Entrance fees and resource protection for units of the national park system : hearing before the Subcommittee on Public Lands, Reserved Water, and Resource Conservation of the Committee on Energy and Natural Resources, United States Senate, Ninety-ninth Congress, second session, on S. 2130 to preserve, protect, and revitalize the national park system, S. 2204 to amend the Land and Water Conservation Fund Act of 1965, as amended, to permit the use of park entrance, admission, and recreation use fees for the operation of the national park system, and for other purposes, June 12, 1986