16 U.S.C. § 410ii-4
The Secretary shall seek to enter into cooperative agreements with the owners, including the beneficial owners, of the properties located in whole in or in part within the park or the archeological protection sites. The purposes of such agreements shall be to protect, preserve, maintain, and administer the archeological resources and associated site regardless of whether title to the property or site is vested in the United States. Any such agreement shall contain provisions to assure that (1) the Secretary, or his representative, shall have a right of access at all reasonable times to appropriate portions of the property for the purpose of cultural resource protection and conducting research, and (2) no changes or alterations shall be permitted with respect to the cultural resources without the written consent of the Secretary. Nothing in this subchapter shall be deemed to prevent the continuation of traditional Native American religious uses of properties which are the subject of cooperative agreements.
16 U.S.C. § 410ii-4