Canada’s Growing Concern Over Water Quality and Sustainability

Water quality has a significant impact on the well-being of human populations and ecosystems. Without water, there is no biological life. It is essential for food production and agriculture, and crucial for industrial activities and municipal services. Canadians consider fresh water as the nation’s most valuable resource and are increasingly concerned about growing threats to the quality and adequate supply of clean water.

Worries over eutrophication and toxic contamination, cost of water treatment, impact of climate change and constant supply of safe drinking water have been growing. Pollution from agriculture and the impact of fertilizer run-off on aquatic biodiversity is also a main concern. Because the Great Lakes are surrounded by densely populated cities and intensive agricultural operations, risks to water quality are high. The International Joint Commission has noted that the Great lakes face threats from nutrient run-off, algal blooms, and heavy metal and pharmaceutical contamination.

In Canada, although toxic effluent is strictly regulated, run-off ending up in the watersheds is commonplace. High concentrations of phosphorus and nitrogen from fertilizers result in eutrophication. This causes an overgrowth in algae that depletes oxygen supplies needed to support aquatic plants and animals. Eutrophication is a serious water quality concern for the Prairie provinces, southern Ontario, and Quebec.

Environment Canada collects statistics on the quality of freshwater at 173 monitoring stations around the country. The Canadian Council of Ministers of the Environment‘s developed the Canadian Water Quality Index (CWQI) to provide a convenient way of evaluating and summarizing complex water quality data to report water quality information to both management and the public. CWQI looks into various factors such as dissolved oxygen, pH, conductivity, total nitrogen, and total phosphorus. The index has a rating of between 0 (worst water quality) and 100 (best water quality).

Dissolved Oxygen

Dissolved oxygen is measured in terms of the amount of free gaseous oxygen (O2) dissolved in an aqueous solution. It is vital for the metabolism of aerobic aquatic organisms and is essential for maintaining a healthy ecosystem. Dissolved oxygen decreases with higher temperature, salinity, and elevation. It comes from the atmosphere and from photosynthesis by aquatic plants. It can be exhausted through chemical oxidation, respiration by aquatic animals and microorganisms and during the decomposition of plant biomass and other organic material. Dissolved oxygen can drop to very low levels in winter months when water is trapped under ice. Dangerously low levels kills aquatic plants and animals.


pH is a measure of the acidity or alkalinity of a water body. If the pH of water is too high or too low, it will kill the aquatic creatures living in it. pH levels also has an effect on the solubility and toxicity of chemicals and heavy metals in the water. Most aquatic organisms prefer a pH range of 6.5-9.0. The alkalinity of a body of water is rises in the presence of carbonate-rich soils (carbonates and bicarbonates) such as limestone. It becomes more acidic due to sewage outflow and aerobic respiration. The process of decomposition can also lower pH levels.


Conductivity is a measure of the ability of water to carry an electric current. This is directly influenced by the concentration of ions in the water. These conductive ions come from dissolved salts and inorganic materials such as alkalis, chlorides, sulfides and carbonate compounds. Conductivity and salinity have a closely related and both have a strong impact of the aquatic ecosystem. However, conductivity is easier to measure and is used in algorithms estimating salinity. The greater the salinity level, the less dissolved oxygen available for organisms. Majority of aquatic animals can only surive in a specific salinity range. Thus, it is important to maintain adequate conductivity in bodies of water to ensure a healthy aquatic ecosystem.

Nitrogen and Phosphorus Concentrations

These compounds are naturally occurring elements essential for the survival of all living organisms. The rise in the nitrogen or phosphorus levels in natural waters often stem human activities. Major sources of excess nitrogen come from agricultural runoff from manure and synthetic fertilizers, from municipal and industrial waste-water discharge, and atmospheric deposition. Although high levels of nitrate and phosphorus is not toxic to aquatic animals, the overgrowth of algae depletes dissolved oxygen thereby harming or killing aquatic species.

The Fraser Institute ranks Canada relatively well on a comprehensive index of environmental performance, ranking 10th out of 33 high-income OECD countries. However, it ranks 23rd in terms wastewater treatment rate. While investing in new wastewater treatment facilities have helped, contamination from agricultural sources remains an issue. Sound public policies are critical to protect aquatic biodiversity and drinking water sources.

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Canada’s Growing Concern Over Water Quality and Sustainability
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