The Grand River, formerly known as the River Ouse, is a large river in Ontario, Canada. It lies along the western fringe of the Greater Golden Horseshoe region of Ontario which overlaps the eastern portion of southwestern Ontario, sometimes referred to as Midwestern Ontario, along the length of this river. From its source near Wareham, Ontario, it flo…The Grand River, formerly known as the River Ouse, is a large river in Ontario, Canada. It lies along the western fringe of the Greater Golden Horseshoe region of Ontario which overlaps the eastern portion of southwestern Ontario, sometimes referred to as Midwestern Ontario, along the length of this river. From its source near Wareham, Ontario, it flows south through Grand Valley, Fergus, Elora, Waterloo, Kitchener, Cambridge, Paris, Brantford, Ohsweken, Six Nations of the Grand River, Caledonia, and Cayuga before emptying into the north shore of Lake Erie south of Dunnville at Port Maitland. One of the scenic and spectacular features of the river is the falls and Gorge at Elora.