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New Hampshire Department of Environmental Services

Media Center

DATE: August 30, 2018
CONTACT: Amanda McQuaid (603) 271-0698 (O), 848-8094 (C)

State Issues Cyanobacteria Lake Warning for Danforth Bay in Freedom, New Hampshire

Concord, NH – A second cyanobacteria bloom has been reported on Danforth Bay in Freedom, New Hampshire. Based on visual evidence reported August 15 and again August 24, the cyanobacteria bloom was accumulating along shorelines and coves, appearing as blue-green scums, flecks and patches. Others have described bright green clouds throughout the waterbody. The first advisory was removed on August 22 as the bloom quickly dissipated. The current bloom was reported to resurface August 24 and noted to be more widespread than first observed. The bloom may disperse and move through the connecting waterbodies of Danforth Bay (Broad Bay or Lake Ossipee). Samples were collected by Green Mountain Conservation Group and the Volunteer Lake Association on August 29, 2018. Cyanobacteria were identified as Oscillatoria and Anabaena/Dolichospermum. Cyanobacteria cell concentrations ranged from thousands to over one million cells per milliliter in some of the worst parts of the bloom collected along shorelines. Samples were collected from the deeper areas of the bay, indicating very few colonies of a different species of cyanobacteria, Microcystis. NHDES issues lake warnings when cell concentrations are greater than 70,000 cells/ml. As a result, the New Hampshire Department of Environmental Services (NHDES) has issued a cyanobacteria lake warning for those who use the waterbody for recreation. The bloom can come and go quickly and tends to be patchy. It is advised to avoid contact with the bloom. Please continue to monitor your individual shoreline for changing conditions.

This warning is not based on a toxin evaluation and is intended as a precautionary measure for short term exposure. 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. 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 but 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.

The warning went into effect on August 24, 2018, and will remain in effect until additional samples reveal cyanobacteria levels have diminished. NHDES will sample weekly to monitor the bloom on this waterbody.

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

cyanobacteria bloom at Danforth Bay in Freedom, New Hampshire

Cyanobacteria blooms have resurfaced on Danforth Bay in Freedom, NH since August 24, 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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