Under all alternatives, mitigating surface-disturbing activities in the Brown/Howe Dinosaur Area ACEC would benefit the protection the paleontological values of concern.
Prohibiting the sale or exchange of lands in the ACEC, unless such disposals are consistent with management objectives, would improve management effectiveness and efficiency and resource protection in the area. Allowing exchanges consistent with resource objectives (paleontological values) would allow management flexibility to acquire high-value paleontological resources in the area while preventing land disposal that would transfer these resources out of BLM management.
Under all alternatives, limiting motorized vehicle use to designated roads and trails would reduce the routes available for recreational and other uses. Restrictions on motorized travel would decrease the potential for impacts to surface paleontological resources by allowing the closure of routes that result in adverse impacts to paleontological values.
All alternatives require fencing and signing of quarry sites in the Brown/Howe Dinosaur Area ACEC, which would benefit visitor safety and may reduce degradation of paleontological values from human disturbance.
All alternatives only allow fossil collection, excavation, or removal in the Brown/Howe Dinosaur Area ACEC under a permit issued by the Wyoming BLM State Director and only by institutions and individuals engaged in BLM-approved research, museum, or educational projects. These requirements would result in beneficial impacts by protecting the integrity of paleontological resources and enabling the advancement of scientific knowledge and research on these values in the area.
Allowing surface-disturbing activities in the ACEC, only if they are preceded by a paleontological sensitivity survey and monitored during construction, when necessary, would result in adverse impacts to ROW and minerals development and other surface-disturbing activities. The survey may delay activities or require mitigation or placement to limit impacts to paleontological values, but would continue to allow some activities while protecting the integrity of fossil-bearing material in the area. Restrictions on surface disturbance would benefit paleontological values of concern in the ACEC.
Managing the Brown/Howe Dinosaur Area ACEC as available for locatable mineral entry, open to mineral leasing, and open to mineral materials disposal would benefit these resource uses. Allowing mineral development would have an adverse impact on the paleontological values of concern in the ACEC. However, the low potential for development of these resources (BLM 1994c) would minimize the adverse and beneficial impacts of allowing locatable mineral entry. Requiring operations on oil and gas leases and mineral materials disposal to conform to the applicable provisions of the regulations (43 CFR 3100) and other terms and conditions determined necessary by the authorized officer to avoid damage to these resources would minimize adverse impacts to paleontological resources. Restrictions from the management of the ACEC and other resources result in major (2,196 acres) and moderate (3,163 acres) constraints on oil and gas development in this area.
Under Alternative A, the Brown/Howe Dinosaur Area ACEC is open to ROW authorizations, subject to the requirements for surface-disturbing activities described above, which would result in adverse impacts to paleontological resources in the ACEC. Requiring paleontological sensitivity surveys before approving minor ROW authorizations in the Brown/Howe Dinosaur Area ACEC may cause long-term adverse impacts to ROWs by increasing authorization processing times and potentially requiring mitigation, relocation, or modification of facilities if paleontological resources are found. Due to the small size of this area compared to the size of the Planning Area, these impacts may be minimal.
Under Alternative B, the BLM would expand the Brown/Howe Dinosaur Area ACEC by 15,246 acres. The management and impacts described under Impacts Common to All Alternatives and, unless otherwise noted, under Alternative A would apply to the expanded ACEC area. Expanding the ACEC would increase restrictions on resource uses in the area and increase the protection of the paleontological values of concern in the area.
Under Alternative B, restrictions on mineral development in the expanded ACEC would result in greater adverse impacts to the use of these resources than under Alternative A. Restrictions on minerals development would result in greater beneficial impacts to paleontological values of concern compared to Alternative A.
