Learn How to Spot Cyanobacteria Blooms This Summer

Learn How to Spot Cyanobacteria Blooms This Summer
The bacteria can grow in lakes and ponds as water warms, posing health risks

WATERBURY, VT — As you get ready to swim and play in Vermont’s lakes and ponds this summer, state health and environmental officials are offering tips on how to check the water for cyanobacteria blooms that can harm your health.

Cyanobacteria – sometimes called blue-green algae – are microorganisms that live in natural waters. Under certain conditions, these bacteria can collect into a bloom that can lead to skin rashes, diarrhea, sore throat, stomach problems and more serious issues.

What a cyanobacteria bloom looks like

Cyanobacteria blooms:

• Become visible as a layer on top of the water or shoreline.
• 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.
• Do not have leaves.

What to do if you think you’ve spotted a cyanobacteria bloom

• Avoid contact with the water. If you come in contact with it, rinse off thoroughly as soon as possible.  
• Talk with your health care provider if you experience symptoms or are concerned about possible exposure. 
• Do not let pets or livestock swim in or drink the water as they are at higher risk for serious illness.

“Cyanobacteria blooms can produce harmful toxins, so if you see a bloom, it’s best to stay out of the water,” said Bridget O’Brien, an environmental health scientist at the Health Department. “Exposure to water during a bloom is especially dangerous for kids, pets and other animals that might accidentally swallow it.”

People can report possible blooms to a beach manager, local Town Health Officer and on the state’s cyanobacteria tracker. Because not all locations can be monitored and the tracker’s online map does not show real-time conditions at your favorite swimming area, it’s important to know how to spot a bloom in the water. 

“Reports about bloom conditions submitted by volunteers and the public have been invaluable for understanding where blooms occur in the region, which can allow us to target monitoring efforts and remediation measures," said Peter Isles, an aquatic biologist with the Department of Environmental Conservation.

The Health Department and the Department of Environmental Conservation work closely with the Lake Champlain Committee, which trains volunteers around the state to monitor Lake Champlain and other bodies of water for cyanobacteria blooms. Email [email protected] to get involved.

Learn more about cyanobacteria and see a video and photos of what is – and isn’t – a cyanobacteria bloom: HealthVermont.gov/Cyanobacteria, and find translated information including “Cyanobacteria Alert” and “Beach Closed” signs in 12 languages.

Get more tips for having a fun, safe and healthy summer at HealthVermont.gov/summer-safety-tips.

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About the Department of Health

We have been the state's public health agency for more than 140 years, working every day to protect and promote the health of Vermonters. Visit HealthVermont.gov ─ Join us @HealthVermont on Facebook, Instagram, YouTube and WhatsApp.

About the Department of Environmental Conservation

The Department of Environmental Conservation is responsible for protecting Vermont's natural resources and safeguarding human health for the benefit of this and future generations. Visit dec.vermont.gov and follow the Department of Environmental Conservation on Facebook and Instagram