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  • Title

    Monitoring and Assessment of Suisun Marsh Salinity Control Gates Action

    Lead California Department of Water Resource [DWR]
    Description The Suisun Marsh Salinity Control Gates (SMSCGs) have the potential to provide an increase in low-salinity-zone habitat for endangered Delta Smelt. Operation of the SMSCGs in summer and fall to improve Delta Smelt habitat are called for in the Biological Opinion and Incidental Take permit for the Central Valley Project and State Water Project. To support the adaptive management of the action, DWR is planning to monitor the change in water quality, phytoplankton, zooplankton, fishes, and clams resulting from the action.
    Science topics Delta Smelt, Phytoplankton, Salinity
    Updated November 17, 2022
  • Title

    Suisun Marsh Salinity Control Gates Action Pilot Study

    Lead California Department of Water Resource [DWR]
    Description In summer 2018 we used a unique water control structure in the San Francisco Estuary to direct a managed flow pulse into Suisun Marsh. Field monitoring showed that turbidity and chlorophyll were at higher levels in Suisun Marsh, representing better habitat conditions, than the upstream Sacramento River region throughout the study period. Fish monitoring data suggested that small numbers of Delta Smelt colonized Suisun Marsh from the Sacramento River during the 2018 Flow Action.
    Science topics Delta Smelt, Phytoplankton, Salinity
    Updated September 28, 2023
  • Title

    Suisun Marsh Salinity Control Gate Study

    Lead California Department of Water Resource [DWR]
    Description Description Suisun Bay and Marsh are a key part of the habitat for Delta Smelt, but during drier periods such as summer, Delta Smelt may be at least partially excluded from Suisun Marsh due to high salinities. The purpose of this proposal is to provide scientific support a management action for Smelt, operation of the Suisun Marsh Salinity Control Gates (SMSCG). This facility is currently to tidally pump water into the Marsh to improve fall and winter habitat conditions for waterfowl, but could also provide a tool to manage aquatic habitat for Delta Smelt in other periods. Specifically, by using the SMSCG to direct more fresh water in Suisun Marsh, our prediction is that reduced salinities will improve habitat conditions for Delta Smelt in the region. Need The status of Delta Smelt is dire. As part of the Resources Agency's Delta Smelt Resiliency Strategy, in August 2018 we conducted pilot operations of the SMSCG to support Delta Smelt , with promising results. Based on this early success, we expect that the SMSCG will be used as a seasonal tool to support Delta Smelt in summer-fall in coming years as part of the coming FWS Biological Opinion and DFW ITP. Neither has been completed, but SMSCG operations for fish are expected to be required in each. Hence, the proposed study is intended to provide a scientific evaluation and guidance for an expected SMSCG action in 2020. Objectives The primary objective of this project is to evaluate the effectiveness of the SMSCG action. Questions to be addressed include: • Did the action improve habitat conditions for Delta Smelt in the Suisun Region? • Does the Suisun Region typically have better habitat and food web conditions than the upstream River Region? • Do Delta Smelt respond favorably to the SMSCG flow action? • Does operation of the SMSCG affect other fishes and clams?
    Science topics Salinity
    Updated April 29, 2022