Fifth Circuit Rules In Corps’ Favor, Affirms Dismissal Of Bonnet Carré Lawsuit

A three-judge panel in the U.S. Fifth Circuit Court of Appeals, made up of Chief Judge Priscilla Richman, Judge James C. Ho and Judge Kurt D. Engelhardt, has ruled in favor of the U.S. Army Corps of Engineers regarding a lawsuit that challenged the usage and operation of the Bonnet Carré Spillway on the Lower Mississippi River in Louisiana and sought to compel the Corps to prepare a supplemental Environmental Impact Statement, which plaintiffs argued was required by the National Environmental Policy Act (NEPA).

The plaintiffs included Harrison and Hancock counties in Mississippi; the Mississippi cities of Biloxi, D’Iberville, Pass Christian and Diamondhead; the Mississippi Hotel & Lodging Association; and the Mississippi Commercial Fisheries United Inc.

The Bonnet Carré Spillway is the lowermost spillway of the Mississippi River and Tributaries Project (MR&T), which was enacted following the Great Flood of 1927. The MR&T refers to a series of actions the Corps takes and flood control structures the Corps uses to pass high water from the Mississippi River and its tributaries and shield river communities, in large part, from inundation.

Floodways and spillways along the river have trigger points. For Bonnet Carré Spillway, the trigger point is a flow rate of 1.25 million cubic feet per second (cfs.) at the Carrollton Gage in New Orleans. Levees on both sides of the river are designed to handle no more than that flow rate and its associated stage. Flood water above New Orleans is diverted through Bonnet Carré Spillway and into Lake Pontchartrain to the north. That freshwater eventually makes it to Lake Borgne, the Mississippi Sound and the Mississippi Gulf Coast.

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Historically, the Corps has had to use the spillway about once every 10 years. Bonnet Carré was completed in 1931, and its first opening was in 1937. There was a 23-year gap from 1950 to 1973, after which the spillway was used four times in 10 years. Since 2008, though, the spillway has been opened seven times, including three consecutive years from 2018 to 2020, and unprecedented dual separate openings in 2019.

“Unfortunately, the spillway’s aid to New Orleans comes at a cost to the environment and to the Mississippi-based plaintiffs in this case,” the judges wrote in their decision. “Through its injection of freshwater into Lake Pontchartrain and the Mississippi Sound, the spillway’s deployment takes a toll on a host of environmental and economic interests, causing everything from disruptions to oysters, sea turtles and shrimp, to toxic algae blooms, seafood warnings and beach closures.”

Plaintiffs argued that the Corps’ increased usage of the spillway signified a material change in its use. Initially, the lawsuit also argued that the Corps was liable for damages from spillway operation.

Judges acknowledged the Corps is using the spillway more frequently of late. The panel of judges pointed to a study by scientists at Louisiana State University (LSU) that “projects a notable increase in river flow ‘as a result of riverbed aggradation’ and ‘sand bar growth,’ and perhaps more predictably, rising global temperatures and intensified hydrologic cycles. The decision noted that, according to the Corps, flow and sedimentation dynamics on the river historically connected a flow rate of 1.25 million cfs. in New Orleans to a stage of 20 feet on the levees. That stage now stands at 17 feet with a flow rate of 1.25 million cfs.

Looking at the increased operation of the spillway, the judges did identify a change—just not a change in the Corps’ metrics for operating Bonnet Carré.

“What is changed in this case is the reality of the conditions in which the Corps must operate the spillway,” the judges wrote. “In this regard, however, the true culprit for the plaintiffs’ environmental misfortunes is not the Corps or the spillway, but the environment itself. Regardless of cause, the increased operation of the spillway that aggrieves the plaintiffs and harms the Mississippi Sound is traceable to the fact that the spillway must now be used more often, not that it must now be used in defiance of its original operational plan. New plans by an agency require a supplemental EIS; new circumstances do not.”

The judges did include a glimmer of hope for plaintiffs and, perhaps, a path forward.

“The upshot of the foregoing analysis is straightforward,” they wrote. “Because the Corps has no duty to prepare the supplemental EIS the plaintiffs seek, the plaintiffs have no [grounds to claim] unlawful agency inaction, and the Corps is immune from their suit claiming otherwise.

“For better or worse,” the judges concluded, “Congress and the Corps have authority to act on the plaintiffs’ dire environmental concerns. The federal courts do not.”