For Immediate Release: October 11, 2021

Media Contact:

Ben Truman │ Vermont Department of Health

802-316-2117 / 802-863-7281
[email protected] 

Cyanobacteria Blooms are Continuing into Fall
Watch for blooms if you or your pets are near Vermont waters

BURLINGTON, VT – Foliage season is in full swing and the summer heat is fast becoming a memory, but health officials want Vermonters to still be on the lookout for cyanobacteria blooms and avoid any they see.

“Cyanobacteria blooms most often occur in the summer months, but they have been reported as late as November in recent years,” said Bridget O’Brien, an environmental health scientist with the Department of Health. “People continue to be out enjoying the state’s waters, so it’s important to be aware that cyanobacteria may still be present, and to keep children and pets away from blooms along the shorelines.”

Cyanobacteria are tiny microorganisms that are a natural part of fresh water ecosystems. Under certain conditions – including warm, sunny weather – cyanobacteria can multiply quickly, creating blooms on the water’s surface that can wash up along shorelines. They can produce toxins harmful to humans and animals that may cause skin rashes, diarrhea, a sore throat, stomach problems, or more serious health problems. Children and pets are at higher risk because they are more likely to drink the water while swimming or playing, and pets may lick the cyanobacteria off their fur.

Climate change has increased water temperatures by 2°F to 7°F in Lake Champlain over the past 50 years and extended the warm season by several weeks. This and other factors provide favorable conditions for continued cyanobacteria blooms.

“If you come into contact with water that may contain cyanobacteria, rinse off as soon as possible,” said O’Brien. “If you get your drinking water from a lake or a pond, be sure to treat it. Don’t use untreated water for drinking, cooking, showering or bathing, or for brushing your teeth.”

O’Brien said it’s important to know what to look for. Blooms are usually green or blue-green and can often make the water look like pea soup or spilled paint, but they can be other colors and consistencies too. A video of cyanobacteria and photos of what is – and isn’t a bloom are available at

If you think you see a bloom, you can send in a report and upload photos to the Health Department using this online form. People heading to the water can check the Cyanobacteria Tracker map for where blooms have been reported – but remember that bloom conditions can and do change rapidly.

If you think you see a cyanobacteria bloom:

  • Avoid contact with the water.
  • Do not let children, pets or livestock swim in or drink the water.
  • If you come in contact with cyanobacteria, rinse off thoroughly as soon as possible.
  • Talk with your health care provider if you have concerns from possible exposure.

Learn more about cyanobacteria at

# # #

About the Department of Health
We have been the state's public health agency for more than 130 years, working every day to protect and promote the health of Vermonters.
Visit — Join us on Facebook — Follow us on Twitter

Last Updated: