By Sara Powers

(CBS DETROIT) – The Michigan Department of Human Health and Services warned Michiganders, and those visiting Michigan throughout the summer, to be aware of the harmful algal blooms.

File photo of and algae bloom | Algae coats rocks along the Lake Erie shoreline. (Photo by Aaron P. Bernstein/Getty Images)

Harmful algal blooms (HABs) form due to the rapid overgrowth of cyanobacteria, also known as blue-green algae.

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This bacteria is naturally found in rivers and lakes, but some cyanobacteria produce toxins, call cyanotoxins, which are harmful to humans and animals.

“Before going in the water, we recommend Michiganders look for visible algal blooms or scums on any lake, and that people and pets stay out of water in areas that look affected,” said Dr. Joneigh Khaldun, chief medical executive and chief deputy for health for Michigan Department of Health and Human Services. “If you may have had contact with or swallowed water with a HAB and feel sick, call your doctor or Poison Control at 800-222-1222. If symptoms are severe, seek emergency medical attention as soon as possible.”

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HABS typically happen in Michigan from May through October, and most commonly in August and September.

In 2020, 61 HABS in 35 different Michigan counties were reported.

For more information on HABs in Michigan, visit,

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