All five Yahara lakes saw cyanobacteria (blue-green algae) blooms throughout the summer of 2019. One bloom in particular on Lake Mendota was quite large, covering at least an area from Picnic Point to the Memorial Union on August 1st. The bloom was well-documented by photos from community members as having a green pea soup-like consistency.
Cyanobacteria blooms are often bright green, but can also appear in shades of brown, blue, and white. Typically, blooms are spotted on warm days with calm winds. On August 1st, Madison reported a high of 81 degrees with an average wind speed of two miles per hour.