October 2013 San Francisco Estuary & Watershed Science: Science & Policy for the Delta Using Science to Restore California’s Bay-Delta Judith A. Layzer Associate Professor of Environmental Policy, Department of Urban Studies and Planning Massachusets Institute of Techniology Cambridge, MA 02139 jlayzer@mit.edu The State of California and the U.S. Department of Interior have committed to relying on science as a guide to both restoring the Bay–Delta ecosystem and deciding how much water can be exported from that system. In theory, upholding this commitment should be straightforward. In practice, however, figuring out how science can and should guide policymaking is challenging when the problem at hand is complex and multifaceted, and features a cast of savvy, powerful stakeholders with sharply dif- ferent interests. One reason is that participants in such controversies have long used debates over science as proxies for debates over values. The conflict over the Bay– Delta is no different; recently, for example, representatives of large-scale water users dismissed the suggestion that too much water is being exported from the Bay–Delta system, although more than three-quarters of the scientists surveyed by the Public Policy Institute of California (PPIC) believe that excessive water withdrawals pose a problem (Anonymous 2013). To make progress in this situation, state and federal policymakers should take a series of bold steps. First, they should articulate a single, clear, overarching goal of ecologi- cal restoration for the Bay–Delta. Next, they should establish an adaptive process for soliciting scientific advice and adjusting management to ensure it is consistent with that goal. And finally, they should emphasize the translation of scientific research into compelling political stories that highlight both the intrinsic value of ecological restoration and its necessity for achieving other highly valued goals. My argument is rooted in the recognition that improvements in the scientific under- standing of a problem do not necessarily lead to “better” or more rational policies to address that problem (Layzer 2012). In fact, more science can actually exacerbate policy conflicts, particularly when a policy dispute features players with sharply dif- ferent values (Graham et al. 1988). In part, this is because additional science can reveal new sources of uncertainty, which advocates can exploit. But, more important,