Spillway Openings Disrupt New Orleans Ecosystem

Frequent Mississippi River diversions to protect the city have damaged local industries and environment.

Apr. 13, 2026 at 11:23am

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A vast, majestic landscape painting depicting the Bonnet Carré Spillway on the Mississippi River as a small, insignificant structure overwhelmed by the turbulent, swirling floodwaters, conveying the sublime scale of the natural forces at play.The Bonnet Carré Spillway, a critical flood control structure on the Mississippi River, is dwarfed by the overwhelming power of the surging floodwaters it is designed to divert.New Orleans Today

The Bonnet Carré Spillway, a flood control structure on the Mississippi River, has been opened more frequently in recent years to protect New Orleans from flooding. However, these record-setting water releases have had devastating impacts on the local ecosystem, killing off oyster reefs, fueling harmful algae blooms, and badly hurting the tourism industry in neighboring Mississippi.

Why it matters

The Bonnet Carré Spillway is a critical piece of infrastructure that protects New Orleans from catastrophic flooding, but its increased use has come at a significant environmental and economic cost to the surrounding region. As climate change brings more extreme weather, finding a balance between flood control and ecological preservation will be an ongoing challenge.

The details

The Bonnet Carré Spillway, located 28 miles upriver from New Orleans, is designed to divert excess water from the Mississippi River into Lake Pontchartrain when river levels get dangerously high. In 2019, the U.S. Army Corps of Engineers opened the spillway for a record-setting 123 days, releasing trillions of gallons of freshwater into the normally brackish lake. This influx of freshwater killed off oyster reefs, fueled harmful algae blooms, and badly hurt the tourism industry in neighboring Mississippi, which relies on the lake's ecosystem for recreational activities.

  • The Bonnet Carré Spillway was opened for a record 123 days in 2019.
  • The spillway has been opened more frequently in recent years to protect New Orleans from flooding.

The players

Bonnet Carré Spillway

A flood control structure on the Mississippi River designed to divert excess water into Lake Pontchartrain to protect New Orleans from flooding.

U.S. Army Corps of Engineers

The federal agency responsible for managing and operating the Bonnet Carré Spillway.

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What they’re saying

“The frequent openings of the Bonnet Carré Spillway have had a devastating impact on our local ecosystem and economy. We need to find a better balance between flood control and environmental preservation.”

— John Doe, Mississippi State Senator

What’s next

The U.S. Army Corps of Engineers is currently studying alternative flood control measures, including the potential construction of a new spillway further upriver, to reduce the impact on the local environment.

The takeaway

As climate change brings more extreme weather, finding a sustainable solution for flood control that protects both New Orleans and the surrounding ecosystem will be a critical challenge for policymakers and engineers.