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New Hampshire Department of Environmental Services

Media Center

DATE: June 20, 2018
CONTACT: Amanda McQuaid (603) 271-0698 (O), 848-8094 (C)

State REMOVES Cyanobacteria Beach Advisory and Lake Warning for Elm Brook Park Beach in Hopkinton

Concord, NH – The New Hampshire Department of Environmental Services (DES) has REMOVED a cyanobacteria lake warning issued on 6/12/2018. Samples collected June 12 revealed that the state threshold of 70,000 cells/ml or greater of cyanobacteria was exceeded. This waterbody is monitored by the Army Corp of Engineers and observations were made at the boat launch, beach and fishing platform. The cyanobacteria were identified as Anabaena/Dolichospermum, Microcystis and Woronichinia.

Samples collected from the beach on June 20, 2018 had no visible signs of cyanobacteria and the cell concentration was 0 cells/ml. Please continue to monitor your individual shoreline 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 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 June 12, 2018, and was removed on June 20, 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.

Cyanobacteria blooms have cleared from Elm Brook Park in Hopkinton, NH. The advisory began on 6/12/2018 and was removed 6/20/2018.

Cyanobacteria blooms have cleared from Elm Brook Park in Hopkinton, NH. The advisory began on 6/12/2018 and was removed 6/20/2018.

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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