By Graham Bradner, Executive Director for the Delta Conveyance Design and Construction Authority
California’s Delta Conveyance Project is among the most significant water infrastructure investments in the state’s history. It is a modern upgrade to a more than 60-year-old water delivery system that serves millions of Californians and supports much of the state’s economy. The project is intended to address well-documented risks to water supply and reliability from sea-level rise, seismic vulnerability, and increasingly variable hydrology driven by climate change.
Because of its scale and importance, the project demands a high standard of technical rigor, transparency, and realism in how costs and risks are assessed. The Delta Conveyance Design and Construction Authority (DCA) – the purpose-built organization designing and engineering the project – follows a disciplined and transparent public process to drive down costs, manage risk, and maintain construction schedule. The DCA’s approach reflects both the complexity of the project and its responsibility to the public water agencies that will ultimately decide whether to fund the project.
That responsibility starts with transparency. At every step of the process, DCA has gone above and beyond standard industry practices for the design of public infrastructure projects by making its technical work, assumptions, and decisions accessible to the public via the DCA’s Board Meetings, website, and social media channels. Californians deserve this level of rigor for a project of statewide importance.
The most recent early-stage estimate, published in 2024, is designated generally as a Class 4 estimate under guidelines from the Association for the Advancement of Cost Engineering. That designation carries a broad accuracy range, which was publicly disclosed in the total project cost summary. Early-stage estimates are intended to support planning, feasibility analysis, and alternatives evaluation. They do not represent final construction pricing.
The Class 4 cost estimate is the industry accepted standard for projects at this stage of concept design. It’s based on a significant amount of engineering work, informed by subsurface soil investigations, and reviewed for constructability. At this stage, the project description details the overall alignment of the tunnel and location of major facilities, including Sacramento River intakes, pumping plants, shafts, conveyance structures, and supporting infrastructure. Key assumptions, risks, and contingencies are publicly documented, and the estimate is intended to become more precise as engineering advances.
It is also important to understand what the published total project cost represents. The Delta Conveyance Project is more than just a tunnel – its cost estimate accounts for the full water conveyance system: surface intakes, a high-capacity pumping plant, aqueduct connections, power and grid upgrades, environmental mitigation, a community benefits program, roadway and utility relocations, and years of permitting and regulatory work. Tunnel and shaft construction are defined components within this broader system, and their costs are identified separately within the estimate and include appropriate contingency consistent with the current level of design.
As the project advances, the estimate will mature. Before participating water agencies consider funding decisions, the cost estimate will advance to a Class 3 level, supported by additional geotechnical data, more detailed engineering, and independent peer review. That estimate will be publicly released and used to inform further economic and financial analyses. This staged approach allows uncertainty to be reduced over time and supports informed, transparent decision-making.
Risk management is addressed directly and systematically throughout this process. The current estimate includes a 30% construction contingency consistent with industry practice for a project at this stage, informed by identified risks and design maturity. In addition to the contingency, the cost estimate also includes risk treatment cost allowances to help manage uncertainty at the current conceptual stage of the project.
As engineering progresses, risks will be refined or reassessed, and contingency will be adjusted accordingly. Cost tracking and review are continuous, not piecemeal, and are reinforced by governance: eighteen public water agencies, each accountable to their own boards and ratepayers, will review the work in open public meetings before DWR’s final decision to move forward with advancing the project is made.
California is planning this project to address water supply reliability challenges in large part to respond to climate-driven swings between prolonged drought and intense atmospheric rivers. Modernized conveyance will allow the state to maintain reliability for communities, farms, and businesses that depend on the State Water Project.
The project deserves analysis grounded in accurate transparent data and a realistic assessment compared to similar projects. That conversation should rely on the publicly documented cost estimates developed through the engineering process, not speculative figures that are sometimes cited to suggest the project is infeasible.
Graham Bradner is the Executive Director for the Delta Conveyance Design and Construction Authority. He is a licensed Professional Geologist, Certified Engineering Geologist, Certified Hydrogeologist in the state of California, and has over 25 years of experience in the evaluation, design and construction of large-scale water supply infrastructure projects.
