Common Watersnakes "may inhabit just about any permanent body of water" and are found in about half of Ohio's counties.
atlas.ohparc.org
Lake Erie Watersnakes, a subspecies, are found on 15 islands in the western basin and on Marblehead.
They are not poisonous but will bite "viciously."
Common Watersnake (Nerodia sipedon) - Ohio Herp Atlas – OHPARC

Lake Erie Watersnakes, a subspecies, are found on 15 islands in the western basin and on Marblehead.
They are not poisonous but will bite "viciously."