Old River Control Structure is a floodgate system in a branch of the Mississippi River in central Louisiana . It regulates the flow of water leaving the Mississippi into the Atchafalaya River , thereby preventing the Mississippi river from changing course . Completed in 1963 , the complex was built by the U.S. Army Corps of Engineers in a side channel of the Mississippi known as " Old River " , between the Mississippi 's current channel and the Atchafalaya Basin , a former channel of the Mississippi . The Old River Control Structure is actually a complex containing the original low-sill and overbank structures , as well as the auxiliary structure that was constructed after the low-sill structure was damaged during the Mississippi River Flood of 1973 . The complex also contains a navigation lock and the Sidney A. Murray Jr . Hydroelectric Station
Mississippi River Flood of 1973
Mississippi flood of 1973
Old River Control Structure