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Although you might not live directly on the shore of a lake or stream, everyone lives in a watershed. A watershed is an area of land or a drainage basin that contributes water to a stream, lake, or other water body. Often the boundary of a watersheds is determined by land features such as mountains and hills that cause water to flow down slope into specific valleys and lowlands.

Hydrocycle - the path of water through a watershed

Because of the nature of water to flow and seep throughout our environment, almost every activity in a watershed eventually touches a lake or stream. No matter where you live, activities such as construction, washing cars on the street, pet waste disposal, livestock keeping, fertilizer and pesticide use, and improper disposal of cleaning supplies or motor oil may impact water quality.

So how do we keep our houses, pets and gardens in shape and still keep the water clean? Here are some easy things you can do...

Buffer lakes and streams

A buffer is an area or zone of native vegetation along the edge of a water body. Buffers, also called riparian zones, work as physical barriers, filtering pollutants from runoff before they can enter a water body. Buffers also help prevent shoreline erosion and provide shade, food, and shelter for wildlife.

If you have waterfront property, keep a healthy native plant community growing along the shoreline. If you are visiting your local stream or lake, avoid crushing or uprooting the plants at the water's edge. Cross streams and enter lakes at designated use areas to preserve the natural shoreline set aside for wildlife use and protection. Learn more at shoreline practices for a healthy lake or the value of riparian vegetation pages.

Don't feed the ducks

You may enjoy strolling to the park to feed the ducks, but this activity is unhealthy for the ducks and has health consequences for people as well. Feeding the ducks and geese can make them dependent on us for food; a source that isn't as healthy for them as native plants and foods. It can also unnaturally increase their population numbers, and cause them to stop migrating. This winds up being bad for us when large groups of non-migratory waterfowl cause swimmer's itch or fecal contamination at your favorite swimming beach. These large groups can also contribute phosphorus to the lake through their feces, sometimes causing algae blooms. So remember, let the wildlife be wild, and Don't Feed the Ducks!


Working native plants into your landscape is a great way to enjoy the beautiful textures of the Northwest. Native plants are often more disease resistant and require less fertilizer than ornamental plants and lawns. These features are important because reducing the use of fertilizers, herbicides, and pesticides is crucial to protecting our water quality.

If you do need to fertilize your plants use a slow release, organic fertilizer, or enrich your soils with compost recycled from you own yard wastes.

To learn more about native plants and landscaping you can click on the underlined links below.

Septic system maintenance

Proper maintenance of home septic systems is one way home-owners can help keep a lake healthy and clean. To see how you can keep your system functioning properly and prevent harm to nearby lakes or ponds check out on-site septic systems - the hidden polluters. Also visit Public Health Seattle & King County's Web page for septic system owners to find out more about maintaining your system.


Much, much more

King County Water & Land Resources Division has many informational booklets, pamphlets and fliers that describe how you can help maintain healthy water quality. To learn more about cleaning substitutes, car washing techniques, noxious weeds, hazardous waste, keeping livestock, and similar topics visit the King County Water and Land Resources Division site or visit the King County search page.

For questions about lakes in King County, please contact or call the Water and Land Resources Division front desk at 206-477-4800.