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Thursday, August 6, 2009

Public Health Warning Remains in Effect

From Cowlitz County Public Health Press Release 8-6-09

Public health warning remains in effect despite visible improvement in Silver Lake conditions

Signs posted by Cowlitz County Health Department warn the public to avoid direct contact with water remain at Silver Lake. The presence of blue-green algae was confirmed late last week by the Washington Department of Ecology. Tests for toxins produced by blue-green algae including microcystin and anatoxin take approximately five days and are still pending.

“The posted signs are intended to inform the public of the possible risks associated with exposure to lake water,” explained Deputy Health Officer Jennifer Vines, “the decision to swim in the lake is up to the individual.” The caution signs represent the first of three levels of warning with respect health threats associated with blue-green algae presence in lakes.

The Washington Department of Health has investigated reports of four illnesses and one report of illness in a dog, all associated with Silver Lake exposure, and considers them suspicious for microcystin toxicity. The Department of Health is looking into sending blood samples from one of the individuals to the Centers for Disease Control for microcystin testing and confirmation.

Investigation by Cowlitz County environmental health specialists this week along with reports from citizens who live near the lake confirm that the water is visibly clearer. “Fortunately we have not received any more reports of illness potentially related to lake exposure,” Vines said. “The problem is,” she continued, “algae are more likely to release toxins into the water as they die off.”

Scientists do not know exactly when or why blue-green algae release toxins. Cowlitz County Health Department will remove the cautionary signs once testing shows levels of algae below the accepted safety threshold of the World Health Organization. The Health Department will visit the lake twice weekly for visual inspection and water sampling. If toxin level testing shows unsafe levels, the Health Department will post new signs with a stronger warning to the public and, if toxin levels are dangerously high, may prohibit swimming in the lake.

Because exposure to blue-green algae can cause disease, 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

Drinking water from public water systems or private wells in the areas around the lake is unaffected by the lake water and remains 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.

Algal 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 unaware of other potential blue-green algal blooms in the county. The public is urged to watch for conditions of blue-green algal 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 has long, bright green strands.
· Dead fish, waterfowl, or other animals

More information on algae can be found at

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