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Canada is richly endowed with water. Possessing one of the largest renewable supplies of freshwater in the world, it has access to upwards of 20% of the world's surface freshwater and 7% of the world's renewable water flow.
Although our resources are large, from 1971 to 2004 the freshwater supply decreased in southern Canada, where 98% of the population lives. Over the same period, water yield, or the average annual renewable freshwater supply, fell by 9%. Annually, this represents an average loss of 3.5 billion cubic metres, the equivalent of 1.4 million Olympic-sized swimming pools—almost as much water as was supplied to Canada's entire residential population in 2005.
Water yield is the result of precipitation and melted ice that flow over and under the ground, eventually reaching rivers and lakes. For most of the country, water yield peaks in the spring as snow and ice melt and precipitation increases, whereas demand for water increases in the summer.
Canada's water yield
Canada has an average annual water yield of 3,472 billion cubic metres. This almost equals the amount of water in Lake Huron, giving Canada one of the largest renewable water supplies in the world. Brazil has the largest total water yield, followed by Russia.
Canada, however, has the most renewable freshwater per person each year: 109,837 cubic metres per person compared with Brazil, at 43,756 cubic metres per person. While total water yield is comparable between the United States (3,051 billion cubic metres) and Canada (3,472 billion cubic metres), the renewable freshwater per person in the United States is just 9.1% of that in Canada because the United States has a much larger population.
Canada's average annual water yield per unit area is 348 litres of renewable freshwater for every square metre of the country, higher than the yield in drier countries such as Australia and South Africa but three times less than a tropical rainy country like Brazil. The Pacific Coastal drainage region has the highest water yield, followed by Newfoundland and Labrador. Drainage regions both in and north of the Prairies produce the least water.
Four drainage regions comprise most of the Prairies and stretch across the southern parts of Alberta, Saskatchewan and Manitoba. This collection of drainage regions yields just 12% of what the Great Lakes drainage region yields, 6% of what the Maritime Coastal drainage region yields and only 3% of what the Pacific Coastal drainage region yields.
Industrial water use
In 2005, an estimated 42.1 billion cubic metres of water were withdrawn from the environment and used in household and economic activities in Canada.
In 2007, three industry groups (that cover most industrial water use) used a total of 33.6 billion cubic metres of water: thermal-electric power producers (fossil-fuel and nuclear) withdrew 83% of this total, manufacturers used 16% and mining, 2%. In 2007, the three groups' water costs totalled $1,624.2 million.
These three groups discharge almost as much waste water into the environment as they withdraw: 32.8 billion cubic metres in 2007. Thermal-electric power producers accounted for 83% of this total, manufacturers, 14% and mining, 2%.
Virtually all the water (99.8%) the thermal-electric power producers take in is used for cooling. Most of this water (75%) is not treated before discharge.
Manufacturing industries discharged 4,725.0 million cubic metres of water in 2007; 38% was not treated before being released. Most was discharged to surface freshwater bodies (79%) and to public and municipal sewers (10%).
Of the 755.0 million cubic metres of water discharged by mining operations, 58% was not treated before discharge. Most of the total discharged (66%) was returned to surface freshwater, 16% was discharged to groundwater and 11% to tailing ponds.
Residential water use
In 2007, 86% of households received their water from a municipal water supply and 12% had a private well. That year, $807 million was spent on operation and maintenance for the acquisition and treatment of water at drinking water plants.The largest components of this cost being labour ($302 million), energy ($199 million) and materials ($198 million).