NEW ORLEANS (WVUE) - For the first time, the Bonnet Carre Spillway could operate twice in one calendar year.
Only weeks after the spillway closed, the National Weather Service predicted the Mississippi River will reach 16.9 feet at the Carrollton gage in New Orleans, just shy of the 17-foot mark which normally corresponds with an opening.
“If this forecast plays out, there is a real possibility of running the spillway,” Ricky Boyett, a Corps spokesperson, said.
The spillway in St. Charles Parish is designed to divert river water into Lake Pontchartrain to prevent flooding downriver in New Orleans and some of its suburbs.
Boyett said the trigger for opening the spillway would depend on how much water the river is expected to carry.
Technically, by federal law, the spillway operates when the river's flow in New Orleans reaches 1,250,000 cubic feet per second.
The river measured 16.39 feet at the Carrollton gage (engineering spelling) Sunday morning.
Forecasters expect it to crest at 16.9 feet on May 11.
One mitigating factor could involve the Red River's flow as it empties into the Atchafalaya River near Vidalia, Louisiana.
The Old River Control Complex -- series of giant structures -- sends just enough water down the Atchafalaya to prevent the Mississippi from changing course toward Morgan City.
However, the Red River's flow also plays into the calculations.
Congress mandates that 30 percent of the combined flow of the Red and Mississippi must be sent down the Atchafalaya.
“If the Red River is falling," Boyett said, “then we would be putting more through Old River [from the Mississippi]."
That could lower the Mississippi’s flow in New Orleans.
However, the Red has also been high for much of the winter and early spring.
Flow projections are expected later this week, according to Boyett.
Boyett said a Bonnet Carre opening would mark the first time the spillway had operated twice in one season.