State Issues Cyanobacteria Advisory for Swains Lake in Barrington, New Hampshire

A cyanobacteria bloom has been observed on Swains Lake, appearing in a variety of colors including green, yellow, blue, and white. An alert was initially shared to begin the communication on this bloom. Since then, conditions have reportedly worsened in some locations and have dissipated in others. Samples will be collected on June 3 and NHDES will update the details of this advisory. Advisories are issued when cyanobacterial cell concentrations exceed 70,000 cells/ml. While samples have not yet been collected, there have been several photos showing the severity of the blooms. As a result, the New Hampshire Department of Environmental Services (NHDES) has issued a cyanobacteria bloom 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. Updates will be posted June 3, 2021.

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 June 2, 2021 and will remain in effect until NHDES confirms that cell concentrations of the bloom have subsided.

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.