Seattle Parks and Recreation says it has found algae scum with toxins at Green Lake, but that it’s only harmful where the scum is found.

Toxic algae has been found in accumulated scum along the shores of Green Lake; however the lake is not closed and remains open to many activities.

King County Department of Natural Resources has been conducting weekly testing of water collected at the east and west swimming beaches at Green Lake as well as scum samples submitted through the State Toxic Algae Program. After each test, the information is reviewed by Public Health – Seattle & King County. Tests have 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 does not recommend closure at this time.

People and pets should not wade or play in the lake where the scum has accumulated. Dog owners should be especially cautious not to allow animals to drink from the lake in these areas. If there is water contact for a pet, it is important to rinse the pet well to remove all algae.

The lake remains open to fishing, boating, stand-up paddling boarding and other recreational activities. Seattle Parks and Recreation’s lifeguarded beaches do not open until Saturday, June 20. Before that date, individuals who choose to open water swim are recommended to swim only when accompanied by a boat and to stay away from scum patches.

An early summer-like spring has promoted the algae bloom, and continued warm weather continues to promote it.

Green Lake is home to cyanobacteria, also known as blue-green algae that are regularly present in small numbers. When nutrients are plentiful and the weather is warm, the conditions are right for an algae bloom to take place. Winds can concentrate the buoyant cyanobacteria into accumulations or scums along the shoreline, which may increase the amount of toxin that could be ingested by pets or people using the lake recreationally.

Symptoms of illness from liver toxin are flu-like and may include abdominal pain, diarrhea and vomiting. If symptoms occur after ingesting lake water, park users should consult a health care professional immediately. Pets are at highest risk.

For more information on cyanobacteria, please visit the Washington Department of Health toxic algae website at www.doh.wa.gov/CommunityandEnvironment/Contaminants/BlueGreenAlgae.