Beach Monitoring

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The City tests water at Log Boom Park and ƛ̕ax̌ʷadis Park from June to September each year for bacteria. If water tests find high bacteria, this means there is poop in the water from people, pets, or wildlife. Poop can carry germs that can make people sick from swimming or playing in the water.
The City also tests for toxic algae if there are visual signs of a bloom present.

Sign up here to be notified if a park has been placed into a "no swimming" status as a result of high levels of bacteria. Please ensure that "Beach Monitoring" is selected from the list of subscription topics.

Use the map below to view other King County swimming beach bacteria levels:

Lake swimming beach bacteria and temperature - King County, Washington

CURRENT RESULTS

UNDERSTANDING BACTERIA RESULTS

The City collects three water samples at each park and tests for bacteria. Results are the number of bacteria per 100 mL of water (about a quarter-cup). If a bacteria result was above 320 bacteria/100 mL, that sample had high bacteria.

When looking at the three bacteria results for the day, if there were two or three high bacteria results on the same day, Public Health will generally recommend that people stay out of the water.

If there was only one high bacteria result that day, also look at the 30-day metrics. The 30-day geometric mean is one way to average all the bacteria results from the past 30 days. If the 30-day geometric mean bacteria was above 100 bacteria/100 mL, or if there were 2 or more high bacteria samples in the past 30 days, Public Health will generally recommend that people stay out of the water at that beach.

If there were no high bacteria results that day, Public Health will generally say it is OK to swim in the water. The 30-day metrics do not matter when there were no high bacteria results that day.