Alternative D. However, adverse impacts to mineral materials disposal would still exist in areas of high-potential for sand and gravel. Under Alternative D, management of and impacts from ROWs and renewable energy in the Sheep Mountain ACEC and the larger area designated as an ACEC under Alternative B would be the same as under Alternative B.
Under Alternative D, motorized vehicle use in the Sheep Mountain ACEC and most of the larger area managed under Alternative B is limited to designated roads and trails (24,945 acres). Impacts to motorized travel would be similar to Alternative A.
Similar to Alternative B, under Alternative D, the BLM can stipulate, where feasible, treatment and maintenance activities in the Sheep Mountain ACEC to protect wildlife, while still allowing maintenance and treatments to occur. In the larger area proposed as an ACEC under Alternative B, the standard guidelines related to surface disturbance and the management of other resource objectives would manage these activities; therefore, under Alternative D, impacts in this area would be similar to Alternative A.