Freshwater yield dwindling

Canada's renewable freshwater supply dropped dramatically over three decades in the most populated areas of the country, with the prairies particularly hard hit, according to a new report from Statistics Canada.

"If we want to be able to manage our water and understand what's happening with water over time, we need to know where it is, how much we have and how that's changing over time," said co-author Heather Dewar.

Dewar and her colleagues examined data on incoming freshwater supplies, from precipitation and melting snow, from across southern Canada, where 98 per cent of the country's population lives.

The annual reduction they calculated is equivalent to the water in 1.4 million Olympic-size swimming pools. Between 1971 and 2004, there was a total loss of 8.5 per cent of southern Canada's water yield.

The report, titled Human Activity and the Environment, didn't point to the reasons for the decreases over the course of 34 years. Dewar said that is better left to scientists.

They quickly weighed in on Monday. "It is clearly climate warming," said John Pomeroy, director of the Centre for Hydrology at the University of Saskatchewan.

"As Canada warms, evaporation generally increases due to shorter winters," Pomeroy said in an e-mail from western China where he is on a speaking tour.

He said as temperatures have risen since the 1970s, the Great Lakes have had more ice-free periods and therefore longer evaporation periods. Across the Prairie provinces, groundwater and pond levels have dropped for most of the last 25 years.

"The Canadian Rockies are warming as rapidly as anywhere on earth -- we are finding about 3 to 4 degrees Celsius in winter since 1962 at high elevations."

And regional water issues appear to be on the verge of becoming more pronounced. Monday's report from Statistics Canada said although Canada is endowed with huge volumes of fresh water, it's unevenly distributed.

The combined southern portions of Alberta, Saskatchewan and Manitoba have both sporadic and decreasing freshwater yields -- a fact that leads to both floods and droughts, the report said. At the same time, the demands are increasing. The population of the region grew to 4.5 million in 2006 from 1.6 million in 1971.

This part of the prairies gets just 12 per cent of the new water, primarily precipitation, that is seen in the Great Lakes drainage region.

Studies such as the Statistics Canada report are often difficult to stomach when Alberta has just gone through a cool and rainy summer, said Joe Obad of Water Matters, a conservation group.

"When everything looks green, it just slips off of peoples' political radar and makes it harder for decision-makers to make tough decisions."

But the Alberta government needs to pay serious attention to its long-standing promise to examine and re-vamp the province's water allocation system to deal with population growth and other climate changes in the years to come, Obad said.

Jim Webber, general manager of the Western Irrigation District in Strathmore, said the Statistics Canada report was "an interesting read, but you can paint any picture you want if you have enough numbers."

He said southern Alberta has seen many recent wet years, but "precipitation shortfalls can be handled by water management techniques and infrastructure."

Canada's Water Supply

- For most of the country the bulk of the water yield comes in April, May and June, as snow and ice melt, and precipitation increases. As spring turns into summer, new supplies decline even as human demand for water increases.

- More than 90 per cent of Canada's water withdrawn goes to support economic activity, about nine per cent is used by the residential sector.

- Sixty per cent of all of Canada's irrigated land is found in Alberta.

- Canada is one of the largest producers of hydroelectricity in the world, and the volume of water involved in hydroelectric generation is many times larger than all other uses of water in the country combined.

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