About The South Saskatchewan River Basin
Economic and Social Importance
- The South Saskatchewan River is one of the largest, and arguably most important rivers in Saskatchewan.
- It is the single largest supplier of water in Saskatchewan for drinking water, irrigation, industrial uses, and recreation, with almost 50% of the provincial population in Saskatchewan relying on the South Saskatchewan River for their daily needs.
- Agricultural irrigation is the single largest consumptive water use from the South Saskatchewan River, followed by industrial, and municipal uses.
- On average, about 30% of the flow in the South Saskatchewan River is consumed by human use. Up to 50% of the flow in the South Saskatchewan River is allocated to Alberta, while allocation to Saskatchewan is 25%, with the remaining flow going to Manitoba.
- Major industrial users include; power production from the Gardiner Dam Hydroelectric Station and the Queen Elizabeth Power Station; fertilizer plants; potash mines; and petroleum related operations, including oil and gas extraction and exploration.
(Statistics taken from the Partners for the Saskatchewan River Basin, State of the Saskatchewan River Basin Report, 2009).
The South Saskatchewan River begins in Rocky Mountains in Alberta where two mountainous tributaries join to create the South Saskatchewan River: the Oldman, and Bow Rivers. Shortly downstream from their confluence they are joined with the Red Deer River, just before crossing the Saskatchewan-Alberta border, at which point the joined rivers officially become the South Saskatchewan River.
From there, the South Saskatchewan River travels northeast, becoming Lake Diefenbaker. From the northern shores of Lake Diefenbaker the river flows out of the Gardiner Dam towards the City of Saskatoon. The river continues north to eventually become the Saskatchewan River at the confluence of the North and South Saskatchewan Rivers, known as “the forks.”
From the forks, the Saskatchewan River passes through the Saskatchewan Delta, into Lake Winnipeg, which eventually drains into Hudson Bay through the Nelson River.
In total, the South Saskatchewan River receives runoff from 120 000 km2 of Saskatchewan, and the Saskatchewan portion of the river is approximately 720 km long.
The South Saskatchewan River passes through four eco-region areas known as Mixed Grassland, Moist Mixed Grassland, Aspen Parkland and the Boreal Transition. These regions are characterized by rich soils, and thick glacial drift. Many of the features were shaped 10 000 – 14 000 years ago during the ice age that covered most of Canada. Hills, plateaus, and escarpments are the result of areas where the bedrock has come to the surface and resisted erosion. Most of the landscape features of the prairies were formed by glacial movement or melting, and the formation of proglacial rivers and lakes from the meltwaters of glacial retreat. The thick surficial materials deposited by the glaciers of the ice age formed excellent shallow groundwater aquifers. These are relatively fresh aquifers on which many rural residents rely. Below the shallow groundwaters, vast fields of deep aquifers exist within the underlying shales. These aquifers, while plentiful, are often highly saline.
Overall, water quality in the South Saskatchewan River meets most of the guidelines for water quality set out in the provincial water quality index. Mercury is perhaps the most significant risk to water quality, as the flooding of Lake Diefenbaker upstream of the Gardiner Dam dissolved natural mercury in what was previously agricultural land, pasture, or native vegetation. Algae blooms in Lake Diefenbaker are another reoccurring problem, as many of the upland agricultural areas drain into the lake, causing problems with nitrogen concentrations.
Many other land uses in the South Saskatchewan River Basin adversely impact the quality of water in the South Saskatchewan River. Many municipalities draw water from the river for treatment and distribution for the daily needs of urban and rural residents. In some locations, such as the City of Saskatoon, a high standard for wastewater treatment ensures that water returned to the river is relatively clean, however not all municipalities provide secondary treatment for wastewater. In addition, some residents discharge their wastewater directly into the South Saskatchewan River. Technically this requires a permit, but not all such discharges are identified by the Saskatchewan Watershed Authority and remedied. In many large urban centres along the river stormwater is captured during rain events and discharged directly into the river as well, without treatment or the benefit of settling ponds. Many groundwater wells have been drilled through the surface soils and once abandoned, these wells provide a vector for groundwater contamination. In intensive agricultural areas, fertilizer application on croplands and high density livestock production contribute nitrogen and phosphorus loading to the river from surface drainage. Potash and chemical plants, oil and gas wells, and pulp and paper mills located along the river also contribute effluent to the South Saskatchewan River with various concentrations of heavy metals and salts. Even recreation on the river and Lake Diefenbaker can adversely impact water quality in the South Saskatchewan River from oil and gas leaks, and by damaging aquatic ecosystems which normally help to assimilate water contaminants All of these potential sources of contamination contribute to an ongoing risk to water quality in the South Saskatchewan River. Through the South Saskatchewan River Source Water Protection Plan, the South Saskatchewan River Watershed Stewards seek to prevent or mitigate some of these risks.
River and Lake Water Levels