Rio Grande Outstanding Natural Area Act - Establishes the Rio Grande Outstanding Natural Area, which shall consist of specified land along the Rio Grande River in southern Colorado from the southern boundary of the Alamosa National Wildlife Refuge to the Colorado-New Mexico State line, encompassing the River and its adjacent riparian areas.
Establishes the Rio Grande Outstanding Natural Area Commission to assist Federal, State, and local authorities in the development and implementation of an integrated resource management plan for the Area, which shall coordinate existing Federal, State, and local plans. Directs the Commission, upon approval of the plan by the Secretary of the Interior, to assist the Secretary in implementing the plan by taking steps to preserve and interpret the natural resources of the Area and its surrounding area. Provides that the plan will be binding on private lands within the Area only if the landowner agrees. Permits the Secretary to acquire land within the Area from willing sellers only.
Terminates the Commission ten years and six months after the enactment of this Act.
Prohibits the Secretary or any other Federal agency from approving or issuing any permit or providing any assistance for construction of any new dam, reservoir, or impoundment on any segment of the Rio Grande River or its tributaries within the Area's exterior boundaries.
Revokes all reservations of public lands within the Area for Federal purposes that have been made by an Act of Congress or executive order and restores such lands to public land status. Withdraws all public lands within the Area from settlement, sale, location, entry, or disposal under public land laws.
Prohibits any Area land or water from being designated as a wild, scenic, or recreational river.