South Saskatchewan River Basin
The South Saskatchewan River has three major tributaries: the Red Deer River, which originates just east of Lake Louise ski area in Banff National Park; the Bow River, which originates on Bow Glacier north of Lake Louise; and the Oldman River, which originates in the mountains west of Pincher Creek. The river formed by the confluence of the Bow and Oldman is called the South Saskatchewan River; the Red Deer River joins it just east of the Saskatchewan border. The combined area that these four rivers drain is the South Saskatchewan River Basin and includes about one-fifth of Alberta. Approximately 41% of this area drains to the Red Deer River, 21% to the Bow, 22% to the Oldman, and 16% to the South Saskatchewan.
Population and Geography
The population density in the South Saskatchewan Basin is greater than that of most of Alberta. As of 1988, over a million people, or 46% of Alberta's population, lived in the basin; 87% of them in a 100-km-wide corridor between Red Deer, Calgary and Lethbridge. Approximately 2 billion m3 of water are withdrawn from the rivers in the basin each year. Irrigation accounts for 96% of the water consumption in the basin, municipal use for 3% and industry for 1%. The average annual discharge of the South Saskatchewan River below its confluence with the Red Deer River is approximately 7 billion m3 .
There is great variation in the amount of precipitation that falls in the basin. In an average year, the mountains and foothills receive over 700 mm of precipitation; a large proportion falls as snow. This area has a net moisture surplus, which means precipitation exceeds eaporation and excess water is available for runoff. The western part of the prairie grasslands receives about 520 mm of precipitation. Evaporation exceeds precipitation and the area is very dry with an average moisture deficit of about 170 mm. The eastern part of the basin receives only about 300 mm of precipitation and has a net moisture deficit of 350 mm; this is the driest region in Alberta.
Approximately 75% of the flow in the rivers in the South Saskatchewan Basin comes from mountain snowmelt. About half of the annual flow in the rivers surges through the system in only two months, from mid-May to mid-July. For the rest of the year, natural flows in the rivers can be very low. Given the rich, easily cultivated soils of the prairie and the long, warm growing season, it is easy to understand the attraction the area had for farmers. The limiting factor is water: as rain, as lakes and as flow in the rivers. The obvious solution to the early settlers of southern Alberta was irrigation-not only using the water where and when it was available, but also storing water that could later be redistributed as needed. The story of settlement in the South Saskatchewan Basin becomes the story of irrigation, of canals, of reservoirs....
The first irrigation project in Alberta was in 1879 when a settler named John Glenn dug a ditch to divert water from Fish Creek to irrigate 6 ha of hay meadow. By 1920, private companies, including the Canadian Pacific Railway, had built extensive canal systems and major reservoirs, including Chestermere Lake, McGregor Lake and Little Bow Lake Reservoir; about 72,000 ha of land in the basin was under irrigation. The spread of irrigation farming slowed under the stress of drought, depression and World War II. However, after the war, the Prairie Farm Rehabilitation Administration (PFRA) of the federal government undertook several major projects including Travers Reservoir; Milk River Ridge Reservoir; St. Mary Reservoir and improvements to its extensive canal system; and Waterton Reservoir, which is used to supply water to St. Mary Reservoir. By 1960, the area under irrigation had increased to 240,000 ha. In 173, the federal government turned all its projects over to the provincial government. By 1980, the irrigated area had increased to 336,000 ha. In the 1980s, three new large offstream reservoirs were built; Badger Lake, Crawling Valley and Forty-Mile Coulee. Two new onstream reservoirs were also built or were under construction: Gleniffer Lake, with the primary objective to regulate flow of the Red Deer River; and the Oldman Dam to store water for irrigation. By 1990, the South Saskatchewan Basin contained 8 onstream reservoirs, 17 large offstream reservoirs, 22 smaller reservoirs and approximately 8,000 km of major or local canals.
Irrigated land is frequently in a different sub-basin than the source of the water it receives. For example, 28% of the water diverted from the Bow River goes to irrigate farms in the Red Deer basin and 15% goes to farms in the Oldman Basin. Similarly, 35% of the water taken from the Oldman River is used on land that drains directly to the South Saskatchewan River.
