The Clean Water Act (CWA) of 1972 controls pollutant discharge from what the EPA calls "point sources," like industrial and municipal facilities, into any navigable waters of the United States. Point sources are required to obtain a National Pollutant Discharge Elimination System (NPDES) permit, which requires compliance with technology- and water quality-based treatment standards. These polluters -- mercury from Company A or untreated sewage from City B -- are east to identify and fall easily under the enforcement powers of the EPA. However, waterway pollution from what EPA calls "nonpoint" sources (NPS) are far harder to control.
What are nonpoint sources of pollution?
Nonpoint pollution comes mainly from our own backyards. NPS pollution is caused by rainfall, snowmelt or irrigation moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even our underground sources of drinking water. These pollutants include:
According to the EPA, nonpoint source pollution is the leading remaining cause of water quality problems. Nonpoint pollution is known to have harmful effects on drinking water, wildlife and -- as we are now learning -- our sport and seafood fisheries.
Clearly, as urbanization continues, the effects of nonpoint pollution will only worsen unless we all participate in efforts to reduce or prevent the problem.
What can be done?
Some activities aimed at preventing nonpoint pollution are federal responsibilities, such as ensuring that federal lands are properly managed to reduce soil erosion. Some are state responsibilities, for example, developing legislation to govern mining and logging, and to protect groundwater. Others are best handled locally, such as by zoning or erosion control ordinances. And each individual can play an important role by practicing conservation and by changing certain everyday habits.
What can private citizens do?
According to the EPA, the best ways private citizens can help reduce the effects of nonpoint water pollution are: