Only Alternative D designates the PETM ACEC. However, Alternative B manages ACECs that completely overlap this area, making it the most effective for protecting the paleontological and geological values of concern. In both the PETM ACEC area and the greater-PETM area covered by the Clarks Fork Basin/ Polecat Bench West Paleontological Area, Foster Gulch, and McCullough Peaks South ACECs, Alternative B would be the most restrictive of oil and gas development, withdrawals, renewable energy development, ROW authorizations and other surface-disturbing activities, and motorized vehicle use. Under alternatives A and C, none of the area in the PETM ACEC or the greater-PETM area would be designated as an ACEC for the protection of paleontological values of concern. Management under these alternatives generally would be the least restrictive of mineral use and would provide the least protection from surface disturbance for the paleontological resources in the area. Alternative A would be the least restrictive of ROW and motorized vehicle use, followed by alternatives C and D.