The Park

Green Lake Remains Open Despite Detected Toxic Algae in Areas of the Lake

June 4, 2015 7:51pm

photo via Garet Munger

UPDATE: Thanks to reader Garet for providing a photo of the scum as it appeared when the testing took place on May 29. Garet also brings up a good point: “The appearance of the scum is variable over time.  It can appear as brown as in these pictures, bright green, turquoise, pea soup green and shades in between.  It also shows up as a cloud in the water.  As the warning signs say: ‘If in doubt stay out’.”

Garet also shared the toxin analysis, which can be viewed here:


Toxic algae has been found in accumulated scum along the shores of Green Lake yet again. However the lake is not closed and remains open to many activities, according to the Seattle Parks Department.

The toxic algae was detected during the weekly tests submitted through the State Toxic Algae Program. Tests revealed that the toxins are currently found in the scummy algae that accumulate and drift in some places along the lakeshore. Due to toxicity levels and algae movement, Public Health did not recommend to close the lake, which means it is still open to fishing, boating and stand up paddle boarding. And currently the Lake’s two beaches are still slated to open with Park’s Dept Lifeguards on June 20.

According to a Parks Department press release, an early summer-like spring has promoted the algae bloom, and continued warm weather continues to promote it.

But this stuff is nothing to mess around with. Known as cyanobacteria, or blue-green algae, the blooms can cause flu-like symptoms, abdominal pain and worse for people and pets. With the temperatures heating up over the next few days however, pets are at the biggest risk as they may drink water from the lake. So keep a tight leash on dogs, pack a water to go and make sure to spread the word if you see other dog walkers who let their dogs drink from the lake.