On Friday, July 14, 2023, the New Hampshire Department of Environmental Services (NHDES) has identified the presence of cyanobacteria in Mascoma Lake during routine monitoring activities. A recent sample collected revealed density of cyanobacteria, measuring 100,800 cells per milliliter (cells/mL). It is important to note that advisories are issued when cyanobacteria cell counts reach 70,000 cells/mL.
While the current cyanobacteria density does reach the health advisory level, our drinking water supply is under no present threat. The bloom occurred on the South side of Mascoma Lake, far away from the lake outfall.
At any point during periods of hot and dry weather, coupled with low wind conditions, cyanobacteria blooms are more likely to occur and become visible. These blooms can manifest as greenish patches or surface scums on the lake's water.
To ensure public safety, NHDES advises residents and visitors to Mascoma Lake to adhere to the following precautions:
• Do not wade or swim in the water, particularly near surface blooms.
• Refrain from drinking the lake water and avoid using it for domestic purposes.
• Prevent pets or livestock from entering or approaching the water, as they are particularly vulnerable to toxic cyanobacteria.
• For more information and to report any sightings of a cyanobacteria bloom, you can contact NHDES through their website. For update advisories, you can also visit their Healthy Swimming Mapper on their website.
Authorized by: Chief Phillip J. Roberts Date: 7/14/2023