Public water agencies throughout California are looking to spend billions of dollars in the Sacramento-San Joaquin Delta to address a fundamental physical reality: The existing water system in the southern Delta poses an intractable environmental problem. The only solution is to construct a new, sufficiently sized conveyance system to move water supplies. State and federal agencies have been working toward a solution for 10 years. Occasionally, one group or another has suggested dramatically constricting the water system by downsizing its capacity.