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Health Advisory September 22, 2003 Contact: Bonnie Widerburg (503) 731-4180 Public health officials at the Oregon Department of Human Services (DHS) and Coos County Health Department are advising lakefront property owners, visitors and other interested persons of another bloom of Microcystis aeruginosa in Tenmile Lakes, located about 10 miles north of Coos Bay on the Oregon coast. Similar advisories were issued for these same lakes in 1997, 2001 and 2002 for recreational contact. Drinking water advisories have been made for the lakes each year since 1997. Microcystis aeruginosa is a blue-green algae capable of producing a dangerous liver toxin called microcystin. The toxin poses danger to humans or animals using the water. Ingestion of the water is the most significant hazard, but direct contact with algae may also pose some toxin hazard as well as possible skin reactions. Samples of the water collected on Sept. 8 contained this algae species at levels ranging from 0 cells per milliliter of water to 2,463 cells per milliliter. Current guidance for the toxin in water suggests that cell concentrations greater than 2000 may be hazardous to users of the water. Since samples and cell counts do not necessarily represent the highest concentrations in the lakes, officials are advising that direct water contact be avoided at any point where there is visible algae or where the water has a bluish or blue green color. Water from the lakes should not be used for domestic purposes unless it has first been carefully treated as recommended below. At current cell densities, it is very likely that toxin levels exceed 1 microgram of toxin per liter of water, the maximum level considered tolerable in drinking water. Future samples found to have greater than 15,000 cells per milliliter will be tested for toxin, which is standard procedure for bodies of water with known blooms of Microcystis aeruginosa. Until further notice from DHS and Coos County Health Department, it is advised that:
Drinking Water Treatment Guidelines:
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