; and (2) except as provided in subsection (c), ensure a permanent end to grazing on the land covered by the donated permit or lease. (c) Horse Lake common allotment If the land covered by a permit or lease donated in the Horse Lake allotment under subsection (a) is covered by another valid grazing permit or lease in the Horse Lake allotment that is not donated, the Secretary shall reduce the authorized livestock grazing level in the Horse Lake allotment to reflect the donation of the permit or lease under that subsection. V National Conservation Areas 501. Purpose The purpose of this title is to establish the Massacre Rim Dark Sky National Conservation Area, Kiba Canyon Range National Conservation Area, Smoke Creek National Conservation Area, Pah Rah National Conservation Area, and Fox Range National Conservation Area to conserve, protect, and enhance for the benefit and enjoyment of present and future generations the cultural, archaeological, dark sky, natural, scientific, geological, historical, biological, wildlife, educational, and scenic and visual resources of the Conservation Areas. 502. Establishment For the purpose described in section 501, subject to valid existing rights, there are established in the State the following National Conservation Areas: (1) Massacre rim dark sky national conservation area The Massacre Rim Dark Sky National Conservation Area, comprising approximately 134,144 acres of Federal land in the State, as generally depicted on the map entitled Truckee Meadows Public Lands Management Act: Massacre Rim Dark Sky National Conservation Area