Alternatives B and D are the only alternatives that designate the Clarks Fork Canyon area as an ACEC. Due to the larger size and more restrictive management, Alternative B would be the most effective for protecting the glacial features, open space, recreational opportunities, special status species plants and wildlife, and wildlife habitat values of concern in the ACEC. Alternative B would be most effective for managing threats from motorized vehicle use and surface disturbance resulting from ROW development and locatable mineral entry by including the greatest restrictions on these activities. Management of mineral materials disposal and oil and gas leasing under alternatives B and D would be similar within their respective ACEC boundaries, although the larger area managed under Alternative B would be less restrictive under Alternative D. Alternative A generally would provide the least restrictive management and would be the least effective for protecting the values of concern. Alternative A would be the most beneficial to motorized travel and would include management for locatable and mineral materials similar to Alternative C. Alternative C would be the most beneficial to ROW authorizations.