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Center for Watershed Sciences

Research



Delta Futures Project

Envisioning Futures for the Sacramento-San Joaquin Delta - 2007

PPIC/UC Davis Report

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.

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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Cosumnes Project

Cosumnes Research Group

(P.I.s: Mount, Moyle, et al)

The Cosumnes River is the last river without major dams on the western slope of the Sierra Nevada. Thus it is one of the few systems in which the ecological impacts of natural variation in seasonal flows can be studied. In addition, the Cosumnes River Preserve occupies large stretches of the river's lower reaches and has sought, by means of levee breaches and other strategies to reinstate seasonal flooding, restore riparian vegetation and improve conditions for native plant and animal species.

In 1998, the David and Lucile Packard Foundation provided seed money to a group of UCD faculty (originally termed the Cosumnes Consortium) to conduct studies to help inform management and restoration decisions on the Preserve and in the surrounding North Delta region. This work provided the foundation for what has now become a 7-year multi-disciplinary study of the ecological response of river and floodplain to annual and interannual changes in runoff conditions.

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Cosumnes I

(P.I.s: Mount, Moyle, et al)

Expanding upon the initial Consortium studies, in 2000 the Watershed Center began a 3-year study of the hydrogeomorphic conditions and aquatic biology of the Lower Cosumnes River and its highly regulated neighbor, the Mokelumne River. This effort focused on identifying the hydrologic and geomorphic processes necessary for restoring and sustaining the ecologic integrity of floodplains.

The project included the following elements: upper watershed hydrologic modeling; lower watershed groundwater hydrology; geomorphology of the floodplain; biogeochemistry and nutrient cycling in aquatic and floodplain habitats; ecology of fish and aquatic invertebrate communities, riparian bird surveys; and an analysis of the reestablishment of riparian forests.

Reports and publications from the Cosumnes I project can be found at: http://baydelta.ucdavis.edu/

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Restoration of fall flows

(P.I.s: Fogg, Mount)

During the late 1900's late summer and fall flows have declined within the Cosumnes River. These declines in baseflow have reduced access to historic spawning habitat for Fall run chinook salmon. This study, funded by the USFWS: investigated the loss of baseflow contributions to the river caused by regional groundwater overdraft; documented the seasonal hydraulic disconnection between much of the river and the complex regional aquifer; and estimated the volume of water needed to partially reconnect the river with the aquifer, reduce seepage losses and partially reinstate baseflows.


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Cosumnes II

(P.I.s: Quinn, et al)

Cosumnes I focused primarily on the relationship between hydrologic conditions and aquatic ecosystems; Cosumnes II builds on this earlier work, but emphasizes the connection between aquatic and terrestrial systems in floodplain environments. This project is addressing:

  • The relationship between restoration activities and the spread of invasive species, focusing on Leipium latifolium;
  • Measuring and modeling of surface and subsurface water balance to better understand the interaction between groundwater and riparian zone processes;
  • Measuring evapotranspiration from riparian forests;
  • Examining the links between aquatic and terrestrial habitats via a study of bat habitat utilization and foraging, insect emergence and productivity and trophic interaction through food webs, including primary production and nutrient exchange;
  • Continued monitoring of birds (building on a decade of time-series and spatial data) as an indicator of restoration success.
  • Continued monitoring of geomorphology, water quality, food web and aquatic species parameters initiated under Cosumnes I.

The Cosumnes II phase of the project is due to end in spring, 2006. Reports and papers to date are posted at: http://baydelta.ucdavis.edu.

Trowbridge, W. B. (2007), The Role of Stochasticity and Priority Effects in Floodplain Restoration, Ecological Applications, 17(5), 2007, pp. 1312–1324. (638 KB, PDF)

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McCormack-Williamson Tract/North Delta Project

Restoration Planning, Design and Monitoring

(P.I.s: Mount, Moyle, et al)

The McCormack-Williamson Tract is a North Delta island located immediately downstream of the confluence of the Cosumnes and Mokelumne Rivers. Owned by The Nature Conservancy California, the island offers opportunities for restoration of of critical tidal freshwater marsh and floodplain habitat. There is also the potential that the island could be managed in such a way as to moderate flood flows in the North Delta.

In 2000, the Watershed Center began the research and baseline studies necessary to inform restoration planning and design, and the monitoring of restoration success. This study included analysis of historic geomorphic conditions, characterization of the modern hydrologic and sedimentologic regime, and baseline studies of aquatic and riparian resources.

Reports from this study are posted at: http://baydelta.ucdavis.edu

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Modeling of Restoration Scenarios and Science Panel

(P.I.s: Schladow, Mount)

In 2002, the Watershed Center began working with The Nature Conservancy California, the California Department of Water Resources and the North Delta Improvements group on an effort to model a range of restoration scenarios for the McCormack-Williamson Tract. This involved expanding and modifying existing hydraulic models, examining the effects of flood flows and other upstream events, evaluating the water quality effects of various scenarios and investigating the sediment-trapping efficiency of levee breaches and other restoration alternatives such as setback levees.

