Under Alternative A, the BLM would manage the Sheep Mountain Anticline to protect its geologic features and its recreational and interpretive uses. Management for the area is designed to protect the outstanding scenic values while continuing to provide limited developed recreational facilities and motorized access.
Under Alternative A, restrictions on mineral development would result in adverse impacts to these resource uses in the ACEC. The limited development potential for mineral resources in the ACEC would minimize the adverse impacts of these restrictions on mineral development. Restrictions on minerals development would benefit the values of concern by reducing the potential degradation of resources and the development of facilities and infrastructure that would impact scenic values.
Under Alternative A, the BLM withdraws the Sheep Mountain Anticline ACEC from appropriation under the mining laws and requires a plan of operations for existing mining claims for all locatable mineral exploration (except casual use). Withdrawing the ACEC would result in adverse impacts to locatable mineral development in the ACEC by prohibiting development of these minerals—no new claims could be staked—particularly where the potential is high for gypsum (2,649 acres) and bentonite (267 acres). Valid existing mining claims represent valid existing rights and would not be affected by the withdrawal (see Section 4.2.1 Locatable Minerals).
Under Alternative A, the Sheep Mountain Anticline ACEC is open to oil and gas leasing with primarily major and moderate constraints; however, the low development potential for oil and gas resources in this area limits impacts to oil and gas development and, conversely, limits development that may impact the values of concern in the ACEC.
Under Alternative A, prohibiting surface-disturbing activities such as geophysical exploration (except casual use), mineral materials disposal, and construction activities (except those related to development of recreation facilities or wildlife habitat) above caves and cave passages would result in adverse impacts to these resource uses by limiting these activities in the ACEC. Surface-disturbing activities elsewhere in the ACEC would be allowed, subject to restrictions on such activities addressed under other resources. The low potential for sand and gravel in most of the ACEC would limit adverse impacts to mineral materials disposal. The low potential for sand and gravel also would limit mineral material extraction and associated adverse impacts to cave and geologic values.
Limiting motorized travel in the ACEC to designated roads and trails and managing the area for the existing semi-primitive motorized and primitive recreational settings would result in adverse impacts to motorized vehicle use. Limiting motorized travel to designated roads and trails would reduce the available routes. These restrictions would maintain or enhance the recreational settings by eliminating unnecessary or undesirable vehicle routes, increasing opportunities for nonmotorized use, and allowing the closure of routes that result in adverse impacts to the values of concern.
With the exception of oil and gas leasing, management and impacts under Alternative B are the same as those under Alternative A.
Under Alternative B, making the ACEC administratively unavailable to oil and gas leasing would result in greater adverse impacts to the development of these resources than under Alternative A. The low development potential for oil and gas in the ACEC (ranging from low on 4,387 acres to very low on 7,141 acres on the remainder) would minimize these adverse impacts. Making the ACEC administratively unavailable to oil and gas leasing would provide the most protection to the values of concern of any alternative.
Alternative C does not designate the Sheep Mountain Anticline as an ACEC; the BLM would manage the area in accordance with multiple use principles consistent with other resource objectives.
The area is open to locatable mineral entry (except 172 acres), mineral leasing, and mineral materials disposal under Alternative C. There are moderate (7,790 acres) or major (3,446 acres) constraints on oil and gas development in most of the area, with these activities subject to standard restrictions in the remainder. Minerals management under Alternative C may result in greater development of these resources and therefore greater adverse impacts to the values of concern, compared to the other alternatives.
Alternative C limits motorized vehicle use to designated roads and trails; impacts from travel would be the same as alternatives A and B.
Except for oil and gas leasing, restrictions on surface-disturbing activities, and VRM, management and impacts under Alternative D would be the same as under Alternative A.
Under Alternative D, the BLM applies an NSO restriction on most of the ACEC and a CSU on the remainder. The effects of this management would result in greater adverse impacts to the development of leasable minerals than Alternative A, but these adverse impacts would be minimized because of the low to very low development potential for oil and gas in the area. The restrictions on leasable minerals would provide greater protection to the values of concern than alternatives A and C, but less than Alternative B.
Under Alternative D, the BLM would manage the Sheep Mountain Anticline ACEC as VRM Class II. Although none of the other alternatives includes specific VRM for this ACEC, the area is VRM Class II under alternatives B and C and VRM Classes III and IV (5,123 acres) under Alternative A, due to other resource considerations. Management as VRM Class II would require changes to the design and mitigation of BLM-authorized actions that would result in adverse impacts in the form of additional costs and delay for discretionary projects in the ACEC. Conversely, this VRM would benefit the values of concern, particularly the scenic qualities, by reducing or mitigating the visual contrast of BLM-authorized actions.
Alternative D imposes more restrictions on surface-disturbing activities than alternatives A and B. In addition to surface disturbance restrictions over cave and cave passage, this alternative only approves surface-disturbing activities elsewhere in the ACEC if the effects can be mitigated. Such a requirement would benefit geologic and related scenic values of concern for the area by limiting alterations to the visual environment, but may result in additional delay or expense for range improvements, ROW authorizations, and other surface-disturbing activities.
This area would be designated an ACEC under all the alternatives (6,627 acres). The values of concern managed for in the Spanish Point Karst ACEC are caves, recreational opportunities, sinking stream segments, an important aquifer recharge area, and important water quality functions. Threats to this ACEC include surface disturbance from mineral and ROW development and aerial spraying of pesticides onto aquifer recharge areas. Management and impacts to the area are the same under all alternatives.