Saltwater Encroachment Worries Corps On Mississippi

All Things Considered:

The biggest problem is saltwater from the Gulf of Mexico coming up the mouth of the Mississippi and threatening industrial and municipal water intakes more than 60 miles inland.
During normal flows on the Mississippi, freshwater is pushing down and out of the mouth of the river. But with low flows during drought, the Gulf of Mexico starts to push saltwater up the Mississippi River.
"Saltwater is denser than freshwater and so it travels on the bottom," says Stack. "It travels in what we call a wedge."
To stop the encroaching wedge, the corps built a $5.8 million sill on the bottom of the river. It's like a deep underwater levee designed to hold the saltwater at bay.
The sill has held since September, and the wedge is now receding. But it wasn't enough to prevent the saltwater from reaching the drinking water intakes for Plaquemines Parish, the parish south of New Orleans that stretches all the way to the mouth of the Mississippi.
"We've been through five hurricanes and an oil spill, had a couple of chemical spills, and right before this salt water intrusion, I said, 'What's next?' " says parish President Billy Nungesser.
The parish had to barge in fresh water from upriver and buy drinking water from neighboring Orleans Parish. Nungesser is worried about next time."The real challenge will be if we see a worse situation than we saw last year where that wedge reaches New Orleans because you couldn't barge in enough water to satisfy the needs of the city of New Orleans," he says.

After the spring of 2011, when too much water was the main concern for the Corps, it would seem like they wouldn't be so busy with too little water.  Au contraire, mon frere.