High bacteria levels: Stay out of Seattle’s poop-filled Magnuson Beach
Jun 11, 2025, 1:30 PM
A sign warns people to stay out of the water. (Photo: Joe Raedle, Getty Images)
(Photo: Joe Raedle, Getty Images)
Seattle Parks and Recreation is warning beachgoers to stay out of the water at Magnuson Beach for the foreseeable future.
The King County health department listed the water around Magnuson Beach as a “high bacteria” area.
High bacteria levels at Magnuson Beach in Seattle
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King County Public Health collected three water samples in separate parts of Magnuson Beach on June 9, which recorded high bacteria levels.
“We test the water for bacteria, which tells us whether 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,” King County Public Health wrote.
The health department based its decision on how many Colony Forming Units (CFU) are found, which is a count of the number of bacteria per 100 mL of water (about a half-cup of water), according to King County.
Of the three bacteria samples from Magnuson Beach, Bacteria Sample A was 1,000 CFU, Sample B was 890, and Sample C was 860.
“We use the bacteria test results to predict the chance that people will get sick from germs that might be in the water. There are many different types of germs that can come from poop (bacteria, viruses, parasites, etc.), and it is not possible to test for each one,” King County Public Health wrote. “Instead, we test for one type of bacteria that is easy to measure and is commonly used to predict the risk of getting sick from swimming.”
There is no information on how long the closure will be in effect.
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