Local Health Department still monitoring Silver Lake for Cyanobacteria
From Cowlitz County Health Department Press Release 8-14-09
The Cowlitz County Health Department continues to monitor Silver Lake weekly for cyanobacteria, also known as blue-green algae which can produce toxins hazardous to humans and their pets. Last week water samples collected at Streeters, Kerr and Silver Lake Motel showed microtoxin and anatoxin levels well below thresholds that are considered unsafe. Tests for cyanobacteria levels and toxins on samples collected from Kerr and Streeters earlier this week are still pending.
“The lake is looking visibly better,” said Deputy Health Officer Jennifer Vines, “and we will continue to monitor until levels of cyanobacteria are known to be at safe levels.” The Health Department will provide updates to the public as test results return.
The cautionary signs posted by the Cowlitz County Health Department are the first of three levels of warning with respect to health threats associated with cyanobacteria presence in lakes. There are currently no formal restrictions on use of the lake for swimming or other activities, but the signs will remain in place until cyanobacteria levels are below the safety threshold determined by the World Health Organization.
If toxin levels exceed the accepted safety thresholds, the caution signs may be replaced by more strongly worded warning signs. If toxin levels were to reach dangerous levels, the lake could be closed to swimming.
Public health officials continue to recommend:
· No swimming or wading
· No wind surfing or sail boarding
· No water contact for animals
· Precautions against contact with water while boating or fishing
Public water systems and private wells in the areas around the lake are not affected by the lake water and remain safe to drink.
Eating fish out of the lake is considered safe as long as organs like liver and kidney, the organs where toxins can build up, are carefully removed and not consumed.
Algae blooms may be caused by a combination of factors including temperature and the presence of nutrients like nitrogen and phosphorus found in fertilizers and waste from humans, animals, and agriculture.
Cowlitz County Health Department is not aware of any other potential blue-green algae blooms in the county. The public is urged to watch for conditions of blue-green algae blooms and to report them at (360) 414-5583. Conditions may include:
· Water that looks like thick pea soup or green paint
· A thick mat or foam on the beach
· An unpleasant odor
· Extremely small organisms that are hard to pick up and hold, unlike more common but harmless green algae, which have long, bright green strands.
· Dead fish, waterfowl, or other animals
More information on algae can be found at http://www.doh.wa.gov/ehp/algae.
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