As the Mississippi River rises, the Bonnet Carre Spillway will open on Wednesday as the Army Corps of Engineers look head off potential flooding caused by a rising Mississippi River.
It will mark just the 13th occasion it has opened in the Spillway’s 91 year existence. But it would also be the second straight year it has opened and the third time in the past four years.
Chris Brantley, the spillway’s project manager for the U.S. Army Corps of Engineers, said the decision to open comes when the river is flowing past the spillway toward New Orleans at a rate of 1.25 million cubic feet per second. Brantley said the current rate 1.1 million.
However, the river water is steadily rising and that flow is projected to surpass the 1.25 million rate.
While the New Orleans area has seen ample rain over recent weeks, the projected change comes from a high volume of rain that has fallen in the Tennessee and Ohio river valleys in past weeks. More rain is expected to fall over those areas over the coming week.
“They’ve been getting a series of fronts … we’ve gotten rainfall, but not like they’ve had,” Brantley said. “There’s a larger drainage area up there, basically from the Rockies to the Appalachians … everything in between drains into the Mississippi River.”
When the river flows at the trigger point of 1.25 million cubic feet per second, the Spillway’s job is to maintain that consistent flow, take the excess and divert it into Lake Pontchartrain.
It will be the fifth time since the year 2008 the Spillway has opened. The most recent occasion came on March 8 of last year, and prior to that openings in 2016, 2011 and 2008. Last year’s opening saw roughly half of the spillway’s 350 bays opened. The last time all bays were opened came in 1983.