Belle Chasse, La. -- The U.S. Army Corps of Engineers is ready to begin work on building an underwater barrier, known as a sill, in the Mississippi River in Plaquemines Parish.
It is because low river levels are allowing saltwater from the Gulf of Mexico to invade the river, which is the source of drinking water for this area.
Because of the drought elsewhere in the country and Plaquemines Parish's close proximity to the Gulf, saltwater is infiltrating the river's fresh water.
"Right now what we're seeing is the toe of the wedge. The saltwater is on the bottom of the river and it comes upriver in a wedge, and so we're seeing the toe of the wedge," said Col. Ed Fleming of the Corps of Engineers.
To slow the saltwater's migration into the river, the Corps will begin work Tuesday on constructing an underwater barrier in the river, north of the Myrtle Grove area and close to the Phillips 66 refinery, corps and parish leaders said.
"The purpose of the sill is to arrest the further development of saltwater and to slow it down from continuing to move up the Mississippi River," Col. Fleming stated.
Fleming said, at noon Tuesday, a section of the river will be closed to vessel traffic for about 12 hours so crews can begin laying the underwater piping. Then there will be closures off and on, until all of the work is done.
"There will be temporary closures of the river... As the sill is constructed there will probably be one-way traffic only for a short stretch of the river between river mile 63 and 65," Fleming continued.
Parish President Billy Nungesser said the drinking water remains safe to drink, but he is urging residents, especially in lower Plaquemines, to conserve water. He said the water in some areas is saltier than normal.
Nungesser said four barges filled with fresh water are in place in Port Sulphur, but testing had not been completed by state health officials. He also said that a tie-in with the Orleans Parish water system had been completed, but the pipes have not been turned on yet.
"We're actually going to hold off taking [water] from Jefferson until we open the line with Orleans because we need both of them to give the pressure that we need to actually mix it in the plant," Nungesser stated.
When it comes to saltwater intrusion in the river and constructing sills, the Corps says it has lots of experience in that area.
"This is the third time that we've constructed the sill. It was constructed once in 1988 and it was constructed again in 1999 and both times we saw the benefits that we predicted," stated Fleming.
"Over a year ago we were looking at the flood of record, 17 feet on the Carrollton gauge and here we are now looking at drought conditions with below two feet on the Carrollton gauge. It's amazing what the Mississippi River can do," Fleming said.
