The Grand River is a designated heritage river, with the largest watershed in Southwestern Ontario. The river starts in Dundalk, and flows down into Lake Eerie after meandering and curving its way through 310 kilometers of cities and countryside. It was an important trade route and thoroughfare for the indigenous people, who called it O:se Kenhionhata:tie or “Willow River”.

Other large local rivers that flow into the Grand include the Conestogo River, the Speed River, and the Nith River. The river is popular today with Canoeists and Kayakers, and can be generally be paddled from West Montrose to Lake Eerie with few portages.

The river was also once used as a landmark to distinguish lands granted to the Six Nations. In 1784, the Haldimand Tract was given by the British Crown to the Iroquoian Six Nations who had been their allies during the American War of Independence. At the time, the treaty promised the Six Nations ownership of the lands within 10km of either side of the river from beginning to end. That promise was reduced in 1821 to include lands only south of Elora. Much of this land was later sold, though in a number of cases the terms, nature, and acceptance of the sales are debated.