Thurston County residents should avoid swimming, fishing and letting pets near Lake Lawrence, Clear Lake and Offutt Lake after health officials expanded a toxic algae advisory to all three lakes.
Thurston County Public Health & Social Services posted the updated warning Monday, Sept. 28. Lab samples taken Sept. 22 found microcystin toxin levels above the state recreation guideline of 8.0 micrograms per liter (µg/L) at each lake.
Clear Lake recorded the highest reading at 155.0 µg/L, nearly 20 times the safety threshold. Lake Lawrence measured 43.7 µg/L, and Offutt Lake came in at 26.0 µg/L, according to the county's algae advisories page.
The advisory had previously covered only Clear Lake and Offutt Lake, based on Sept. 21 samples. The addition of Lake Lawrence means the advisory now covers three lakes, up from two.
Toxin levels climbing
All three lakes showed sharply higher microcystin concentrations compared with earlier samples. Clear Lake doubled from 77.0 µg/L on Sept. 21 to 155.0 µg/L one day later. Offutt Lake jumped from 10.5 µg/L to 26.0 µg/L over the same period.
The county issued a separate advisory for Lake Lawrence on July 24 after a July 21 sample measured 9.7 µg/L. The Sept. 22 reading of 43.7 µg/L represents more than a fourfold increase.
What residents should know
Microcystin is a liver toxin associated with gastrointestinal illness and liver damage, according to the county's advisory page. The county's Sept. 22 advisory also described microcystins as a possible human carcinogen, as reported by The Jolt.
Children face higher risk because their lower body weight means a smaller dose can cause harm. The toxin can affect a child's liver or central nervous system more severely, according to the county.
Dogs are especially vulnerable. They can ingest toxins by drinking lake water or licking their fur after swimming.
The county advises residents to:
- Avoid drinking lake water
- Stay out of the water in areas with visible algae
- Keep pets and livestock away from the shoreline
- Practice catch-and-release only for any fish caught during a bloom
- Avoid eating fish from affected lakes
- Steer clear of scum while boating
The county also warns that a lake can look clear and still contain dangerous toxin levels. Only lab testing can confirm whether a bloom is toxic.
What's next
County staff will continue collecting weekly samples. An advisory will not be lifted until two consecutive weeks of testing show microcystin levels below the 8.0 µg/L guideline, the county stated in its Sept. 22 advisory. No target date for lifting the advisories has been announced.
Residents can report illness or concerns about a specific lake by calling (360) 867-2626 or emailing [email protected].
