Lawsuit Filed to Protect Imperiled Gulf and Mississippi River Species from Bonnet Carré Spillway Impacts

Defenders of Wildlife and Healthy Gulf (formerly Gulf Restoration Network) filed a federal lawsuit in the Southern District of Mississippi against the U.S. Army Corps of Engineers and Mississippi River Commission for violating the Endangered Species Act by failing to consult with federal wildlife agencies on the consequences of opening the Bonnet Carré Spillway on numerous endangered and threatened species. 

The recent April 3, 2020 opening of the Spillway—a flood control mechanism on the lower Mississippi River northwest of New Orleans—highlights the urgent need to evaluate the consequences of rerouting polluted river water into the sensitive estuary of the Lake Pontchartrain basin and Mississippi Sound. When opened, the Spillway diverts floodwaters from the Mississippi River into the Lake Pontchartrain basin and Mississippi Sound. The diverted water carries sediment and pollutants, including agricultural fertilizer and pesticide runoff, decreases salinity levels and water temperatures, and causes eutrophication, triggering harmful algal blooms which in turn create hypoxic dead zones (low oxygen areas). Yet, the Army Corps and Mississippi River Commission have never rigorously studied the effect of opening the Spillway imperiled wildlife or protected habitats as required by the Endangered Species Act.  

This lawsuit seeks to compel the Army Corps and Mississippi River Commission to evaluate the impact of opening the Spillway on protected species, including loggerhead sea turtle, leatherback sea turtle, green sea turtle, Kemp’s ridley sea turtle, hawksbill sea turtle, piping plover, red knot, West Indian manatee, Gulf subspecies of Atlantic sturgeon, and their habitats.  

“The fact that the Army Corps has had to open the Bonnet Carré Spillway four times in three years is unprecedented and has impacted Lake Pontchartrain and the Mississippi Sound in ways never contemplated by the Corps of Engineers,” said Cynthia Sarthou, executive director of Healthy Gulf. “Clearly it is time for the Corps to take a fresh look at how the project is being managed and what can be done to reduce negative impacts to threatened and endangered species.” 

The agencies estimate that they open the Spillway roughly every 10 years. But the agencies have now opened the Spillway six times in the last nine years, including three years in a row in 2018, 2019 and now 2020. As more extreme storms and varied weather increase the number and intensity of floods in the lower Mississippi River valley region, it is likely that the Spillway will be opened more frequently and for increasingly longer duration in the future.  

“The latest Spillway opening makes action to protect imperiled species all the more urgent,” said Defenders of Wildlife attorney Maggie Coulter. “We are taking these federal agencies to court to force them to study the consequences of more frequent Spillway openings, and ensure imperiled wildlife and their habitats are protected as required by the Endangered Species Act.”