Bagnell Dam impounds the Osage River in the U.S. state of Missouri, creating the Lake of the Ozarks. The 148-foot (45 m) tall concrete gravity dam was built by the Union Electric Company (now AmerenUE) for the purpose of hydroelectric power generation as its Osage Powerplant. It is 2,543 feet (775 m) long, including a 520-foot (160 m) long spillway and a 511-foot (156 m) long power station.