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photo: Delta chanel, agriculture land, and residential neighborhood

The Delta

The watershed of San Francisco Bay includes nearly 40% of California and extends northward into Oregon. Named for its two central rivers, 50 percent of the Sacramento-San Joaquin Delta's flows are diverted to 4.5 million acres of farmland and to 23 million residents. The Delta is a major stopping point for hundreds of thousands of migrating birds along the Pacific Flyway and two-thirds of the salmon in California waters. But threats from earthquakes, floods, droughts and non-native species are pushing the Delta toward a crisis.

 

UC Davis/PPIC Report

Comparing Futures for the Sacramento-San Joaquin Delta (2008)

The 2007 Envisioning Futures report (below) concluded that the Delta is no longer sustainable and that the need for a new Delta strategy is urgent. This follow-up report, Comparing Futures for the Sacramento–San Joaquin Delta, now takes a closer look at the range of viable options for the Delta. Among the central findings: A peripheral canal—conveying water around the Delta instead of through it—should be part of a long-term strategy for the Delta to serve both water supply and environmental objectives.

The report is authored by a multidisciplinary team of experts, including University of California, Davis scientists Jay Lund, William Fleenor, William Bennett, Richard Howitt, Jeffrey Mount, and Peter Moyle and the Public Policy Institute’s (PPIC) Ellen Hanak. [ >>> About the authors ]

Publications

  • Comparing Futures for the Sacramento-San Joaquin Delta
    Jay Lund, Ellen Hanak, William Fleenor, William Bennett, Richard Howitt, Jeffrey Mount and Peter Moyle. July 2008. Public Policy Institute of California.
    • Technical Appendices
      Underlying the conclusions of the Comparing Futures report is extensive technical information and analysis. Much of this information is contained in ten appendices, which deal in detail with topics ranging from the viability of delta fish populations to levee sustainability decisions. Each of these appendices underwent substantial external review prior to publication.

Videos

Comparing Futures for the Sacramento-San Joaquin Delta - Technical Appendices Workshop
Conversations with authors of the recent Public Policy Institute of California report's appendices.
This two-day workshop, which took place on November 12 & 13, 2008, featured presentations and question-and-answer sessions focusing on material contained within each appendix to the report.

Related Publication

A new paper on flooded islands and their effect on the future of Delta fish:

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UC Davis/PPIC Report

Envisioning Futures for the Sacramento-San Joaquin Delta (2007)

Beginning in December 2005, a group of faculty and researchers affiliated with the UC Davis Center for Watershed Sciences/John Muir Institute of the Environment and the nonprofit Public Policy Institute of California (PPIC) began meetings to discuss the future of the Delta. The intent was to complete a major independent report analysing options for managing the increasingly unstable Sacramento-San Joaquin Delta. The group included Ellen Hanak (Economist) with PPIC and from UC Davis: Jay Lund (Civil and Environmental Engineering), Jeff Mount (Geology), Peter Moyle (Wildlife and Conservation Biology), Richard Howitt (Agricultural and Resource Economics), and William Fleenor (Civil and Environmental Engineering).

The report, available February 7, 2007, can be found for purchase or free download on the PPIC Web site at http://www.ppic.org/main/publication.asp?i=671. In addition to the 300 page report, there is an 8 page research brief.

The sustained multi-disciplinary deliberations benefited greatly from three outreach efforts: 1) discussions with stakeholders and policy makers regarding the Delta, 2) discussions with Delta hydrodymanics experts and 3) discussions with experts on Delta ecosystems. Beyond the deliberations and discussions were extensive background reading by the report authors and computer modeling of water supply adaptations and economic impacts (using CALVIN) and modeling of agricultural production economics within the Delta for various salinity conditions (using DAP). These modeling efforts were conducted largely by two PhD students, Stacy Tanaka and Marcelo Olivares. These are described in the report.

Publications

Supplemental Materials

Several earlier reports were found to be especially useful for understanding the Delta and the history of policy for the Delta. Two of these have been scanned to make them more publicly available:

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Delta Levee Vulnerability Study

This project developed an index of the vulnerability of levees in the Sacramento-San Joaquin Delta. This involved the development of: 1) an Accommodation Space Index, to calculate that space in the Delta that lies below sea level and is filled neither with sediment nor water; and 2) a Levee Force index, a proxy for the cumulative forces that can cause levee failure. This project showed that the Levee Force Index increases significantly over the next 50 years, demonstrating regional increases in the potential for island flooding. Additionally, there is a two-in-three chance that 100-year recurrence interval floods or earthquakes will cause catastrophic flooding and significant change in the Delta by 2050.

