State Removes Cyanobacteria Advisory for Webster Lake in Franklin, New Hampshire

The New Hampshire Department of Environmental Services (DES) has REMOVED a cyanobacteria advisory for Webster Lake that was issued on 06/02/2021. Cyanobacteria advisories are issued when concentrations exceed 70,000 cells/ml. Cyanobacteria were identified as Anabaena/Dolichospermum. Samples initially collected on 6/2 contained levels >70,000 cells/ml. Follow-up samples were collected on 6/7 and contained little to no cyanobacteria. Very few cyanobacteria cells were found (Dolichospermum @ 1,000 cells/ml). While the bloom has dissipated, NHDES advises that lake-goers look out for green surface accumulations in the future. Keep in mind that pollen accumulations can also contain cyanobacteria. 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 June 2, 2021 and was removed on June 7, 2021.

Visit the NHDES Beach Program website for photos and more information about cyanobacteria.
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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.