Jay Famiglietti, one of a handful of expert witnesses in Jessica Yu's "Last Call at the Oasis," is a thoughtful scientist with an engaging manner who specializes in water. In particular, he studies — and tries to raise public awareness about — the rapid depletion of water supplies caused by agricultural overuse, rampant development and global climate change. His analyses are thorough and clear, and he presents them, at public meetings and straight to Yu's camera, with good-natured patience. For the most part, that is. At one point, contemplating a future of unchecked consumption and political paralysis, he sums it all up in blunt layman's terms: "We're screwed."

That might serve as an alternative name for Yu's film.

Yu wraps a lot of bad news into a slick, informative, fast-moving package. Dwelling mostly on the United States, she weaves stories of drought and pollution together with larger-scale explanations of the worldwide water crisis.