Submitted photo

By Tim Nelson, Land Services Director of Cook County MN - August 6, 2021

Tim Nelson, Land Services Director, Photo: Submitted 

There has been an increase of Algae blooms in some of our inland lakes this summer due to the warm weather and water conditions, and the increase in blue-green algae has been particularly noticeable.   With the increase in blooms, there has also been an increase of concerns as to how that might affect our health and safety associated with the use of the lake water.  At the local level of Government, Cook County is also concerned about the potential adverse impacts that the algae blooms may have on environmental health.  Since we do not have the local expertise regarding the testing and impacts of these algae blooms, we have been consulting with the Minnesota Department of Health (MDH) and the Minnesota Pollution Control Agency (MPCA).  The following are some excerpts from the MPCA web page regarding “Harmful Algae Blooms” or HAB’s:

When temperatures climb and the summer sun beats down, conditions are ripe for Minnesota lakes to produce harmful algae blooms, some of which can be harmful to pets and humans.  Blue-green algal blooms are often described as looking like pea soup or spilled green paint. However, blooms aren’t always large and dense and can sometimes cover small portions of the lake with little visible algae present. Blooms can also produce a swampy odor when the cells break down.  Blue-green algae blooms are harmful when they produce toxins that can make humans and animals sick. Most blooms are not harmful. 

You can't tell by looking at a bloom if it is harmful or not, but the MPCA suggests performing two simple tests, the “jar test” or the “stick test,” using rubber or latex gloves. To perform the jar test, fill a jar about three-quarters full and screw a lid on, then refrigerate undisturbed overnight. If, the next morning, the algae have settled near the bottom, it’s likely the lake does not have a lot of blue-green algae. If the algae have formed a green ring at the top of the water, there is a strong possibility the lake does have a blue-green algae community. For more detailed directions, and to learn about the “stick test,” see https://www.pca.state.mn.us/sites/default/files/wq-swm1-04.pdf