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Reduce Pollutants Caused By Your Household

Algae is the biggest problem in Lake Sammamish, and the primary factor causing this critical problem is runoff of nutrients into the lake, particularly phosphorus.
Learn more about the problems with algae →

We all contribute to the problem so we all must work to prevent our lake from becoming unswimmable. Here are some ideas:

Lawn & Garden

Excess nutrients/fertilizer cause algae growth.

  • Use fertilizer sparingly – 3 times/year maximum.
  • To minimize runoff of chemicals, use an organic fertilizer such as All Natural Lawn Restore or Whitney Farms Natural & Organic Lawn Food. These cost more than chemical-based fertilizers, but our lawns are not huge and the few dollars extra are well worth it.
  • Use herbicides on a spot basis only as required.
  • If you use a professional garden service, pick one that is environment-friendly.
  • Don’t burn leaves or grass clippings near the lake.
  • Keep a “chemical free” zone of vegetation by the water’s edge.

Learn about buffers & rain gardens in our “Lakeside Landscaping” flyer →


  • Preferably wash cars at commercial locations where wastewater is treated, reused, or routed to the sanitary sewer (rather than the storm sewer which drains into the lake).
  • If washed at home, use phosphate-free soap sparingly and wash on grass.
  • Recycle used motor oil and antifreeze at an approved facility. Schucks takes motor oil and hazardous waste facilities take antifreeze (now there is a permanent one at the Eastgate transfer station).

Soil Erosion

  • Our soil contains phosphorus so don’t allow runoff into the lake. Sweep up dirt rather than washing it off of sidewalks and patios.
  • Maintain an area of vegetation between exposed soil or lawn and the water’s edge to trap runoff.


  • Scoop and flush, or put in garbage pet droppings to prevent adding nutrients to the lake.
  • Similarly dispose of duck and goose droppings from docks, patios and floats rather than sweeping or washing into the lake.
  • Don’t feed the geese.

Invasive Species

  • Drain and clean your boats, jet skis, and trailers thoroughly before putting into Lake Sammamish.
  • Clean your hiking boots, waders, off-road vehicles, kayaks, canoes, and paddle boards.
  • Let your lake neighbors and boating friends know of the threats and what they should do to prevent introductions of these aquatic hitchhikers.
  • Do not release aquatic pets or plants into lakes, wetlands or streams.

Learn about the invasive plant milfoil and how to remove it →

For more on how to do your part to keep our lakes and streams clean see Bellevue Utilities’ Preventing Water Pollution.

Copyright 2013 • Save Lake Sammamish • Site Design by Adrian Tiliacos