Thurston County health officials are warning residents to stay out of four local lakes after lab tests found toxic algae blooms. Samples from Lake Lawrence and Offutt Lake showed microcystin levels above the state's safety threshold. Advisories cover Lake Lawrence, Offutt Lake, Clear Lake and Pattison Lake, prompting county officials to urge people, pets and livestock to steer clear of affected water.
Reports described microcystin toxin levels at some lakes as above the state's 8.0 µg/L recreation guideline. The county flagged trouble at Lake Lawrence, where a sample showed microcystin at 15 micrograms per liter, according to a Thurston County health advisory — nearly double the state's 8.0 µg/L recreation guideline. That followed an earlier Aug. 14 sample at the same lake that had come in just barely over the line, at 10 micrograms per liter, as reported by KIRO 7.
Clear Lake and Offutt Lake Spike Weeks Later
Clear Lake and Offutt Lake joined the warning list on Sept. 22, when the county announced toxic algae blooms had been confirmed in both, as reported by chronline.com. A sample pulled from Clear Lake the day before, on Sept. 21, measured microcystin at 77.0 µg/L, nearly ten times the state guideline, per the same report. A sample from Offutt Lake taken that same day came back at 10.5 µg/L.
Clear Lake's numbers kept climbing. A later sample taken Sept. 28 detected microcystin at 178.0 µg/L, according to Thurston County's water recreation page — more than 20 times the state's recreational threshold. Pattison Lake entered the picture most recently, with a sample taken Oct. 16 showing microcystin at 135.0 µg/L, also far above the 8.0 µg/L guideline, per a county health advisory.
Why Officials Say Looks Can Be Deceiving
County health officials stress that an algal bloom's harmfulness cannot be judged by sight alone, which is why Thurston County tests its lakes regularly rather than relying on visual inspection. Blooms can appear blue, green, orange or red, and are often foamy or can resemble spilled paint or scum floating on the surface.
Even a lake that looks clear of algae can still carry toxins, the chronline.com report notes. That uncertainty is also echoed by the Washington State Department of Ecology, which says people and animals can become seriously ill or even die after exposure to freshwater toxic algae, and that toxicity is difficult to predict and can only be confirmed through laboratory testing, according to ecology.wa.gov.
What Officials Are Telling Residents to Avoid
Health officials are advising residents not to drink lake water, swim, wade, windsurf or water-ski in any of the four affected lakes, and to avoid areas of visible scum when boating. People should also keep pets and livestock away from the shoreline, since animals that drink contaminated water can become ill.
Anglers are being told not to eat fish caught from the lakes during an active bloom, and to practice catch-and-release instead. Microcystins are liver toxins and possible human carcinogens, the chronline.com report explains, underscoring why officials are treating the exposure risk seriously for both people and animals that spend time near the water.
Thurston County plans to keep collecting weekly samples from all four lakes until officials receive two consecutive weeks of results showing microcystin levels below the state's recreational guideline, at which point the advisories could be lifted. The pattern isn't isolated to Thurston County — the Tacoma-Pierce County Health Department issued its own toxic algae caution advisory for Bay Lake this month, advising people and pets to avoid areas with visible algae, according to tpchd.org.
