Water quality in Saskatchewan is affected by a variety of human activities. Uses that consume large quantities of water while degrading its quality include agriculture, mining and milling, oil and gas production, and municipal and domestic uses (see Table WQ-1). In Saskatchewan, most water pollution originates from non-point (i.e., unconfined) sources such as agricultural runoff. Point sources of pollution, which originate from a specific localized origin such as an effluent pipe, are carefully monitored and for the most part have been cleaned up. Agriculture is Saskatchewan’s leading industry and its biggest consumer of provincial water resources. Irrigation, which alone accounts for two-thirds of all provincial water consumption, is a chief contributor to water contamination. Surface runoff and return flow from irrigated fields may contain dissolved salts and other pollutants such as chemical fertilizers and pesticides, which wash into nearby watercourses or leach through the soil into underlying groundwater. Similarly, waste and by-products from intensive livestock operations can potentially contaminate water systems though leakage and percolation.
Domestic and municipal activities also impact water quality. Urban centres sometimes discharge large amounts of industrial waste and underground leachates. Although the larger cities use tertiary sewage treatment to remove pathogens and solid wastes, the risk for accidental waterway contamination still exists. Smaller centres are not as thorough in their treatment of sewage, and run a greater risk of surface and groundwater contamination. Leaching of wastes from landfill sites can also contaminate groundwater; and storm-water runoff from the urban watershed picks up contaminants, washing them into drainage basins and ultimately into natural waterways and aquatic ecosystems. Mining and milling operations are a potential source of water pollution if their tailings and residual wastes are not properly contained and treated. Until reclaimed, decommissioned mine sites are especially dangerous sources of groundwater contamination. Effluents from wood processing mills are carefully monitored and controlled in Saskatchewan. The pulp mill at Meadow Lake, for example, has successfully eliminated the discharge of polluted effluent through its zero-effluent treatment system. Wastewater from the mill is collected, decontaminated, evaporated (to produce a clean distillate), and then recycled back into the milling process.
Oil and gas production, through accidental oil spills and improperly disposed drilling wastes, may release toxins into surface and groundwater sources. Dams and water control structures also directly impact water quality in Saskatchewan’s waterways. Changes in the water’s temperature (thermal pollution) and chemistry are often observed downstream from dams and reservoirs. In addition, dams trap sediment, contaminants, and nutrients in their upstream reservoirs. The accumulation of nutrients (such as nitrates and phosphates from agricultural runoff) in a water body will stimulate the growth of algae and deplete the water oxygen. This can lead to the death of fish, and produce visual and odour problems that reduce the water’s aesthetic and recreational appeal. Poor water quality threatens the survival of sensitive aquatic ecosystems both upstream and downstream of a water control structure.
Surface and groundwater quality in Saskatchewan is assessed through the Water Quality Index (WQI), a composite measure of the chemical and organic makeup of the water in a particular drainage basin. Depending on the specified use (e.g., recreation, irrigation, livestock watering, protection of aquatic life) of the water in that basin, its quality is rated from “poor” to “excellent.” Drinking water for human and livestock consumption is a high-priority use in Saskatchewan, and is therefore subject to stringent testing and treatment measures. Source water must be tested to ensure safe levels of biological, chemical, and physical contaminants that make it suitable for drinking. The most common method for removing harmful bacteria and viruses from drinking water is through the addition of chlorine. In Saskatchewan’s rural areas, surface and groundwater quality and the provision of clean water for domestic consumption are major concerns. Groundwater forms the most abundant and most widely distributed of Saskatchewan’s water reserves, and provides 30% of the province’s population with its domestic water; however, the quality, yield, and reliability of Saskatchewan’s groundwater vary significantly. Groundwater in deep wells is difficult to treat, and water quality in dugouts and small reservoirs is generally quite poor.
Agencies such as SaskWater, Saskatchewan Environment, and the Saskatchewan Watershed Authority are directly involved in the management of the province’s water resources. Saskatchewan Environment’s Drinking Water Quality section ensures safe drinking water for the province. The Saskatchewan Watershed Authority, a Crown corporation, was established through the consolidation of water management divisions at SaskWater, Saskatchewan Environment, and the Saskatchewan Wetland Conservation Corporation. The Saskatchewan Watershed Authority has a broad mandate to manage and protect water quality in Saskatchewan.