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Strategic Water Supply Roadmap

Aerial image shows a lake surrounded by green hills.

About the District's Water Supply Roadmap

Approved Tuesday, Feb. 28, 2023, by the Marin Water Board of Directors, the District's water supply roadmap combines a mix of short-term water supply strategies with pre-design work to support medium- and longer-term options. The integrated roadmap has five main elements.

Elements of Water Supply Roadmap:

Water Conservation Element (near-term) 

  • Build upon the District's industry-leading conservation program and pursue a variety of identified activities to incentivize further water use efficiency. 

    • What's in progress: The District’s Water Efficiency team is engaged in work to shape a Water Efficiency Master Plan that is intended to yield beneficial changes to water use rules, ordinances and incentive programs. Marin Water hosted a Water Efficiency Customer Workshop in late August, and contracted with a research firm for a professional survey of District customers to gather more feedback for the master plan and inform future targeted outreach campaigns to connect with customers about our water efficiency programs. Staff are also working to develop a Water Loss Reduction Program. The District has also contracted with a data science firm to evaluate existing water loss, consider technological solutions and develop a suite of water loss control best practices.

Water Shortage Contingency Plan (completed) 

  • The District’s approved Water Shortage Contingency Plan is ready to be implemented as needed should water supply conditions warrant.  

Electrify Lake Soulajule (near-term) 

  • This measure provides PG&E line power to the pump station at Lake Soulajule so that the lake can be operated more frequently.  

  • Estimated water yield: 420 AFY.  

  • Estimated cost: $6 million 

  • Cost per AF: $1,800. 

    • What's in progress: A recently completed load study by PG&E shows the amount of energy needed to power the Soulajule Pump Station may not be initially available from the electric utility. District engineers are still in the design stage of this project, and staff are looking into various alternatives to meet the energy load requirement for electrical service. Marin Water is also working on designs for a pipeline that would replace the open-channel flow currently utilized and ensure more of the water pumped from Soulajule makes it to Nicasio Reservoir. The District is also pursuing efforts to secure grant funding to offset the cost of this important project.

Phoenix-Bon Tempe Connection (near-term) 

  • This project installs a connection from Phoenix Lake to Bon Tempe reservoir, increasing District control over water flows.  

  • Estimated water yield: 260 AFY 

  • Estimated cost: $5 million  

  • Cost per AF: $1,611 

    • What's in progress: Marin Water is currently working on the design aspect of this reservoir connection project. Connecting the Bon Tempe and Phoenix Reservoirs will require nearly a mile and half of new pipeline, as well as a new pump station. Several steps in that process have been accomplished to date:

      • Engineering staff have mapped out the alignment for the new pipeline, and a geotechnical consultant has been hired to report on potential impacts.

      • District staff are working with regulatory agencies to determine permitting requirements.

      • Marin Water has submitted an application to PG&E for new service to power the new pump station, and a request for proposals has been prepared for pump station design.

Forecasting and Stream Release Automation (near term) 

  • This initiative aims to improve forecasting capabilities and stream release automation to better manage releases. 

    • What's in progress: Marin Water staff obtained the necessary permissions for equipment installation and installed streamflow measurement equipment in late September near Shafter Bridge. However, that equipment was stolen shortly after installation, demonstrating how even simple projects can be impacted by unforeseen variables. Staff is now working to reinstall equipment with upgraded protections in place. Similar work is planned at Walker Creek to further improve the accuracy of streamflow releases.

Operational Strategy for Maximizing Sonoma Water supply (near-term) 

  • Develops operational rules to guide the timing and quantity of water purchased from Sonoma to maximize take of supplemental water in dry years while minimizing risk of reservoirs spills.  

    • What's in progress: The strategy will seek to balance water supply risk and District costs by analyzing system supply and demand over long periods of time and a wide range of conditions. Work is expected to continue through the winter.

Dedicated Conveyance (medium-term) 

  • Develop dedicated conveyance to storage in two phases.  

  • Phase 1 – Stafford Lake to Soulajule/Nicasio  

  • Phase 2 – North Marin Aqueduct to Stafford Lake 

  • Estimated water yield:  3,000-3,150 acre-feet 

  • Estimated cost: $111-$158 million 

    • What's in progress: In September 2023, Marin Water contracted with Carollo Engineers for work on the Marin-Sonoma Regional Conveyance Project that will enable the delivery of supplemental winter water from the Russian River to a District reservoir. This phase of work will delve into details such as hydraulic modeling, right-of-way assessments, permitting requirements, environmental and cultural impacts, as well as an assessment and comparison of constructability factors such as soil types, underground utility congestion and traffic impacts. This level of detail will lead to a comprehensive alternatives analysis and selection of a preferred alternative by the summer of 2024.

Raising Dams (long-term) 

  • Develop an additional storage via movable spillway or raising of dams at Kent, Nicasio or Soulajule reservoirs.  

  • Estimated yield: 5,000 acre-feet 

  • Estimated cost: $90 million 

    • What's in progress: Marin Water selected TERRA/GeoPentech (TGP) for preliminary engineering services as part of the Water Supply Storage Improvements Project to explore opportunities for providing additional local reservoir storage capacity. This phase of work involves detailed analysis of hydrologic modeling, areas of potential inundation, right-of-way assessments, permitting requirements, environmental and cultural impacts, as well as investigating and comparing constructability factors such as soil types, quality and availability of borrow material and construction costs. This level of detail will lead to a comprehensive alternatives analysis and selection of a preferred alternative by the end of 2025.

Increase Storage via Regional Partnerships (long-term) 

  • Pumping existing groundwater from the Santa Rosa Plain aquifer for consumption could create the necessary capacity to store winter water from Sonoma County.  

Petaluma Brackish Desalination (near-term) 

  • Monitor advances in desalination technology, track installation of desalination plants in California and perform feasibility analysis for Petaluma brackish desalination which could conceptually yield 5,000 acre-feet.  

    • What's in progress: The District contracted in October 2023 with Kennedy/Jenks Consultants, Inc., to investigate subsurface conditions and feasibility of desalination of the Petaluma River near San Pablo Bay. This work follows an initial collaboration between Marin Water and the City of Petaluma to review groundwater availability for a potential brackish desalination plant near this Sonoma County city. That review, also conducted by Kennedy/Jenks, found the groundwater in the area around Petaluma is not saline water, with few exceptions. The current work involves the potential to locate an ancient (paleo) riverbed channel near San Pablo Bay that could be used to support a subsurface intake structure for a desalination plant.

Recycled Water Expansion (near-term) 


Click the scrolling arrows on the photos below to learn more about ongoing water supply development projects:



Strategic Water Supply Assessment

Creation of the Roadmap was guided by the Strategic Water Supply Assessment which was developed by Jacobs Engineering with support from Marin Water's project team. The final report and background on that process are below.

Strategic Water Supply Assessment Final Draft Report (May 2023)

This report was prepared by Jacobs Engineering, with review by Marin Water staff.

Background Information on the Strategic Water Supply Assessment

Goals of the Assessment

The District has initiated a strategic assessment of various water management alternatives that could support community water needs in times of future shortages. The effort is intended to:

  1. Build on extensive previous water supply planning efforts and incorporate new options
  2. Evaluate current risk to District’s water delivery reliability under recent and future extended drought scenarios
  3. Determine a timeline for developing alternative water management options to maintain resiliency
Projects included in Assessment
  • Water Transfers with Conveyance through Bay Interties
  • Sonoma-Marin Partnerships 
  • Local Supply Enhancements
  • Desalination
  • Recycled Water
  • Water Conservation
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