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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 Warning for Winter Harbor on Lake Winnipesaukee in Wolfeboro, New Hampshire

Concord, NH – A cyanobacteria bloom has been observed along shorelines of Winter Harbor on Lake Winnipesaukee in Wolfeboro, New Hampshire. Based on visual evidence, the bloom is accumulating along shorelines, appearing as tiny spots in the water. This is a unique cyanobacteria bloom called Gloeotrichia, appearing as small, fuzzy balls in the water. Each colony may contain about 5,000 cells. As a result, the New Hampshire Department of Environmental Services (NHDES) has issued a cyanobacteria warning for those who use this area of the waterbody for recreation. It is also advised to look out for accumulations in other areas of the lake or shorelines. Please continue to monitor your individual shorelines 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 30, 2018, and will remain in effect until additional samples reveal cyanobacteria levels have diminished.

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 bloom at Winter Harbor on Lake Winnipesaukee in Wolfeboro, New Hampshire

A cyanobacteria bloom of Gloeotrichia has been observed along Winter Harbor on Lake Winnipesaukee in Wolfeboro, NH this week (August 30, 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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