Gene Coulon Beach re-opens to swimmers

The swimming beach re-opened after bacteria levels decreased dramatically in a little over a week.

After a week and a day, it is safe to go back in the water.

On Tuesday, June 18, King County released its most recent bacteria testing results for the local lake’s swimming beaches and Gene Coulon Memorial Beach Park in Renton has the green light.

According to the King County website, water testing at Gene Coulon Beach — the most southern swimming beach in Lake Washington — shows that bacteria levels are once again low and that the beach is safe for swimming.

The latest results show that the three samples from the water at the beach had 12 bacteria, 120 bacteria and 140 bacteria per 100 milliliters of sample water.

When bacteria results are above 320 bacteria per 100 milliliters of sample water, that is when bacteria levels are considered high. If two of the three bacteria samples (labeled “Sample A”, “Sample B”and “Sample C”) are over the 320 bacteria/100 mL threshold, then the county will recommend the public to not swim in that water.

On Monday, June 10, the reports had found that Gene Coulon had 550 bacteria per 100 milliliters of sample water, which led to the beach’s brief closure.

The water at more than two dozen lake beaches that are popular swimming spots are regularly tested for bacteria every year from mid-May to mid-September. If water tests find high bacteria, it means that there are high levels of poop from people, pets, or wildlife in the water, which can carry germs that make people ill.

Kennydale Beach in north Renton is also open to public.

For more information on water quality in King County’s swimming beaches, visit