Iowa has 31 million acres in farmland, with 23 million of that planted to corn and soybeans, Northey said. Nine million acres of land is drained by tiles, underground drains that efficiently remove water from fields.
These drains also mainline nitrogen directly to streams. Underground nitrogen is “the most critical conservation concern” in the Upper Mississippi River Basin, said a 2010 USDA study of conservation practices.
Artificial wetlands can help get the nitrogen out. With the help of a federal conservation program, Iowa has built 70 shallow wetlands to filter tile-line water. “We’re seeing a 40 to 70 percent reduction in the amount of nitrogen coming out,” Northey said. “It’s pretty dramatic.”
The artificial wetlands are expensive, and they don’t work on every property. “We’re building five to 10 a year,” said Northey, a member of the federal-state hypoxia task force. “It would take building hundreds of years to get all of that.”
Scavia, with the University of Michigan, said significant changes are needed to shrink the dead zone – and quickly. The dead zone appears to be reaching a “tipping point” where the system is becoming increasingly sensitive to nutrient inputs, he said, and climate change exacerbates the problem as it warms water and increases intense storms.
Scavia’s solution? Fix the federal “farm bill,” which determines agriculture policy and subsidies. “It’s that difficult, and that simple,” he said. “It’s how much we incentivize producers. I believe farmers understand and do want to protect the environment.”
Voluntary methods are all well and good, said Rota, of the Gulf Restoration Network, but he wants to see enforceable standards as well. His group and others recently filed a lawsuit asking the EPA to set national criteria for nitrogen and phosphorus runoff. “We need that minimum bar to start making progress,” he said, “because so far, we’ve only seen the dead zone trending bigger.”
The EPA has so far refused to set national criteria, saying the best approach is to work with states to develop their own standards and cleanup plans.
For his part, Northey said the first step is education. Through the task force, he has taken Iowa farmers down to the Gulf and brought people from Mississippi back up to see what Iowa farmers are doing.
The rivers forever link farmers in the Midwest and fishers in the Gulf.
“Maybe it doesn’t seem like it when you’re working on your farm on a cold November morning, but we are tied to those folks,” Northey said. “We are tied, up and down the river, all together.”
This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.