skip navigation
New Hampshire Department of Environmental Services

Media Center

DATE: September 26, 2018
CONTACT: Amanda McQuaid (603) 271-0698 (O), 848-8094 (C)

State REMOVES Cyanobacteria Lake Warning for Danforth Bay in Freedom, NH

Concord, NH – The New Hampshire Department of Environmental Services (DES) has REMOVED a cyanobacteria lake warning issued for Danforth Bay on 8/24/2018. An advisory was first issued on August 16 when accumulations occurred along shorelines of Danforth Bay. Samples were collected (by volunteers) from various shorelines and beaches and delivered to NHDES. The samples had ranging cyanobacterial cell concentrations, from thousands to millions of cells/ml of Oscillatoria and Anabaena/Dolichospermum. Follow-up samples were collected 8/22/2018 and inspections were made by the Green Mountain Conservation Group (GMCG). Samples were collected along Danforth Bay, Broad Bay, and Lake Ossipee. All samples were clear of cyanobacteria blooms with very few colonies of Aphanocapsa found in Lake Ossipee. The bloom had seemingly dissipated in Danforth Bay, but resurfaced on August 24, 2018. The advisory was reissued and samples were again collected by Green Mountain Conservation Group on August 29. Samples from shorelines of Danforth Bay contained millions of cells of (primarily) Oscillatoria. Samples were also collected from Danforth (lower) Pond, Broad Bay, Leavitt Bay, Berry Bay and Lake Ossipee. The warning was only issued for Danforth Bay. Through weekly observations by local volunteers and GMCG, it was reported that the bloom was still present. Samples were finally collected on September 25 by NHDES Volunteer Lake Assessment Program staff. There was no evidence of cyanobacteria in grab samples from Danforth Bay. The advisory has been removed 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 24, 2018, and was removed on September 26, 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

copyright 2017. State of New Hampshire