Morganza Spillway

The Morganza Spillway or Morganza Control Structure is a flood-control structure in the U.S. state of Louisiana along the western bank of the Mississippi River at river mile 280, near Morganza in Pointe Coupee Parish. The spillway stands between the Mississippi and the Morganza Floodway, which leads to the Atchafalaya Basin and the Atchafalaya River in south-central Louisiana. Its purpose is to divert water from the Mississippi River during major flood events by flooding the Atchafalaya Basin, including the Atchafalaya River and the Atchafalaya Swamp. The spillway and adjacent levees also help prevent the Mississippi from changing its present course through the major port cities of Baton Rouge and New Orleans to a new course down the Atchafalaya River to the Gulf of Mexico. The Morganza Spillway, operated by the U.S. Army Corps of Engineers, was opened during the 1973 and 2011 Mississippi River floods.

The Great Mississippi Flood of 1927 was the most destructive river flood in the history of the United States, in large part due to the Mississippi River swelling to 80 miles (130 km) wide in spots. To prevent a repeat of the Great Flood of 1927, and better control river flooding in general, Congress passed the Flood Control Act of 1928 to authorize the United States Army Corps of Engineers to build the Bonnet Carre Spillway (located 33 miles (53 km) above New Orleans and completed in 1931), the Birds Point floodway in Missouri, and the Morganza Floodway as part of the 1928 Mississippi River and Tributaries Project.

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