Hypoxic Zone Decrease Possible with Management

July 31, 2000

Scientific information released last week shows that managing the Mississippi River's flow as it empties into the Gulf of Mexico may be an effective tool to decrease the size of the Gulf of Mexico's hypoxic zone, according to the American Farm Bureau Federation. After the scientific review of the low-oxygen hypoxic zone, it has been reported that the area has shrunk to just 1,700 square miles.

Louisiana Universities Marine Consortium researcher Nancy Rabalais reported that the decrease is likely due to low river stages of the Mississippi River in southern Louisiana. "This information supports the idea that managing the flow of the river at its delta is one tool that can be used to decrease the size of the hypoxic zone," said AFBF President Bob Stallman. "This is good news for farmers in the Mississippi River Basin."

Farm Bureau recently asked the Environmental Protection Agency's Mississippi River/Gulf of Mexico Nutrient Management Task Force to reduce, through the use of control structures, the Mississippi River flow into the hypoxic zone at critical times of the year. In addition to decreased river flow this year, researchers say that wind and current patterns were more active, thus having a role in the decreasing size of the hypoxic zone. Calm waters and high river flows in the spring and early summer of 1999 set the stage for the biggest hypoxic zone since measurements began in the mid 1980s.

The governmental task force charged with recommending solutions to the hypoxia situation, which could include limits on nitrogen loading in the Mississippi River, met in June, but was unaware that the hypoxic zone was not forming as it had the previous year. The EPA, meanwhile, urged the task force to decrease nitrogen load limits by as much as 40% to deal with the situation.

"Even a compromise goal of a 30-percent reduction in nitrogen loading in the river, taken to its logical conclusion, would have translated into farmers having to reduce nitrogen fertilizer use by as much as 68%," Stallman said. "That would be catastrophic. This year's data proves we've still got a lot to learn before setting any large goals for numeric reduction of nitrogen loads in the Mississippi River."

Additional information regarding river flow management to control hypoxia can be found at the AFBF web site http://www.fb.com/issues/analysis/#environment.