MYRTLE GROVE - The US Army Corps of Engineers has started construction on a 1,500-foot wide underwater levee to prevent saltwater from pushing upstream into the drought-ridden low water levels of the Mississippi River, according to CNN. 

The corps announced last week it would begin dredging sediment from the bottom of the river and pile it near Myrtle Grove, where water from the Gulf and river water are clashing and threatening some water treatment plans in southern Louisiana. The sediment will be used to make a sill which will keep the denser saltwater from the river.

Ricky Boyett, the chief of public affairs for the New Orleans District of the Army Corps, told CNN the "toe" of the saltwater is already approaching the planned location of the sill, which will be 40 to 50 feet high in a space where the water is 90 feet deep. 

The sill is designed to be temporary, Boyett said; the problem typically resolves itself once the river sees more rainfall upstream.