Canada is now the biggest supplier of oil to the United States, thanks to the Alberta tar sands—a controversial billion-dollar project to extract crude oil from bitumen sands, using a very toxic process that has generated international cause for concern. Four barrels of glacier-fed spring water are used to process each barrel of oil, along with vast amounts of electricity. The waste water is dumped, filled with carcinogens and other chemicals, into leaky tailings ponds so huge that the piles can be seen from space. Downstream, people and communities are already paying the price with contaminated water supplies and clusters of rare cancers. Evidence mounts for industry and government cover-ups. In a time when wars are fought over dwindling oil and a crisis looms over access to fresh water, which will we allow to turn out to be more precious to us?