16 U.S.C. § 459u
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.
16 U.S.C. § 459u