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Harmful Algal Blooms (HABs)

The Michigan Department of Health and Human Services (MDHHS) and the Michigan Department of Environment, Great Lakes, and Energy (EGLE) are requesting that all suspected Harmful Algal Blooms (HABs) be reported by emailing or by calling EGLE at 1-800-662-9278. This allows suspect HABs to be evaluated and possibly tested for cyanotoxins, which can affect human and animal health, and for public health concerns to be addressed. In addition, any reports of HABs and associated illness in either humans or animals are being reported to the Centers for Disease Control and Prevention.

MDHHS will continue publishing the Harmful Algal Bloom Reports map, which shows verified HAB reports and results of cyanotoxin tests. During June-November, the map will be updated weekly and can be found online at and also at Contact with questions about the map.

Background Information on HABs

Ranging from microscopic, single-celled organisms to large seaweeds, algae are simple plants that form the base of food webs. Sometimes, however, their roles are more sinister. Under the right conditions, algae may grow out of control — and a few of these “blooms” produce toxins that can kill fish, mammals and birds, and may cause human illness or even death in extreme cases. Other algae are nontoxic, but eat up all of the oxygen in the water as they decay, clog the gills of fish and invertebrates, or smother corals and submerged aquatic vegetation. Still others discolor water, form huge, smelly piles on beaches or contaminate drinking water. Collectively, these events are called harmful algal blooms, or HABs. Harmful algal blooms, or HABs, are a growing problem in every U.S. coastal and Great Lakes state.

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