The proposals are Gargantuan: a 400-mile Grand Canal from the icy rivers of northern Canada to the Great Lakes, or an irrigation trench through the Rocky Mountains to the parched American West.

Could the U.S.-Canada Free Trade Agreement, now in the process of ratification, make such massive diversions of fresh water a reality?The subject was debated Thursday when two Canadian experts disclosed that the trade agreement treats water like newsprint, computers and other "goods" now subject to tariffs.

The treaty will eliminate those tariffs and offer the United States "national treatment" when it comes to Canadian water, said former trade negotiator Mel Clark and Don Gamble of the Rawson Academy of Aquatic Science in Ottawa.

The discovery, they said, contradicts claims by the Conservative government of Prime Minister Brian Mulroney that water was not part of the trade deal.

When questioned in Parliament, Trade Minister John Crosbie indirectly confirmed that water exports are possible under the treaty.

But Crosbie told opponents that Canada cannot be forced to sell water or any other natural resource.

"We are not obliged to sell one thimbleful of (water) to the United States," he said, citing a federal announcement last November that large-scale water diversions will not be contemplated.

Frank Quinn of the government's Inland Waters Directorate told The Associated Press that Canada wanted water exempted from the trade deal but abandoned the demand in final compromises with U.S. negotiators.

"In the 11th hour, we didn't get all the changes we wanted," he said.

Quinn said the world General Agreement on Tariffs and Trade, which both countries recognize, allows a member to ban exports of natural resources on grounds of conservation and environmental protection.

On that basis, he said, Canada will not permit diversions of fresh water.

Border towns in Alberta, Manitoba and New Brunswick export small quantities to local water systems in Montana, North Dakota and Maine, and there are proposals to export water by tanker from British Columbia and Quebec.

In any case, Quinn said, even the thirstiest U.S. states are no longer considering long-distance diversions because of the cost. Instead, they are focusing on a transition from agricultural to municipal use of local water.

Should the United States run dry, Canada does seem a handy solution.

With 7 percent of the world's land area, Canada has 9 percent of its renewable fresh water supply and only 1 percent of its population. Eight percent of the country is covered by lakes.

The problem is that 60 percent of the water flows north toward the Arctic and is inaccessible to most Canadians, who live huddled near the U.S. border.

Thus the grand schemes.

Newfoundland engineer Tom Kierans has spent 30 years promoting his dream of turning Arizona desert into lush farmland with water diverted from the rivers of northern Quebec and Ontario, now flowing north into James Bay.

Pumping stations would propel the water into a Grand Canal across the Canadian Shield to the Ottawa River and on to Lake Huron. From the Great Lakes, it would be pumped to the prairies and desert. The estimated cost of construction alone: $100 billion.

The same pricetag was put on a 1964 idea proposed by Ralph M. Parsons Ltd., California engineers, to divert the Yukon and McKenzie rivers through the Rocky Mountain Trench of western Canada into the United States.

A comprehensive Canadian study in 1985 advised a "cautious approach" to such projects but called it "imprudent to reject all exports out of hand."

The author of that report, Professor Peter Pearse of the University of British Columbia, told the AP the Grand Canal was "not in anybody's interest on ecological or economic grounds."

He said it would cost $2,000 per thousand cubic meters simply to get the water to the U.S. Southwest.

Environmentalists oppose transferring water from one basin to another because of the ecological impact and disruption to Indians and Inuit dependent on fishing and hunting.