Army Corps Will Open Bonnet Carre Spillway Friday

Apr 2, 2020

The Army Corps of Engineers will open the Bonnet Carre Spillway at 10 a.m. Friday morning to ease pressure on Mississippi River levees in the New Orleans area.

Located in Norco, the Bonnet Carre Spillway acts as a release valve for the Mississippi River. When the river’s flow reaches a certain velocity, the Corps opens the structure, diverting part of the flow into Lake Pontchartrain. Doing so protects the levees in the New Orleans area, which are only designed to handle a flow of about 1.25 million cubic feet per second.

At a press conference Thursday afternoon, Col. Stephen Murphy, who oversees the New Orleans District of the Army Corps of Engineers, said 10 to 20 of the structure’s 350 bays would be opened Friday morning. Eventually, somewhere between 95 and 105 bays are likely to be opened, based on current river forecast models.

Officials currently expect to keep the spillway open for about four weeks, though that could be extended if the Mississippi River watershed gets more rainfall that is currently forecast.

Friday’s opening marks the first time the spillway has been opened in 2020.

Last year it was opened twice, for a total of 123 days, which was an all-time record. The prolonged influx of river water caused all kinds of damage to the ecosystem. It decimated fisheries like oysters and caused algal blooms that closed Mississippi beaches for weeks.

Historically, the spillway was only used once every 10 years, on average. Friday’s opening means it will have been operated six times in the last 10 years.

Spillway openings sometimes draw hundreds of spectators, but this one will be closed to the public due to coronavirus concerns.

Support for the Coastal Desk comes from the Greater New Orleans Foundation and the Walton Family Foundation.