BERLIN — The N.H. Department of Environmental Services has removed a cyanobacteria advisory for Jericho Lake issued on Aug. 15.

The cyanobacteria were identified, containing mostly Anabaena/Dolichospermum. The bloom quickly dissipated and samples on Monday revealed that the bloom is no longer present at the beach area. 

The state advises continued monitoring of the shoreline for changing conditions.

DES monitors public beaches and public waters of the state for cyanobacteria. Once a cyanobacteria advisory has been issued, the department returns to affected waterbodies weekly until the cyanobacteria standards are again met. DES advises lake users to avoid contact with the water in areas experiencing elevated cyanobacteria cell conditions. DES also advises pet owners to keep their pets out of any waters that have a cyanobacteria bloom.

This advisory was not based on a toxin evaluation and was intended as a precautionary measure for short-term exposure.

Cyanobacteria are natural components of water bodies worldwide, though blooms and surface scums may form when excess nutrients are available to the water.

Some cyanobacteria produce toxins that are stored within the cells and 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 may include liver and central nervous system damage. Be cautious of lake water that has a surface scum, changes colors or appears to have green streaks or blue-green flecks aggregating along the shore.

The advisory went into effect on Aug 15 and was removed on Aug. 20.

Go to 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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