Learn About Stormwater

This page contains many links to information about stormwater, which is the primary cause of water pollution in the United States. Most stormwater in King County moves through separate sewer systems and does not go to a treatment plant before flowing into waterways.

You can help protect Washington’s waters from stormwater pollution.

Things you can do to reduce stormwater pollution:

⦁    Check for water leaks.

⦁    Find out where your roof runoff water goes:

–  If there is a splash block that feeds into a natural wooded area, nature is essentially doing the job of a raingarden.

–  If roof runoff is running a channel through your lawn, you need to correct this problem. Consider installing a raingarden.

⦁    Consider reducing the size of your lawn. For most homeowners, lawns are the third largest impervious surface. They soak up only a small amount of water before becoming saturated, and any chemicals and animal waste quickly are leached off.

⦁    Do not use poisonous chemicals on your lawn or landscape plantings. Besides being unhealthy for children, pets, bees, and other pollinators, in a residential landscape, homeowners or commercial operations could over-saturate with poisonous chemicals.

⦁    Mulch any bare soil. Bare soil is another challenge often forgotten. Mulching will help retain water, as well as reducing water use.

⦁    Consider using sand in winter for de-icing purposes. Winter salting with sodium chloride is another potential polluter of stormwater runoff.

⦁    Compost your lawn (use a mulching mower)!  This helps reduce water use, is healthy for your lawn, and also helps with infiltration.

⦁    Disconnect your downspouts and/or use rain barrels. The City of Portland has a guide on disconnecting downspouts, as well as a guide on the use of rain barrels.

⦁    Consider landscaping with native plants, hardy perennials, and trees, especially evergreen trees.


Adopt-a-Stormwater pond project: You can adopt your local stormwater pond in your neighborhood, church, school, or place of business, to help encourage the growth of native plants and wildlife, including such pollinators as bees, butterflies, and birds. Become part of the Million Pollinator Gardens project! (See printable brochure.)


Test your knowledge of stormwater. Take the King County Stormwater “Jeopardy” quiz – 10 questions:


King County Stormwater Services main page (includes quiz & science page)


What Is Stormwater?

Stormwater is essentially rainwater, that hits the surfaces of human developments (including roads), collecting contaminants and rushing into streams, rivers, and our oceans.

“Quite simply, stormwater is runoff that flows into pipes, ditches, streams, and other receiving water bodies. Conversion of natural areas to urbanized or developed areas increases flows and water pollution, and threatens properties with flooding. Impervious surfaces such as roofs, roads, parking lots, and sidewalks prevent water from potentially soaking into the ground or being taken up by vegetation.”

Source: leg.wa.gov/JTC/Documents/Studies/Stormwater/FinStormwater101Guide_091511.pdf

Why Should I Care About Stormwater?

Conversion of natural areas to developed areas increases the water flow and water pollution, because such impervious surfaces as roofs, roads, parking lots, and sidewalks prevent water from potentially soaking into the ground or being taken up by vegetation, which can in turn threaten areas with flooding.

Many issues that are threats to our aquatic life in Puget Sound and surrounding waters are summarized on the WSU Stormwater Channel. Enjoying watching these educational materials, and learn more about stormwater.

“Stormwater is now the primary cause of water pollution in the United States, resulting in numerous federal, state, and local regulations.”

Source: leg.wa.gov/JTC/Documents/Studies/Stormwater/FinStormwater101Guide_091511.pdf

What Happens If We Don’t Control Stormwater?

Pollution is a planet killer. All life is affected….

Puget Sound Salmon Contain Cocaine and Amphetamines

Take a look at some stormwater disasters!

What You Can Do

Please help! Here is just a partial list of what you can do:

  • Educate yourself. Check out our Stormwater Education page.
  • Educate your children (see below).
  • Go to meetups that talk about stormwater policy issues. Join the Sammamish Friends meetup group to get updates about stormwater advocacy events in Sammamish.
  • Give public comment at a city council meeting. For some ideas about what to say, check out our Advocacy page.
  • Speak .., then help us…please consider a donation to Sammamish Friends. Be sure to direct your gift to…

Talk To Your Children About Stormwater!

Check out Seattle Time’s interactive FlipBook:

Stormwater - What You Otter Know

Stormwater – What You Otter Know

The following is a ten-question, multiple-choice quiz covering the basics of stormwater. This is a good resource for kids.


Other Resources



The above sites contain some really good, plain-language explanations of stormwater, including definitions, common pollutants and their effects on fish and wildlife, and a few Best Management Practices (BMP) for businesses (through a link) and homeowners, listed in bullet-points.  Probably one of the best resources for basic information in King County.

Information presented to the Sammamish Planning Commission on June 17, 2010, providing at least provides a basic frame of reference for us. The City of Sammamish is currently updating their stormwater plan.

Stormwater 101