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New Hampshire Department of Environmental Services

Media Center

DATE: August 8, 2018
CONTACT: Amanda McQuaid (603) 271-0698 (O), 848-8094 (C)

State REMOVES Cyanobacteria Lake Warning and Beach Advisory for Greenwood Pond in Kingston, NH

Concord, NH – The New Hampshire Department of Environmental Services (DES) has REMOVED a cyanobacteria lake warning issued on 7/5/2018. The advisory was issued based on visual evidence of accumulations of cyanobacteria around the pond, appearing as dark blue-green globs throughout the water. The state threshold for posting advisories is 70,000 cells/ml of cyanobacteria. Samples collected 7/6/2018 contained Oscillatoria at over 19 million cells/ml. Other types of cyanobacteria were Woronichinia and Anabaena/Dolichospermum at 175,000 and 4,000 cells/ml, respectively. Samples collected from Greenwood Pond Beach on July 13, 2018 had no visible accumulations of cyanobacteria. There were no cells of cyanobacteria in samples collected near the beach, though green accumulations were observed at other areas of the pond. Samples were collected from the middle of the pond on 7/18 and Oscillatoria were enumerated to be 92,500 cells/ml. Samples were again collected from the beach on 7/25 and there was no sign of cyanobacteria from this location. Later that day, reports of the green globs were again observed. Samples were collected again on August 8, 2018 and there were no signs of cyanobacteria at the lake, near the beach. Please continue to monitor your individual shorelines for changing conditions.

Cyanobacteria are natural components of water bodies worldwide, but blooms and surface scums may form when excess nutrients are available to the water. Some cyanobacteria produce toxins that are stored within the cells that can be 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 include liver and central nervous system damage. 

NHDES advises lake users to avoid contact with the water in areas experiencing elevated cyanobacteria cell conditions typically where lake water has a surface scum, green streaks or blue-green flecks or globs aggregating along the shore. NHDES also advises pet owners to keep their pets out of any waters that have a cyanobacteria bloom.

NHDES routinely monitors public beaches and public waters of the state for cyanobacteria. Once a cyanobacteria lake warning or beach advisory has been issued, NHDES returns to affected waterbodies on a weekly basis until the cyanobacteria standards are again met.

The warning went into effect on July 5, 2018, and was removed on August 8, 2018.

Visit the NHDES Beach Program website for photos and more information about cyanobacteria at
Updates on advisories and warnings may be obtained at
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.

NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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