The Grand River flows 290 kilometers (km) south from just below Georgian Bay in south-central Ontario to the northeast end of Lake Erie. Its 6965 sq. km watershed drains the historic heartland of Ontario, discharging more than two cubic kilometers of water per year. The Nith, Conestogo, Speed and Eramosa rivers are the main tributaries of the Grand, whose waters eventually flow over the Niagara Falls on their journey down the Great Lakes-St. Lawrence waterway to the Atlantic Ocean.
The Grand River is generally calm and flat but includes sections squeezing through deep gorges and dropping across steep rock faces. Over its entire length, the river drops 352 meters (m) in elevation. In its upper reaches the Grand passes Luther Marsh, a valuable staging and breeding area for waterfowl and other marsh wildlife (it supports over 237 species of birds). Further south the river passes through the scenic Elora Gorge, an unusual limestone canyon with caves, rapids and waterfalls. Between Cambridge and Paris the river winds along a shoreline covered by the rare Carolinian tree species of the protected Grand River Forest.
The first European to descend the Grand River was the famous explorer La Salle in 1669. The river's importance grew as more and more people settled along its banks. Communities developed around mills powered by the flow of the river and its tributaries. Many 19th century mills, foundries, factories and engineering works are still found along the Grand, giving it an historical charm. In recognition of its harmony with the human settlement around it, the Grand River has been designated as a Canadian Heritage River.
The effects of industrial, agricultural and urban development have taken their toll on the Grand River. Seventy-eight percent of the watershed is farmland while natural vegetation covers only about 19%. Rehabilitation efforts led by the Grand River Conservation Authority have improved water quality over the last decade and restored the Grand to a healthy treasure for the millions of people who live nearby.