I just found a wonderfully informative website [1] developed by the Water Education Foundation. They have a page [2] to determine where your water comes from if you are in California.

California, like most of the arid West, has a rich history when it comes to water. It includes monumental feats of human engineering, shady political dealings, acts of God, and the eternal struggle of man versus nature. If you have never read Cadillac Desert [3] by Marc Reiner, I highly recommend it. It will change the way you look at water and water projects.

If documentary films are more your thing, I also recommend at least checking out the PBS [4] series based on the book, which covers water issues in California, the western U.S. and internationally. Unfortunately you can no longer purchase this series, and it was filmed prior to DVDs, so your only chance to see it is by checking your local library and/or university. It is worth it.