The public health advisory for no swimming and boating at Pontoosuc Lake has been temporarily lifted as a result of lab analysis determining low levels of cyanobacteria in the lake. The advisory was issued on Friday, July 26, due to the state’s Department of Public Health identifying visual evidence of an algae bloom with the potential of cyanobacteria.
At this time, test results determine the levels of cyanobacteria fall well below the standard health-based threshold, according to the state’s Department of Public Health. Per the results, a sample with the highest level revealed 11,000 cells (of cyanobacteria) per milliliter versus the public health threshold of 70,000 cells per millileter which determines a public health risk.
Public Health Director Gina Armstrong says that despite the low levels of cyanobacteria, conditions may further the growth of algae bloom.
“Because the visual presence of algae does not automatically correlate to the presence of harmful cyanobacteria, continuous testing is necessary to monitor water safety,” said Armstrong. Lab testing and analysis will continue weekly, beginning this Wednesday, July 31, to monitor water safety. In the event cyanobacteria levels rise to a harmful threshold, the public health advisory will be immediately reinstated, she said.
Algae blooms can change the water’s appearance from slightly discolored to resembling pea soup or thick paint. Blooms frequently appear blue or green but could be another color, such as brown or red. You cannot tell if a bloom has toxins by looking at it. Algae blooms can also give the water a bad odor or taste.
For additional information, the public is encouraged to visit the following websites:
- Massachusetts Department of Public Health: www.mass.gov/dph/algae
- Massachusetts Department of Environmental Protection: https://www.mass.gov/guides/cyanobacterial-harmful-algal-blooms-cyanohabs-water
- U.S. Centers for Disease Control and Prevention: https://www.cdc.gov/habs/index.html
- U.S. Environmental Protection Agency: www.epa.gov/cyanohabs