The scum indicates a significant bloom of blue green algae. Blue green algae can produce toxins that are harmful to humans and animals.
The lakes will be monitored weekly for blue green algae toxins while the blooms persist. Lake Erie sampling began in July and no toxin levels of concern have been detected at this point. Results on toxin levels in Heart and Campbell should be available in the next two weeks.
Conditions can change quickly with toxin production so as a precaution people and pets should avoid swimming in areas of obvious bright green color and scum. Fish should be gutted and washed well prior to cooking and eating.