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Lack of rain worsens drought but limits algae blooms

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Blue Green Algae
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MADISON (WKOW) - It's that time of year when blue-green algae (cyanobacteria) blooms, but lack of rain may mean less blooms for southern Wisconsin lakes.

"When you say cyanobacteria, people tend to think, 'oh, bacteria, that's something I want to pay attention to,'" Director of Marketing and Communications for Clean Lakes Alliance Adam Soderstend said. "So cyanobacteria, which is blue-green algae's official term, closes the lake effectively. It's toxic to people, it's toxic to pets - it's not good."

Cyanobacteria is found in many bodies of water and can become dangerous when blooms appear, though not every bloom is dangerous. These bacteria are able to create toxins that can be harmful to animals and humans.

If exposed, through ingestion, inhalation or skin contact, humans may experience stomach pains, diarrhea, skin rashes or other illnesses. The toxins may kill pets, fish, and waterfowl if strong enough.

What drives the bacteria to bloom? According to Adam Soderstend, it's phosphorus along with sunshine. Runoff after heavy rains may bring in phosphorus which can be found in manure from livestock, leaf litter, and soil.

However, southern Wisconsin has seen a lack of rain. Each month after January, Madison has recorded less than normal rainfall amounts leading to drought conditions, as well as a lack of bacteria blooms in lakes.

"We have found time and time again, when we can control runoff, we can reduce cyanobacteria blooms," Soderstend said. "Drought years have proven - the years we haven't had rain - we've had far less beach closures due to cyanobacteria blooms. Breezy days and cooler water temperatures also help reduce these blooms. Blooms tend to thrive during hot days with little to no wind.

A handful of beaches have already had to close due to these blooms. Before heading to a beach in Dane County you can check its status here through Dane County Public Health, or here through Clean Lakes Alliance.

Blaise Keller

Meteorologist – WKOW TV Madison

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