OTTAWA - You could fill more than a million Olympic-sized swimming pools every year with all the renewable water that dries up across Southern Canada, a new report says.

A Statistics Canada study released Monday says water yield has fallen by an average of 3.5 cubic kilometres a year over the last three decades.

The agency equates the annual loss to 1.4 million Olympic-sized swimming pools. Put another way, that's almost as much water as Canadians drank and used in toilets, showers and to water their lawns during the entire year of 2005.

This represents an overall loss of 8.5 per cent of the water yield in the southern part of the country between 1971 and 2004.

"It's always hard to grasp these volumes of water," said Heather Dewar, managing editor of the agency's study.

"And the water's not lost; it's really in a state of flux. That water is somewhere else. It is striking that there is a downward trend over that time period, though."

The study doesn't offer any explanations for why Canada's renewable water is drying up. Dewar says the work will help the government determine if and to what degree climate change has played a role.

But a prominent author and water activist says climate change is just part of the problem.

Maude Barlow, head of the Council of Canadians and the United Nations' senior adviser on water issues, says Canadians take water for granted.

"We've always thought we're immune from that. 'Oh, that's somewhere in Africa, that's somewhere in India,'" she said.

"No, it's right here. Obviously it's not the kind of crisis it is in other places, but we have a declining water stock in this country."

Canada's annual freshwater supply is about 3,470 cubic kilometres — roughly the volume of Lake Huron. Freshwater comes from rain and melted ice that eventually reaches rivers and lakes.

The agency says more than 90 per cent of freshwater withdrawn from the environment went to support economic activity. About nine per cent was used for residential purposes.

Statistics Canada defines "Southern Canada" as a jagged and elongated U-shaped line that starts in the middle of British Columbia, dips across northern Ontario and rises again from Quebec City to the northwestern tip of Newfoundland.

Some parts of Canada have more freshwater than others. The Pacific Coastal and Newfoundland and Labrador drainage regions have the most water. Drainage regions in and north of the Prairies have the least water.

The study says the Prairies are even more parched than two drought-stricken countries.

"Compared internationally, the renewable freshwater per unit area of the Prairies is less than that for either Australia or South Africa," it says.

The amount of renewable water also varies throughout the year. In most parts of the country there's more water in the spring than summer. The study notes summer is when people use the most water, particularly in July and August.

Bureaucrats have been raising red flags for years over how little Ottawa knows about the country's freshwater supply. The government has even formed a working group of high-ranking civil servants from several departments to study water issues.

Last year, the group wrote a report warning a lack of information about water is putting the health of Canadians and the economy at risk.

Although Canada has a fifth of the world's supply of fresh water, only seven per cent of it is renewable. That's less renewable water than Brazil and Russia, and about the same as the United States.

There could be much more freshwater underground. However, Canada is still about two decades away from mapping a number of key aquifers.

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