Monitoring Special Study

The California Department of Water Resources (DWR) and the United States Bureau of Reclamation (Reclamation) submitted the Monitoring Special Study (MSS) Final Report to the State Water Resources Control Board (Water Board) on May 21, 2026.

 

DWR and Reclamation prepared the MSS Report to meet requirements detailed in Section B(1)(iv) of the 2018 Water Quality Control Plan for the San Francisco Bay/Sacramento–San Joaquin Delta Estuary (Bay-Delta Plan). The MSS is designed to accomplish the following MSS Plan goals:

  • Characterize the spatial and temporal distribution and associated dynamics of water level, flow, and salinity conditions in the southern Delta waterways.
  • Identify the extent of low-or null-flow conditions and any associated concentration of local salt discharges.
  • Inform the development of a Long-Term Monitoring and Reporting Plan.

 

Between 2021 and 2025, DWR and Reclamation convened twenty-one public coordination and Technical Workgroup meetings with participating agencies to plan and implement the MSS. The MSS reflects a comprehensive integration of participant perspectives gathered through this collaborative process. Public coordination meetings were open to the general public and attended by more than twenty different interested parties. Implementation of the MSS included large data collection and model refinement efforts as well as methodology workshops, to achieve the defined goals of the MSS. Technical studies, available data, supporting documents, and detailed meeting notes used in developing the MSS are posted below.

 

Background

On December 12, 2018, the Water Board amended the Water Quality Control Plan (2018 Bay-Delta Plan). The amendments included revised salinity objectives for the southern Delta and instructed DWR and Reclamation to develop a MSS.

 

On September 19, 2022, DWR and Reclamation submitted the MSS Plan to the Board after receiving ongoing feedback from all participating agencies, including Board staff. On May 5, 2023, the Board approved the MSS Plan, providing five conditions for the MSS to satisfy, as listed and discussed in the Conditional Approval letter (linked below).

 

Contact
For more information on the MSS, please contact Bill McLaughlin at William.McLaughlin@water.ca.gov. 

 

Dye Tracer Study conducted at Paradise Cut on July 19, 2022 using rhodamine dye to measure mean transport and dispersion rates of water in upper Paradise Cut with the goal of understanding high salinity water exchange and downstream transport into Old River.

Available Data

  1. UAV/Drone Imagery from 2021-2024  
  2. UAV/Drone Videos 
  3. High-Speed Salinity Transects from 2021-2023
  4. Data Links to Point Source Electrical Conductivity (EC) Timeseries Data
  5. MSS Modeling Inputs and Outputs

Document List

  1. Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Estuary
  2. Monitoring Special Study Plan for the 2018 Bay-Delta Plan 

    Appendix A - Response to Comments on the April 2022 Draft Monitoring Special Study Plan
    Appendix B - Outreach to Participating Organizations informing Development of the Draft Monitoring Special Study
    Attachment 1 - High Speed Salinity Transect Mapping Work Plan 
    Attachment 2 - Point Source and Ion Sampling Work Plan 
    Attachment 3 - SCHISM 3D Hydrodynamic and Water Quality Modeling Work Plan Attachment 4 - Water Quality Data Assimilation Work Plan 

  3. Conditional approval letter from the Water Board (May 5, 2023)
  4. NEW - Monitoring Special Study Final Report (Chapters 1 - 6)

    Appendix A - Outreach to Participating Organizations Since Publishing the Monitoring Special Study Plan
    Appendix B - Supplemental Stable Stable Water Isotope Analysis
    Appendix C - Low Water Metrics
    Attachment 1 - High-Speed Salinity Transect Mapping
    Attachment 2 -  Salinity Point Source and Ion Sampling
    Attachment 3 - Circulation, Channel Depletion, and Barrier Assumptions for Modeling the South Delta, 2024 Revision
    Attachment 4 - Data Integration and Source Inference for Modeling
    Attachment 5 - Clifton Court Forebay Gate Characterization, Scheduling Study, and Facilities Comparison
    Attachment 6 - MSS Operational Effects and Sensitivities Historical Data Analysis and Modeling Study
    Attachment 7 - 2021 Old River Tracy Barrier Flow Study
    Attachment 8 - 2022 Old River Null Zone Study
    DWR and USBR Joint Transmittal Letter to the State Water Resources Control Board

Public Coordination Meetings

Technical Workgroup Meetings

  • Technical Workgroup #1: June 14, 2021, Paradise Cut Flushing
  • Technical Workgroup #2: July 13, 2021, Water Quality Data Integration (Data Assimilation)
  • Technical Workgroup #3: July 19, 2021, Salinity Point Source and Ion Sampling
  • Technical Workgroup #4: January 13, 2022, SCHISM & Related Modeling
  • Technical Workgroup #5: March 17, 2022, Discussion of the 1980 Report
  • Technical Workgroup #6: September 15, 2022, High Speed Salinity Transect Mapping
  • Technical Workgroup #7: December 9, 2022, SCHISM and Data Assimilation
  • Technical Workgroup #8: June 30, 2023, MSS Modeling Assumptions Response to Comments
  • Technical Workgroup #9: December 12, 2023, MSS Data Assimilation: an Introduction 
  • Technical Workgroup #10A: April 18, 2025, Draft MSS Report Review Check-in
  • Technical Workgroup #10B: May 20, 2025, Draft MSS Report Review Follow-up
  • Technical Workgroup #10C: July 24, 2025, Draft MSS Report Review Follow-up
  • Technical Workgroup #11: March 12, 2026, Final MSS Report

Contact

For program related inquiries contact:

Bill McLaughlin 
Department of Water Resources

Division of Operations and Maintenance

Water Initiatives Planning and Management Branch 

Delta Water Infrastructure Management Section

Address: 1600 Ninth Street

Sacramento, CA 95814 

Phone: (916) 873-5748
Email: William.McLaughlin@water.ca.gov

 

 

 

 

Tags

State Water Project ... Water Quality