Canada's fresh water could become subject to international trade regulations after Ontario issued a permit letting a small Canadian company draw water from Lake Superior for exporting to Asia. The permit has heightened fears that Canada could be obliged to sell its fresh water to the United States.At least one trade expert says the permit issued by Ontario's environment ministry in effect transforms water into a tradable commodity that is now subject to North American Free Trade Agreement (Nafta) and World Trade Organisation(WTO) provisions covering the trade of that good.