|Type||Formerly part of the Glacial Lake Agassiz, reservoir|
|Primary inflows||Winnipeg River, Saskatchewan River, Red River|
|Primary outflows||Nelson River|
|Catchment area||984,200 km2 (380,000 sq mi)|
|Basin countries||Canada, United States|
|Max. length||416 km (258 mi)|
|Max. width||100 km (60 mi) (N Basin)
40 km (20 mi) (S Basin)
|Surface area||24,514 km2 (9,465 sq mi)|
|Average depth||12 m (39 ft)|
|Max. depth||36 m (118 ft)|
|Water volume||284 km3 (68 cu mi)|
|Residence time||3.5 years |
|Shore length1||1,858 km (1,155 mi)|
|Surface elevation||217 m (712 ft)|
|1 Shore length is not a well-defined measure.|
Lake Winnipeg is a large, 24,514-square-kilometre (9,465 sq mi) lake in central North America, in the province of Manitoba, Canada, with its southern tip about 55 kilometres (34 mi) north of the city of Winnipeg. It is the largest lake within the borders of southern Canada, and it is part of the most undeveloped large watershed of southern Canada.
Lake Winnipeg is the sixth-largest freshwater lake in Canada, and the third-largest freshwater lake contained entirely within Canada, but it is relatively shallow (mean depth of 12 m (39 ft)) excluding a narrow 36 m (118 ft) deep channel between the northern and southern basins. It is the eleventh-largest freshwater lake on Earth. The east side of the lake has pristine boreal forests and rivers that are being promoted as a potential United Nations World Heritage Park. The lake is elongated in shape and is 416 km (258 mi) from north to south, with remote sandy beaches, large limestone cliffs, and many bat caves in some areas. Manitoba Hydro uses the lake as one of the largest reservoirs in the world. There are many islands in the lake, most of them undeveloped.
The lake's watershed measures about 984,200 square kilometres (380,000 sq mi), and covers much of Alberta, Saskatchewan, Manitoba, northwestern Ontario, Minnesota, and North Dakota. Its tributaries include:
- Saskatchewan River (through Cedar Lake)
- Red River (including Assiniboine River)
- Winnipeg River (draining Lake of the Woods, Rainy River and Rainy Lake)
- Dauphin River, (draining Lake Manitoba and Lake Winnipegosis)
- Bloodvein River (on the East side, draining from the Canadian Shield)
- Poplar River
- Manigotagan River
Lake Winnipeg drains northward into the Nelson River at an average annual rate of 2,066 cubic metres per second (72,960 cu ft/s), and forms part of the Hudson Bay watershed, which is one of the largest in the world. This watershed area was historically known as Rupert's Land when the Hudson's Bay Company was chartered in 1670.
The lake consists of three distinct regions, the smaller South Basin, the larger North Basin, and the “Narrows” connecting them. Another way to describe lake size is by the linear distances across the lake in different directions. When measured along its north/south long axis, Lake Winnipeg is about 436 km long. At its widest point it is about and 111 km wide. The long length of the lake means that there are significant variations from one part of the lake to another.
Still another way to describe a lake’s size is by the volume of water it contains. This often varies seasonally because it depends on weather and river flows. Lake Winnipeg is shallow and consequently contains less water than many other large lakes. On average, Lake Winnipeg is only about 12 m deep although its deepest point is about 36 m. Estimates of the volume of water in it range from 284 cubic km (Manitoba Government ”Quick Facts” web page) to 371 cubic km of water (Kalff 2002). While these are huge volumes by most familiar measures, they are much smaller than many other large lakes. For example, volumes of some other large lakes in North America are: Lake Superior, 12,230 cubic km; Lake Michigan, 4,940 cubic km; Lake Huron, 3,537; Lake Erie, 483 cubic km, and Lake Ontario 1,637 cubic km (Kalff, 2002).
How big is the watershed that drains into Lake Winnipeg?
The watershed draining to Lake Winnipeg is huge, estimated to be nearly 1 million square km. It extends from near Lake Superior in the east, from west of Banff in the west, and from northern South Dakota in the south. Its drainage is about 40 times larger than its surface, a ratio bigger than any other large lake in the world. It drains large areas of northwestern Ontario, Manitoba, Saskatchewan, Alberta, North Dakota and Minnesota and small areas of Montana and South Dakota. It contains several internal drainage basins, areas that do not normally discharge to the rivers flowing to the lake but can sometimes do so in high-water seasons. Given the massive watershed and the relatively small volume of water in the lake, it is dominated by events in its watershed. It is not surprising to find it showing the effects of materials being added to it as a result of activities in the watershed.
Where does the water in the lake come from?
