Although the Bonnet Carre’ Spillway is already being opened to avoid flooding with heavy rains from the Ohio Valley, a second opening is possible this year from a late northern ice melt.
“We’re anticipating a possible spring flood with a snow melt from up North, and another spillway opening this year is possible depending on the snow melt,” said Matt Roe, spokesman for the U.S. Army Corps of Engineers. “That would be historic because it’s never happened twice in one year.”
The Corps had already observed the frequency of spillway openings with four in the last 10 years.
The Corps recently started the 12th opening of the spillway since its construction to deal with the rain-swollen waters of the Mississippi River. The Corps didn’t anticipate the opening initially, but quickly shifted its position when the water flow escalated and reached the trigger for the opening, which is 1.25 million cubic feet per second.
By last Tuesday, the river had crested at 17 feet, a level expected to remain until March 25, an outlook that depends on the weather forecast. The Corps had 92 bays open with plans to open another 33, Roe said. More bays could be opened depending on the river level.
The Carrollton gauge was at 16.57 feet by last Monday. The river was forecast to crest March 14 and stay at or above 17 feet through March 26 before it starts to fall, Roe said.
As for Norco, Roe said guide levees route the river water from the spillway to Lake Pontchartrain. The spillway is designed to choke the water flow at 1.25 million cubic feet per second.
Roe said fishermen were taking advantage of the high waters, and he’d seen at least two Asian carp reeled in.
“There is really not anything you can do at that point regarding them coming in,” Harry Blanchet, biologist administrator of the fisheries division with the Louisiana Department of Wildlife and Fisheries, said. “They are coming in with higher water and access through the brackish water with river flow into the spillway opening.”
The carp, a freshwater fish, is being monitored by the Corps. It’s an invasive species being watched to determine if it’s competing with native species for food.
Blanchet said they also anticipate algae blooms and some fish kills associated with the river’s nutrient-rich waters.
“Nutrients are a good thing, but you can have too much of a good thing,” he said.
Overall, the high waters are good for fresh water fishing with fish like catfish and bass, Blanchet said.
“We can certainly hope the crawfish will be there as they always are,” he said. “They really thrive on these episodic events because they don’t have that established fish population. Crawfish is kind of a different critter so these flood events are good for new areas.”
Also, visitors are asked not to bring drones to the spillway area.