The full report is posted at: http://repositories.cdlib.org/jmie/sfews/vol3/iss1/art5/

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Ecology of Delta Smelt Project

Arguably one of the most imperiled and controversial fish species, recent record-low abundance of threatened delta smelt is responsible for dramatic reductions in freshwater allocated from the Delta and San Francisco Estuary to central and southern California. This project is an urgent effort, mounted in conjunction with federal and state agencies, to provide basic research on the delta smelt population. An interdisciplinary team is quantifying mortality due to changes in food webs processes and exposure to pollutants for field-caught delta smelt to compare with estimates of their losses to the federal and state water export facilities in an array of population models. Exploratory data analyses were used to synthesize existing biological information and develop conceptual models to guide the work (See link to published monograph on delta smelt ecology, below). With collaborators Dr. Swee Teh of Veterinary Medicine, Dr. Wim Kimmerer at SFSU, and Dr. James Hobbs, former graduate student and current CALFED Science Fellow at UCB, an interdisciplinary program has been implemented to assess fish growth and spawning location using otolith microstructure analyses, as well as tissue condition using various biomarkers. This approach has been very effective at distinguishing effects of poor-feeding success from exposure to pesticide runoff for individual field-caught specimens.

Information from this research is being used to develop stage-structured population models to assess multiple effects on the dynamics of the population. We are also using this information to calibrate a recently completed individually-based population model that is integrated with a hydrodynamic particle-tracking model (with collaborators Dr. Kenny Rose, LSU, and Dr. Steven Monismith, Stanford). The overarching goal of these efforts is to provide the state and federal Resources agencies with management and restoration options for the threatened population.

Delta smelt ecology monograph can be found at: http://repositories.cdlib.org/jmie/sfews/vol3/iss2/art1/

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Stockton Deep Water Ship Channel Project

The Central Valley Regional Water Quality Control Board has listed the San Joaquin River Deep Water Ship Channel (DWSC), located near Stockton, California, as "impaired" under the Clean Water Act. The dissolved oxygen concentrations in the DWSC routinely fall below the Board's water quality standard during periods in the late summer and early fall of each year, especially in the eastern portion of the channel. The cause of the dissolved oxygen sag is related to low San Joaquin River inflows, warm water temperatures, and reduced tidal mixing that occur in combination with high biological oxygen demand. Low dissolved oxygen concentrations cause physiological stress to fish and can block upstream migration of salmon in the SJR.

The Regional Board has required that a total maximum daily load (TMDL) for the DWSC be developed for controlling the DO problem. The structured field experiments, data collection/analysis, scientific reports and modeling provided by this project will yield a detailed understanding of how hydrodynamic and biogeochemical processes interact to produce reductions in dissolved oxygen concentrations along the San Joaquin River. This in turn will provide a basis for the development of management options.

This work is being conducted in collaboration with Stanford University, the US Geological Survey and UC Santa Barbara.

Publications

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Sacramento Perch Project

The Sacramento perch (SP) is a native sunfish that once was abundant, but is now extirpated from almost all of its former habitats throughout the Sacramento-San Joaquin watershed. Recovery strategies for SP in the San Francisco Estuary have been proposed for study, but have not been developed because of the general lack of biological knowledge, i.e., life history, physiological tolerance limits, behavioral tendencies.

This project proposes to: 1) summarize existing information on SP emphasizing factors contributing to survival of introduced populations, collapse of native populations, and persistence of some native populations, 2) document early life history of SP and the factors contributing to survival of early life history stages, 3) document physiological tolerance limits and preferences of juvenile and adult SP, specifically regarding upper and lower temperature limits, upper salinity limits, upper and lower pH limits, lower dissolved oxygen limits, and upper velocity limits, 4) document the genetic variation within and among the extant populations of SP by examining variation at microsatellite loci, and 5) develop reestablishment strategies for SP, including analysis of institutional, physical, and biological barriers to their reintroduction into the San Francisco Estuary and Central Valley.

Publications

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Monday August 17, 2009