Blue-green Algae Blooms

What is a blue-green algae bloom?

Blue-green algae, or cyanobacteria, reproduce quickly in fresh water when the conditions are right with sunlight, warm temperatures, and nutrients. In a few days, a clear pond or lake can become cloudy with algae growth. This is called a bloom.

A blue-green algae bloom can look like paint floating on the water and it can vary in color from bright green, or a bluish, brownish, or reddish green. These blooms can occur any time of year, but are most common in the summer and fall.

What is a toxic bloom?

Not all blooms are toxic. Some blue-green algae produce toxins or poisons that eventually break down and are destroyed naturally. Ingesting the algae while they are poisonous can cause serious illness.

What if I see a bloom?

If you notice a bloom or signs of poisoning, avoid all contact with water containing algae. Keep children, pets and livestock away from the water. Call Thurston County Environmental Health Division at (360) 867-2626 to report the bloom. If the bloom is outside of Thurston County, call the local health department or Washington State Department of Ecology at (360) 407-6000 to report it.

Contact with Blue-green Algae can be Poisonous!

Blue-green algae can produce nerve toxins and liver toxins. Call your doctor or veterinarian right away if you or your pets have signs of poisoning.

Signs of neurotoxin poisoning appear within 15-20 minutes after ingestion.

- In people, signs may include numbness of the lips, tingling in fingers and toes, and dizziness.

- In animals, signs include weakness, staggering, difficulty breathing, convulsions, and death.

It may be hours or days before signs of liver poisoning appear.

-  Liver toxins can cause abdominal pain, diarrhea and vomiting in humans and death in animals.

If a test shows that a bloom is toxic, county health officials will decide whether to issue a health advisory for the lake. Notifications are posted at the lakes. Health officials will continue to test the lake until it is safe to lift the health advisory.

Visit Thurston County Environmental Health Division’s website to check for lake advisories.