Water rights in the western United States are often determined by what you might call the I-was-here-first principle. This frontier-era rule reserves plenty of water for early birds, less for latecomers, and none at all for the rivers themselves. It also turns a river into a sort of used-car lot, allowing people to buy, sell, and steal as many shares of water as they possibly can. As Indian physicist and activist Vandana Shiva writes in Water Wars: Privatization, Pollution, and Profit, that kind of "cowboy economics" increasingly governs water management worldwide -- much to the detriment of the world's ecosystems and poorer citizens. Reviewer Michelle Nijhuis delivers the verdict on Water Wars, only on the Grist Magazine website.