Grand Lake St. Marys was hand-dug in the 1800s by Irish ... area after the canal system became obsolete, but toxic algae blooms plague the lake in the present day. The lake is only six or seven ...

A sign at the Grand Lake St. Marys campground boat docks warns of toxic algae that can be encountered in warmer months. Efforts are underway to improve the water quality. These days, the lake is a ...