(USN&WR)

Each spring, the cycle of death begins anew. Nitrogen and phosphorus, leached from fertilizer, pass from farmland into streams, from streams into rivers—the Mississippi, the Potomac, the Susquehanna—and then, finally, into some of the country's great bodies of water: the Gulf of Mexico, the Chesapeake Bay. There the chemicals collect each summer, spawning the growth of algae, which deplete the water of oxygen and lead to ghostly aquatic wastelands. Marine life, if mobile enough, will swim away; the rest will suffocate and die.

Scientists have monitored the growth of these so-called dead zones since the late 1970s. They have tried to promote policies to reduce their size, without much success. Last summer, the dead zone along the Gulf of Mexico coast spanned nearly 8,000 square miles— its third-largest occurrence on record and roughly the size of Massachusetts.

Although states have tried to address the problem, cooperation among them is suffering, and federal leadership and funding are lagging. And now, scientists say, there is a new obstacle: the impact of ethanol production on water quality.

Spurred by recent ethanol mandates and, to a lesser extent, high commodity prices, U.S. farmers are planting record-size crops. From 2006 to 2007, corn acres rose by about 15 million, mostly in the Mississippi River basin. Mid-Atlantic farmers are expected to plant 500,000 more acres of corn, soybeans, and wheat this year than they did in 2006, a 7 percent jump.

To grow more crops, particularly corn, farmers usually have to use more fertilizer. Fertilizer runoff is the primary contributor to dead zone formation, the source of three quarters of the nitrogen and more than half of the phosphorous in the water. In a recent study, researchers at the University of British Columbia and the University of Wisconsin found that the U.S. government's goal to produce 36 billion gallons of ethanol by 2022, with a maximum of 15 billion from corn, would most likely increase the nitrogen flow to the Gulf by 10 to 20 percent.

"It is hard to be critical of a farmer if your crop is all you have," says Simon Donner, the paper's coauthor. Yet the new biofuel policies, he says, seem to make it all but impossible to control dead zones in the near future, since cleaning up the Gulf would require at least a 30 percent reduction in nitrogen levels.

As is often the case, federal subsidies benefit some at the expense of others. Hard data are lacking, but anecdotes of economic distress abound. At the end of last summer, for example, fishermen, crabbers, and shrimpers in Grand Isle, La., called a news conference to call attention to the threat of dead zones to their livelihood. Some reported hauls down hundreds of thousands of pounds. The ecological impact may be worse: Unlike nitrogen, which eventually evaporates as a gas, phosphorus lingers in the water, contributing to dead zones of the future and the potential for significant environmental damage.

Finding more. Not only are dead zones not going away, scientists say, but they are becoming more frequent and intense. A 2004 U.N. report documented nearly 150 dead zones worldwide, and scientists continue to come across new ones, including some apparently caused by climate change. Researchers at Oregon State University, for example, identified a recurring dead zone in the Pacific Northwest in 2002; during the 2006 cycle, it caused "mass die-offs" of marine life on the seafloor.

So far, the federal response has been desultory. In 2001, a government task force called for a 75 percent reduction in the size of the Gulf of Mexico dead zone by 2015. It was an ambitious goal and ultimately a hollow one. Virtually no federal funding has been provided. Instead, states were asked to address the problem voluntarily; little coordination followed. A new "action plan" for the Gulf was released in March, but that plan merely called upon individual states to propose solutions "as soon as possible, but no later than 2013."

Efforts in the Chesapeake region have met similar problems. Last year, local officials acknowledged that the goal of cleaning up the bay by 2010 would not be met. A report card issued by the University of Maryland puts the bay's overall health at a C-, up from a D+ in 2006.

Stopping runoff. Congress recently passed a sweeping farm bill that provides, for the first time, more than $400 million to improve water quality in the Chesapeake Bay. No doubt that money will be useful. Leaky septic tanks in thousands of private homes need replacement; sewage treatment facilities could benefit from newer technologies. But experts say the biggest help could come from better conservation practices, such as fences or buffer strips to help prevent runoff. "I once did a survey of Iowa farmers," says Donald Scavia, a professor in the School of Natural Resources and Environment at the University of Michigan and an expert on dead zones. "They said they would be absolutely willing to do those things if they would be paid to do them. They want to live in a landscape that is more diverse, but they don't want to lose money doing it."