
Toxic algae in Green Lake last summer. Photo from Seattle DogSpot.
KING 5 reported last week that Seattle’s unusually warm winter and potentially hotter than normal temperatures this summer means that the potential for toxic algae formation in Green Lake this summer is extremely high.
Blue-green algae is present in Green Lake throughout the year. It becomes toxic when warm weather and more activity in the lake stir up phosphorus sediments from the bottom of the lake and other nutrients that the algae feed on.
In these seasonal conditions, the algae blooms grow rapidly and become toxic to people and pets who swim in the lake. Even a small amount of toxic algae can cause severe liver and neurologic toxicity in dogs.
For the last 3 years, Green Lake has been closed for several weeks, usually in late summer and early fall, due to high levels microcystin, a potent liver toxin produced by toxic blue green algae which can cause life-threatening health problems in both people and dogs.

If you see signs like this at lakes in Washington this summer, keep your dog far away from the water. Photo from Seattle DogSpot.
A dog exposed to toxic algae can also contract respiratory paralysis which can kill it within 30 minutes from the start of these symptoms: tremors, weakness, drooling, paralysis, muscle rigidity, involuntary urination and defecation, and seizures.
Last summer the algae first appeared in Green Lake last August, and for several weeks the lake was off limits to both people and pets.
But due to Washington’s warm winter and potentially hotter-than-normal summer, officials warn that toxic algae could form sooner and last longer than in past years.
Help is on the way for Green Lake. Last November, the Seattle City Council approved an accelerated plan for reducing the amount of toxic algae by treating it with alum, but that program won’t start until 2016.
In the meantime, if you take your dog to Green Lake this summer (or any other lake in Washington) you should watch for signs warning people to keep their dogs away from the water due to toxic algae blooms.
You can also check the Washington’s freshwater algae bloom monitoring program map to see what lakes and rivers are closed due to high microcystin levels.
Remember, even a tiny amount of toxic algae can kill your dog, and it’s important to heed the warning signs and keep your dog far away from any lake that has it.
Leave a Reply