Defenders and Healthy Gulf Prevail in Court Case to Protect Imperiled Gulf and Mississippi River Species from Bonnet Carré Spillway Impacts

Defenders of Wildlife and Healthy Gulf won a critical victory for imperiled wildlife in and around the Gulf of Mexico when a district court ruled last night that the U.S. Army Corps of Engineers (Corps), U.S. Fish and Wildlife Service (FWS), and NOAA Fisheries must engage in a prospective Endangered Species Act (ESA) consultation for the threatened and endangered species and critical habitat that are affected by Bonnet Carré Spillway openings. 

“Today’s ruling ensures that the Corps must rigorously study the effects of opening the Bonnet Carré Spillway on imperiled species that depend on the sensitive estuarine and marine habitats in Lake Pontchartrain and the Mississippi Sound before those impacts occur,” said McCrystie Adams, managing attorney with Defenders of Wildlife. “This is a huge win for threatened and endangered species like the Gulf sturgeon, West Indian manatee, and highly imperiled sea turtles whose habitats have been subjected to a rush of polluted freshwater each time the Bonnet Carré Spillway is opened.”

In 2020, Defenders of Wildlife and Healthy Gulf filed a federal lawsuit in the Southern District of Mississippi against the Corps 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 Corps responded by engaging in limited, after-the-fact informal consultations with FWS and NOAA Fisheries regarding individual openings. 

Defenders of Wildlife and Healthy Gulf challenged these after-the-fact consultations, arguing that meaningful ESA consultation must be conducted before Spillway openings so that the Corps can consider mitigation measures or alternatives to protect species like the Gulf sturgeon, West Indian manatee, Kemp’s ridley, loggerhead and green sea turtles, piping plover and red knot, as well as critical habitat for the Gulf sturgeon and piping plover.

When opened, the Spillway diverts trillions of gallons of floodwaters from the Mississippi River into Lake Pontchartrain and the Mississippi Sound, causing catastrophic impacts to wildlife. The diverted water decreases salinity levels, carries excess nutrient loads—which lead to the growth of harmful algal blooms and may be accompanied by “hypoxic” or “anoxic” (low oxygen) conditions—creates a massive muddy plume, and spreads pollution.