The Ausable River is a river in southwestern OntarioCanada which empties into Lake Huron at Port Franks, Ontario. The Ausable's initial source is in a moraine near the community of Staffa, Ontario located in the municipality of West Perth, Ontario at a point above sea level. Although the river has a total measured length of over , because of its meandering course, the mouth in actuality is only from its source near Staffa. The Ausable drains of land, and falls in elevation from source to outlet.