Update: Raising MS river sill

By late September, saltwater from the Gulf of Mexico may overtop an emergency sill built on the bottom of the Mississippi River to protect Belle Chasse, La.'s, water plant intake, an Army Corps of Engineers official said Sept. 13. 

The Corps is also trying to determine whether the saltwater could move far enough upriver to threaten drinking water in St. Bernard Parish or even New Orleans. 

Corps models show the saltwater sill "will be overtopped in the mid- to end of September range," said Dana Ray, acting chief of the Corps' New Orleans District office of emergency management.

The leading edge of saltwater moving north from the GoM was just nine miles south of the sill, according to the Corps' website. 

A Corps spokesperson said increasing the ability of the sill to block saltwater moving upriver would be discussed at a Sept. 15 news conference, which is to include Corps, Governor's Office of Homeland Security and Emergency Preparedness. 

Discussions will "provide updates on the steps taken to address the emergency and plans moving forward." (NOLA.com 09/14/23)

UPDATE: FRIDAY PRESS CONFERENCE

Saltwater from the Gulf moving up the Mississippi River will cause the Army Corps of Engineers to add to the height of an underwater levee it built this summer to protect water supplies for Plaquemines, St. Bernard and New Orleans, the Corps announced the morning of Sept. 15 at a news conference. 

The earthen sill built in July near Alliance will be elevated so its top will only be 30 feet below the water surface. But that still may not block saltwater from contaminating water supplies upriver, officials warned, in part because a deep notch will be included in the elevation project to allow shipping to continue. 

"(I)f no action is taken, you potentially could see the saltwater wedge all the way up to the French Quarter," said Col. Cullen Jones, commander of the Corps' New Orleans District. "But we have no intention of not taking any action." 

The sill, now 45 feet high and built in an area where the river is 90 feet deep, will be extended outward beyond its present 1,500-foot length. (NOLA.com 09/15/23) Saltwater in Mississippi River will require a higher sill | Environment | nola.com