Cyanobacteria bloom prompts state DES to issue advisory for Silver Lake in Hollis
CONCORD — The state Department of Environmental Services on Monday issued a cyanobacteria advisory for Silver Lake, a popular swimming and recreational area within Silver Lake State Park on Route 122 in Hollis.
The advisory means that people who use the lake for swimming and other recreation should avoid contact with the water in areas experiencing elevated cyanobacteria cell conditions, which are known as blooms.
The cyanobacteria advisory went into effect Monday and will remain in effect until DES personnel confirm that cell concentrations of the bloom have subsided.
The advisory is not based on a toxin evaluation, officials said, but is intended as a precautionary measure for short term exposure.
Surface blooms can rapidly change and accumulate in various locations around a waterbody.
Although cyanobacteria are natural components of water bodies worldwide, blooms and “surface scums” may form when excess nutrients are available to the water.
Some cyanobacteria produce toxins that are stored within the cells and released upon cell death. Because the toxins can cause a wide range of both acute and chronic health effects that range in severity, swimmers and other users should remain cautious of lake water that has a surface scum, changes colors, or appears to have green streaks or blue-green flecks aggregating along the shore.
Acute health effects, for instance, include irritation of skin and mucous membranes, tingling, numbness, nausea, vomiting, seizures and diarrhea.
Chronic effects may include liver and central nervous system damage.
DES officials urge anyone who notices anything resembling cyanobacteria to refrain from wading, swimming, or drinking the
water, keep all pets out of the water, and promptly contact DES at 848-8094 or HAB@des.nh.gov.
More information can be found at www.des.nh.gov/water/healthy-swimming/harmful-algal-blooms.
Dean Shalhoup may be reached at 594-1256 or dshalhoup@nashuatelegraph.com.