Lock and Dam 52, completed in 1928, is located at Ohio River Mile 939.9. This site, and Lock and Dam 53, are the only remaining movable wicket dams on the Ohio. Both will be removed when the Olmsted Locks and Dam become operational. When the navigation system was completed in 1929, there were 51 similar projects. The U.S. Army Corps of Engineers' maneuver boat raises and lowers the wooden wickets, determined by river conditions.The M/V RAY A. ECKSTEIN is shown locking downbound. The vessel, owned and operated by Marquette Transportation Co., Inc., is headquartered in Paducah and named for the company's founder.