Water sources: rivers


Rivers are of immense importance to the geology, biology, history and culture of Canada. Although they contain only a small portion of the total amount of water in the country at any given time, rivers play a vital role in the hydrological cycle. They act as drainage channels for surface water; provide habitat, nourishment and means of transport to countless organisms; offer travel routes for exploration, commerce and recreation; leave valuable deposits of sediments; provide the power to produce much of the electrical energy we use; and create the majestic scenery that is such an integral part of the Canadian landscape.

By the numbers

The following tables provide a sense of Canada’s ranking among the largest of rivers in the world.

World's largest rivers

This table ranks the world's largest rivers by the size of drainage area in thousand kilometers squared.

Based on drainage area
Rank Name Drainage area (1000 km2)
1 Amazon 6 915
2 Congo 3 680
3 Murray 3 520
4 La Plata 3 100
5 Ob 2 990
6 Mississippi* 2 980
7 Nile 2 870
8 Yenisei 2 580
9 Lena 2 490
10 Niger 2 090
11 Amur 1 855
12 Yangtze 1 800
13 Mackenzie* 1 790
14 Ganges 1 730
15 Volga 1 380
16 Zambezi 1 330
17 St. Lawrence* 1 030

This table ranks the world's largest rivers by length in kilometers.

Based on length
Rank Name Length (km)
1 Nile 6 670
2 Mississippi* 6 420
3 Amazon 6 280
4 Yangtze 5 520
5 La Plata 4 700
6 Hwang Ho 4 670
7 Mekong 4 500
8 Lena 4 400
9 Congo 4 370
11 Niger 4 160
12 Ob 3 650
13a Yenisei 3 490
13b Murray 3 490
14 Volga 3 350
15 Indus 3 180
16 St. Lawrence* 3 060
17a Ganges 3 000
17b Yukon* 3 000

*Partly or entirely in Canada

This table ranks the world's largest rivers by average annual total discharge in kilometers cubed per year.

Based on average annual total discharge
Rank Name Average annual total discharge (km3/year)
1 Amazon 6 923
2 Ganges 1 386
3 Congo 1 320
4 Orinoco 1 007
5 Yangtze 1 006
6 La Plata 811
7 Yenisei 618
8 Lena 539
9 Mississippi* 510
10 Mekong 505
11 Chutsyan 430
12 Ob 404
13 Amur 360
14 Mackenzie* 325
15 St. Lawrence* 318
16 Niger 302
17 Volga 255

Source: Adapted from World Water Resources and Their Uses, Joint SHI/UNESCO Product, prepared by Prof. Igor A. Shiklomanov, 1999.
* Partly or entirely in Canada.

Rivers are natural watercourses, flowing over the surface in channels, which drain discrete areas of land. The existence, size and flow of a river are influenced by: the availability of surface water, a channel in the ground, and an inclined surface. In this sense the term “river” includes all kinds of watercourses, from the tiniest of brooks to the largest of rivers.

In actual fact, Canada has some very large rivers, with many of these situated north of 60 degrees latitude. The Mackenzie River, for example, is over 4000 kilometres long and is the country’s largest river.  The longest of Canada’s rivers are depicted in the table below.

Longest rivers in Canada (kilometres)

*Canadian portion only
Numbers have been rounded

Drainage Patterns

It is important to remember that all of this water is interconnected. The area that drains all precipitation received as a runoff or base flow (groundwater sources) into a particular river or set of rivers is call a drainage basin or watershed. And all these small watersheds combine to make up regional watersheds, which in turn join others to form continental watersheds.

Rivers in Canada flow into five continental watersheds; one to each surrounding ocean: the Pacific, the Arctic, and the Atlantic as well as to Hudson Bay and to the Gulf of Mexico. A river's watershed or drainage basin -- the area supplying it with water -- is separated from the watersheds of neighbouring rivers by higher lands called drainage divides


Map of Canada's Continental Watersheds

Details can be found below

Map of Canada's Continental Watersheds. Approximately 60% of Canada's fresh water drains to the north, while 85% of the population lives along the southern border with the United States. The map shows Canada's most populous cities (about 6 out of 10 Canadians live in the country's 30 largest cities), the five major drainage areas, and drainage flow. The shaded areas in the southern part of the map show those regions of the country with a population density greater than one person per square kilometre.

