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New Hampshire Department of Environmental Services

Media Center

DATE: July 17, 2018
CONTACT: Amanda McQuaid (603) 271-0698 (O), 848-8094 (C)

State REMOVES Cyanobacteria Lake Warning for Post Pond in Lyme, NH

Concord, NH – The New Hampshire Department of Environmental Services (DES) has REMOVED a cyanobacteria lake warning issued on 6/29/2018. A Beach advisory and lake warning was issued on 6/29 due to visual evidence of a bloom accumulating at Chase Beach on Post Pond. The bloom quickly dissipated the same day. Samples were collected from the beach on July 3, 2018 and no cyanobacteria cells were observed. Samples collected along Post Pond Lane revealed that the state threshold of 70,000 cells/ml or greater of cyanobacteria was exceeded in other areas of the pond. The cyanobacteria were identified as Anabaena/Dolichospermum at 78,290 cells/ml. As of July 3, the beach advisory for Chase Pond was removed, but the lake warning remained in effect. Samples were collected July 12, 2018 again at the beach, boat launch, and 3 sites along Post Pond Lane. The highest concentrations observed were only 3,750 cells/ml. Since July 12, no blooms have been observed in the pond. 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 29, 2018, and was removed on July 17, 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.

The cyanobacteria lake warning for Post Pond in Lyme, NH was issued July 29, 2018 and removed on July 17, 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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