Pet owners are being warned about toxic algae in the water after the death of dogs in other states.
The dangerous chemicals may be in Illinois waterways, reported the Daily Herald.
The algae looks like blue-green globs in the water, and the toxins can be produced when the algae is exposed to sunlight.
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The water is closed to swimming at several Wisconsin beaches along Lake Michigan due to reports of the algae, according to WKOW.
Officials warn the bacteria is harmful or even fatal to pets and can cause health concerns for humans as well.
Wisconsin officials said people can still enjoy the beach, just stay out of the water until the algae levels are safe again.
Illinois health officials warn of toxic blue-green algae following dog deaths in other states
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