Corps begins constructing underwater sill to halt saltwater intrusion in Mississippi River


The U.S. Army Corps of Engineers, New Orleans District began construction of an underwater sill on Oct. 11 across the bed of the Mississippi River channel to prevent further upriver progression of salt water from the Gulf of Mexico.

The Mississippi River’s volume of water has fallen to a level that allows salt water to intrude upstream. Saltwater from the Gulf of Mexico moves upriver in a wedge shape that may stretch up approximately 20 miles from the bottom to the surface of the river.

To stop the salt water from moving upriver and reduce the risk to freshwater intakes, the New Orleans District began construction of an underwater barrier sill at river mile 64 near Myrtle Grove to arrest the progression of saltwater intrusion.

The sill is being created using sediment dredged from a designated area just upstream for this purpose. Throughout the construction phase, the Corps will test salinity levels in the river to determine where the saltwater wedge is and how high the sill may need to be built. Read the entire announcement.