Morganza Q and A

When is it used?

The structure is used during emergency flooding to divert excess floodwater from the Mississippi River into the Atchafalaya Basin. When deciding to open the structure, the Army Corp of Engineer considers "current and projected river flows and levee conditions, river currents and potential effects on navigation and retaining walls, extended rain and stage forecasts, and the duration of high river stages."

Specifically, the Corps considers opening the floodway when the river reaches 57 feet at the structure or when flows at the Red River Landing are predicted to reach 1.5 million cubic feet per second and rising.

(Pictured above, workers close a gate in the Morganza Spillway in 2011.)

Authorities began taking steps Friday to sink a barge in Bayou Chene with the hope it will mean Iberville and nearby parishes are spared from devastating backwater flooding if the Morganza Spillway is opened as expected.

Gov. John Bel Edwards released a statement Friday afternoon announcing the Louisiana Coastal Protection and Restoration and the St. Mary Levee District began the process to install a temporary barge flood gate on Bayou Chene.

The U.S. Army Corps of Engineers is expected to make their final decision on the spillway's opening May 28.

The decision to sink the barge is expected to bring relief to areas downstream of the spillway's impact area by reducing the amount of backwater flooding in the area.

The measure will have authorities install a barge in Bayou Chene - a tributary of the Atchafalaya River which leads into populated areas of Iberville, St. Martin, St. Mary, Terrebonne and Assumption parishes - and sink it, stopping the water flow. The spillway, if opened, would flood water into the Atchafalaya and down into those parishes, so putting the barge in place is intended to protect those residents from backwater flooding.


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The state recently approved $80 million in funding to place a permanent structure at Bayou Chene, but that construction will take several years.

The anticipated spillway opening would not occur until June 2. The process of installing the barge would begin Tuesday and would take seven days. If the spillway is opened, it could take up to two weeks before water travels down the Atchafalaya Basin and reaches Morgan City, giving authorities ample time to fully submerge and prepare the barge to lessen additional backwater flooding.

“To be clear, the barge flood gate on Bayou Chene will be in place by the time the spillway is opened,” said CPRA Chairman Chip Kline. “The CPRA has agreed to fully fund the sinking of the barge and is not asking any cost-share from the locally-affected parishes."


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