Except as provided in section 459s of this title

After June 6, 1942, the lands acquired for the Acadia, French Creek, Shenandoah, and White Sands recreational demonstration projects shall be added to and become a part of Acadia National Park, Hopewell Village National Historic Site, Shenandoah National Park, and White Sands National Monument,1

The Secretary of the Interior is authorized to execute on behalf of the United States all necessary deeds and leases to effect the purposes of sections 459r to 459t of this title. Every such deed or lease shall contain the express condition that the grantee or lessee shall use the property exclusively for public park, recreational, and conservation purposes, and the further express condition that the United States assumes no obligation for the maintenance or operation of the property after the acceptance of such deed or during the term of such lease, and may contain such other conditions not inconsistent with such express conditions as may be agreed upon by the Secretary and the grantee or lessee: Provided, That the title and right to possession of any lands so conveyed or leased, together with the improvements thereon, shall revert to the United States upon a finding by the Secretary, after notice to such grantee or lessee and after an opportunity for a hearing, that the grantee or lessee has not complied with such conditions during a period of more than three years, which finding shall be final and conclusive, and such lands and improvements thereon, upon such reversion to the United States, shall be returned to the jurisdiction of the Department of the Interior and upon determination of the Secretary may be considered as surplus real property to be disposed of in accordance with section 1303 of title 40.

In order to facilitate the administration of former recreational demonstration project lands and to consolidate the holdings of the grantees to whom such lands have been or may be granted pursuant to sections 459r to 459t of this title, the Secretary of the Interior may authorize any such grantee to exchange or otherwise dispose of any lands or interests in lands conveyed to it in order to acquire other lands or interests therein of approximately equal value.

For the aforesaid purpose, the Secretary is authorized to execute a release, as to the particular lands involved, of any condition providing for a reversion of title to the United States, that may be contained in the conveyance by the United States to said grantee. No such release shall be executed, however, unless the grantee shall agree, in form satisfactory to the Secretary, that the lands to be acquired by it shall be subject to the conditions contained in the original conveyance from the United States, except that in lieu of a provision for reversion, the grantee shall agree to convey said lands to the United States upon a finding by the Secretary in accordance with the procedure provided in said sections, that the grantee has not complied with such conditions during a period of more than three years. Lands so conveyed to the United States shall be subject to administration or disposition in like manner as recreational demonstration project lands that revert to the United States under the terms of the aforesaid sections.