Mississippi River's 1926 dead zone holds lessons for Gulf of Mexico today

The Mississippi Delta
Nitrogen from agricultural fertilizer runoff on Midwest farms is carried to the Gulf of Mexico by the Mississippi River, where it has created a hypoxic zone the size of Connecticut and Rhode Island put together. Above, the Mississippi Delta is seen at sunset in 2010.
Eric Gay/AP

Here in the land of 10,000 lakes, zebra mussels and Asian carp have generally topped the list of recent marine environmental concerns. But in the 1920s, before wastewater treatment plants were built, there were far bigger problems.

A 1926 survey of the Mississippi River between Minneapolis and Hastings turned up three fish.

"Not three species of fish," said Rebecca Flood, an assistant commissioner at the Minnesota Pollution Control Agency. "Three fish."

Back then there was so much sewage in the Mississippi River that algae took over and just about everything else died off. The river in the Twin Cities is much cleaner today, and the fish are back. But there's a similar, even larger problem festering now just past the river's southern end, in the Gulf of Mexico.

This time, the pollution that feeds the algae for the most part is fertilizer from Midwestern farms -- including Minnesota's. Just as in 1926, oxygen levels have plummeted. The fish population, the ecosystem in general, and the industries that depend on it are all in peril.

Scientists call that part of the Gulf a hypoxic zone. It's also known as the dead zone. And its the size of Connecticut and Rhode Island put together.

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Flood says Minnesota can do a better job of reducing runoff into waterways that drain into the Mississippi and contribute to the dead zone. The MPCA is developing guidelines with the goal of cutting phosphorous runoff into the Mississippi River watershed 35 percent by 2025, and nitrogen runoff by 20 percent. Part of the strategy will be to work with farmers to help them reduce the amount of fertilizer they use -- and money they spend.

"My experience with individual farmers is that they're pretty cautious and stingy about wasting money, and this is a waste of money to have our fertilizers going down to the Gulf of Mexico," she said.

Details of Minnesota's nutrient reduction plan will be available for public comment in early October. The proposal is just one of many being drawn up by the 12 states that are part of a task force that's trying to shrink the dead zone. But reducing nutrient runoff from farms isn't as easy as reducing fertilizer, says Bill Northey, co-chair of the task force that met in Minneapolis Tuesday. He's an Iowa farmer, and his state's agriculture commissioner.

"When we're talking about nitrogen, we're talking about soil organic matter. It's in the crop residue that's there from last year. As our water goes through those soils it'll pick up nitrogen -- sometimes from the fertilizer, sometimes from the residue, sometimes from the organic matter," he said. "We have to manage all of that to try to reduce the amount of nitrogen that's leaving those farms."

In 2008 the task force set a goal of reducing the dead zone to 5,000 square kilometers -- an ambitious goal that so far has proved elusive. The zone measured roughly 15,000 square kilometers, or roughly 5,875 square miles, this year.

Nancy Stoner, the EPA's acting assistant administrator for water, admits the agency can't claim success.

"It's a very difficult goal, and even if we put in all the practices by 2015 that are necessary to reduce the dead zone, there's a lag time," she said. "That's one of the challenges we have: to continue to make progress, to continue to motivate people."

And motivating people is about all the EPA says it can do. The task force recommendations do not carry the force of law. The EPA has said setting nutrient rules would be too complex, and it can better fight water pollution by working with states.

But Ann Alexander, an attorney with the Natural Resources Defense Council, says the dead zone will continue to be a problem until the EPA steps up to the plate.

"I imagine there is a lot of nervousness on their part given the intensity of the opposition that they're getting from many different quarters," she said. "They're getting opposition from agriculture, from manufacturing industries, from sewage treatment authorities.

The NRDC has sued the EPA in an effort to force the agency to act. Last week, a federal judge gave the EPA six months to decide whether to set nitrogen and phosphorous pollution standards -- or explain why they're not needed.