CHESHIRE TOWNSHIP, Mich. (WOOD) — Health officials are lifting a warning about harmful algae blooms in Swan Lake southwest of Allegan.

The Allegan County Health Department issued the advisory in July after blue-green algae blooms were found on the lake in Cheshire Township, staining the water green. It said that tests from Nov. 30 found no toxins produced by the algae, likely due to cold weather.

The toxins can make people and pets sick, causing digestive distress, fatigue and convulsions. They can be deadly.

The health department reminded lake-goers that it’s impossible to tell by sight which algal blooms may be toxic, so you always avoid contact with any water where you see algal mats.

You can call the Michigan Department of Environment, Great Lake and Energy at 800.662.9278 or email to report algae blooms if you are concerned about them.