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State Removes Cyanobacteria Advisory for Middle Danforth Pond in Freedom, New Hampshire
The New Hampshire Department of Environmental Services (NHDES) has REMOVED a cyanobacteria advisory for Middle Danforth Pond that was issued on 8/26/2021. Cyanobacteria advisories are issued when cell concentrations exceed 70,000 cells/ml. Samples collected on 9/1/21 contained Planktothrix ranging from 1,000 to 48,000 cells/ml. Surface water samples contained just 1,000 cells/ml while samples collected from deeper in the water column (5 meters deep) contained 45,000 to 50,000 cells/ml. NHDES advises that lake-goers look out for blue-green surface flecks in the future (these visible accumulations can represent thousands to millions of cells at times). Please continue to monitor your individual shoreline for changing conditions.
This advisory was not based on a toxin evaluation and was intended as a precautionary measure for short term exposure. 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 advisory went into effect on August 26, 2021 and was removed on September 2, 2021.
- Visit the NHDES Beach Program website for photos and more information about cyanobacteria.
- View updates on cyanobacteria advisories.
- 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 HAB@des.nh.gov.