Beaver Basin Wilderness Act - Designates specified land and inland water within the Pictured Rocks National Lakeshore in Michigan as wilderness and as a component of the National Wilderness Preservation System, which shall be known as the Beaver Basin Wilderness.
Makes the line of demarcation the boundary for any part of the Wilderness that is bordered by Lake Superior. Considers the surface water of the Lake, regardless of the fluctuating lake level, to be outside of the boundary of the Wilderness.
Provides for the continuation of the use of boats powered by electric motors on Little Beaver and Big Beaver Lakes.
Specifies this Act's effect on: (1) treaty rights; (2) management of the water of Lake Superior within the boundary of the Pictured Rocks National Lakeshore; (3) the use of motors on the surface water of the Lake adjacent to the Wilderness; and (4) the beaching of motorboats at the line of demarcation.