The expanded ACEC is withdrawn from appropriation under the mining laws, administratively unavailable for mineral leasing, and closed to mineral materials disposal under Alternative B. Withdrawal from locatable mineral entry would result in adverse impacts to the use of mineral resources because no new claims could be staked; these impacts would be greatest in the approximately 1,462 acres of high-potential for bentonite and 3,079 acres of high-potential for gypsum in the expanded ACEC. The development potential within the Alternative A ACEC boundaries is low, which would limit the potential for adverse impacts to mineral development. The development potential for oil and gas in the ACEC is very low; therefore, adverse impacts to this resource use from the restrictions under Alternative B would be minimal. Adverse impacts from closing the area to mineral materials disposal would be greatest on the approximately 1,662 acres of high-potential for sand and gravel. Mineral restrictions, including the withdrawal, under Alternative B would result in greater beneficial impacts to paleontological resources in the area compared to alternatives A and C by decreasing mineral activity and associated disturbance that could degrade paleontological values. Decreased mineral activity also may reduce new roads and may decrease access opportunities for recreational collectors or access that could degrade resource values.
Under Alternative B, managing the ACEC as an ROW avoidance/mitigation area would result in greater adverse impacts to this resource use by limiting new ROW authorizations in the ACEC. Under Alternative A, the area proposed for expansion under Alternative B is open to ROW authorizations, subject to the standard requirements for surface-disturbing activities and paleontological resources. The more restrictive ROW management under Alternative B would reduce or mitigate surface disturbance and would provide more protection for paleontological resources than under Alternative A.
The management of and impacts from the Brown/Howe Dinosaur Area ACEC under Alternative C are the same as those under Alternative A.
Under Alternative C, the BLM would manage the area proposed for expansion under Alternative B primarily as an ROW avoidance/mitigation area (11,057 acres), with only a small portion (4,189 acres) open to ROW authorization. Therefore, ROW management is more restrictive than under Alternative A and impacts to the values of concern in this area would be similar to those under Alternative B.
The management of and impacts from the Brown/Howe Dinosaur Area ACEC under Alternative D are the same as those under Alternative A, except for surface-disturbing activities and VRM.
Similar to Alternative A, Alternative D allows surface-disturbing activities if preceded by an on-the-ground survey and monitoring. However, Alternative D may result in greater adverse impacts to paleontological values of concern because surveys and monitoring are only required in PFYC 3 through 5 formations on a case-by-case basis. Compared to the other alternatives, Alternative D may result in fewer adverse impacts to ROW placement and other surface-disturbing activities.
Under Alternative D, adverse impacts to locatable and leasable mineral uses and beneficial impacts to paleontological values of concern would be less than under Alternative B. Under Alternative D, the BLM manages the existing ACEC and the expansion area proposed under Alternative B as open to mineral materials disposal. Impacts would be the same as under alternatives A and C.
Under Alternative D, the BLM manages the Brown/Howe Dinosaur Area ACEC and the area proposed for expansion under Alternative B as ROW avoidance/mitigation areas. Impacts would be the same as under Alternative B.
Under Alternative D, the BLM manages the Brown/Howe Dinosaur Area ACEC and the area proposed for expansion under Alternative B as VRM Class III. Although none of the other alternatives includes specific VRM for this ACEC, managing it as VRM Class III would be more restrictive than VRM Class IV under Alternative C (14,588 acres) and less restrictive than VRM Class II under alternatives A and B (8,440 acres and 20,752 acres, respectively). Management as VRM Class III would allow BLM-authorized actions that result in surface-disturbing activities with reduced mitigation and siting restrictions, and related benefits to some resource uses and adverse impacts to paleontological resources, compared to VRM Class I and II areas.
The BLM would designate the Carter Mountain area as an ACEC under alternatives A and D (10,867 acres) and designate and expand it by 5,706 acres under Alternative B. The BLM would not designate the Carter Mountain area as an ACEC under Alternative C. Management of this area would vary by alternative. The values of concern in the Carter Mountain area are vegetation and wildlife resources, including alpine tundra and crucial winter range. Threats to this area include surface disturbance from mineral, ROW, and renewable energy development, and theft and vandalism. In addition, the proposed expansion area under Alternative B contains cultural features, recreational opportunities, special status species habitat, and fragile soils, and supports watershed functions. Threats to the Alternative B expansion area are the same as those to the ACEC under Alternative A, except that they do not include theft and vandalism.