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  • Title

    Monitoring and Evaluation of the North Delta Food Subsidies and Colusa Basin Drain Study

    Lead California Department of Water Resource [DWR]
    Description The North Delta Food Subsidies – Colusa Basin Drain Study monitors and evaluates the effects of the North Delta Flow Action on the Delta food web.
    Science topics Delta Smelt, Fish, Flows, Water management
    Updated April 29, 2022
  • Title

    Directed Outflow Project

    Lead U.S. Bureau of Reclamation [USBR]
    Description The U.S. Bureau of Reclamation (USBR) and California Department of Water Resources (DWR), along with collaborators, are continuing efforts to evaluate the hypothesized benefits of outflow and outflow alteration for Delta Smelt. The collective aim of these efforts is to better inform management actions that will bolster and stabilize the Delta Smelt population. The planned five-year Directed Outflow Project (DOP) seeks to assist in evaluating the overarching hypothesis that habitat quality and quantity is improved in the summer/fall when X2 is below 81 km and the LSZ occurs in Suisun Bay and Marsh, and this improvement in habitat conditions will translate into a greater catch density, health, and growth for Delta Smelt using this area
    Science topics Flows, Fish, Water management, Delta Smelt
    Updated April 29, 2022
  • Title

    A Multi-Stock Population Dynamics Framework for the Recovery of Sacramento River Chinook Salmon

    Lead University of Washington [UW]
    Description The purpose of this project is to construct a multi-stock salmon population model and management strategy evaluation (MSE) tool that addresses the cross-linkages between water use and fishery ecosystem response. Recent federal court judgment concluded that insufficient evidence was provided for prescribing specific flow restrictions in two recent conservation measures. The inability to provide adequate evidence was a byproduct of not having the correct quantitative tools at hand. We propose to build these tools by furthering technological developments of previous analyses of Central Valley Chinook population dynamics. Specifically, our work will integrate multiple salmon populations together into a single model that can reconstruct historical population dynamics such that environmental conditions and water resource use can be used as predictors of biological responses of multiple populations. Our goal is to integrate populations into a single model so that the effect of water management and fishery management policies can be examined in light of all fish populations simultaneously. This pertains to the biological interactions between the populations as well as the way in which fisheries impact individual populations depending on growth and maturation rate of each population. All analysis will be framed in the context of historical and proposed water use patterns.
    Science topics Flows
    Updated April 29, 2022
  • Title

    North Delta Flow Action: Role of Improved Yolo Bypass Flows on Delta Food Web Dynamics

    Lead California Department of Water Resource [DWR]
    Description Description In a collaborative effort between CA Department of Water Resources, US Bureau of Reclamation, CA Department of Fish and Wildlife, United States Geological Survey, San Francisco State University, and UC Davis, this study will investigate the role of augmented summer and fall flows in the Yolo Bypass and North Delta areas on lower trophic food web dynamics and the benefits to listed fish species. Using both continuous and discrete sampling approaches, this study will relate hydrologic patterns to chlorophyll-a, nutrients and primary productivity, plankton densities and composition (phytoplankton and zooplankton), contaminant concentrations, as well as water quality parameters such as electrical conductivity, turbidity, temperature, and dissolved oxygen. In addition, caged hatchery Delta Smelt will be monitored to determine the effects of the managed flow action and increased food web productivity on fish survival, growth, and behavior. Need Due to the food-limited nature of the San Francisco Estuary, it is critical to understand mechanisms that result in successful food web productivity including phytoplankton blooms. Food limitation is one of the primary hypothesized causes of the Pelagic Organism Decline. In 2011 and 2012 there was evidence that a moderate Yolo Bypass flow pulse during fall agricultural drainage periods was followed by phytoplankton blooms in the lower Sacramento River. Managed flow actions in the following years showed an increase in food web productivity could be repeated;however, results varied across years and flow actions indicating more research is warranted to understand correlations between flow and abiotic conditions, and the biological response of the food web. The increases of summer/fall flows in North Delta, has been considered a management strategy as part of complying with USFWS Delta Smelt Biological Opinion Action 4. The augmentation of flows through the Yolo Bypass/North Delta is also included as one of several Delta Smelt Resiliency Strategies by Natural Resources Agency. Objectives • Determine if managed flow actions through the Yolo Bypass stimulate increased primary productivity locally and downstream, and if it is repeatable. • Characterize how nutrients, chlorophyll and plankton (composition and density) in the Toe Drain, Cache Slough Complex, and lower Sacramento River change in response to flow pulses. • Determine if nutrient subsidies of the source water and downstream are limited by abiotic and biotic factors. • Characterize spatial differences and transport of pesticide contaminants in the Yolo Bypass in response to the flow actions. • Determine survival, growth and behavior of caged hatchery Delta Smelt before and after the flow action in the Yolo Bypass.
    Science topics Flows, Water management
    Updated April 29, 2022
  • Title

    Directed Outflow Project [DOP] - Paired Habitat Sampling

    Lead U.S. Bureau of Reclamation [USBR]
    Description Special study supporting water quality, food web, and biological measures regarding seasonal outflow and Delta Smelt.
    Science topics Flows, Water management
    Updated April 29, 2022