Cyanobacteria in Vermont

Cyanobacteria (also known as blue-green algae) are common native algae in lakes, ponds and rivers around the world.  In Vermont, they can be found in any water body or river.  Some species of cyanobacteria produce toxins and these toxins have been documented in some Vermont lakes.   Not all algae blooms include cyanobacteria and cyanobacteria aren’t always toxic. 

We can all safely swim, fish, and boat in Vermont’s lakes and ponds if we learn to recognize these algae.  The information here will help you know when it is best to find another place for your family or pets to enjoy the water.

Play it safe – learn to recognize and avoid these algae

To report a cyanobacteria bloom, call
1-800-439-8550 (the VT. Dept of Health)
Email after hours, weekends and holidays:  (Please provide photos if you can.)

The Department of Health identifies three categories of cyanobacteria conditions. The following links will provide more detail.

  1. Generally Safe - few if any cyanobacteria present,
  2. Low Alert - small amounts of cyanobacteria present, open for recreation using caution around cyanobacteria
  3. High Alert - large amounts of cyanobacteria present, not safe for recreation

Microscopic view of algae - link to 'What you should know about cyanobacteria'                                           Water with algae - link to 'What you should do if you see a bloom'                              


Close up of algae bloom - link to 'What causes cyanobacteria blooms?'                                          Leaves and water with algae - link to 'Learn More'


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