Bagnell Dam

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 2543 feet long, including a 520-foot long spillway and a 511-foot long power station. The facility with eight generators has a maximum capacity of 215 megawatts.

The dam derives its name from Bagnell, Missouri at the dam site which preceded the dam. It in turn derives its name from William Bagnell who platted the town in 1883.

The dam is located at show location on an interactive 38°12′09″N, 92°37′35″W in Miller County, Missouri. According to the United States Geological Survey, a variant name is Osage Dam.

Construction started on the dam in 1929 and was completed in 1931. The resulting reservoir, the Lake of the Ozarks, has a surface area of 55,000 acres (223 km²), over 1150 miles of shoreline (1850 km), and stretches 92 miles from end to end (148 km). At the time of construction it was one of the largest man-made lakes in the world and the largest in the United States.

The stock market crash of 1929, which precipitated the Great Depression occurred just months after construction began on Bagnell Dam. The project employed thousands of laborers, providing a large economic boost to the rural area around the dam, and to the state as a whole, at a time when jobs were scarce.

Construction of the dam allowed for thirteen floodgates, as the original design called for. However, only twelve floodgates were installed, and the thirteenth spillway opening is walled shut with concrete. The engineers calculated that twelve floodgates provided a large enough margin of safety. It may be apocryphal that Union Electric officials did not want to jinx the dam with the unlucky number 13.