Water Quality photo identifier

Land use and Nonpoint Pollution

Residential development photo in Snohomish County, Washington State. Author unknown.

Nonpoint: Pollution from Urban Living

Clearing for buildings, parking lots, and landscaped areas occurs at a rapid rate in Washington State. Rainfall runs quickly and directly into streams, dramatically increasing their volume and peak flows, and reducing summer flows. Runoff may contain high concentrations of heavy metals, lawn and garden chemicals, bacteria, silt, petroleum products, and nutrients.

Septic systems serve approximately 1.4 million suburban and rural Washingtonians, a number that is growing each year. The exact number of failing systems is not known. Common problems include poor soils, obsolete design, improper siting, poor construction, poor operation and maintenance, and limited knowledge on the part of local professionals and owner/operators.

For more information about septic systems, please see the University of Washington publication Septic Sense (PDF).

Another issue of growing concern is pet waste. Increasingly, fecal coliform linked to cats and dogs makes its way to urban streams. Education is needed to show animal owners the importance of controlling waste in urban areas.

In the short term, these pollutants can harm aquatic organisms, damage shellfish beds, and restrict water recreation. In the long run, they can create serious problems such as excessive algae growth, ground water contamination, loss of fish habitat, and contaminated sediments.

Related information

Urban Waters Initiative

Water Quality success story: Keeping Pollution out of Urban Waters - "Greening up" recycling (Ecology publication)




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Last updated September 2013