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Green Lake toxic algae warning signIf you see a yellow WARNING sign at Green Lake, there are toxic algae in the lake.

The lake is not safe for people or pets.

  • Swim only where a lifeguard is present. Do not swim in other areas.
  • Keep pets out of the lake.
  • Do not drink lake water.
  • Clean fish well and discard guts.
  • Avoid areas of scum when boating.

At Green Lake, you can still swim where a lifeguard is present. For lifeguard locations and hours, go to Seattle Parks Green Lake page . The lifeguards check these two beaches often to make sure there are not toxic algae at the beach. Do not swim in other areas of the lake when there is a toxic algae warning!

At other lakes besides Green Lake, if you see a yellow WARNING sign, do not swim anywhere in that lake. Green Lake is the only lake that keeps some beaches open when there are toxic algae in the lake. To read the warning sign for other lakes, and for more information on toxic algae, go to the Northwest Toxic Algae website .

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