Multiple Seattle beaches closed after water samples test high for bacteria
Jun 25, 2025, 2:02 PM
A sign warns people to stay out of the water due to contamination. (Photo: Joe Raedle, Getty Images)
(Photo: Joe Raedle, Getty Images)
is warning that several Seattle beaches have returned high bacteria samples, and summer beachgoers are being urged to stay out of the water.
High bacteria detections were located at Madison Park, Madrona Park, Matthews Beach, and Mt. Baker Beach.
High bacteria levels at multiple Seattle beaches
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collected three water samples in separate parts of each beach on June 23, which recorded high bacteria levels.
鈥淲e 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,鈥� King County Public Health wrote.
The health department based its decision on how many Colony Forming Units (CFU) were 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.
- Madison Park: Sample A, 560, Sample B, 390, Sample C, 340.
- Madrona Park: Sample C, 870.
- Matthews Beach: Sample A, 1100.
- Mt. Baker Beach: Sample B, 4900, Sample C 470.
鈥淲e 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,鈥� King County Public Health wrote. 鈥淚nstead, 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.鈥�
There is no information on how long the closure will be in effect.
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