Parks and Rec has issued an algae bloom warning for Green Lake, closing it to some activities including drinking. No, we did not think you were drinking from Green Lake, but if you’ve got a dog, best pack a Perrier for him:
Seattle Parks and Recreation Acting Superintendent Christopher Williams, with the support of Public Health – Seattle & King County, has closed Green Lake to some activities because of the presence of a cyanobacterial toxin in amounts exceeding the Washington Department of Health’s draft recreational guidelines.
“Rather than risk the health of any park user, we’re closing the lake to some activities until we have confirmation that the water is safe,” said Acting Superintendent Williams. “The level of toxicity leads us to err on the side of caution to limit the risk of anyone ingesting the water.”
The lake is open to fishing and boating — activities in which users are unlikely to ingest the water. The closure will be in effect until the algae bloom has completed its lifecycle. This could be weeks or months, depending on the fall weather and how it affects the algae in the lake.
Warm, dry weather will promote the continuation of the bloom. Blooms have been known to last into November in particularly warm autumns, and typically disappear as the weather gets colder.
The lake was closed in 1999, 2002 and 2003 for toxic algae blooms. Intense blooms of blue-green algae have occurred in Green Lake since 1916.
Treating the lake with alum inactivates the phosphorus that is released from the bottom sediments and prevents stimulation of the algae growth. Green Lake was successfully treated with alum in 1991 and 2004. The water quality improved for several years following treatment on both occasions, and has been very good since 2004.
Green Lake is home to photosynthetic cyanobacteria, or “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.
(Photo by Travis S.)