The Morganza Floodway is located 186 river miles above New Orleans on the west bank of the river in Pointe Coupee Parish. Intended to operate during emergency flooding, the purpose of the Floodway is to divert excess floodwater from the Mississippi River into the Atchafalaya Basin. It was constructed in 1954 to maintain a flow of 1.5 million cfs below the floodway and has only been operated once before in 1973 to relieve pressure on the Low Sill Structure at the Old River Control Structure.
The Morganza Floodway is comprised of two parts. The first component is the floodway. At twenty miles long and five miles wide, it consists of a stilling basin, an approach and outlet channel, and two guide levees. The second element is a control structure, which is 3,906 feet in length and contains 125 bays. If necessary, the Morganza Floodway can move up to 600,000 cubic feet per second of water.