MELISSA BLOCK, HOST:
In the words of Mark Twain: The Mississippi River will always have its own way; no engineering skill can persuade it to do otherwise. Well, the way of the Mississippi of late has been drought. And while the traffic problems created upriver have gotten lots of attention, the drought is also creating a different set of problems down-river. So we're going to focus our attention now in a place where the mighty Mississippi empties into the Gulf of Mexico.
Here's NPR's Debbie Elliott.
(SOUNDBITE OF WATER)
DEBBIE ELLIOTT, BYLINE: An old-fashioned staff river gauge, behind the New Orleans district office of the U.S. Army Corps of Engineers, shows the Mississippi is running just shy of six feet above sea level at the river bend.
MIKE STACK: Just about back to normal at this point. But it's only done that really since Christmas.
ELLIOTT: Mike Stack is chief of emergency management for the Corps. He's been dealing with near historic lows on the river here since August. 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.
STACK: Saltwater is denser than freshwater and so it travels on the bottom. So as the Mississippi River flows, the flows coming down from the north, the Mississippi River is trying to push the water out to the Gulf of Mexico. As the flows get low enough, the Gulf of Mexico starts to push the water up the Mississippi River along the bottom. And so it travels in what we call a wedge.
ELLIOTT: 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.
Billy Nungesser is parish president.
BILLY NUNGESSER: We've been through five hurricanes and an oil spill. We had a couple of chemical spills. And right before this saltwater intrusion, I said what's next?
ELLIOTT: The parish had to barge in fresh water from upriver and buy drinking water from neighboring Orleans Parish. Nungesser is worried about next time.
NUNGESSER: 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.
(SOUNDBITE OF A FERRY HORN)
ELLIOTT: The river is deep and wide here with at least a 45-foot deep channel. Combine that with the proximity to the Gulf and you have an ideal shipping gateway.
(SOUNDBITE OF MACHINERY)
ELLIOTT: At the busy Port of New Orleans, stevedores use cranes to load crates of chicken onto the Skulptor Tomskiy, a hulking white ship bound for Eastern Europe.
(SOUNDBITE OF MACHINERY)
ELLIOTT: Ships come in from the Gulf bringing everything from rubber and steel to coffee and twine. Barges come down river carrying grain, fertilizer and other goods.
GARY LAGRANGE: Oh, it's huge.
ELLIOTT: Gary LaGrange is president and CEO of the Port of New Orleans.
LAGRANGE: It's a huge convergence point in the sense that the Lower Mississippi River, as an example, 291 miles from Baton Rouge to the mouth of the river constitutes the largest port system in the world - bigger than Rotterdam, Singapore, Shanghai, or any of those.
ELLIOTT: LaGrange says the drought hasn't hurt the Port of New Orleans yet. But upriver, where the channel gets shallow north of Baton Rouge, barge loads are lighter.
LAGRANGE: Anything that's got to go in transit between Karo(ph) and St. Louis, we're concerned - but so far so good.
ELLIOTT: But the drought does raise more complicated questions for Louisiana's deteriorating coast. The Delta depends on high water to bring sediment that helps rebuild coastline, sediment that's choked off in a drought.
Mark Davis heads the Tulane's Institute on Water Resources Law and Policy. He says with persistent drought and sea level rise, the future of Louisiana's fragile coast is at best uncertain.
MARK DAVIS: Things won't be the same. We will have to be real clear on what kind of river we need delivered here. We have no idea at this point how big a river we're going to need 20 years from now to maintain, you know, the viability of this lower end.
ELLIOTT: Davis says talk of diverting water from the Mississippi system to help arid Western states has officials up and down the river talking about the need for comprehensive water resources plan for the mighty river.
DAVIS: It's the sort of thing that the Great Lakes did when they did their compact not so long ago, when they essentially declared we're not sure what we need water for but we're pretty sure we're not a mine.
ELLIOTT: America's Wetland Foundation director Val Marmillion says the sheer size and scope of issues confronting the river make consensus hard to come by.
VAL MARMILLION: The Mississippi basin is an orphan. It has a lot of users and a lot of interests who have found the Mississippi very beneficial to their various interests. But no one is taking care of the whole.
ELLIOTT: Whether it's drought now or flood next year, Marmillion says it's time to treat managing the Mississippi as a legacy issue.
Debbie Elliott, NPR News.
(SOUNDBITE OF MUSIC)
AUDIE CORNISH, HOST:
This is NPR News. Transcript provided by NPR, Copyright NPR.