Note: The views and opinions expressed in this commentary are those of the author and do not necessarily reflect the official policy or position of Maven’s Notebook.
COMMENTARY: How the Delta Conveyance Project is being designed with sound engineering and transparency
By Graham Bradner, Executive Director for the Delta Conveyance Design and Construction Authority
Because of its scale and importance, the project demands a high standard of technical rigor, transparency, and realism in how costs and risks are assessed. The Delta Conveyance Design and Construction Authority (DCA) – the purpose-built organization designing and engineering the project – follows a disciplined and transparent public process to drive down costs, manage risk, and maintain construction schedule. The DCA’s approach reflects both the complexity of the project and its responsibility to the public water agencies that will ultimately decide whether to fund the project.
That responsibility starts with transparency. At every step of the process, DCA has gone above and beyond standard industry practices for the design of public infrastructure projects by making its technical work, assumptions, and decisions accessible to the public via the DCA’s Board Meetings, website, and social media channels. Californians deserve this level of rigor for a project of statewide importance.
The most recent early-stage estimate, published in 2024, is designated generally as a Class 4 estimate under guidelines from the Association for the Advancement of Cost Engineering. That designation carries a broad accuracy range, which was publicly disclosed in the total project cost summary. Early-stage estimates are intended to support planning, feasibility analysis, and alternatives evaluation. They do not represent final construction pricing.
The Class 4 cost estimate is the industry accepted standard for projects at this stage of concept design. It’s based on a significant amount of engineering work, informed by subsurface soil investigations, and reviewed for constructability. At this stage, the project description details the overall alignment of the tunnel and location of major facilities, including Sacramento River intakes, pumping plants, shafts, conveyance structures, and supporting infrastructure. Key assumptions, risks, and contingencies are publicly documented, and the estimate is intended to become more precise as engineering advances.
It is also important to understand what the published total project cost represents. The Delta Conveyance Project is more than just a tunnel – its cost estimate accounts for the full water conveyance system: surface intakes, a high-capacity pumping plant, aqueduct connections, power and grid upgrades, environmental mitigation, a community benefits program, roadway and utility relocations, and years of permitting and regulatory work. Tunnel and shaft construction are defined components within this broader system, and their costs are identified separately within the estimate and include appropriate contingency consistent with the current level of design.
As the project advances, the estimate will mature. Before participating water agencies consider funding decisions, the cost estimate will advance to a Class 3 level, supported by additional geotechnical data, more detailed engineering, and independent peer review. That estimate will be publicly released and used to inform further economic and financial analyses. This staged approach allows uncertainty to be reduced over time and supports informed, transparent decision-making.
Risk management is addressed directly and systematically throughout this process. The current estimate includes a 30% construction contingency consistent with industry practice for a project at this stage, informed by identified risks and design maturity. In addition to the contingency, the cost estimate also includes risk treatment cost allowances to help manage uncertainty at the current conceptual stage of the project.
As engineering progresses, risks will be refined or reassessed, and contingency will be adjusted accordingly. Cost tracking and review are continuous, not piecemeal, and are reinforced by governance: eighteen public water agencies, each accountable to their own boards and ratepayers, will review the work in open public meetings before DWR’s final decision to move forward with advancing the project is made.
California is planning this project to address water supply reliability challenges in large part to respond to climate-driven swings between prolonged drought and intense atmospheric rivers. Modernized conveyance will allow the state to maintain reliability for communities, farms, and businesses that depend on the State Water Project.
The project deserves analysis grounded in accurate transparent data and a realistic assessment compared to similar projects. That conversation should rely on the publicly documented cost estimates developed through the engineering process, not speculative figures that are sometimes cited to suggest the project is infeasible.
Graham Bradner is the Executive Director for the Delta Conveyance Design and Construction Authority. He is a licensed Professional Geologist, Certified Engineering Geologist, Certified Hydrogeologist in the state of California, and has over 25 years of experience in the evaluation, design and construction of large-scale water supply infrastructure projects.
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