Sorting Out the Results
Yesterday, Nov. 3, we received a notice from Thurston County that the Microsystin levels previously reported as high are now below the State guidelines: “No Notable Presence of Cyanotoxins” (LINK). This result was from a sample taken on Oct. 29th.
Before that, on Oct. 29th, we received a notice that a sample taken on Oct. 22 showed the very high level (41.7) of Microsystin. This prompted the release of a Health Advisory (LINK).
Note: Thurston County Public Health and Social Services Environmental Health Division measure the presence of various toxins when they do water sampling.
Microcystin is a toxin that is released by blue-green algae or cyanobacteria (toxic algae). The State guideline for an acceptable level of microsystin is 8.0 ug/L (ug/L = micrograms per liter). When the measured level is above the State guideline, the County issues a Toxic Algae Health Advisory.
Recent Results
| Date Notice Received | Sample Collection Date | Toxin Concentration | Above State Guideline (8.0 µg/L) |
| 11/3/2025 | 10/29/2025 | Microcystin: Below 8.0 µg/L | No |
| 10/28/2025 | 10/22/2025 | Microcystin: 41.7 | YES |
Use this link to see Thurston County’s chart of collection dates, sample locations, and test results going as far back as 2011: LINK
QUICK LINKS
You can sign-up to automatically receive these Public Health Advisories using this LINK.
