How are river corridors established and what is the maximum corridor allowed?

Corridor boundaries are established to protect the free-flowing condition, water quality, and outstandingly remarkable values for which the river was designated. Generally, the corridor width for designated rivers cannot exceed an average of 320 acres per mile which, if applied uniformly along the entire designated segment, is one-quarter of a mile (1,320 feet) on each side of the river. Boundaries may be wider or narrower, but are not to exceed the 320 acre average per mile per Section 3(b) of the Wild & Scenic Rivers Act without approval by Congress. The acreage of any islands located above the ordinary high water mark within the designated corridor count against the acreage limitation; lands below the ordinary high water mark do not count against the acreage limitation. In Alaska, the allowable boundary is 640 acres per mile for rivers located outside of national parks.

Corridor boundaries for federally designated and administered wild and scenic rivers may vary based on a number of conditions, but are usually delineated by legally identifiable lines (survey or property lines) or some form of on-the-ground physical feature (i.e., topography, natural or manmade features such as canyon rims, roads, etc.), which provide the basis for protecting the river’s identified values and practicality in managing those values.

In certain site-specific cases, including where acquisition of lands may be involved, a survey may be needed to monument the boundary of the designated wild and scenic river corridor.

Interagency Wild & Scenic Rivers Council