More than half of all synthetic fertilizers ever produced has been used in the past 15 years. In the United States, approximately 20 percent of the nitrogen in these fertilizers seeps into ground water, rivers, and streams, gradually making its way into coastal waters. Other sources of nitrogen include animal wastes, waste-water treatment plants, and the combustion of fossil fuels. When these fuels burn, nitrogen compounds are released into the atmosphere, and then fall in acid rain, adding significant amounts of nitrogen to some coastal waters. Nutrient pollution often crosses local and state boundaries, making it difficult for various government agencies to act cohesively.
Rivers can carry pollution for long distances.
One of the many sources of excess nitrogen in the Gulf, for instance, might be runoff from a farm in Iowa. And nitrogen from the atmosphere is a nationwide problem. Large watersheds that cut across several states need uniform protection. Much needs to be done to help state and local authorities address this problem. The federal government should take the lead on issues that span multiple jurisdictions or threaten federally protected natural resources.