Why King County beaches may close, reopen more often this spring and summer

With summer right around the corner, King County officials this week will begin monitoring water quality at popular lake beaches using an updated process to decide when to close and reopen them.

In past years, environmental scientists collected water samples every week at more than two dozen beaches from mid-May to mid-September, Public Health – Seattle & King County said in a news release. 

Scientists test water for bacteria that indicates fecal pollution that usually comes from people, pets or wildlife such as geese. Scientists also sort through data, looking for potential public health risks, the agency said. 

But the process that has been used to decide when to close and reopen beaches is based on “now-outdated scientific guidelines,” the health agency said. A higher number of tests showing poor quality were needed to close a beach and a higher number of tests showing good water quality were needed to reopen it.

The new standards for opening and closing beaches are based more on real-time water-quality data the agency receives each week — which means beaches will close and open more quickly. 

So while swimmers may see beach-closure signs more often, the signs will likely be up for shorter durations, the agency said.

“And overall, we expect beaches will be open for about the same amount of time as under the old decision-making protocol,” Public Health said. 

“Bacterial counts in the environment change quite dramatically week to week (in fact it changes daily),” wrote Sharon Bogan, a Public Health spokesperson. “The new protocol is based more on what the current week’s lab results show for bacteria as opposed to the previous protocol that was based more on results from the previous two weeks.”

Public Health urges beach visitors to help keep the water free from harmful bacteria in the following ways:

• Don’t feed geese and ducks near the beach. Feeding them makes them poop, which makes the water quality worse.
• Always shower before swimming.
• Make sure babies and toddlers wear good-quality swim diapers.
• Report water quality concerns to your local parks department.