Among the potential impacts of climate change, accelerated sea level rise and a reduced Sierra snowpack are the most certain. Both will pose significant challenges for water supply and flood management. Water utilities have already begun to plan for these changes, but flood control agencies are lagging behind and face greater regulatory constraints. State leadership is needed to resolve some threats, including the risk of catastrophic failure in the Sacramento-San Joaquin Delta. This report was prepared as part of the Preparing California for a Changing Climate project.