Mississippi River Rises Prompt Test Opening of Bonnet Carré Spillway

ST. CHARLES PARISH, La. — The U.S. Army Corps of Engineers will conduct a test opening of the Bonnet Carré Spillway on Monday, April 21, at 10 a.m. This action comes as the Mississippi River rises due to recent heavy rainfall upstream, bringing water levels close to the trigger point for a full spillway opening that would help prevent flooding in metro New Orleans and nearby areas.

The Bonnet Carré Spillway, built nearly 100 years ago, is a crucial flood control structure designed to manage the flow of the Mississippi River. When the river flow rate reaches approximately 1.25 million cubic feet per second, which corresponds to around 17 feet on the Carrollton gauge, the Corps can open the spillway. Current projections indicate the river may crest in New Orleans at 16.5 feet on April 27, according to forecasts released on Friday.

“Operation of the spillway is still in the forecast,” said Matt Roe, a spokesman for the New Orleans district of the Corps. He noted that while the agency is preparing for a potential opening, it will continue to monitor the river levels and forecast data before finalizing that decision.

The test opening is standard procedure for the Army Corps, conducted annually when water levels rise significantly, regardless of whether an actual opening will occur. “It’s just a real-world experience for the crews to get out and open the structure,” Roe said.

The spillway helps relieve pressure on the levee system in South Louisiana. However, letting fresh water into Lake Pontchartrain can adversely affect local fisheries, including shrimp and oyster populations. The last time the Bonnet Carré Spillway was opened was in 2020.

During the test, crews will open a few bays in the structure to simulate an actual operation before closing them within the day. This process is labor-intensive, involving the lifting of timber beams known as “needles” to manage water flow.

“When the river is high enough, like it is going to be on Monday, we do have water passing through the structure, and so it will very closely emulate an actual operation,” Roe explained.

While Monday’s test is not a full-scale opening, it signals the seriousness of potential flood conditions that the Corps is monitoring. Roe emphasized that officials are in constant communication with the National Weather Service to compare forecasts with actual conditions on the ground.

This system of flood management plays an essential role in protecting New Orleans and its surrounding parishes. As the Corps assesses the situation, both local residents and environmental advocates will be watching closely for updates on the state of the Mississippi River and the spillway’s operation.