Hydroelectric power generation
As the rivers of the South Saskatchewan Basin flow down the mountains, they release tremendous energy. This energy was first harnessed by Calgary Power Ltd. (now TransAlta Utilities Corporation) soon after the turn of the century. The first two plants, one on a canal in Calgary, and one at Horseshoe Falls near Seebe, were "run-of-the-river" plants and did not involve reservoirs. The first dam on Lake Minnewanka was providing power by 1923. In 1929 the Ghost Reservoir was built, and in 1932, Upper Kananaskis Lake was raised ad regulated to feed generators at the Seebe plant on the Bow River. The most rapid expansion of hydroelectric power developments in Alberta occurred soon after the Second World War. The Minnewanka Dam was raised, and the present-day Cascade Power Plant was built by 1942. By 1952 the dam on Lower Kananaskis Lake was raised and generating plants were installed at both Upper and Lower Kananaskis Lakes, Spray Lakes Reservoir with its three generating plants had been built, and Barrier Lake and Bearspaw Reservoir had been created and generators installed.
Today, TransAlta Utilities Corporation owns and operates 11 hydroelectric plants on the Bow River upstream of Calgary. Total generating capability is 325 megawatts, about 10% of the company's total potential and about 5% of the total power generated in Alberta (the other 95% is derived from coal-fired thermal generating plants).
Recreation, Fish and Wildlife
This basin has the warmest climate, the highest population density and the lowest availability of lakes; therefore, almost all water bodies are popular for recreation. There are parks, day-use areas and boat launches on almost every lake and reservoir. Many lakes and reservoirs provide angling for northern pike and yellow perch and many are stocked with trout for sport fishing. In the mountain lakes, such as Kananaskis, Crowsnest, and Spray Lakes Reservoir, the reward for the angler may lie more in the spectacular scenery than in the catch, but stocked rainbow trout grow rapidly in the warm, productive, prairie reservoirs such as Blood Indian Creek and Crawling Valley reservoirs, and Tyrrell Lake. For example, rainbow trout in Tyrrell Lake grow at one of the fastest rates in North America, and Blood Indian Creek Reservoir is regarded by many Albertans as the best trout fishery in the province. Many of the larger reservoirs, such as McGregor Lake and Travers Reservoir, support commercial fisheries for lake whitefish. Beach and cottage activities are popular on the natural lakes in the northern part of the basin - Gull, Sylvan, Buffalo and Pine. Sailing is very popular on Glenmore Reservoir and Chestermere Lake; windsurfing and iceboating are favourite activities on Ghost Reservoir.
The South Saskatchewan River Basin plays a vital role in Alberta, providing water to irrigate half a million hectares of land, supplying water for the domestic needs of over one million people, generating electrical power, and providing recreation and sport fishing for Albertans and tourists from the rest of Canada and the world.
The Milk River Basin
The Milk River rises in the foothills of Montana as two major forks, the North Milk River and the south fork of the Milk River. The North Milk River carries water diverted to it from the St. Mary River in Montana and therefore its flow is often surprisingly high during the hot, dry summers of southern Alberta. The south fork carries only natural flow; in summer the volume is occasionally so low that water movement is negligible. The Milk River traverses eastward across the southernmost part of Alberta, then re-enters the United States near the tiny hamlet of Wild Horse. The southern flank of the Cypress Hills is drained by a few streams that cross into the United States before joining the Milk River, which then continues eastward to join the Missouri River, then the Mississippi River which enters the Gulf of Mexico at New Orleans.
The population of the Alberta portion of the Milk River Basin was less than 2,000 in 1988. The town of Milk River and the village of Coutts are the largest population centres.
The basin in Alberta is almost all flat to undulating dry grasslands, cut by the Milk River and indented by dry coulees carved by glacial meltwater. However, the northernmost part of the basin which straddles the Alberta-Saskatchewan border includes a strikingly green, forested surprise-the Cypress Hills. Rising to nearly 1,500 m, this is the highest Canadian land between Labrador and the Rocky Mountains. These hills were never glaciated, the soil is rich and rainfall is adequate to support forests of pine and spruce. As Captain Palliser wrote in his journal in 1859, "These hills are a perfect oasis in the desert we have travelled."
Outside of the Cypress Hills, water is scarce in the Milk River Basin. There are few sloughs and no significant lakes. There is more moisture in Cypress Hills area, but even here there are few lakes, and the only one in the Atlas, Reesor, is maintained by flow diverted from nearby Battle Creek.
The Milk River Basin is not an area where water-based recreation abounds. It does, however, present an expanse of vast open spaces, a dramatic canyon, rolling grasslands and spectacular prairie vistas. To visit the basin is to relive the history of the prairies. Standing on a grassy knoll staring into a golden sunset conjures visions of the past: of buffalo, of whisky-traders, of the Northwest Mounted Police, of the incredible isolation and hardships of the early settlers. A sojourn here is not soon forgotten.