For the second consecutive summer, the Cowlitz County Health Department is warning the public to avoid algae blooms in Silver Lake.
The lake is not closed to recreation. However, the public is strongly encouraged to avoid contact with the water where algae is visibly present, health officials said.
"People can still use the lake, but they just need to stay away from any algae bloom," said Janis Housden, the health department's public information officer.
Health officials Monday posted cautionary signs read "toxic algae may be present" after routine monitoring found the blooms last week. Additional education signs are posted as well.
Some species of algae produce toxins harmful to humans and pets if they swallow or touch the green and scummy growth. Health officials took water samples Monday and sent them to the state Department of Ecology to be checked. Test results are expected early next week, Housden said.
Algae blooms give the water an overall green or blue-green color. It's often accompanied by an unpleasant odor.
There have been no reports of illness of humans or animals from contact with Silver Lake. Drinking water from public water systems or private wells in the areas around the lake is unaffected by the bloom and is safe to drink. Fish are safe to eat as long as the digestive organs are removed.
Symptoms of exposure to certain algae toxins include stomach cramps, vomiting, diarrhea, headache, blurred vision, convulsions or severe muscle and joint pains. Skin irritations, allergic reactions, rashes and blisters are also possible. Symptoms may occur within minutes, hours or even up to days after exposure.
Anyone who has these symptoms should see a doctor.
In August 2009, health department officials posted signs for about two weeks warning people and their animals to avoid contact with the lake water after harmful toxins were discovered in the algae bloom.