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Rivers of Canada

St. Lawrence River (Mixedwood Plains)

Source: Lake Ontario
Mouth: Gulf of St. Lawrence
Direction of flow: northeast
Length: 1,197 kilometres (3,058 kilometres to head of St. Louis River, Minnesota)
Origin of name: on St. Lawrence’s Day in 1535, explorer Jacques Cartier gave the saint’s name to a bay at the river’s mouth; in the early 1600s, it was adopted for the entire river
Mohawk name: Kaniatarowanenneh, meaning “big waterway”

Fed by Lake Ontario, Canada’s “great river” drains about one million square kilometers. The St. Lawrence is framed by the Laurentian Highlands to the north and the Appalachian Mountains to the south. It starts out as a freshwater waterway from just east of Kingston, Ont., and forms the border with the United States to Cornwall, Ont. It then broadens into a number of lakes on its way to Montréal.

From Trois-Rivières to Québec, the freshwater flow is reversed with the tides. The riverbed drops dramatically at the mouth of the Saguenay River, where fresh water mixes with cold Arctic salt water. At its estuary, the St. Lawrence doubles in width to more than 100 kilometres before emptying in the Gulf of St. Lawrence.

River life
It’s an awesome avian spectacle: every spring and fall, more than 750,000 greater snow geese stage in the tidal marsh of the Cap Tourmente National Wildlife Area, on the north shore of the St. Lawrence River. The geese build up their reserves for the 3,000-kilometre trip to their prime breeding grounds on Baffin and Bylot islands or for the 900-kilometre journey back to their wintering grounds along the Eastern Seaboard of the United States. Once they’re done feeding on the rhizomes (roots) of bulrushes during the fall migration, the tidal marsh at Cap Tourmente is stripped bare.

Click on image to enlarge

The geese that stop along the St. Lawrence River are part of the only population of this subspecies in the world. Jacques Cartier, Samuel de Champlain and Jesuit priests all wrote about the great flocks at Cap Tourmente in accounts of their travels. At the beginning of the 20th century, the greater snow geese were near extinction. Today, their numbers stand at more than 800,000, due in part to the establishment of wildlife sanctuaries and restrictions on hunting.

Cultural legacy
The St. Lawrence is at the heart of most major developments in early Canadian history. When Jacques Cartier first explored the river in 1535, Iroquois were already settled in communities at Stadacona (Québec) and Hochelaga (Montréal). It was known as Rivière du Canada until the early 1600s. As the main route into the interior of the continent from Europe, the St. Lawrence was used by French explorers and traders to establish a colonial empire. By the mid-18th century, most of the land along the river between Montréal and Québec was divided into the long, narrow farms of the seigneurial system.

The mighty river served as a route for commerce, starting with the fur trade and later with timber. With the completion of the St. Lawrence Seaway — a system of locks, canals and channels linking the Great Lakes and the St. Lawrence River with the Atlantic Ocean — in 1959, the river became one of the most important transportation and industrial corridors in the world.

Current state
For centuries, the St. Lawrence River has been intensively exploited. By the second half of the 20th century, its banks were largely urbanized between Montréal and Québec and its waters heavily polluted. In 1970, the Canadian government conducted its first water-quality study of the St. Lawrence. Conservation efforts to protect the waterway have only been introduced in the last 30 years. Some of the main sources of pollution include municipal wastewater and industrial effluents.

A recent report by the St. Lawrence Action Plan, a Canada-Quebec initiative, indicates that the river is now healthier than it was during the second half of the 20th century. The level of toxic contamination has decreased and some animal populations, such as the northern gannet, which was on the verge of disappearing in the 1960s, have recovered. In some areas, the water is safe enough for swimming and freshwater fish are generally fit to eat. But contaminants trapped in sediments still present a threat to the St. Lawrence. The beluga population is still endangered, though its population has stabilized in recent years. And the river’s biodiversity continues to be affected by habitat loss and other human disturbances, as well as the invasion of foreign species.


St. Lawrence River: Islands in the stream A map of the Thousand Islands region of the St. Lawrence river can be zoomed in on. Buttons allow the viewer to control the zoom and the location of the view. An inset box allows the viewer to move the zoom area around the entire depicted region.


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Quiz :

In what year was the Red River Colony founded?