Widespread bacterial pollution found in three-quarters of WA beaches last year

As the summer heat ramps up, Washington’s beachgoers are more inclined to take a trip to the beach for a swim, but recent findings suggest that a beach day may not be safe.

A new study from Environment America Research and Policy Center (EARPC) found that roughly 76% of Washington’s beaches recorded at least one day with unsafe fecal contamination in 2024.

Washington’s contaminated beaches

A total of 63 beaches were tested for fecal indicator bacteria, and 48 beaches in Washington recorded potentially unsafe levels of fecal indicator bacteria in 2024.

Additionally, 19 of the beaches tested in 2024 had potentially unsafe levels of bacteria on at least 25% of all days they were tested. Earlier this year, numerous King County beaches recorded high contamination levels, which included Madison Park, Madrona Park, Matthews Beach, and Mt. Baker Beach.

EARPC also provided data that detailed which Washington beaches had the highest percentage of potentially unsafe test days. Pierce County’s Titlow Park led the pack with 11 days of contaminated water in 2024, 65% of the total days it was tested.

The EARPC stated that swimming in contaminated waters could cause gastrointestinal illnesses as well as respiratory diseases, ear and eye infections, and skin rashes. Each year, an estimated 57 million cases of illness from swimming in oceans, lakes, rivers, and ponds are reported in the U.S.; however, a vast majority of these illnesses also go unreported.

As of this reporting, two beaches in King County have high levels of bacteria, and beachgoers are advised to stay out of the water, including Green Lake’s East Beach and Juanita Beach.

What causes a polluted beach?

A contaminated beach can stem from various factors, including outdated and deteriorating sewage systems, polluted stormwater, and livestock.

Sanitary sewer systems, used in most parts of the country, can spill sewage that is dangerous to humans if their sewer lines become blocked or are poorly maintained. Sewage can then spill into stormwater through cracks in its piping and contaminate beach water. Sanitary sewer systems overflow as often as 75,000 per year in the U.S., according to EARPC.

Polluted stormwater can also be guided toward rivers due to the development of water-repellent surfaces such as parking lots, roads, and large homes. Polluted water that would formerly be absorbed into wetlands or forests now spills into the water as a result of the new developments.

Fecal pollution from livestock production can also be traced back as a cause of contaminated beaches, specifically large factory farms that produce high volumes of manure. Lagoons holding waste from these farms can also flood into waterways during periods of heavy rainfall.

Determining a contaminated beach

King County Public Health will collect three water samples at separate parts of each beach throughout the year and determine if it has high bacteria levels.

“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.”

The health department bases 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.

“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.

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