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Fall 2007 Vol. 7 No. 3



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An Orphan River Mississippi River, Memphis, Tenn., courtesy U.S. Army Corps of Engineers

Closer Care Needed for Mississippi's Water Quality

No river has played a more central role in American literature and history than the Mississippi, the river that carried Huckleberry Finn's raft and serves as the symbolic dividing line between east and west. And the Mississippi's economic and ecological importance continues to be enormous. Tens of millions of people in 10 states depend on it for drinking water and recreation, and hundreds of millions of tons of grain and other goods are shipped along the waterway every year. The rivers of about 40 percent of the continental United States drain into the Mississippi, which is also home to the longest river wildlife and fish refuge in the lower 48 states.

Despite its significance, however, the Mississippi is an "orphan" in terms of efforts to monitor its water quality and reduce pollution, says a new report from the National Research Council that evaluates efforts to implement the Clean Water Act on the Mississippi. Currently there is no single system to monitor pollution levels along the river's entire length, the report observes. And though states on the Mississippi have assumed most authority for implementing the Act, the resources they dedicate to monitoring the river vary widely, as do their standards for water quality.

This lack of coordination has made it difficult to address pollution problems in the river, some of which are significant, the report says. Although the Clean Water Act has successfully reduced direct discharges of pollution from industry and wastewater treatment plants, less-direct forms of contamination -- for example, nutrients and sediments that enter the river and its tributaries through runoff -- are still a problem in the Mississippi. High levels of nutrients, such as nitrogen and phosphorous from fertilizers used on farm fields, are polluting the river itself and contributing to an oxygen-deficient "dead zone" in the northern Gulf of Mexico. Sediments are a more complex challenge; in the upper Mississippi they often are too plentiful and considered a pollutant, while in the lower river, sediments are too scarce -- a shortfall that is contributing to losses of coastal wetlands in southern Louisiana.

Turbid waters spill into Gulf of Mexico where sediments deposit to form the Mississippi River delta, courtesy U.S. Geological SurveyAddressing these and other water-quality problems will require the U.S. Environmental Protection Agency to take a stronger leadership role in implementing the Clean Water Act along the Mississippi and in the northern Gulf of Mexico, the report says. For example, EPA should take the lead in establishing a single program to monitor water quality in the entire Mississippi. In addition, the agency should develop water-quality standards that protect the river and Gulf from excessive nutrient pollution. And EPA should develop what is known as a federal Total Maximum Daily Load for these nutrient pollutants; this is a limit set on the total amount of a pollutant that the river and northern Gulf can accept and still meet water-quality standards. The agency has successfully led a multistate effort to better manage nutrient pollution in the Chesapeake Bay, the report notes, and it should draw upon that experience when stepping up its efforts along the Mississippi.

States should take steps to improve their teamwork as well, the report says. In particular, states along the lower Mississippi should strive to create a cooperative organization similar to one already in place for states along the upper river. And the report calls on the U.S. Department of Agriculture to aggressively apply its conservation programs in order to reduce polluted runoff from agriculture. EPA should work with USDA to ensure that these programs are targeted to areas where runoff of nutrients and sediments is most severe.   -- Sara Frueh


Mississippi River Water Quality and the Clean Water Act: Progress, Challenges, and Opportunities. Committee on the Mississippi River and the Clean Water Act, Water Science and Technology Board, Division on Earth and Life Studies (2007, approx. 284 pp.; ISBN 0-309-11409-8; available from the National Academies Press, tel. 1-800-624-6242; $56.00 plus $4.50 shipping for single copies).

The committee was chaired by David A. Dzombak, Walter J. Blenko Sr. Professor of Environmental Engineering, and director, Steinbrenner Institute for Environmental Education and Research, Carnegie Mellon University, Pittsburgh. The study was funded by the McKnight Foundation.



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Copyright 2007 by the National Academy of Sciences