Check for Cyanobacteria Blooms Before Swimming in Lakes & Ponds
By Bridget O’Brien, MSPH, Senior Toxicological/Radiological Analyst, Vermont Department of Health
Cyanobacteria, also known as blue-green algae, are naturally found in Lake Champlain and other Vermont lakes and ponds. Some types of cyanobacteria can produce toxins, or poisons, that can be harmful to humans and animals.
It is important to know what cyanobacteria blooms look like so you can check the water before swimming and make other plans if you think you see a bloom. Blooms most commonly look like green pea soup or spilled paint on the water’s surface. They are usually green or blue-green in color, but they can also be brown, purple, red, or white. Blooms often start to form at the edge of the water where the water is warm and shallow.
Cyanobacteria blooms can produce harmful levels of toxins, so if you see a bloom, don’t swim, wade, or boat in the area and don’t let pets or livestock swim in or drink the water.
You can be exposed to cyanobacteria and their toxins from swimming and playing in the water with blooms, or even drinking surface water that hasn’t been treated properly. The health effects from cyanobacteria depend on the amount someone is exposed to, how they are exposed, whether toxins are being produced, and the type of toxin.
Swallowing water with toxins, including while swimming, may cause stomach problems like abdominal pain, diarrhea, or vomiting, or neurological symptoms like numb lips, tingling fingers and toes, or dizziness. Touching or breathing in droplets of water with cyanobacteria may result in skin, eye, nose, or throat irritation.
Because dogs and other animals will drink discolored water and lick scum off their fur, they can get very sick if they go in or drink water with a cyanobacteria bloom.
If you realize you or your pet has been in contact with a cyanobacteria bloom, rinse off with clean water and contact your health care provider if you feel sick or veterinarian if your pet is experiencing symptoms.
To see where blooms have recently been reported, view photos and a video of what cyanobacteria blooms look like, or to report suspected blooms to the Health Department, visit: www.healthvermont.gov/cyanobacteria