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The Lacey-area lake joins Black Lake south of Tumwater on the list of lakes with outbreaks of toxic algae in the past two weeks at levels high enough to trigger health advisories, county environmental health director Art Starry said.
There have been no reports to health officials of illness to humans or pets from the toxic algae blooms, Starry said.
A sample of algae collected at the state Department of Fish and Wildlife boat launch Sept. 21 on Pattison Lake showed 38.3 parts per billion of the algae toxin microcystin. Anything over 6 ppb means the lake is not safe for water contact by people and pets, environmental health officer Cathy Hansen told lake residents via email Wednesday.
There is no way to tell if an algae bloom is toxic without testing. Health officials say that when tests show the presence of the poison at unsafe levels, people, pets and livestock should stay away from the water until further notice. As a precaution, water contact should be avoided anytime a lake has an obvious green to blue-green appearance.
In their toxic form, blue-green algae can sicken and kill pets, waterfowl and other animals and cause serious illness in humans.
State health department guidelines call for the lakes to be tested weekly until the toxins drop below safe levels. The algae blooms typically occur during sunny, calm weather when nutrient levels in the water are elevated. With cooler weather, the toxins normally break down and are destroyed naturally.
Lakefront residents can reduce the risk of algae blooms by reducing the amount of phosphorous and nitrogen they contribute to the water. Residents can help by maintaining their septic systems, using lawn and plant fertilizers and pesticides sparingly, preventing surface water runoff from livestock and restoring native vegetation along lake shorelines and streams feeding into lakes.
John Dodge: 360-754-5444
jdodge@theolympian.com
