How is it determined which uses or activities are “grandfathered” on federal lands and which are not?

Most current uses and activities on rivers and adjoining federal lands may continue. Of primary consideration in any river or land-use limitation is the protection and enhancement of the free-flowing condition, water quality, and outstandingly remarkable value(s) that resulted in the river’s designation. Those uses that clearly threaten these values will be addressed in the planning process, or through site-specific environmental analyses on a case-by-case basis where federal lands are involved.

Interagency Wild & Scenic Rivers Council