Our Watershed

The Grand River watershed is the largest in southern Ontario and includes all the land drained by the Grand River and its tributaries. View a map of the Grand River watershed.

At 6,800 square kilometres, it's about the same size as the province of Prince Edward Island.

The Grand River starts in the highlands in Dufferin County and travels about 310 km before emptying into Lake Erie.

About a million people live within the watershed, with most residing in the larger urban areas of Kitchener, Waterloo, Guelph, Cambridge and Brantford. Cities, towns and villages make up about five per cent of the land.

The watershed includes 39 municipalities and two First Nations territories. In some cases, only a portion of the municipality is within the Grand River watershed.

The Grand River watershed is home to the Six Nations of the Grand River Territory and the Mississaugas of the Credit First Nation. Six Nations is the most populous First Nation in Canada, with about 13,000 residents living on an 18,800 hectare territory near Brantford. A similar number of members live "off reserve". The Mississaugas of the New Credit First Nation have a population of about 2,500 people, many living "off reserve". 

The watershed is also an intensive agricultural area, with farms making up about 70 per cent of the watershed.

The Grand River starts in the Dufferin Highlands at an elevation of 525 metres (1,722 feet) above sea level. It flows south about 310 kilometres (193 miles) to Lake Erie at Port Maitland, which is about 174 metres (571 feet) above sea level.

Watershed fast facts

• Four major rivers feed into the Grand: the Conestogo, Nith, Speed and Eramosa
• The combined length of all of the rivers and streams is about 11,000 kilometres
• The watershed crosses four climate zones: Dundalk Upland, Huron Slopes, South Slopes and Lake Erie counties.
• It crosses two forest regions: the Great Lakes-St. Lawrence and Deciduous (commonly called the Carolinian forest).
• The GRCA manages floods and keeps the rivers flowing in dry weather with a network of seven reservoirs.
• Roughly 80 species at risk are found in the watershed.
• More than 90 species of fish are found in the river system, about half of all species in Canada.
• Close to 250 species of birds have been reported at Luther Marsh Wildlife Management Area.
• Forest cover in the watershed was as low as five per cent in the early 1900s, but today forests cover about 19 per cent of the land.
• River flows, reservoir levels, weather and water quality are all tracked in real-time by a large network of gauges that feed their data to the GRCA website around the clock.
• Municipal water systems draw their water from wells and the river system, in contrast to most major Ontario communities, which depend on the Great Lakes.