Corps Considers Changes to Louisiana’s Morganza Flood Control Structure

The U.S. Army Corps of Engineers will hold public meetings next week on plans to tweak the way the Morganza flood control structure is operated during floods.

The Morganza flood control structure diverts water from the Mississippi River into the Atchafalaya floodway to help prevent too much water from getting downriver.

Built in 1955, the Morganza flood control structure north of Baton Rouge diverts water from the Mississippi River into the Atchafalaya floodway to help prevent too much water from getting downriver.

Normally, the structure is opened when the river reaches a flow rate of 1.5 million cubic feet per second and rising.

However, the river bottom has changed over the years, which has led to higher water flow levels. During the 2011 flood, operators found that the water height in the river got to 59.6 feet before that 1.5 million cubic feet per second trigger to open the structure was met, said Ricky Boyett, Corps spokesman. The control structure was designed to be operated when the water states is at 57 feet at the structure.

Normally, the structure is opened when the river reaches a flow rate of 1.5 million cubic feet per second and rising. However, the river bottom has changed over the years, which has led to higher water flow levels in 2011.

Boyett told The Advocate the Corps is proposing making sure the structure is operated so that the river water height doesn’t get higher than 57 feet when there is a 10-day forecast of a river flow at 1.5 million cubic feet per second.

Other tweaks call for the structure to be initially opened to limit the rise of water in the floodway to one foot a day for the three first days, changing the gate opening and closing sequence to minimize scour damage, and keeping some of the floodway open to help drain the front bay area quicker.

Meetings will be held in St. Martinville, Morgan City and Baton Rouge.