Jon Margolis has a very interesting piece in the American Prospect today on Canada's water wars. The country has 20 percent of the world's freshwater and only 0.5 percent of the population. Water's becoming scarce in many places around the world. Why shouldn't Canada ship its surplus out? Well, for one, NAFTA would make it difficult for Canada to pass new environmental laws for its lakes once companies start engaging in the water trade:

According to an August 2004, report by the International Joint Commission, one of the bi-national bodies established to govern and protect the Great Lakes, most climate change models predict lower lake levels as the earth warms. And the same report appears to acknowledge that once a body of water has become "a commercial good or saleable commodity," any effort to protect it could fall afoul of NAFTA. The message seems to be that if you want to protect any of the lakes, or perhaps any bays or inlets thereof, pass the law before some company starts selling the water.

Although I'm sure he's aware of it, Margolis doesn't detail the various—and often serious—environmental problems with bringing in the tankers to haul water out of Canada: fluctuations in water level can accelerate erosion and destroy the surrounding soil, and any transport of water risks introducing new species to new environments, with all the disasters that can bring. And once Canada starts selling its water, NAFTA sharply limits what the government can do to address these problems.

Now in the context of this particular article, the case for conservation seems strong. A bunch of American developers want the Southwest to continue its totally unsustainable population explosion, so they're trying to pillage Canadian water supplies. One could suggest that Americans start choosing to live where there are natural water supplies—although that, as Margolis points out, would probably mean depopulating California. Or, as an interim measure, we simply could learn to conserve water; the United States is terrible in that regard, especially our practice of "irrigating fields that produce crops already in surplus."

But neither suggestion really addresses the underlying issue. About 1.5 billion people around the globe lack freshwater. In about 20 years demand for freshwater will exceed supply by 56 percent. As Margolis notes, "in 1997 the United Nations concluded that the best—perhaps the only—way to get water to them was through a system of international markets and trade." I don't know how true that is, exactly; most countries could stand to manage their own resources more carefully before thinking about water from elsewhere, but it sure looks like we'll have to start talking about a global water trade eventually, which, I think, will get rather dicey.