Okla. Stat. tit. 82, § 895

Municipalities are prohibited from annexing property which is covered by any body of water subject to the control of the Grand River Dam Authority or from annexing any property located within one thousand (1,000) feet of the high water mark of such body of water, without prior approval of the Grand River Dam Authority Board of Directors. Provided, however, municipalities may annex property by crossing a body of water if the property has been improved with a bridge or similar permanent structure.