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Officials open Bonnet Carre Spillway for 11th time in history to mitigate Mississippi River flooding in Louisiana

In an effort to mitigate river flooding, officials opened the Bonnet Carré Spillway in Louisiana on Sunday for just the 11th time in history.

Relentless rain after Christmas led to devastating flooding across Missouri and Illinois over the past two weeks, killing more than 20 people. Rivers, including the Mississippi, swelled to above-normal heights, contributing to flooding issues in many communities.

As the excess water surges south, the U.S. Army Corps of Engineers opened the Bonnet Carré Spillway, roughly 15 miles west of New Orleans, to control flooding. Water will be diverted to Lake Pontchartrain.

The spillway hasn't been opened since record flooding in 2011.

Since its construction in 1931, the spillway has been opened 11 times. The current opening is also the earliest ever in a year.

Officials linked the severe rainfall this early in the season to El Niño as persistent storms washed the region before the new year.

Twenty bays were opened on Sunday, allowing 12,000 cubic feet per second of water to enter the spillway, according to The Times-Picayune.

Officials will continue to monitor the need for opening additional bays in order to keep the river flow below the 1.25 million cubic feet level, which would be enough to fill the Louisiana Superdome in one second.

The U.S. Army Corps continue to monitor the need to open the Morganza Spillway near Baton Rouge, Louisiana. The controversial decision to open would lead to direct flooding into farmlands in the region.

"What we're witnessing right now is really an engineering miracle," New Orleans Mayor Mitch Landrieu said in a press conference before Sunday morning's Bonnet Carré Spillway opening.

"What you're about to see is a levee system that is managed as a risk reduction [system], making sure we do what we're supposed to do and when we're supposed to do it, to protect lives and protect homes."