On Wednesday, Sept. 7, the Minnesota Pollution Control Agency (MPCA) and Minnesota Department of Health(MDH) collected and analyzed water samples from a small bay on the west side of Riley Lake in Eden Prairie in response to a report of a dog becoming ill after swimming in the lake the previous weekend. Test results confirmed the lake did experience a harmful blue-green algae bloom.
Blue-green algae are a type of bacteria present at low levels in many Minnesota lakes and ponds. When water is stagnant, warm and rich in nutrients — especially phosphorus — bacteria can grow quickly, forming what are called “blooms.” These blooms typically look like pea soup or bright green paint. They can also produce a strong, swampy odor as the bacteria breaks down.
Not all blue-green algae are harmful, but there is no way to determine if a waterbody is toxic just by looking at it. If there is algae visible in a body of water or if the water clarity is less than 3-feet deep, it is best to be cautious and avoid contact. Pets are particularly susceptible because they tend to swallow more water than humans while swimming. It is always a good practice to shower or rinse off after wading or swimming in lakes.
Click on the following links for more information from the MDH and MPCA about blue-green algae and how to report potential blooms.