December 22, 2021 – Commissioner’s order: Out of state licensed providers should read this memo from DPH Commissioner Manisha Juthani, MD and note the list of professions authorized by the Commissioner’s order

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: