COVID-19 Community Levels Map Update, Dec. 8, 2022: The Centers for Disease Control and Prevention has listed Fairfield, Hartford, Litchfield, Middlesex, New Haven, Tolland, and Windham Counties in the Medium/Yellow category as part of its COVID-19 Community Levels Map. New London County is currently listed in the Low/Green category. Visit the CDC COVID-19 Community Levels Map for updates.

Blue Green Algae (Cyanobacteria)

Blue-green algae blooms have raised concerns in Connecticut and across the nation because these organisms can produce a wide array of neurotoxins, liver toxins, cell toxins and skin irritants.  In still and  warm summer waters, populations of blue green algae may increase to the extent that a normally clear surface can become thick and murky.  This overgrowth is called a “bloom”.  Blooms are considered harmful due to the potential to cause health effects in people and pets over-exposed to these organisms.


Facts about Cyanobacteria and Cyanobacterial Harmful Algal Blooms (CDC)


For more information, view the following resources:


Contact Information:

  • To Report a Bloom:  If you believe that you have observed an algae bloom contact your Local Public Health Department or the CT Department of Energy and Environmental Protection (860 424-3020), or send an email to
  • For Health Concerns: If you have questions about health effects or exposure concerns, contact the DPH Environmental Health Section's Public Beach Program (860 509-7758).


Circular Letters: