Cranes were used Wednesday morning to lift heavy wooden timbers from sections of the Bonnet Carre Spillway structure.

NEW ORLEANS — The U.S. Army Corps of Engineers has begun opening a historic flood control structure west of New Orleans to divert water from the rising Mississippi River and ease pressure on levees that protect the city.

Cranes were used Wednesday morning to lift heavy wooden timbers from sections of the Bonnet Carre Spillway structure. That allows some of the water from the rain-swollen river to flow through the structure and over a broad expanse of land into Lake Pontchartrain.

Wednesday's opening of the structure marks the first time it has been operated in consecutive years. It is also the third time in four years that it has been operated. It's the 13th time it's been operated since construction was completed in 1931.

The U.S. Army Corps of Engineers anticipates opening approximately 30 bays Wednesday and possibly increasing that number to 200 bays over time. The spillway is expected to be open for about one month.

The Bonnet Carre Spillway is used to divert water from the Mississippi River to Lake Pontchartrain when the river's water flow gets too high. Plans to open the spillway were announced as the rate of flow at New Orleans approached 1.25 million cubic feet per second, which is what the New Orleans river levees are designed to handle.

Because of heavy rain from the Mississippi River and Ohio River valleys, the river's water level are at a point where the corps said it believes could put stress on New Orleans-area flood walls.

Rain-swollen rivers are spilling over their banks across the South after the wettest winter in the Mississippi River Valley in the last 124 years.

"That's what's bringing us all this water. We still have spring rains to get through and snowmelt in the north to get through, so there's no telling when the flood fight will end here or when the Bonnet Carre Spillway will close," Col. Michael Clancy said, District Engineer for the Corps.

The spillway has opened several times in recent years, including 2008, 2011, 2016 and 2018.

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