A new report says renewable water resources have declined in Southern Canada over the past three decades.
Statistics Canada says water yield in the southern part of the country, the area in which 98 per cent of the population lives, fell by an average of 3.5 cubic kilometres a year between 1971 and 2004.
The agency equates the annual loss to 1.4 million Olympic-sized swimming pools, and almost as much water as was supplied to Canada's entire residential population in 2005.
This represents an overall loss of 8.5 per cent of the water yield in Southern Canada over 34 years.
Canada's total annual renewable freshwater supply is about 3,470 cubic kilometres, roughly equivalent to the volume of Lake Huron.
It's the result of precipitation and melted ice that flow over and under the ground, eventually reaching rivers and lakes.
The Pacific Coastal drainage region has the highest water yield in the country, followed by the Newfoundland and Labrador drainage region. Drainage regions in the Prairies and north of the Prairies produce the least water.
Water yield is also distributed unequally throughout the year. In much of Canada, the bulk of the water yield comes in spring and declines through the summer months. However, demand increases in the summer, and is highest in July and August.