KING COUNTY, Wash. — As the summer heat ramps up in the region, health officials warned that several King County beaches have returned high bacteria samples, urging beachgoers to stay out of the water.
High bacteria detections were found at Madison Park Beach, Gene Coulon Beach, and Seward Park/Andrews Bay Beach, Public Health — Seattle and King County announced.
High bacteria levels at multiple King County beaches
Public Health collected three water samples in separate parts of each beach on May 11, which recorded high bacteria levels at each beach.
“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,” the department stated.
Public Health 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.
A beach is deemed contaminated with bacteria if two or three samples return a result of more than 320 CFUs on the same day.
The following list includes beach samples with elevated bacterial CFUs:
- Madison Park Beach: Sample A, 1,900; Sample B, 2,900; Sample C, 2,000
- Gene Coulon Beach: Sample B, 860; Sample C, 14,000
- Seward Park – Andrews Bay Beach: Sample A, 1,200; Sample B, 690; Sample C, 680
Gene Coulon Beach tests nearly 44x higher than the safety level
Gene Coulon Beach recorded two bacteria samples noticeably higher than the Public Health 320 CFU threshold. Sample C revealed 14,000 CFUs, which was nearly 44 times higher than King County’s baseline for a contaminated beach, while Sample B reported 860 CFUs, which was nearly three times higher.
“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,” 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.”
The summer heat ramped back up in late April, reaching the low 80s in parts of the greater Seattle area. Options for cooling off at a local beach are limited, but not completely out of the picture.
Public Health noted that while a majority of beaches tested in the summers of 2020-2025 had good water quality at least 95% of the time, it is still recommended to check the Public Health beach bacteria map before spending a day at the beach.
Beaches that remain open for public use include Madrona Beach, Magnuson Beach, Meydenbauer Beach, and Luther Burbank Beach, among others.
There is no information on how long the closures will be in effect.
This story was originally published on mynorthwest.com.