The Humber watershed is a hydrological feature of south-central Ontario, Canada, principally in north and west Toronto. It has an area of , flowing through numerous physio-graphic regions, including the Oak Ridges Moraine and the Niagara Escarpment. The watershed is bounded on the west by the Credit River, Etobicoke Creek and Mimico Creek watersheds, and on the east by the Garrison Creek, Don River and Rouge River watersheds, all six of which empty into Lake Ontario; on the north by the Nottawasaga River which empties into Lake Huron; and on the northeast by the Holland River, which empties into Lake Simcoe.