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Some energy industry economists are already suggesting that the oil sands could face water shortages by then. We know that low water levels can be hard on or even lethal to spawning fish and the eggs they produce. A low water level not only starves them of oxygen, it concentrates pollutants that are naturally occurring or introduced to the river system. Low oxygen levels on the Athabasca are now a fact of life in winter, as are high levels of polycyclic aromatic hydrocarbons (PAHs), which occur naturally in the Athabasca River and its tributaries.

By most accounts, the Authority’s groundwater permit program serves as an effective tool in managing use of the region’s primary water resource by limiting withdrawals from the Edwards Aquifer to 572,000 acre-feet per year, as required by the Edwards Aquifer Authority Act. At one time, critics claimed that this approach would stymie economic growth, but that has proved not to be true. Even though the city of San Antonio has not increased water usage since 1996, its population has grown by more than 60 percent.

When the warming ended and the ice sheets returned, some of these animals found refuge in places such as the Old Crow Flats of the Yukon that were too dry and cold to grow ice. In time, though, most of the animals were unable to withstand the rapid-fire cycles of cooling and warming that followed. Among the thirteen species of mammals that Harington unearthed at Gold Run Creek in the westcentral part of the Yukon Territory in the 1970s, seven of them—the giant short-faced bear, American Beringian lion,2 American mastodon, woolly mammoth, horse, helmeted musk ox, steppe bison—are extinct.