Natural Resources Canada's Atlas of Canada provides additional information and maps on Canada’s geography including: fresh water, drainage patterns, and Canada’s watersheds

Sculpting the earth

As a swiftly flowing river, water can erode the underlying terrain. Where the river slope is flatter, the river slows down and deposits materials. This usually occurs in the lower reaches and especially near the mouth of the river, either at a lake or an ocean. A river can carve steep valleys, especially in higher parts of the drainage basin. In the lower parts of the basin, deposits may create deltas at the river's mouth.

The volume of water flowing in a river, together with the speed and timing of the flows, determines how a river shapes the surrounding landscape and how people can use its waters. Rainfall, snowmelt, and groundwater all contribute to the volume of flow, producing variations from season to season and year to year.

In Canada, most high flows are caused by spring snowmelt. This is the season when floods are most likely to occur. Rainstorms can also cause high flows and floods, especially on small streams. The effects of floods and storms can be much less severe on rivers with large drainage basins. The lowest flows for rivers in Canada generally occur in late summer, when precipitation is low and evaporation along with consumption by plants is high, and in late winter, when rivers are ice covered and the precipitation is stored until spring in the form of ice and snow.

See also Erosion and Sedimentation section

Measuring River Flows

Environment Canada's Water Survey of Canada, along with many contributing agencies, presently measures the rate of flow (discharge) in rivers and records the levels of lakes and rivers at more than 2600 locations in Canada.

How do you measure water in lakes and rivers?

  • Water levels are read manually by gauge readers or continuously recorded either electronically or on graph paper or in digital form.
  • Rate of flow (or discharge) requires multiple measurements of channel depth, width, and flow velocity to yield the average discharge in the stream crossing for a given water level. Measurements can be made electronically from a bridge, by wading into a stream, by boat, or from a cableway strung across the river. In winter, the measurements are made through the ice.
  • With sufficient measurements of flow over a variety of water levels (including extreme lows and highs), a water level-discharge relationship is established at each location so that the discharge can be computed from measured water levels.
  • Historical records from 5000 active and discontinued sites permit the estimation of streamflow at ungauged locations.

The following table indicates river flows at various locations in Canada.

This table shows typical river flows in meters cubed per second. The annual average, as well as the highest and lowest daily averages, are also indicated.

Typical river flows at various locations in Canada
(from lowest to highest daily average, m3/second)
Location River Annual average Daily average
      Highest Lowest
Prince Edward Island Dunk River at Wall Road 2.55 84.7 0.212
Saskatchewan Qu'Appelle River near Lumsden 5.44 436 0
New Brunswick Lepreau River at Lepreau 7.37 340 0.028
Manitoba Manigotagan River near Manigotagan 8.93 103 0.065
Ontario Rideau River at Ottawa 37.2 583 1.48
Newfoundland Gander River at Big Chute 119 1 170 2.78
Alberta Athabaska River at Hinton 175 1 200 10.8
Yukon Yukon River at Whitehorse 243 646 32.6
Saskatchewan South Saskatchewan River at Saskatoon 254 3 940 14.2
Quebec Rivière aux Outardes à la Centrale de Chute-aux-Outardes 387 2 830 10.5
New Brunswick Saint John River below Mactaquac 809 11 100 21.5
Ontario Ottawa River at Britannia 1 180 5 060 245
Newfoundland Churchill River above Upper Muskrat Falls 1 740 6 820 253
British Columbia Fraser River at Hope 2 720 15 200 340
Ontario Niagara River at Queenston 5 880 9 760 2 440
Ontario St. Lawrence River at Cornwall 7 350 10 700 4 500
Northwest Territories Mackenzie River at Norman Wells 8 480 33 300 1 680

Note: This table is based on historical data to 1999, extracted from the national HYDAT database.

Water level and discharge information such as this is essential for the wise management of Canada's water resources. For example, the information can be used to

  • allocate water between various users;
  • manage water resources or minimize the impacts of extreme flows (e.g., flood protection, floodplain mapping, diversion canals, and irrigation);
  • design and construct bridges, canals, culverts, roadways, water supplies, irrigation facilities, and countless other structures;
  • plan and conduct environmental programs and assessments related to water quality, fisheries, and wildlife habitat; and,
  • ensure that the nation's water resources are developed in a manner that conserves and protects the environment.

