Manchester, NH – The City of Manchester Health Department announced today that the public beach at Crystal Lake remains closed to swimming due to a confirmed cyanobacteria bloom.
The cyanobacteria bloom was observed during routine water sampling and confirmed via laboratory analysis, in water samples taken on Monday June 30, 2025. Follow-up samples collected on July 7, 2025 are still above acceptable levels. Thank you to the New Hampshire Public Health Laboratory for their assistance with this expedited testing.
A cyanobacteria bloom is an excessive growth of cyanobacteria capable of producing toxins harmful to human and animal health. Cyanobacteria blooms can appear in various unusual colors and shapes, and the NH Department of Environmental Services advises the public to avoid contact with water that appears “scummy”, turbid, colorful, globular, or has concentrated flecks or specks.
Avoid all contact with bloom material or with water, including swimming, wading, kayaking, and other recreational activities in the vicinity of a bloom. Keep pets and livestock away from the water in the vicinity of a bloom. For more information about blooms click here.
The Crystal Lake public beach will remain closed until there is no visible evidence of a bloom and follow-up samples are within acceptable limits. The Manchester Health Department will be re-assessing the area on Monday and will collect samples as part of our routine water sampling activities.
The Health Department will issue a press release when the new results are available.