Harmful Algal Blooms (HABs)

There are different types of naturally occurring algal blooms that may be seen on lakes and rivers. Most are not harmful. However, there are some that are made of cyanobacteria that have the ability to produce toxins, causing a harmful algal bloom (HAB).

HABs form due to a rapid growth of cyanobacteria, also called blue-green algae, which are naturally found in lakes, rivers and ponds. Toxins found in cyanobacteria (cyanotoxins) that can be found in blooms can be harmful to people and animals. 

To help the public know where HABs have been reported, a Michigan Harmful Algal Bloom Reports map is available online at Michigan.gov/HABsMap.

What should people do if they think they have found a HAB? 

If people think they have found a HAB or have any suspicion of a HAB: 

  • Do not let people, pets or livestock in the water or near the shore in affected areas. 
  • Always rinse off people and pets after contact with any lake water. 
  • If there is a posted HAB advisory or closing, follow its instructions. 
  • You can still use unaffected areas of a lake unless a bloom covers most of the lake. 
  • Report suspected HABs to EGLE by e-mailing [email protected] with pictures of the suspected HAB. Reports can also be received via phone at 800-662-9278. 

Additional Information