Michigan Harmful Algal Bloom Reports Map

The Michigan departments of Environment, Great Lakes, and Energy (EGLE); and Health and Human Services (MDHHS) review reports of potential cyanobacterial blooms, also known as harmful algal blooms or HABs, made by citizens or other groups. When possible, EGLE or other agencies will test water samples to determine if cyanotoxins are present.

Access the map here.

The default map layer, using circles, shows locations from the last two weeks of verified HABs that have been reported to EGLE, as well as the results of any cyanotoxin testing that has occurred. Clicking on a data point on the map will show a pop-up window with additional information including the results of cyanotoxin testing. The amount of testing varies depending on the resources available, and not all HABs are monitored until they disappear. This means HABs may be present but not shown on the default map layer. All data for the 2022 season is also available and can be viewed on a separate map layer where squares are used to show results older than two weeks. Results will be updated on Thursdays from June to November.

Report any suspicious-looking algae to EGLE by emailing AlgaeBloom@Michigan.gov with picture(s) of the algae or by calling the Environmental Assistance Center at 1-800-662-9278, so it can be tested, if appropriate.

When cyanotoxins are detected in a water body, recreators should remain cautious about contact with algal blooms on the lake because the amount of toxins and location of the bloom can change over time. It is common for:

• HABs and their toxins to be localized or present in a small area.
• Toxins only to be present in areas with visible cyanobacteria.

This means that you can swim and do other activities in the water body while avoiding areas where you see water that has scums or mats, looks like spilled paint or pea soup or has colored streaks. Visit the HAB Picture Guide for examples of HABs.

The presence of cyanobacteria and their toxins is not unusual in the summer and fall and has been confirmed in water bodies across Michigan. People should be on the lookout for the presence of visible cyanobacterial blooms or scums on any water body, and people and pets should avoid contact with water in affected areas.

In situations in which state and local agencies detect and respond to a HAB, health departments may issue advisories through posting of signs and sending out notices to the public. Public health advisories may indicate a need to avoid areas with algae, specific beaches or the whole water body. Look for and follow all advisory notifications.

For more information on HABs in Michigan, visit www.michigan.gov/habs.