The Ausable River is a river in southwestern Ontario Canada 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 334 metres above sea level. Although the river has a total measured length of over 240 kilometres…The Ausable River is a river in southwestern Ontario Canada 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 334 metres above sea level. Although the river has a total measured length of over 240 kilometres, because of its meandering course, the mouth in actuality is only 64 kilometres from its source near Staffa. The Ausable drains 1,142 square kilometres of land, and falls 158 metres in elevation from source to outlet.