Water is supplied to the lake by three major river systems, the Winnipeg River from the east, the Saskatchewan River from the west and the Red River from the South, by direct inputs of rain and snow to the surface and by several smaller rivers. In earlier times the Saskatchewan River was the largest inflow of water but in recent times the flow of that river has declined while flows in the Winnipeg and Red Rivers have increased with the result that the Winnipeg River has become the largest single source. The Winnipeg River drains mainly Precambrian shield area to the east of the lake while the Saskatchewan River arises in the Rocky Mountains and flows through mostly prairie soils. The Red River drains prairie soils for its whole length. The lake has only one outflow namely the Nelson River which carries water north and east through several smaller lakes on its way to Hudson Bay.
How long does the water stay in the lake?
The inflows of the rivers, and direct precipitation to the surface, combined with the relatively small volume of the lake, give it a comparatively short water residence time of less than one year for the South Basin and about three to four years for the lake as a whole. The water residence time is the theoretical time that would be required to fill the lake up again if all of its water were suddenly removed from it. Freshwater lakes have highly variable water residence times ranging from a few days to thousands of years. The lake with the longest water residence time is Lake Tanganyika in Africa with a water residence time of 6000 years. The water residence times for some other large North American lakes are: Lake Superior 191 years, Great Bear Lake 131 years, Lake Michigan 99 years, Lake Huron 22 years, Lake Ontario 6 years, Lake Erie 2.6 years.
What is the history of the lake?
Northern North America has been covered with glaciers several times and the most recent glacier began to retreat from the area now occupied by Lake Winnipeg about 12,000 years ago. Glacial melt water accumulated at the receding edge of the glacier and formed a huge lake, called Lake Agassiz. The shape and size of Lake Agassiz changed dramatically over time as the glacier receded and as water in the lake drained out from time to time through several channels. The ice was originally up to 4 km thick and it retreated over several thousand years leaving the present-day remnant we know as Lake Winnipeg. The weight of the ice deformed the planet’s crust and it is rebounding upwards very slowly. The northern end of the lake is rebounding faster than the southern part so that the lake is slowly tilting slightly toward the south. As a result, water levels in the south are increasing slowly – at about 20 cm per century - but still enough to raise concerns about erosion of shorelines.
What is the history of human settlement around the lake?
Following the ebb and flow of glaciation, permanent human habitation commenced approximately 8,000 years ago with the ancestral beginnings of the Cree and Ojibway cultures. With water as the source of life, Lake Winnipeg and its tributaries were a dominant influence both in their world view and daily life. Seasonal rhythms would see extended groups come together near the mouths of the rivers at the edge of the lake for summers of fishing, harvesting of rice as well as visiting and celebrations. Many of these groups then followed the great herds of bison to the open prairie in the fall; then they would break into smaller, more sustainable family groups to move inland along the rivers to the Boreal forests for winter. The tempestuous big lake was probably not often traversed by the birch bark canoes of the First Nations, who paddled along its shores thereby becoming intimately familiar with its varied resources and landscapes. Fish and wildlife enriched the diet and provided skins and tools from their seasonal travels, while a sophisticated trade network developed to provide a broader range of material culture, including metal for tools, seeds for cultivation and ideas for technological innovation. The name ‘Lake Winnipeg’ is a gift from ancient times that means ‘murky water’, a reference to the turbid habits of the great lake. It was the abundance of fish in these murky but verdant waters that also lured European habitation in the post-contact period. Early settlement along the shores include fur trade provisioning posts, Métis fishing camps, Icelandic settlers along the west shore and ultimately, summer residences facilitated by the coming of the railway on both sides on the south basin in the early twentieth century.
Lake Winnipeg as a hydro-electric reservoir
The water level in Lake Winnipeg is usually from about 711 to 715 feet above that in Hudson Bay. That is, water leaving Lake Winnipeg via the Nelson River falls over 700 feet on its journey to Hudson Bay. That flow of water offers opportunities to generate hydro-electricity and Manitoba decided during the 1960s to exploit that potential using a series of generating stations along the Nelson River. In order to ensure that sufficient water flow was available in the Nelson River, especially in winter when the demand for power is high, a number of dams and diversions were built. With the construction of the Jenpeg dam on the western arm of the Nelson River where it flows into Cross Lake, the levels of water in the lake could be regulated and water could be allowed to flow out of the lake as it was needed by the generating stations. Several generating stations have been built and others are in various stages of planning.
