NEW ORLEANS — A federal judge in Mississippi has approved Louisiana’s request to be added as a defendant in two lawsuits challenging the way a major Mississippi River flood control structure is operated.

The lawsuits filed in December say that more frequent and extended openings of the Bonnet Carré Spillway are damaging the Mississippi Sound and its fisheries by diluting the sound’s salt water with polluted fresh water.

“The current operation of these structures is paramount to the safety and security of hundreds of thousands of Louisianans, their property, and their livelihoods,” the Louisiana Attorney General’s Office said Tuesday in an unsigned, emailed statement. “Attorney General Jeff Landry is intervening in the suits in order to ensure that, should any changes occur to the management of the spillways, Louisiana has a seat at the table and is able to protect our State’s people and resources.”

District Judge Louis Guirola Jr., of the federal court in Gulfport, Mississippi, noted in both cases that although Louisiana asked to be added as a defendant, its stand is only partly aligned with those of the two original defendants — the Army Corps of Engineers, which operates the spillway, and the Mississippi River Commission, which decides when to open it. He said he may reconsider the state’s “proper classification” if necessary.

The Corps and commission want Guirola to dismiss their suits, but Louisiana doesn’t, he wrote in orders letting the state intervene in the suit filed Dec. 23 by Mississippi cities, towns and business groups, and one filed a week later by then-Secretary of State Delbert Hosemann.

“While Louisiana supports the operation of the Spillway to protect lives and property, it also recognizes that the Corps could take steps to manage water resources differently during high water events,” said the state’s motion to intervene in the earlier lawsuit.

In the state lawsuit, Louisiana joins the corps and commission in opposing Mississippi’s request for an order to use the Morganza Floodway near Baton Rouge to avoid opening the Bonnet Carré Spillway west of New Orleans.
The spillway was opened for most of April, marking an unprecedented three years in a row that water got high and fast enough to threaten damage to the levees protecting New Orleans, prompting use of the spillway.

Calculations based on the Corps’ daily figures indicate it poured about 1 trillion gallons (3.8 trillion liters) of water through brackish Lake Pontchartrain and into the Mississippi during April. That’s about one-tenth the total from the two openings in 2019 — another record for a spillway that once was rarely used more than once in a decade but has been opened seven times since 2008.

Last year’s flooding, including the spillway openings, prompted a federal fisheries disaster declaration and $88 million for fisheries in Louisiana, Mississippi and Alabama.

A third lawsuit, filed in April by the nonprofit Defenders of Wildlife, accuses the Corps and commission of opening the spillway without taking into account how threatened and endangered species would be affected. Nine threatened and endangered species live in or migrate through the Lake Pontchartrain Basin and Mississippi Sound, according to the lawsuit.

The Louisiana Attorney General’s Office does not currently plan to intervene in that lawsuit, according to an email from its press office.