Mississippi River channel if flood-control structures are overtopped or heavily damaged during a severe flood. Failure of the Old River Control Structure, the Morganza Spillway, or nearby levees would likely re-route the main channel of the Mississippi through Louisiana's Atchafalaya Basin and down the Atchafalaya River to reach the Gulf of Mexico south of Morgan City in southern Louisiana. This route provides a more direct path to the Gulf of Mexico than the present Mississippi River channel through Baton Rouge and New Orleans. While the risk of such a diversion is present during any major flood event, such a change has so
Morganza Spillway 2011 event) had been opened by the Corps of Engineers. The Corps estimated the flow rate at . However, on May 25, new estimates from the U.S. Geologic Survey (USGS) described a much higher rate of , resulting in the closure of 3 bays by May 26, and additional closures by May 29, bringing the total to 11 bays with an estimated diversion rate of . The Corps continued to evaluate the flow and close additional bays as appropriate. By June 6, the number of open gates had been reduced to seven, and by June 8, only two gates were