The U.S. Army Corps of Engineers is building a new sill in the Mississippi River to prevent saltwater intrusion.

As the Mississippi River water level lowers, the possibility of a saltwater intrusion increases, and for the third year in a row, southern Louisiana will be facing one.

Construction has begun on a saltwater sill near Myrtle Grove to help mitigate the effects of saltwater intrusion up the Mississippi River.

The sill, or underwater levee, is being built for a third year in a row to head off the potential for New Orleans area drinking water to be threatened.