Water is another major problem. Tar sands plants typically use two to four barrels of water to extract a barrel of oil. Currently, the water consumption is enough to sustain a city of two million people every year. And after it's been through the process, the water is toxic with contaminants, so it cannot be released into the environment. Some of it is reused, but vast amounts of it are pumped into enormous settlement ponds to be retained as toxic waste.
These "ponds" are actually the largest bodies of water in the region--big enough to be seen from space--and some of the world's largest man-made ponds overall, with miles of surface area. It may take 200 years for the smallest particles to settle down to the bottom of this toxic brew, which also contains very high levels of heavy metals and other health-threatening elements.
According to a recent joint study by the University of Toronto and the University of Alberta, the projected expansion of the tar sands projects will kill the Athabasca River, the only abundant source of water in the area. "Projected bitumen extraction in the oil sands will require too much water to sustain the river and Athabasca Delta, especially with the effects of predicted climate warning," the study said. If that amount of water were used, they warned, it would threaten the water supply of two northern territories, 300,000 aboriginal people and Canada's largest watershed, the Mackenzie River Basin.
http://canada.theoildrum.com/node/2931