1. Improve the reliability of water supplies in California,
2. Improve water quality in the Bay-Delta system,
3. Restore ecosystems within the Bay/Delta watershed, and
4. Stabilize Sacramento-San Joaquin Delta levees.
The success of the CALFED Program depends, among many other factors, upon the robustness of its plans and actions to the considerable buffeting that California’s highly variable climate will inevitably impose upon it. The Bay-Delta watershed spans the West Coast precipitation influences of the El Nino-Southern Oscillation climate variations, their interdecadal realization in the Pacific Decadal Oscillation, and other short- and (especially) long-term influences that are less well understood. In addition, recent observed winter-spring warming and streamflow-timing trends are either harbingers or analogs for future global warming effects in the State and threaten to unsettle crucial aspects of the State’s water supply system by adversely impacting the State’s snowpacks and snowmelt runoff. Recent studies of California’s paleoclimate also provide worrying evidence that the erratic precipitation regimes that have been observed (and largely accomodated) during the several hundred years of California’s development have been—by and large—benign and small in comparison to the precipitation variations over the past 1000 or more years. Thus, California’s climate has varied in ways that CALFED must be prepared to accommodate, on time scales from years to decades, as evidenced in its past and present climates as well as in projections of its future climate. These climate fluctuations need to be characterized (i.e., monitored, predicted, projected, or described probabilistically, depending on circumstance) to provide a basis for scientifically sound planning and management actions by the CALFED Program.