Blue-green Algae
When in doubt, stay out!
Algal blooms are a normal part of lake ecology. However, excess nutrients and warm temperatures can result in abundant algae growth and more frequent algal blooms. Certain kinds of algae called blue-green algae (technically known as cyanobacteria) have the potential to produce toxins dangerous to humans and pets. When toxins are produced, they are called harmful algal blooms (HABs).
How to identify a bloom
Many kinds of algae may be found in a lake. Most people are familiar with filamentous algae which resembles long strands of fuzzy green hair and can be easily picked up. Phytoplankton is another type of algae that can’t be seen with the naked eye but, when abundant, can make the water look greenish brown. Both filamentous algae and phytoplankton can be a recreation nuisance but are usually harmless.
If you observe what looks like spilled paint or pea soup in the water, you are likely seeing a blue-green algal bloom. Blue-green algae may produce toxins dangerous to people and pets.
What to do if you see a blue-green algal bloom
Not all blue-green algal blooms produce toxins, but the potential exists. It’s best to avoid or minimize recreation time in areas with blooms. The Minnesota Department of Health’s guidance is “When in doubt, stay out.”
If you come into contact with a suspected blue-green algal bloom, rinse off immediately with fresh water. The same goes for pets. Don’t allow a dog to drink algae-laden water or lick their fur after contact. Seek medical assistance for symptoms such as diarrhea; vomiting; skin, eye, or throat irritation; or difficulty breathing.
Report blue-green algal blooms
If you suspect a blue-green algal bloom, report it to the city’s recreation department or the watershed district. Staff will coordinate to investigate and issue an advisory if warranted.
Also consider reporting the sighting to the bloomWatch app, which can be downloaded from the EPA at https://www.epa.gov/habs/bloomwatch.
What about testing for blue-green algae?
There is no clear and consistent method to predict a blue-green algae bloom. A bloom can appear and quickly dissipate anywhere in a body of water, making it difficult to track or test for toxins. Preventing exposure to blue-green algae is the most effective way to prevent illness.
Suspect a blue-green algae bloom? When in doubt, stay out!