NEW ORLEANS -- It's a tale of two rivers.
The Mississippi is now more than 15 feet below where it was in New Orleans during the high water event in the spring of 2011.
"When the river is exceptionally low, which is right now, the force of the river is much less," said Army Corps of Engineers New Orleans Chief of Operation Chris Accardo.
When the force is much less, saltwater from the gulf creeps upstream in areas where you don't normally see it.
According to the corps, the toe of the wedge of saltwater has already reached mile marker 63 on the river near Myrtle Grove.
The corps now has a plan to construct an underwater levee of sorts designed to increase the flow of water to keep the saltwater a safe distance from fresh water intake systems upriver in Plaquemines, Orleans and Jefferson parishes.
"Think of it when you have a garden hose that's open without a nozzle and you put your thumb on the end of it, what happens? The water comes out faster, you increase the flow," Accardo said.
The corps says it has constructed similar structures twice in recent years, in 1988 and 1999.
It is expected to decide whether to build the structure this year, sometime in the next two weeks.
The low water also presents some challenges for the barge industry.
There is now a 9-foot the draft restriction for any loaded barge that plans to transit the Mississippi north of Baton Rouge.
That's means the barges will have to carry 10 to 20 percent less cargo per trip.
"You're throwing more equipment, more barges to move the same amount of volume at a higher expense and eventually that gets passed on," said David Lane, executive vice president for the New Orleans-based Canal Barge Company. "It's a drastic revenue impact for the operator and it's a cost to the shipper and then eventually they'll throw it on the consumer."
Lane says there are other low water problems for barge companies as well.
"You have delays. You've had several tows go aground over the last few weeks which is a blockage, like blocking the artery there."
WWL-TV Chief Meteorologist Carl Arredondo said it's normal for the Mississippi to go through highs and lows.
He says it's low now because of a combination of low snowfall over the northern plains and a lack of rain in the Ohio Valley and northern Mississippi River.