For Immediate Release
Date: September 29, 2020


Amanda McQuaid , Harmful Algal Blooms Coordinator
(603) 271-0698 |

State Re-Issues Cyanobacteria Advisory for Lake Kanasatka in Moultonborough

Concord, NH – A cyanobacteria bloom advisory was issued for Lake Kanasatka on August 12 and was removed on August 26 when samples confirmed that cell concentrations were below the State threshold of 70,000 cells/ml. However, bloom conditions can rapidly change. Since then, small patches of surface blooms (“scums”) have come and gone along some of the shorelines. Blooms can rapidly change and accumulate in various locations around a waterbody. Alerts have been locally shared as these surface scums have been spotted. The community has shared photos of what they have been observing along their individual shorelines. NHDES has re-issued an advisory at this time as most recent samples exceeded the State threshold. Samples contained cyanobacteria (Varieties of Anabaena/Dolichospermum, Microcystis, Woronichinia, Aphanizomenon and Gloeotrichia) in concentrations that ranged from 200,000 to 400,000 cells/ml. As a result, the New Hampshire Department of Environmental Services (NHDES) has issued a cyanobacteria advisory for those who use the waterbody for recreation. The advisory is not based on a toxin evaluation and is intended as a precautionary measure for short term exposure.

Shoreline accumulations of cyanobacteria on Lake Kanasatka as observed on September 10 & 26.

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 29, 2020, and will remain in effect until NHDES confirms that cell concentrations of the bloom have subsided.
Updates on cyanobacteria advisories may be obtained on the advisory map.
Follow the Beaches Twitter feed.

If you notice anything resembling cyanobacteria, please refrain from wading, swimming or drinking the water. Keep all pets out of the water and contact NHDES immediately. Please call NHDES to report a cyanobacteria bloom at (603) 848-8094 or email