Greater effort is needed to ensure that the river is monitored and evaluated as a single system, said the committee that wrote the report.
The 10 states along the river corridor all conduct their own programs to monitor water quality, but state resources devoted to these programs vary widely, and there is no single program that oversees the entire river, making it an 'orphan' in terms of monitoring and assessment of its water quality, the report says.
'The limited attention being given to monitoring and managing the Mississippi's water quality does not match the river's significant economic, ecological, and cultural importance,' said committee chair David Dzombak.
Dr. Dzombak is Blenko Professor of Environmental Engineering and director of the Steinbrenner Institute for Environmental Education and Research at Carnegie Mellon University in Pittsburgh.
'In addressing water-quality problems in the river, EPA and the states should draw upon the useful experience in the Chesapeake Bay watershed, where for decades the agency has been working together with states surrounding the bay to reduce nutrient pollution and improve water quality. EPA should demonstrate similar leadership for the Mississippi River.'
The report evaluates efforts to implement the Clean Water Act along the Mississippi, which flows 2,300 miles from Minnesota's Lake Itasca to the Gulf of Mexico. The river is used by millions of people along a 10-state corridor for drinking water, commercial shipping, and recreation. Many ecosystems depend on the river's water quality.
Measures taken under the Clean Water Act have successfully reduced much pollution from specific points, such as direct discharges from factories and wastewater treatment plants.
But many of the Mississippi's pollution problems stem from nonpoint sources, mainly nutrients and sediments that enter the river and its tributaries through runoff, the committee observed.
Nitrogen and phosphorous from fertilizers create water quality problems in the river and contribute to an oxygen-deficient 'dead zone' in the northern Gulf of Mexico. Currently, there are no water quality standards for such nutrients along most of the Mississippi River.
Sediments present a more complex problem, the report says. In the upper Mississippi, they are too plentiful and considered a pollutant, while in the lower river, sediments are too scarce, leading to coastal wetlands loss in southern Louisiana.
The Clean Water Act addresses nonpoint source pollution only in a limited way, and the Mississippi's water quality also is affected by physical structures which the act cannot alter, such as dams and levees, so this law alone cannot solve all the river's water quality problems, the report acknowledges.
Under the Clean Water Act, states are responsible for establishing water quality standards and for monitoring water quality, but many states bordering the Mississippi River devote few resources to monitoring and assessing the river, and there is little cooperation among states.
In five states, the Upper Mississippi River Basin Association has promoted cooperative water quality studies and other initiatives, but there is no similar organization for the lower-river states, which should strive to create one, the report suggests.
The Clean Water Act gives most authority for coordinating and overseeing interstate water quality to the EPA, the report observes, recommending that the agency exert federal leadership. That should involve work with states and the four regional EPA offices along the river corridor to develop water quality standards to protect the river and the northern Gulf of Mexico.
The agency also should work with states to develop a federal Total Maximum Daily Load, TMDL, for nutrient pollutants in the river and northern Gulf, the committee reccomends. Required by the Clean Water Act, a TMDL is a numerical limit on the amount of a pollutant that a water body can accept and still meet federal water quality standards.
In addition, the EPA and the U.S. Department of Agriculture should work together more closely to reduce harmful runoff from agriculture, the committee advises.
USDA's conservation programs for protecting water quality should target areas that contribute higher levels of nutrient and sediment runoff to the river, the committee said. Growing interest in biofuels - which may increase crop production and also nutrient runoff from use of fertilizers - makes improved EPA-USDA cooperation in the Mississippi River basin all the more urgent, warns the report.