Over the last several decades, water quality management in the United States has focused on control of point sources of pollution and the use of effluent- (discharge-) based water quality standards. Although the quality of U.S. waters has generally improved, nonpoint sources of pollution have not been as successfully controlled. To help confront this disparity, the U.S. Environmental Protection Agency (EPA) implements the Total Maximum Daily Load (TMDL) program'the objective of which is attainment of ambient water quality standards through the control of both point and nonpoint sources of pollution. Produced in response to a request from the U.S. Congress, Assessing the Total Maximum Daily Load Approach to Water Quality Management recommends two major programmatic changes in the TMDL process.
Over the past 20 years, scientists, coastal managers, and government decision-makers have come to recognize that coastal ecosystems suffer a number of environmental problems that can, at times, be attributed to the introduction of excess nutrients from upstream watersheds. Nutrient over-enrichment is the common thread linking such diverse coastal problems as fish kills, outbreaks of shellfish poisonings, coral reef destruction, and the Gulf of Mexico's "dead zone." Nutrient sources include runoff from agricultural land, animal feeding operations, and urban areas as well as discharge from waste water treatment plants and atmospheric deposition of compounds released during the burning of fossil fuels. Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution , produced jointly by the WSTB and the Ocean Studies Board of the NRC, concludes that the federal government together with state and local agencies should develop a comprehensive national strategy to combat nitrogen and phosphorus pollution in coastal waters . Success in addressing coastal nutrient problems depends on having a solid scientific understanding of the causes of the problem and the full range of possible management alternatives. To this end, the report describes a number of initiatives that could help address nutrient overabundance.
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Environmental problems in coastal ecosystems can sometimes be attributed to excess nutrients flowing from upstream watersheds into estuarine settings. This nutrient over-enrichment can result in toxic algal blooms, shellfish poisoning, coral reef destruction, and other harmful outcomes. All U.S. coasts show signs of nutrient over-enrichment, and scientists predict worsening problems in the years ahead. This report explains technical aspects of nutrient over-enrichment and proposes both immediate local action by coastal managers and a longer-term national strategy incorporating policy design, classification of affected sites, law and regulation, coordination, and communication.
