News of the drying up of Lake Mead, the largest-capacity water reservoir in the United States, and the recent high-profile release of California’s strategy for dealing with the state’s growing water shortages are combining to raise questions of whether Canada will one day be exporting its fresh water south. The prospect of our water being exported in bulk to a thirsty U.S. neighbour captures Canadians’ attention. For one, the subject goes to the heart of concern about our national sovereignty. It is also a scenario that is readily and intuitively grasped: one can see in the mind’s eye Canada’s water flowing north to south — top to bottom on the map of North America — as if through some giant open tap, even though many cross-border rivers actually flow south to north.