It is summer:

As temperatures rise and the sun beats down hotter the conditions become ripe for algae blooms to occur in Minnesota lakes.  These blooms are toxic and dangerous for both humans and our companion animals.

What is it?

It is a harmful algal bloom. They are blue-green algae that contain toxins and noxious chemicals which can pose harmful health risks. 

Why worry?

It can cause skin irritation or upper respiratory problems.  In extreme cases it has caused death when dogs consume the lake water containing these toxins.

Where does it happen?

The severe blue-green algal blooms tend to occur in lakes with poor water quality and can look like green paint, pea soup or a thick green layer.  It tends to result in low water clarity and there is no visual way to tell if the particular bloom is toxic or not.

What to do if you see this on a lake?

People should avoid contact with the water and should not allow dogs to swim or drink from the lake.  It is still unknown what makes some blooms toxic and not others so avoiding all contact is best.

What does it look like?

It can be hard to distinguish blue-green algae from other algae by site.  It usually looks like pea soup or spilt green paint but it can take other forms as well. 

To learn more and to see pictures of blue-green algae and other things that look like it please visit:

Minnesota Pollution Control Agency