Letting your dog take a dip in a lake is an excellent way to help them cool down in the Maine summer heat waves, but beware of the water. With annual algae blooms comes potentially powerful toxins that could cause you harm and even kill your pup.

According to Bangor Daily News, toxic blue-green algae, or cyanobacteria, are more common in Southern states, but have been known to kill dogs in several states and up in Canada. The algae can grow to lethal levels in Maine lakes as well, as the water heats up in mid- to late summer.

While specialists and hundreds of volunteers from the Lake Stewards of Maine are keeping their eyes out for the dangerous algae blooms, they warn residents to be vigilant themselves.

“The toxins, if they’re concentrated enough, are very potent,” Scott Williams, executive director of the Lake Stewards of Maine, told BDN. “This is a problem that should be taken very seriously, but at the same time, people shouldn’t be pushing the panic button.”