To authorize the Secretary of the Interior to adjust the boundary of the Stephen Mather Wilderness and the North Cascades National Park in order to allow the rebuilding of a road outside of the floodplain while ensuring that there is no net loss of acreage to the Park or the Wilderness, and for other purposes.

Amends the Washington Park Wilderness Act of 1988 to authorize the Secretary of the Interior to adjust the boundaries of the North Cascades National Park and the Stephen Mather Wilderness in Washington state in order to provide a corridor of up to 100-feet in width along which the Stehekin Valley Road may be rebuilt: (1) outside of the floodplain between mileposts 12.9 and 22.8; (2) within one mile of the route for such Road; (3) within the boundaries of the Park; and (4) outside of the boundaries of the Wilderness.

Requires that the boundary adjustments be such that equal federally owned acreage amounts are exchanged between the Wilderness and the Park.

Requires lands in the newly designated wilderness to include lands along the route of the Steheken Valley Road that are replaced by the reconstruction. Authorizes the Secretary, if such lands contain fewer acres than the corridor, to designate additional federal lands in the Park as wilderness, but bars such designation from exceeding the acreage amount needed to equalize the exchange. Instructs that these additional lands must be selected from lands that qualify as wilderness.

Prohibits anything in this Act from: (1) authorizing the sale or acquisition of any land or interest in land; and (2) being construed as requiring the Secretary to give this project precedence over the construction or repair of other similarly damaged roads in units of the National Park System.