LYNDEN, Wash. — Whatcom County Department of Health issued a press release yesterday, June 11th, reminding residents to avoid contact with the water at Wiser Lake and not allow pets to swim in or drink the lake water. Wiser Lake is 1 of 5 Washington lakes with toxin levels above state standards.
Caution signage has been posted at Wiser Lake since 2019 due to consistently elevated toxin levels and recent test results indicate an ongoing health risk according to the press release.

Ingestion of lake water poses the primary human health concern. Limited contact from boating or fishing is not a significant risk to people, but waterskiing, swimming or riding personal watercraft poses a greater risk since water may be accidentally ingested.
Pet owners are advised not to let their pets swim in the lake. Pets often lick their fur after swimming and may ingest toxins while grooming.
Microcystin can cause liver damage in people and pets. This and other algal toxins are naturally occurring, although human and animal activity can impact the severity of freshwater algal blooms. Nutrients in fertilizer, pet waste, agricultural runoff and wildlife waste provide food for algal growth.WCHD Environmental Health press release (June 11, 2021)
Washington State Department of Health has set the level of public health concern for microcystin at 6 micrograms per liter (µg/L).
Water samples taken from Wiser Lake since 2014 have exceeded state water quality level (6 micrograms per liter) for microcystin multiple times as detailed below.
Collection Date Toxin Concentration (µg/L) Exceeds 6/8/2021 177.2 Yes 9/1/2020 431 Yes 12/10/2019 0.299 No 10/1/2018 1.9 No 7/17/2018 19.4 Yes 10/17/2016 <MDL No 9/6/2016 165 Yes 8/3/2016 19.8 Yes 10/5/2015 0.216 No 9/28/2015 0.255 No 9/21/2015 192 Yes 9/14/2015 325 Yes 9/2/2015 48.6 Yes 8/22/2014 204 Yes
There is no way to tell if an algae bloom is toxic by looking at it according to experts. Only a laboratory toxin analysis can confirm if a bloom is toxic or non-toxic.
In 2005, the Washington State Legislature established funding for an algae control program. The Freshwater Algae Control Program targets blue-green algae (also known as cyanobacteria) because these algae can produce toxins that pose a health risk to humans, pets, and livestock.
Other Whatcom County lakes from which water samples have been tested over recent years include Lake Padden, Thunderbird Lake, Dickenson Lake, Silver Lake, Toad Lake and Lake Terrell. Besides Wiser Lake, lakes with samples that exceeded maximum quality levels were Lake Terrell (2019) and Toad Lake (2017, 2015) according to the Washington State Freshwater Algae Control Program database.