PLAQUEMINES PARISH, La. — A saltwater wedge in the Mississippi River has prompted the Governor to issue a state of emergency for Plaquemines Parish.
What is a saltwater wedge?
In short, a well-defined layer of dense saltwater is moving upstream through the Mississippi River from the Gulf. It’s underneath the less dense fresh water in the river.
It’s called a wedge because it’s all moving together in a distinct flow. And it’s a problem because the parish water supply comes from the river. It especially affects those on low-sodium diets.
So, how does this happen?
Typically, the volume of water flowing down the Mississippi River is enough to prevent saltwater from heading upstream. But when the water slows down, saltwater drifts upstream from the gulf.
Right now, the Army Corps of Engineers is building an underwater levee of sand to stop the wedge as it heads upstream. The Corps also did this in September of 2022 when a wedge began moving upstream.
They’re also tracking the location of the wedge online and it’s on the move. Data shows the saltwater wedge moved almost three miles upstream since Thursday. It’s now at Myrtle Grove. In 2012, a wedge made it all the way to Belle Chase.
There are water and ice being distributed at the Boothville-Venice and Buras fire stations now, and there’s a drinking water advisory for Plaquemines Parish below the Empire Bridge.
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