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New Hampshire Department of Environmental Services

Media Center

DATE: June 17, 2020
CONTACT: Amanda McQuaid (603) 271-0698 (O), 848-8094 (C)

State Issues Cyanobacteria Advisory for Baboosic Lake in Amherst/Merrimack, New Hampshire

Cyanobacteria blooms at Baboosic Lake

Concord, NH- A cyanobacteria bloom has been observed on Baboosic Lake. Samples were collected on June 17, 2020 at approximately 11 am. The accumulation appeared as green clouds mixed with pollen nearshore and at the main beach. Samples contained Anabaena (Dolichospermum), Oscillatoria and Woronichinia (cyanobacteria). Cell concentrations were 516,000 cells per milliliter of lake water at the beach.  Advisories are issued when cyanobacterial cell concentrations exceed 70,000 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.

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 17, 2020 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 at:
Updates on cyanobacteria advisories may be obtained at:
Follow the Beaches twitter feed:

If you notice anything resembling cyanobacteria, please refrain from recreating in bloom water and DO NOT drink the water. Keep pets and children out of the water and contact NHDES immediately. Call NHDES to report a cyanobacteria bloom at (603) 848-8094 or email



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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
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