A watershed is a geographical area bounded by high elevation lines. Any rainwater falling into this geographical area will travel overland, into:
- Storm Sewers
- Ultimately into Lake Erie
Any runoff water in a watershed has no means to enter a neighboring watershed. The City of Trenton sheds water into the Blakely Drain, Frank and Poet Drain and the Trenton Channel. Both drains empty into Lake Erie in the City of Gibraltar.