Concord, NH - The New Hampshire Department of Environmental Services (DES) has issued a cyanobacteria lake warning for those who recreate on Downing Pond in New Durham, NH, due to extensive bluish-green cyanobacteria seen throughout the pond. The entire pond appears to have cloudy greenish-blue water with small masses of green floating in the water. The cell concentration of cyanobacteria was estimated to be 120,000 cells of cyanobacteria/ml of water. The state standard for cyanobacteria is 70,000 cells/ml of water. Direct contact with the water is discouraged. Please continue to monitor your individual shoreline for changing conditions.

This warning is intended as a precautionary measure to prevent short term exposure to cyanobacteria toxins and is based on microscopic analysis of the water. DES advises lake users to avoid contact with the water in areas experiencing a surface scum or blue-green clouds. DES also advises pet owners to keep their pets out of water that has a surface scum or blue-green clouds.

DES routinely monitors public beaches and public waters of the state for cyanobacteria. Once a cyanobacteria warning has been issued, DES returns to affected waterbodies on a weekly basis until the cyanobacteria bloom is not evident. Cyanobacteria are natural components of water bodies worldwide, but blooms and surface scums may form when excess phosphorus is 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, nausea, vomiting, and diarrhea. Chronic effects include liver and central nervous system damage.

The June 30, 2016 warning will remain in effect until additional samples reveal cyanobacteria levels have diminished. The pond will be resampled late in the week of July 4.


Posted 6/30/16