The Importance of Rivers in Canadian History

Flowing water has provided Canada with more than inspiration. During the period of European colonization, the rivers carried furs, trade goods, and explorers, heralding the influx of settlers into the wilderness.

The arrangement of streams and rivers flowing into Hudson Bay and into the Mackenzie and St. Lawrence Rivers permitted canoes to travel west and north across the length and breadth of the land that became Canada.

Rivers were central to the political and economic development of Canada.  For instance, long before Canada became a nation, the Red River was central to life in Manitoba. Like those along the St. Lawrence, farms were laid out as long, narrow river lots, giving settlers access to the river. As a result, a distinctive western society emerged on the banks of the Red River in the 19th century. This Red River Settlement was a uniquely dual society consisting of near equal numbers of French-speaking Catholic Métis and English-speaking Protestant settlers.

The distant government in Ottawa understood neither the make up of the population or its intimate relationship with the Red River. It inflicted on the people a land survey that ignored the river lot system, alienating people from their way of life. Violence erupted and the tragedy of the Red River Rebellion followed.

Canadian Heritage Rivers

The Canadian Heritage Rivers System, established in 1984, is a cooperative program of the Government of Canada and all of the provincial and territorial governments. The program objectives are to give national recognition to the important rivers of Canada and to ensure long-term management that will conserve their natural, historical, and recreational values for the benefit and enjoyment of Canadians, now and in the future.

Canadian Heritage Rivers System

Details can be found below

Source: The Canadian Heritage Rivers System, 2004. www.chrs.ca

This map of Canada shows the location of the Canadian Heritage Rivers and indicates if they have are designated rivers or nominated rivers. They are as follows:

  • Alsek River, Kluane National Park Reserve, Yukon (designated)
  • Arctic Red River (Tsiigèhnjik), Northwest Territories (designated)
  • Athabasca, Kicking Horse, and North Saskatchewan Rivers, Canadian Rocky Mountains National Parks, Alberta and British Columbia (designated)
  • Bay du Nord River, Newfoundland (nominated)
  • Bloodvein River, Woodland Caribou Provincial Park-Ontario and Atikaki Wilderness Park-Manitoba (designated)
  • Bonnet Plume River, Yukon (designated)
  • Boundary Waters-Voyageur Waterway; Quetico, Middle Falls, and Voyageur Provincial Parks, Ontario (designated)
  • Churchill River, Saskatchewan (nominated)
  • Clearwater River, Clearwater River Provincial Wilderness Park, Saskatchewan and Alberta (Saskatchewan section designated; Alberta section nominated)
  • Coppermine River, Nunavut (nominated)
  • Cowichan River, British Columbia (nominated)
  • Detroit River, Ontario (designated)
  • Fraser River, British Columbia (designated)
  • French and Mattawa Rivers, French River and Mattawa River Provincial Parks, Ontario (designated)
  • Grand River, Ontario (designated)
  • Hayes River, Manitoba (nominated)
  • Hillsborough River, Prince Edward Island (designated)
  • Humber River, Ontario (designated)
  • Jacques-Cartier River, Jacques-Cartier Provincial Park, Quebec (nominated)
  • Kazan and Thelon Rivers, Nunavut (designated)
  • Main River, Newfoundland (nominated)
  • Margaree-Lake Ainslie River System, Nova Scotia (designated)
  • Missinaibi River, Missinaibi Waterway Park, Ontario (nominated)
  • Rideau Waterway, Ontario (designated)
  • Seal River, Manitoba (designated)
  • Shelburne River, Nova Scotia (designated)
  • Soper River, Nunavut (designated)
  • South Nahanni River, Nahanni National Park Reserve, Northwest Territories (designated)
  • St. Croix River, New Brunswick (designated)
  • St. Marys River, Ontario (designated)
  • Tatshenshini River, Yukon (nominated)
  • Thames River, Ontario (designated)
  • The Thirty Mile (Yukon River), Yukon (designated)
  • The Three Rivers, Prince Edward Island (nominated)
  • The Upper Restigouche, New Brunswick (designated)

The first Canadian Heritage River was the French River in Ontario, designated in 1986. Today, there are 39 Heritage rivers across Canada, and more are being added to the system each year.

Additional information is available on the Canadian Heritage Rivers System Web site.

Report a problem or mistake on this page
Please select all that apply:

Thank you for your help!

You will not receive a reply. For enquiries, contact us.

Date modified: