Skip to main content

Hitting the water? What you need to know about harmful algal blooms

The Michigan Department of Health and Human Services earlier this week issued a release with guidance on identifying, avoiding and responding to contact with the harmful algal blooms that can form on lakes, rivers and ponds. Since many DNR subscribers are outdoors with family and friends this summer, we're sharing that update to keep you informed.

If you or your family live near or will be visiting Michigan waters this summer, it's important to be aware of the potential for harmful algal blooms. HABs form due to rapid growth of cyanobacteria, also known as blue-green algae. Cyanobacteria are naturally present in lakes, rivers and ponds; unfortunately, some cyanobacteria produce toxins, called cyanotoxins, that can be present in blooms at levels that are harmful to people and animals.

Last year, HABs were reported in 80 bodies of water in 38 Michigan counties, and their frequency and geographic distribution are increasing across the state. To strengthen the HAB response capacity, nearly a dozen local health departments are part of an MDHHS testing project to do site visits, collect samples, test them for cyanotoxins and send data and samples to MDHHS.

Read the full story ►

These blooms typically occur May to October, and most often in August and September. They can last for days to weeks and change in size, location and toxicity over time. MDHHS’ Picture Guide offers examples of common occurrences. The Michigan Harmful Algal Bloom Reports map shows verified HABs and toxin test results and is updated weekly from June to November.