While three years of hydrological drought conditions have created a fundamental shortage of water supply in California, many water users have questioned the extent to which regulatory and court-imposed restrictions on water removed from the Sacramento and San Joaquin Rivers Delta, in order to protect fish habitat, have contributed to water shortages in 2009. A longer term issue for Congress is how to evaluate management alternatives that will protect species, but also help water users and economies that depend on reliable water supplies and healthy ecosystems. This book discusses California's current hydrological situation and provides background on regulatory restrictions, affecting California water deliveries, as well as on the long-established state water rights system.