Okla. Stat. tit. 82, § 874.2

The Grand River Dam Authority is hereby authorized in its discretion to issue licenses to encroach upon real property owned by the Authority to adjacent property owners for structures built upon the real property prior to June 1, 2005. The Authority shall receive from the licensee for any license issued pursuant to this section the fair market value of the unimproved land and any administrative costs, including appraisals or surveys, required by the Authority.