For Immediate Release: July 2, 2019

Media Contact:
Ben Truman
Vermont Department of Health
802-951-5153 / 802-863-7281


As Vermont Waters Warm Up, Know and Watch for Cyanobacteria

BURLINGTON, Vt – Warm weather is a welcome sign of summer, but it also creates ideal conditions for cyanobacteria to grow in Vermont waters. Cyanobacteria (sometimes referred to as blue-green algae) are tiny microorganisms. In large numbers they sometimes form blooms on the water’s surface and wash up along shorelines — and can produce toxins harmful to humans and animals.

Because State and volunteer citizen monitors have already started to see cyanobacteria blooms forming in Mallets Bay and Missisquoi Bay in Lake Champlain, officials want people to know how to identify a bloom, and to avoid contact with cyanobacteria. Swimming or wading in water with cyanobacteria may cause skin rashes, diarrhea, a sore throat, stomach problems, or more serious health concerns.

“The best way to protect yourself is to know what a bloom looks like, and to stay out of the water when one is present,” said Bridget O’Brien, radiological and toxicological analyst with the Vermont Department of Health. “Blooms are usually green or blue-green and can make the water look like pea soup or spilled paint, but they can be other colors and consistencies too.”

See a video of cyanobacteria and photos of what is – and isn’t a bloom: 

O’Brien said that it is important for people to be mindful of their children when cyanobacteria is present. “It can be difficult, especially on a really hot day,” said O’Brien, “but kids tend to play along the shore where cyanobacteria accumulate, and drink the water when they swim.” O’Brien said pet owners also need to take care. “Dogs are especially vulnerable to the toxic effects of blooms because they will drink the water, lick bloom residue off their fur and eat cyanobacteria scum from the shore.”

“If you think you see a bloom, or even if you are not sure, it’s best to stay away and find a new place to play,” said O’Brien.

“We want everyone who is out enjoying Vermont’s recreational waters to be able to recognize, avoid and report cyanobacteria,” said Lori Fisher, executive director of the Lake Champlain Committee (LCC), which trains and oversees dozens of citizen volunteer water monitors each year.

Volunteer monitors report their findings, which are logged to the Health Department’s Cyanobacteria Tracker map. This interactive tool allows the public to check conditions along Lake Champlain and various inland lakes in Vermont, including recreational swimming areas. Sites are identified as "Generally Safe," "Low Alert" or "High Alert." The Health Department also posts a weekly summary of conditions. Members of the public can also submit their bloom sightings.

If you think you see a cyanobacteria bloom:

  • Avoid contact with the water.
  • Do not let pets or livestock swim in or drink the water.
  • Read and obey posted signs at beaches.
  • Report blooms to beach managers, town health officers or to the Health Department.

If you come in contact with cyanobacteria, rinse yourself off thoroughly as soon as possible. Talk with your health care provider if you have concerns from possible exposure.

To report a bloom, email [email protected]. Send photos of the bloom if you can, and an image of a map or description noting the location of the bloom or the closest street address.

Along with LCC, the Health Department works with the Department of Environmental Conservation, other state agencies, the Lake Champlain Basin Program, recreational site managers, town health officers and drinking water system operators to monitor and track cyanobacteria.

“The State of Vermont is working to reduce the amount of nutrients and other pollutants reaching our lakes and ponds, which can feed cyanobacteria and other algae,” said Angela Shambaugh, aquatic biologist for the Department of Environmental Conservation. “Cyanobacteria is an ongoing concern. The good news is there are things each of us can do in our backyards – no matter where we live – to keep the nutrients that feed cyanobacteria on the land and out of the water.”

To learn more about Vermont’s clean water activities, listen to the DEC’s Clean Water Lectures or follow the Watershed Management Division's blog.

If you are interested in becoming a volunteer monitor or learning how to identify cyanobacteria, email the Lake Champlain Committee at [email protected].

Learn more about cyanobacteria and what you can do:

For more tips and information about staying healthy while enjoying summer in Vermont:

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