Coastal Issues | Water Quality

Water Quality

Coastal waters are valuable resources. They provide food, recreational opportunities, commerce pathways, and solace. They are also home to countless marine and estuarine species.

Since the passage of the Clean Water Act in 1972, we have made great strides in protecting our nation's waters by targeting point source pollutants—pollutants discharged directly from pipes, such as from a factory or sewage treatment plant. However nonpoint source pollution, or polluted runoff, has proven more difficult to control. Today, nonpoint source pollution poses the largest threat to coastal water quality in the United States.

Unlike point source pollution which comes from a single source, such as pipe, nonpoint source pollution comes from many sources. As rain water or snow melt (or even water from a garden hose) washes over impervious surfaces such as roads and walkways, construction sites, agricultural fields or forestry sites, it picks up pollutants from the ground and transports them into our coastal creeks, rivers and estuaries. Pollutants frequently swept up in runoff include fertilizers, lawn chemicals, herbicides, salt from roadways, oil and gasoline leaked from automobiles, soil from construction sites, and untreated sewage from boats, pets, and failing septic systems.

graph of nonpoint pollution

Nonpoint source pollution is the leading cause of impairment for coastal waters and comes from a variety of sources.

This polluted runoff can create serious problems for coastal resources. For example, polluted runoff has been linked to a loss of aquatic species diversity and abundance, including many important commercial and recreational fish species. Nonpoint source pollution has also contributed to coral reef degradation, fish kills, seagrass bed declines, and algal blooms (including toxic algae). In addition, many swimming and beach closures are attributed to polluted runoff. As the Environmental Protection Agency's 2005 "National Coastal Condition Report" indicates, the overall condition of U.S. coastal waters is fair but 28 percent of coastal waters are not suitable for aquatic life and 22 percent are not suitable for human use (such as fishing or swimming).

In Depth: A Closer Look at nonpoint source pollution impacts on recreational beaches, shellfish beds, and coastal habitat.

In Depth: Table summarizing the sources and impacts of nonpoint source pollution

Because almost everything we do in the coastal zone influences water quality, improving and maintaining coastal water quality is intertwined with many other coastal issues, including habitat, community development, and cumulative impacts. For example, coastal habitats such as wetlands or riparian areas (areas along streams and rivers) play an important role in filtering pollutants from runoff. Therefore, protecting a coastal wetland helps maintain healthy waters. Encouraging smart community development that limits the amount of impervious or hard surfaces also helps to reduce the amount of polluted runoff. With fewer paved surfaces, more storm water is able to infiltrate the ground, minimizing the amount of runoff that leaves a site. Similarly, rarely does one new home or the filling of a few acres of wetlands significantly impair our coastal waters. Rather, its the cumulative impacts from growing developments and repeated wetland loss that lead to degraded water quality. Managing the coastal zone to minimize, or at least mitigate, for these cumulative impacts is critical for protecting water quality. Visit these other coastal issue sections to gain a better understanding of how other coastal management efforts help address water quality issues.


NOAA's Ocean Service Education Discovery Kit on Nonpoint Source Pollution — The website provides general educational information about nonpoint source pollution, its sources, what NOAA is doing to address water pollution and what the general public can do to address water pollution. The site also includes several lesson plans for teachers.

The Coastal Nonpoint Pollution Control Program — The website describes the Coastal Nonpoint Pollution Control Program that ensures coastal states have programs in place to address polluted runoff.

Environmental Protection Agency's Polluted Runoff Program — The website includes links to publications, and educational and outreach resources related to nonpoint source pollution.

National Estuarine Eutrophication Assessment — The report evaluates both current eutrophic conditions in estuaries and the effectiveness of management actions aimed at reducing eutrophic conditions.

For additional information contact John Kuriawa.