Southern Louisiana Faces Mississippi Flooding

The Army Corps of Engineers operates two massive flood control structures in southern Louisiana that will have a significant impact on the threat from the record levels of spring flooding on the Mississippi River. The Bonnet Carre Spillway and the Morganza Floodway complex are designed to divert a portion of any flooding to areas away from the Mississippi and the cities and industries that line the river banks.

The Bonnet Carre Spillway is the oldest of the two structures. It was built after the flood of 1927. There are 350 bays, each blocked with removable timbers. The project will divert 250,000 cubic feet of water per second to Lake Pontchartrain.

The Army Corps of Engineers began removing timbers from bays on May 9. By May 13, 2011, an estimate 264 bays will be opened.

The Morganza Floodway will be opened next. The control structure is located on the Mississippi River, 310 mile north of New Orleans and north of Baton Rouge. There are 125 gates in the control structure. The floodway runs south from there to the Atchafalaya River Basin and then to the Gulf of Mexico. The Morganza project is designed to divert 600,000 cubic feet of flood water from the Mississippi River and reduce the threat to Baton Rouge and New Orleans.

Gov. Bobby Jindal of Louisiana states that the Corps will open the gates of the control structure when one of two criteria are met. The first would be when river flows at Red River Landing reach 1.5 million cubic feet per second. Should the Mississippi flood waters threaten to overtop the Morganza flood control structures, the Corps would also have to open the gates. Yesterday's data from the Corps of Engineers showed the Mississippi River at Red River Landing with a flow rate of 1.449 million cubic feet per second.

In the parishes to be affected by the diverted water, state workers and National Guard troops are assisting localities with levee repairs, increasing the height of select levees and building temporary flood barriers. There are 2,000 structures in the floodway itself and an estimated 11,000 more in areas that the flood waters will eventually back up into. Local levees and temporary barriers may protect many of these from damage.

Communities such as Krotz Springs and Morgan City may be spared the worst of the effects due to this work. Projections are that diverted water will take up to twelve hours to reach Krotz Springs, and 72 hours to reach Morgan City.

Jindal is stressing that people living in the Morganza floodway should evacuate now. Emergency services have been going door-to-door to ensure that everyone is notified of the coming threat.

Authorities continue to warn the public against walking or driving on levees. Any incidental damage at this time may weaken the structure. Dozens of sand boils have already been reported in the levee system. A levee breech or the failure of a flood wall due to the long term pressure from flood waters could be catastrophic and every effort is being made to prevent that from happening.

The Mississippi River at Red River Landing is now at 61.86 feet, two inches over the previous record. At Baton Rouge, the river is eleven feet above flood stage but three feet below the record, with a current level of 44.01 feet. The latest river gauge reports show that the flood is upstream from Reserve, Louisiana, which is now showing a river level of 23.6 feet.