Harmful blooms of algae are headed back for recreational waters in The Great Lakes.

Another season of harmful algal blooms in the lakes is coming fast. The Michigan Department of Environment, Great Lakes, and Energy says to expect they could be toxic and have a simple way to test that. WSJM reports the agencies recommend “the stick test.” If the algae can’t be picked up with a stick or paddle and it looks like spilled green paint, it could be toxic and should be reported immediately to the Environmental Assistance Center.

Algae blooms in Lake Erie in 2014 were so bad that the nearby drinking water was impacted.