California has a complex, highly interconnected, and decentralized water system. Although local operations draw on considerable expertise and analysis, broad public policy and planning discussions about water often involve a variety of misperceptions\textemdashor myths\textemdash about how the system works and the options available for improving its performance. The prevalence of myth and folklore makes for lively rhetoric but hinders the development of effective policy and raises environmental and economic costs. Moving beyond myth toward a water policy based on facts and science is essential if California is to meet the multiple, sometimes competing, goals for sustainable management in the 21st century: satisfying agricultural, environmental, and urban demands for water supply and quality and ensuring adequate protection from floods. We focus on eight common water myths, involving water supply, ecosystems, and the legal and political aspects of governing California\textquoterights water system. These are not the only California water myths, but they are ones we find to be particularly distracting and disruptive to public policy discussions.