Death Wish

Wayne Curtis is a freelance writer who's written for The New York Times, Atlantic Monthly, American Scholar, Preservation, and American Heritage, and is the author of And a Bottle of Rum: A History of the New World in Ten Cocktails. He recently traded Maine winters for New Orleans summers.

It's summertime in New Orleans. Time slows. Backyard gardens demand to be weeded nearly hourly. The smell of a passing garbage truck seems to linger in the heavy air for hours, an olfactory postcard tacked to an invisible street corner bulletin board.

And the dead come back to life.

Well, technically, it's the "dead zone" that comes back to life.

"It varies, but it's basically the size of Rhode Island or Connecticut," says Matt Rota, water resources program director at the Gulf Restoration Network, which is based in New Orleans. "Every summer nutrient pollution gets washed down from the breadbasket, and when it hits the warm, salty gulf waters, it basically creates a dead zone where the oxygen is so low that the critters either need to swim away or they die."

The mighty Mississippi transports a lot of soil and silt as it flows down to the Gulf of Mexico. And plenty more, including about a million metric tons of nitrates and 137,000 metric tons of phosphorus, which are flushed into the gulf each year. Much of that comes from agricultural lands well-lavished with fertilizers.

Where exactly do those substances go? About 70 percent of the Mississippi's volume flows past New Orleans and into the Gulf of Mexico through what's poetically called the birdfoot delta. (Look at a map to see why.) Nearly a third of the river flows out through the Atchafalaya Basin, thanks to a vast diversion dam built for flood control. Between the two outflows, the nitrates and phosphorus end up lingering along the broad, shallow coastal shelf that runs from New Orleans hundreds of miles to the west.

These nutrients promote a boom in algae growth. And as the algae blooms and dies, the dead cells drift to the bottom, where they decay and voraciously consume oxygen in the process.

The effect is amplified during the summer months for a couple of reasons. For one, the prevailing gulf currents during warmer months tend to hug the coast while moving slowly westward toward Texas. And seasonal wind conditions contribute to increased stratification in the water column -- not much vertical mixing of the gulf occurs during the summer to bring oxygen down from the surface, so the hypoxia (the technical name for oxygen depletion) grows and grows at the lower levels.

Thus the dead zone comes to life; and fish, eels, and crabs either die or migrate away.

While hypoxia can occur anywhere that nutrients promote algae growth, the dead zone in the northwest gulf is the largest known in U.S. waters. And researchers report that this summer's dead zone is among the top three ever mapped in the Gulf of Mexico.

It doesn't have to be this way. The federal government some years ago embraced a goal of shrinking the dead zone, with the idea of reducing it about two-thirds from its current size. A formal plan, the result of meetings among dozens of government officials, environmentalists, farmers, and other stakeholders along the Mississippi, was developed in 2001.

So what happened? The plan spawned some conferences and further discussions and elaborate organizational charts, but it never received the promised federal funding to move from page to process. "No money has been given to this project, and the dead zone has not been reduced," Rota says. "And the feds are now revisiting the plan with the idea of trimming it back."

Rota notes that solutions are especially difficult in this case, since the pollution is mostly the result of nonpoint sources -- thousands of farmers, sewage treatment plants, and other small-scale contributors create this nutrient overload. In comparison, coping with industrial plant pollution is in many ways much simpler, since the source is clear and any sort of regulation can be narrowly targeted.

But efforts to coordinate among the different states and jurisdictions along the river to develop consistent guidelines for runoff have been, Rota says, "a bureaucratic nightmare."

And future prospects don't look much better.

While ethanol produced from corn has been widely heralded as a way to move the country away from its dependence on oil, the unintended consequences have cast a dark shadow over the Gulf of Mexico.

"It's really frightening to us from a nutrient pollution standpoint," Rota says, "because they're taking all these areas that were in less fertilizer-intensive products -- like soybeans and cotton -- and they're shifting it all into corn production."

"Ethanol is not the be all and end all," adds Dan Favre, campaign organizer with the Gulf Restoration Network.

What's more, Rota says Louisiana's shuttered fertilizer plants -- closed when demand fell off in previous years -- are looking at reopening to supply the booming demand among corn producers. And Louisiana may be looking at a large-scale shift from sugar to corn production to meet the demand. (Ethanol can be made from sugar, but federal tax incentives encourage the production of ethanol from corn.) All of this portends the dumping of even more fertilizer into the Mississippi.

"So we're going to be producing more fertilizer that we ship up into the breadbasket, and then those nutrients are going to wash right back down here and create even more dead-zone problems," he says.

The Mississippi has always been famous for its grand loops and oxbows, whose uncontrollable whims defined the meandering river in the 19th century. Today the river appears increasingly famous for another sort of loop -- the feedback loop. Build a levee here, and flooding gets worse there. Move away from oil here to encourage a more sustainable energy future, and the dead zone grows over there.

"Without policies to reduce and capture this fertilizer runoff," Rota says, "I fear that this trend toward larger dead zones is going to continue."