Beach Read: Cyanotoxins in the Great Lakes

Picture of Jennifer Boehme
Jennifer Boehme
May 24, 2017


“Cyanotoxins: Stay Away from Green Water” arrives just in time for the start of the Great Lakes beach season.

The infographic offers key points and findings from a recent report by IJC’s Health Professionals Advisory Board. May 22-28 also is Healthy and Safe Swimming Week, a project of the US Centers for Disease Control and Prevention.

cyanotoxins infographic hpab


The IJC board report, “Science and Monitoring Assessment for Human Health Effects of Cyanobacterial Toxins in the Great Lakes Region,” describes health impacts that can stem from exposure to cyanotoxins, which may occur while swimming in areas affected by cyanobacteria blooms. Blooms of cyanobacteria occur in warm waters with abundant nutrients like phosphorus and nitrogen. Harmful algal blooms, or HABs, produce toxins that can cause health problems for humans, pets, fish, and wildlife. Different toxins that affect the liver, nervous system, and skin have been identified.

runoff algal bloom lake erie Agricultural runoff and a harmful algal bloom on the Western Lake Erie shoreline, 12 miles east of Toledo. Credit: NASA

Blooms have been regularly found in the Great Lakes, inland lakes, and other places. HABs are occurring more often due to rising water temperatures, and heavy use of fertilizer on lands draining into streams and lakes. New species of cyanobacteria also are being found in the Great Lakes.

While the report’s findings focus primarily on strategies for improving drinking water, cyanobacteria blooms also invade beach areas with cyanotoxins and can make boating unpleasant. The public should be aware of potential health risks from HABs, and that swimming is discouraged where HABs are present. Better monitoring and reporting of toxin levels in the Great Lakes could improve the precision of public warnings and public health protection.

While such monitoring is not common practice, beach closures in the Great Lakes can impact your summer plans. Regular checks for beach closures in your area are a good way to stay informed on beach water quality, as postings can change over the swimming season. Information is available online at BeachCast, a product of the Great Lakes Commission. Lake Ontario Waterkeeper also has a Swim Guide app that includes water quality information for beaches in Canada. cyanotoxins-stay-away-green-water-infographic-full

An infographic summarizing “Science and Monitoring Assessment for Human Health Effects of Cyanobacterial Toxins in the Great Lakes Region.” Credit: Health Professionals Advisory Board

Picture of Jennifer Boehme
Jennifer Boehme