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 waterbody or river during the warmer months of the year.  Some species of cyanobacteria produce toxins and these toxins have been documented in some Vermont waters.  Specialized tests are required to tell whether a particular occurrence of cyanobacteria is actually producing toxins.

The Water Quality Division has worked with the Vermont Department of Health and the University of Vermont to develop protocols for responding to cyanobacteria.  While most occurrences of cyanobacteria associated with toxins have been on Lake Champlain, toxins have been detected in other waterbodies around the state.  The current status of cyanobacteria on Lake Champlain and other lakes, information on identifying possible cyanobacteria, and sources of assistance can be found at the Department of Health webpage:

(http://healthvermont.gov/enviro/bg_algae/bgalgae.aspx).

Identifying Algae that may pose a risk of toxins

Because of the large number of water bodies and the ecology of these organisms, we depend on our staff and the public to inform us of possible cyanobacteria blooms.  A visual assessment of algal abundance is made by the collector and a microscopic examination confirms whether potentially toxic cyanobacteria are present.  Toxin testing is conducted if densities of potentially toxic cyanobacteria are high.  Appropriate warnings and closures are then issued by the Health Department or local officials.  Monitoring and testing continue if the algae persist.

Important basic information

Research on Lake Champlain and elsewhere has shown that high toxin levels which may pose health risks are associated with high algae density (a “bloom”).  Thick surface scums, cloudy green water and foamy shorelines are all indicators of a high density bloom.

• Surface scums can develop and dissipate in a matter of hours.  Cyanobacteria rise to the surface on sunny calm windless days or in protected areas with less wind and wave activity.   A change in wind direction or strength will mix them back into the water.
• Pets and livestock are most likely to encounter cyanobacteria toxins because of their behavior.  Dogs are not particular about what they eat and drink or where they swim.  Livestock may only have one source of water.  Both groups consume large amounts of water.  In Vermont, there have been dog deaths due to cyanobacteria on Lake Champlain. 
• While people are affected by cyanobacteria toxins, most people avoid swimming in or drinking from noticeably green scummy water.  People can become ill after exposure to cyanobacteria, but there have been few recorded deaths.  Young children may be most at risk because, like pets, they are often not particular about what they eat and drink or where they swim. 

Cyanobacteria are present in most waters in the United States, but are usually not a cause for concern. Become familiar with the visual signs of high algae density noted on the Vermont Department of Health webpage.  Keep children and pets out of these areas. Report them to local officials for possible testing.

Vermont Water Quality Division (802) 241-3777

Vermont Department of Health 1-800-439-8550

For more information:

Lake Champlain Basin Program http://www.lcbp.org/bgalgae.htm

Vermont Department of Health http://healthvermont.gov/enviro/bg_algae/bgalgae.aspx

North American Lake Management Society http://www.nalms.org/Resources/BlueGreenInitiative/Overview.htm

New Hampshire Department of Environmental Services http://www.des.state.nh.us/Beaches/cyanobacteria.html