State Issues Cyanobacteria Advisory for Spofford Lake in Chesterfield, New Hampshire

Concord, NH - Concord, NH- A cyanobacteria bloom has been observed on Spofford Lake, appearing as black sludge. This type of cyanobacteria (Lyngbya wollei) is quite unusual and not typically found in NH lakes. Cell concentrations have yet to be determined. However, at this time NHDES has issued an advisory for Spofford Lake. The advisory is not based on a toxin evaluation and is intended as a precautionary measure for short term exposure.

Surface blooms can rapidly change and accumulate in various locations around a waterbody. Please continue to monitor your individual shorelines for changing conditions. NHDES advises lake users to avoid contact with the water in areas experiencing elevated cyanobacteria cell conditions, also known as a bloom. NHDES also advises pet owners to keep their pets out of any waters that have a cyanobacteria bloom.

Cyanobacteria are natural components of water bodies worldwide, though 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. Toxins can cause both acute and chronic health effects that range in severity. Acute health effects include irritation of skin and mucous membranes, tingling, numbness, nausea, vomiting, seizures and diarrhea. Chronic effects may include liver and central nervous system damage. Be 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.

The cyanobacteria advisory went into effect on September 10, 2020 and will remain in effect until NHDES confirms that cell concentrations of the bloom have subsided.