As the weather warms up, Madison residents flock to Lake Mendota, but algae blooms may limit recreational water use.

“I spend a lot of time on the lake, I’m on the UW women’s lightweight rowing, I’m a coxen,” UW-Madison junior Julisa Richart said.

Richart spends fifteen-to-twenty hours per week out on the water. For her, the water quality of Lake Mendota affects every day life. Rowing near algae blooms means taking special precautions.

“We’ll have to sanitize everything and people will have to immediately shower after practice,” Richart said.

Algae blooms occur yearly in Lake Mendota, and close beaches frequently in summertime.

“We know that spring phosphorus is a huge driver, so when you get all these precipitation events in April and May, you’re flushing a lot of the phosphorus that’s found in fertilizers off of the agricultural landscape,” UW-Limnology Researcher Caitlin Soley said.

Although the nature and location of Lake Mendota algae blooms changes every year, wind patterns and rainfall can help predict where or how they occur.

“It really depends on the environmental conditions. It’s not only just nutrient inputs, it’s also temperature—once we get higher temperatures that’s when you see more blue-green algal blooms,” Watershed Engagement Coordinator Katie Van Gheem said.

Clean Lakes Alliance, along with the UW-Madison Limnology Department, helps coordinate citizen monitoring programs, which allow lake-users to get involved in tracking, predicting and spreading awareness about algae blooms.

“People who recreate on the lakes should just be aware of what an algal bloom is, stay away from it if they do see one,” Van Gheem said.

“It’s definitely important for recreation, like for rowing and sailing and anything like that. Just because, even if you’re having fun on the water, even if you’re not directly swimming in it, it’s still in the back of your mind,” Richart said.

To find out more about potential algae blooms and beach conditions this summer, visit

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