Toxic algae were spotted on Lake Mendota near the University of Wisconsin campus and in Lake Waubesa, according to a release from UW officials.
Officials said cyanobacteria, or blue-green algae blooms, were spotted Tuesday in the area of Memorial Union and Hoofers.
The public is urged to avoid contact with the algae and not swim at night when the blooms can?t be seen.
The algae blooms occur when there is little wind and hot temperatures combined with lake nutrients.
Symptoms of a reaction to algae blooms include eye, throat, nose or skin irritation, and vomiting or diarrhea. These symptoms can happen between several hours and a few days after being exposed.