Today the Cowlitz County Health Department will remove warning signs around Silver Lake regarding cyanobacteria, also known as blue-green algae. At the end of July, the lake was found to contain species of cyanobacteria that can produce toxins. Test results from water samples collected for the past two consecutive weeks now show that toxins levels are below the threshold to be considered unsafe.
The Health Department will continue to monitor Silver Lake and will advise the public if toxin levels are above the acceptable level for recreational water.
Public health officials have replaced level 2 warning signs with educational signs. Signs remind residents that algae blooms are unpredictable and 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.
More information on algae can be found at http://www.doh.wa.gov/ehp/algae. To contact the Health & Human Services Departments, please call 360-414-5599.