Algae (Harmful Algal Blooms)

Contact: Gary Kohlhepp 517-284-5540

The MDEQ 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 the MDEQ 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. 

The MDEQ–WRD is developing an approach to monitor, assess, and report on harmful algal conditions, to improve our understanding of the nature, extent, and frequency of HABs in inland waters and near-shore Great Lakes.  The MDEQ defines a HAB as: “An algal bloom in recreational waters is harmful if microcystin levels are at or above the 20 ug/L World Health Organization non-drinking water guideline, or other algal toxins are at or above appropriate guidelines that have been reviewed by MDEQ-WRD.”  A bloom should be considered potentially harmful when “the chlorophyll a level is greater than 30 µg/L and visible surface accumulations/scum are present, or cells are visible throughout the water column”. 

A key concept of this HAB definition is that while high chlorophyll a concentration and visible surface/water column algal accumulation can indicate potential problems, water samples must be analyzed for the presence of toxins to confirm that a bloom may, in fact, be harmful to humans.

 The MDEQ is working to improve our understanding of HABs in Michigan and to develop an effective monitoring strategy.  In addition to providing several grants for HAB monitoring over the last decade, we have sampled multiple targeted and randomly-selected lakes to assess the geographic extent of HABs, and to evaluate the timing and frequency of samples needed to accurately characterize the occurrence and duration of blue-green algal blooms and HAB toxins.  We also continue to monitor several beaches along the Michigan portion of western Lake Erie.  The MDEQ is working with local, state, tribal, and federal partners to ensure that Michigan is a national leader in technology for HAB monitoring, assessment, and rapid communication.  This will include designing an efficient monitoring network and approach for HABs; supporting efforts by governmental and commercial entities to build capacity for existing and potential sampling and analytical methods; and working with our partners to ensure data availability and rapid dissemination of HAB threats to the public.  

If you suspect a harmful algal bloom, please review the HAB FAQ sheet (see link below), along with the ID links.  Algal blooms frequently occur in mid-summer and early fall and are a natural result of higher nutrient concentrations, warm temperatures, and low winds.  Not all algal blooms produce toxins, but to be safe avoid human and animal contact with very thick green scums in surface waters.  You can contact your local health department, local DEQ district office, or the DEQ Pollution Emergency Alerting System (PEAS) if you have concerns about algae in a lake or river or at a beach.


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