Harmful Algal Blooms

EGLE staff discover or receive reports from lake associations, and the broader public each year about nuisance algal conditions.  The number of such reports, particularly the occurrence of cyanobacteria or blue-green algae blooms and concern over the possible presence of algal toxins such as microcystin, appear to have increased in recent years.  In particular, severe blooms were observed in the western basin of Lake Erie in August 2014, and access to drinking water for hundreds of thousands of people was temporarily interrupted due to elevated levels of an algal toxin associated with the bloom.  This event caused EGLE to re-examine and expedite our efforts related to blue-green algae blooms, including what constitutes a harmful algal bloom (HAB); our monitoring approach; sampling protocols; analytical capabilities and costs; information gaps; and communication with other agencies, stakeholders, and the public on this issue. 

Summer is peak season for the formation of harmful algal blooms (HABs) that can present health hazards to people and pets. In Michigan, algal blooms typically occur during periods of warm temperatures, lots of sun, and high nutrient levels.

It is not possible to determine whether algal blooms contain harmful toxins by looking at them, so it is best to avoid contact with any body of water that is covered with algal mats or significant rafts of algae on the surface.

The Michigan Departments of Environment, Great Lakes, and Energy (EGLE) and Health and Human Services (DHHS) sample for HABs on a limited basis and work with local health departments to protect the public when toxins are discovered; however, some areas affected by HABs may go undetected. Suspicious-looking algae can be reported to EGLE by calling the Environmental Assistance Center at 1-800-662-9278 or sending an e-mail to AlgaeBloom@Michigan.gov.