Between 1780 and 1890, Mississippi River levee breeches in the Morganza area caused 15 major floods that affected Pointe Coupée Parish and lands southward to the Gulf of Mexico. The flood of 1912 forced the evacuation of three-fourths of the parish’s population. The flood of 1927 became a major turning point in American history because of both the destruction it caused across the lower Mississippi River valley and the changes it brought to flood-control management. In 1928, Congress passed the Flood Control Act, authorizing the U.S. Army Corps of Engineers to design and build the Mississippi River and Tributaries Project as a comprehensive river-management program. After reviewing the river, its tributaries, and its distributaries, the corps adopted a multi-pronged strategy to prevent another disaster like that of 1927. Although the 1928 law first called for the Atchafalaya Floodway, the Overton Act of 1936 revised the plan to create the Morganza and West Atchafalaya floodways to carry water from the Red and Mississippi rivers through the Atchafalaya Basin to the Gulf of Mexico. The U.S. Army Corps of Engineers completed the Morganza Control Structure and Floodway in 1955. Extending from the Mississippi River’s natural levees through mostly backswamp areas in central and western Pointe Coupée Parish, the control structure is about 4,000 feet long, contains 128 bays, can divert up to 600,000 cubic feet per second, and is opened when a 10-day forecast projects Mississippi River flow of 1.5 million cubic feet per second or more past the structure. The floodway channel averages 5 miles in width and runs 20 miles southwest before entering the Lower Atchafalaya Floodway and continuing toward the Gulf. The structure and floodway were first used in 1973, when major spring flooding damaged the Old River Control Structure to the north; that year, 42 bays were opened to allow a flow of 300,000 cubic feet per second, or 50 percent of capacity. In 2011, 17 bays, or 30 percent of capacity, were opened when flooding threatened to overtop levees farther downriver in Baton Rouge and New Orleans. In both 1973 and 2011, other distributary outlets in Louisiana also helped reduce flow volumes and prevent a recurrence of severe loss of life and property in this flood-prone landscape.
