An influx of salt water in the Mississippi River, which feeds southeastern Louisiana's drinking water supplies, is once again creeping up the waterway. For the third year in a row, an underwater levee is being built to slow the brackish intrusion and prevent it from reaching water intake treatment facilities.

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.

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

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.