Recreational use of the lake
Lake Winnipeg has numerous excellent recreational beaches and these have provided summer recreation for hundreds of thousands of people for decades. The most popular beaches are on the South Basin because they are closer to where most Manitobans live. Excellent beaches are also found in the North Basin but access to them is more limited. The most popular beach is at Grand Beach Provincial Park on the east side of the lake. This area regularly attracts over half a million visitors per year. Tourism of various kinds is a big industry with thousands of cottages (increasingly being converted to year-round use), recreational fishers, boaters, naturalists, campers, and others. Lake Winnipeg supports a vibrant commercial fishing industry. A News Release by the Government of Manitoba (June 25, 2010) cited a value of $50 million per year for the economic activity related to commercial fishing. Some 3000 workers are involved in the industry from catching the fish to processing them for market. The principal commercial species are walleye, sauger and whitefish. The lake is home to many more species than commercial fish including forage fish, invertebrate animals and various species of birds and other wildlife.
The most immediate problems are the algal blooms that cover large areas of the lake late in the summer and in the fall. About 8 000 tonnes of phosphorus enter the lake each year but only a small fraction of that actually leaves the lake and flows down the Nelson system. This phosphorus is available to the algae in the lake and when conditions of warm water and low winds apply, they can form huge blooms easily visible in satellite images. The dominant organisms in these blooms are blue-green types of algae, classified scientifically as specialized types of bacteria called Cyanobacteria. These organisms can produce highly toxic compounds similar in structure to very small proteins and so they represent more than an unsightly nuisance. When these algae die, decomposition of them takes oxygen out of the water and can reduce the oxygen so much that fish and other animal life can suffocate. This problem of excess algae, called “eutrophication” is a world-wide problem in lakes in populated areas. There is good evidence that the root cause behind the problem lies with the amount of the element phosphorus in the lakes. That is, the amount of phosphorus in a lake limits the amount of algae that can grow there because they need phosphorus and cannot make it themselves. The only solution found so far is to cut back on the phosphorus entering the lakes.
Reports from the 1930s described blooms of algae in Lake Winnipeg and so the lake has produced blooms even before it received large quantities of phosphorus from its watershed. Satellite pictures of the lake reveal that the size and frequency of blooms have been increasing in recent years. The two main limitations on the production of these algae are the amount of phosphorus and the amount of light. Algae, like green plants, need both food and light. These algae need other chemical elements too but the other main nutrient element, nitrogen, is one they can make for themselves from nitrogen gas in the air. (Air is about 80 % nitrogen). The South Basin of the lake is normally quite turbid due to inflows of soil particles mainly from the Red River. Light cannot penetrate turbid water very deeply and that limits algal growth there. The North Basin has clearer water with more penetration of light and the algae bloom there more regularly. The other biological problems relate to invasions of the lake by new species (such as the rainbow smelt) and anticipated arrivals of other unwanted species (zebra mussels). Also, several species have been placed on lists of species that are ”rare” or “at risk” of being lost from the lake.
Manitoba Hydro creates hundreds of millions of dollars in electrical power each year by regulating water flows, largely on the Nelson River, including those from Lake Winnipeg, and passing the water through generating stations. This industry massively changes the flow of the rivers so that the maximum discharge is in winter when power demand is high rather than in summer which is the natural seasonal pattern of maximum discharge. The regulation of water levels in the lake has brought into question the stability of shorelines to erosion.
Lake Winnipeg and Lake Manitoba are remnants of prehistoric Glacial Lake Agassiz, although there is evidence of a desiccated south basin of Lake Winnipeg approximately 4000 years ago. The area between the lakes is called the Interlake Region, and the whole region is called the Manitoba Lowlands.
It is believed that Henry Kelsey was the first European to see the lake, in 1690. He adopted the Cree language name for the lake: wīnipēk (ᐐᓂᐯᐠ), meaning "muddy waters". La Vérendrye referred to the lake as Ouinipigon when he built the first forts in the area in the 1730s. Later, the Red River Colony to its south took the lake's name for Winnipeg, the capital of Manitoba.
Lake Winnipeg lies along one of the oldest trading routes in North America to have flown the British flag. For several centuries, furs were traded along this route between York Factory on Hudson Bay (which was the longtime headquarters for the Hudson's Bay Company) over Lake Winnipeg and the Red River Trails to the confluence of the Minnesota and Mississippi Rivers at Saint Paul, Minnesota. This was a strategic trading route for the First British Empire. With the establishment of the Second British Empire that occurred after Britain's loss of the Thirteen Colonies, a quite significant increase in trade occurred over Lake Winnipeg between Rupert's Land and the United States.
Because of its long, narrow shape, the lake exhibits a variety of interesting wind and wave effects, including temporary water level rises of up to one metre in height at its southern shore, a process called seiche. This occurs when prevailing northerly winds blow along the length of Lake Winnipeg, exerting a horizontal stress on its surface. Surface waters move in the direction of the wind and pile up along the leeward south shores.
