Saltwater Now 64 Miles Upstream From The River's Mouth As Mississippi Flow Nears Record Low
EDIT
A saltwater wedge crept along the river bottom nearly 64 miles upriver from the mouth of the Mississippi. "It's almost like a triangle," Jones says. "As this flow in the Mississippi River drops, it loses its ability to keep saltwater at bay." The saltwater intrusion is threatening both municipal drinking water supplies in the New Orleans metro area and commercial water users like oil refineries that depend on fresh water from the Mississippi.
The biggest impact so far is in Plaquemines Parish with about 24,000 people and water-dependent industries south of New Orleans. "The Gulf is winning," says councilman Benny Rousselle. The parish has declared a state of emergency and issued a drinking water advisory. Rousselle says salt water has already compromised two of the parish's water treatment plants and is threatening a third.
"We're bringing in some desalinization units," he says. "To be able to take the salt out and manufacture water. To save Plaquemines' biggest plant, and protect the larger Orleans Parish water system, the Corps of Engineers is trying to block the saltwater from encroaching farther. "We are building, for lack of a better term, an underwater levee," Jones says. "We call it a saltwater sill, but essentially it's a big mound of sand, a berm of sand that stops the saltwater."
EDIT
Some experts say saltwater intrusion could be a more frequent threat now that the Corps is dredging the Mississippi river even deeper for navigation, which allows the saltwater to move in faster. And, then there's climate change. "You're really tasting sea level rise," says Mark Davis, director of the Tulane Institute on Water Resources Law and Policy. "The more sea level rises, the more saltwater comes in," Davis says. "We've made it easier this year because we recently dredged the mouth of the river so it would be deeper, so larger cargo vessels can come in. And that just opens the door for even more salt."
EDIT
https://www.npr.org/2022/10/27/1131452623/saltwater-mississippi-river-drought-gulf-of-mexico