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New Hampshire Department of Environmental Services

Media Center

DATE: September 11, 2018
CONTACT: Amanda McQuaid (603) 271-0698 (O), 848-8094 (C)

State REMOVES Cyanobacteria Lake Warning for Hothole Pond in Loudon/Concord, NH

Concord, NH –The New Hampshire Department of Environmental Services (DES) has REMOVED a cyanobacteria lake warning for Hothole Pond issued on 8/17/2018. NHDES has been monitoring this waterbody throughout the summer in an effort to track the onset of cyanobacteria blooms in Hothole Pond. Volunteers have also been monitoring this waterbody carefully. Samples collected from the deep area of the pond on August 15 revealed a bloom of Anabaena/Dolichospermum estimated to be 194,000 cells/ml. Follow-up sampling on August 27, August 31 And September 7 indicated that the bloom was subsiding, however shoreline accumulations were still occurring. Cyanobacteria cell counts had declined from 194,000 cells/ml on August 15, to roughly 30,000 cells/ml on August 27, to 18,000 cells/ml on August 31, to around 6,000 cells/ml on September 7. NHDES has lifted the warning at this time. 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 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 August 17, 2018, and was removed on September 11, 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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