Furthermore, water depths are known to be extremely variable at the south end of the lake. Many of the recreational beaches on the southern end of the lake feature rustic, seasonal piers for swimmers. It is not uncommon to be able to walk off the end of one of these piers one day into more than waist-deep water, then return a few days later to the same spot to find the water only ankle deep, or even exposed sand.
Setups greater than 1 m above normal lake levels have been recorded along many of southern Lake Winnipeg's recreational beaches, and the associated high waves with their uprush effects have caused considerable storm damage, backshore flood and shoreline erosion. The highest setups occur in the fall, when the northerly winds are strongest.
Algae population and pollution
Lake Winnipeg is suffering from many environmental issues such as an explosion in the population of algae, caused by excessive amounts of phosphorus seeping into the lake, therefore not absorbing enough nitrogen. The phosphorus levels are approaching a point that could be dangerous for human health.
Communities on the lake include Grand Beach, Lester Beach, Riverton, Gimli, Winnipeg Beach, Victoria Beach, Pine Falls, Manigotagan, Berens River, Bloodvein, Sandy Hook, Hecla Village and Grand Rapids. A number of pleasure beaches are found on the southern end of the lake, which are popular in the summer, attracting many visitors from Winnipeg, about 80 km south.
Lake Winnipeg has important commercial fisheries. Its catch makes up a major part of Manitoba's $30 million-a-year fishing industry. The lake was once the main source of goldeye in Canada, which is why the fish is sometimes called Winnipeg goldeye. Common carp were introduced to the lake through the Red River of the North and are firmly established. Walleye (often called Pickerel in Manitoba) and whitefish together account for over 90 percent of its commercial fishing.
Because of its length, the Lake Winnipeg water system and the lake itself was an important transportation route in the province before the railways reached Manitoba. It continued to be a major transportation route even after the railways reached the province. In addition to aboriginal canoes and York boats, several steamboats plied the lake, including Anson Northup, City of Selkirk, Colvile, Keenora, Premier, Princess, Winnitoba, Wolverine and most recently the diesel powered MS Lord Selkirk II passenger cruise ship.
As depicted in Season 6 of the History Channel series Ice Road Truckers, once the lake freezes to a sufficient depth during the winter, it can be crossed by trucks hauling freight to isolated communities in Manitoba.
- "Lake Winnipeg Quick Facts". Retrieved July 14, 2014.
- Massive flood expected to take toll on Lake Winnipeg, feed algae blooms Winnipeg Free Press
- Great Canadian Lakes
- International Lake Environment Committee
- Fur Trade Canoe Routes of Canada/ Then and Now by Eric W. Morse Canada National and Historic Parks Branch, first printing 1969.
- $1.1M for Lake Winnipeg - Winnipeg Free Press
- Canada’s sickest lake, MacLean's Magazine
- "Lake Winnipeg at 'tipping point': report". CBC News. May 31, 2011.
- "Lake Winnipeg declared threatened lake of the year". Winnipeg Free Press. 2013-02-05.
- Manitoba Water Stewardship - Fisheries
- "A profile of Manitoba's commercial fishery". Manitoba Water Stewardship (Department, Government of Manitoba). 2010-05-14. Retrieved 2011-07-29.
- Canadian Action Party (2006) Canadian action party release on devils lake ruling
- Casey, A. (November/December 2006) "Forgotten lake", Canadian Geographic, Vol. 126, Issue 6, pp. 62–78
- Chliboyko, J. (November/December 2003) "Trouble flows north", Canadian Geographic, Vol. 123, Issue 6, p. 23
- Economist, "Devil down south" (July 16, 2005), Vol. 376, Issue 8435,. p. 34
- GreenPeace, "Algae bloom on Lake Winnipeg" (May 26, 2008). Retrieved February 2, 2009
- Daily Commercial News and Construction Record, "Ottawa asked to help block water diversion project: devils lake outlet recommended by U.S. army corps of engineers" (October 20, 2003), Vol. 76, Issue 198,. p. 3
- Sexton, B. (2006) "Wastes control: Manitoba demands more scrutiny of North Dakota’s water diversion scheme", Outdoor Canada, Vol. 34, Issue 1, p. 32
- Warrington, Dr. P. (November 6, 2001) "Aquatic pathogens: cyanophytes"
- Welch, M. A. (August 19, 2008) "Winnipeg’s algae invasion was forewarned more than 30 years ago", The Canadian Press
- Macleans (June 14, 2004) "What ails lake Winnipeg" Vol. 117, Issue 24, p. 38.
- Wilderness Committee (2008) "Turning the tide on Lake Winnipeg and our health"
Media related to Lake Winnipeg at Wikimedia Commons