At the request of the Department of Water Resources, the Center also convened a panel of experts to provide advice on North Delta integrated flood control and ecosystem restoration planning. The experts were asked to address such concerns as: mercury, exotics, dendritic channel creation and function, sediment dynamics, ecological processes, geomorphology, terrestrial and aquatic species, water quality and hydraulics.

Technical reports: Link under development

Science Panel reports: Link under development

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Spawning Habitat Rehabilitation Project (SHIRA)

(P.I.: Pasternack)

Throughout the Northern Hemisphere, rivers that once sustained robust anadromous salmon and trout runs are now regulated and impacted by dams, diversions, channelisation and instream mining. These impacts include loss of the sediment, gravel bars, hydraulic jumps and large woody debris that provide favorable spawning habitat.

The SHIRA project has developed a modeling package to guide the design of spawning gravel restoration projects. Using an interdisciplinary rehabilitation design framework drawing from geomorphology, aquatic biology, civil engineering, and physics, SHIRA allows restoration managers to optimally enhance physical habitat, effectively compare alternate scenarios and identify options least likely to erode. The SHIRA approach is being tested at three demonstration sites: Lower Mokelumne River, Lower Yuba River and the Trinity River.

Reports and publications can be found at: http://shira.lawr.ucdavis.edu/introduction.htm

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Stockton Deep Water Ship Channel Project

(P.I.: Schladow)

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.

In progress.

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Sacramento Perch Project

(P.I.: Moyle, Cech, May)

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.

Final report can be found at: http://watershed.ucdavis.edu/pdf/SPFinalreviewedreport.pdf

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Mountain Meadows Wetlands Project

(P.I.: Moyle)

Mountain meadow wetlands provide important ecological services by providing wetland-associated biodiversity and by contributing to downstream water quality and quantity; however they are experiencing significant degradation due to diversions, logging, mining, and overgrazing, as well as exotic species. State and federal agencies have begun to survey the condition of mountain meadows in the Sierra, but to date these efforts have not been integrated or analyzed in such a way as to identify restoration or protection priorities. This project proposes to: 1) create and promote the use of a Sierra Meadow Health Database to integrate data from several agencies and to identify status and trends of mountain meadows; 2) to describe possible causal relationships between land and water use and meadow health; 3) to develop a new aquatic monitoring protocol appropriate to mountain meadows, based on fish, aquatic invertebrates, and amphibians; and 4) to develop a next-step strategy for meadow conservation and management, including upland land and water management.

This project is being conducted with close collaboration of a non-profit organization, the Natural Heritage Institute, the California Department of Fish and Game, and the US Forest Service

In progress.

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Evaluation of Bear Creek Meadow Restoration Project

(P.I.: Mount)

This project is evaluating the restoration of Bear Creek, immediately upstream of the Fall River, in Modoc County, California. Approximately two miles of degraded meadow creek was restored five years ago by a private landowner. This assessment is reconstructing changes in the hydrologic balance associated with the restoration and the response of riparian and wetland plant communities to changes in groundwater conditions. To date, this work shows substantial changes in shallow groundwater, particularly in the late spring and early summer, and complex responses of plant communities. Additional hydraulic modeling is being conducted to evaluate and predict the geomorphic response of the designed restoration channel and to identify elements of the design which promote channel stability. This work is being conducted by Christopher Hammersmark, a Ph.D. candidate in Hydrologic Sciences.

In progress.

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Delta Levee Vulnerability Project

(P.I.: Mount)

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

(P.I.: Bennett, et al)

This project is an urgent effort, mounted in conjunction with federal and state agencies, to provide basic research on the threatened delta smelt population in the San Francisco Estuary. 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 into a monograph on delta smelt ecology. (sSee link, below.). With collaborators Dr. Swee Teh of Veterinary Medicine, and Dr. Susan Anderson of Environmental Toxicology, an interdisciplinary program has been implemented to assess fish growth and spawning location using otolith microstructure analyses, as well as tissue and genetic 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.

Additional laboratory and field studies are investigating the potential impact of an exotic fish, the inland silverside, on the growth and mortality of delta smelt. Information from this research is being used to develop stage-structured population models to assess multiple effects on the dynamics of the population. Work has also begun to develop an individually-based population model that will be integrated with a hydrodynamic particle-tracking model (with collaborators Dr. Kenny Rose, LSU, and Dr. Wim Kimmerer, SFSU). The overarching goal of these efforts is to provide the state and federal Resources agencies with management and restoration options for this threatened population.

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

In Progress.

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