Newcastle Beach closed to swimming

Published 3:49 pm Friday, May 22, 2026

With the warm weather comes the bacteria – Newcastle Beach in Bellevue is closed until further notice due to high bacteria levels in the water.

According to the King County website, May 19 water testing at Newcastle Beach shows that bacteria levels are high at 1/3 of sampled areas, where they are over 320 colony forming units (CFU) per 100 milliliters of sample water (>320 CFU/100 mL). CFU is a count of the number of bacteria, per 100 milliliters.

While Sample A shows 470 CFU/100 ml in one area, Sample B shows 270 CFU/100 mL and Sample C reveals 160 CFU/100 mL.

Due to these high bacteria levels, the county says that people — and their dogs — should stay out of the water.

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 CFU, it means that there are high levels of biological waste from people, pets, or wildlife in the water, which can carry germs that make people ill.

Green Lake’s West Beach is currently closed, but this is due to toxic algae, not high bacteria levels.

What the county does once a beach is closed

The county first tries to find the source of the high bacteria, which means finding the source of waste getting into the water. Additional testing may be utilized along with contacting local sewage utilities about possible sewage leaks and spills.

When the source of the high bacteria levels are determined, the county will work with beach managers to keep poop out of the water, allowing swimmers to eventually return.

According to the county website, beach managers will be advised to do the following:

• Remind people that dogs are not allowed at the swimming beach, and geese and ducks should not be fed near the beach.

• Clean up goose poop from docks to keep it out of the water at the swimming area.

• Reduce the number of geese near the beach, by using shiny mylar strips (“scare tape”) or specially trained dogs.

• Renovate docks to allow more water circulation through the beach area.

• Improve drainage in the park area near the beach, to reduce bacteria washing into the lake near the beach.

• Reduce poop getting into streams near beaches.

To learn more about King County’s swimming beach data, visit kingcounty.gov/en/dept/dnrp/nature-recreation/parks-recreation/king-county-parks/water-recreation/swimming-beach-bacteria-temperature.