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March 10, 2020  |  Written by Alyson E. Ackerman

DWR CEQA Process Proceeds with Tunnel Proposal Independent Experts Deem “Impractical”

The Department of Water Resources (DWR) is soliciting public comment on the scope of environmental review for a revised Delta tunnel project despite prior findings of independent technical experts that a key project proposal is “impractical,” stating that it “does not recommend” further study.  DWR’s January 15, 2020 Notice of Preparation (NOP) for the Draft Environmental Impact Report (EIR) for the Delta Conveyance Project (Project) proposes two possible tunnel corridors for a 40-foot diameter pipeline that would convey water diverted from the Sacramento River in south Sacramento County to State Water Project facilities in the Discovery Bay area.  The NOP’s timing raises questions among Delta stakeholders about the role of ongoing stakeholder engagement processes in light of the independent technical experts’ December 2019 findings.

The Delta Conveyance and Design Construction Authority (DCA), a joint powers authority consisting of State Water Project contractors deputized by DWR to develop the Project, provides DWR engineering and design support during DWR’s consideration of the Project.  The DCA engaged an Independent Technical Review Panel (Panel) to evaluate five major issues associated with the Project.  One issue was the tunnel corridor alignment.  The Panel evaluated two proposed alignments – the “Central Corridor” and the “Eastern Corridor.”  The Central Corridor, which greatly resembles the former California WaterFix Project (i.e., the “twin tunnels”), runs south through Staten, Bouldin, and Bacon Islands.  The Eastern Corridor is longer, running closer to Interstate 5, south through Canal Ranch Tract and Terminous Tract, to Lower Roberts Island, and westerly to Lower Jones Tract.

In early December 2019, the Panel determined that the Central Corridor is “logistically impractical,” citing accessibility issues.  Specifically, the Panel concluded that the distance from Interstate 5 and narrow farm roads make “supporting large operations, which requires a constant transfer of materials and people in and out, impractical and expensive as well as difficult to price.”  Moreover, the Panel opined that the costs of improvements to provide the necessary reliable and safe access during construction for the Central Corridor would exceed the costs of constructing the longer, Eastern Corridor.  The Panel recommended that the Eastern Corridor be shifted farther east to follow more closely Interstate 5 to Stockton, eliminating the shaft at Lower Jones Tract.

Despite the Panel’s determinations regarding Central Corridor feasibility, the NOP proposes that the Project EIR evaluate both corridors.  This Panel’s report marks the second time a technical review panel recommended DWR use an eastern tunnel alignment for a proposed Delta tunnel project.  In 2010, a technical review panel for the WaterFix Project similarly recommended DWR realign the proposed tunnel corridor eastward because of better conditions both for tunnel construction and boring.

The Panel for the Project further cautioned against over-selling the “reusability” of spoils generated from tunnel boring.  The fate of the tunnel spoils generated by the Project, which could be stored in 10- to 15‑foot high mounds over hundreds of acres, is a key issue for Delta stakeholders.  The Panel opined that soft ground tunnel material is, in its experience, neither a commodity nor an alternative for structural fill.  Instead, the Panel concluded, it is difficult to dispose of and/or find alternative uses for the spoils.  This finding is in contrast to DWR’s position regarding the reusability of spoils for the current Project, as well as its position on the same issue in the former WaterFix Project.

The NOP does not address or include the Panel’s recommendation regarding tunnel alignment and findings on soil reusability.  Moreover, the Panel’s report was not directly provided to the Delta Stakeholder Engagement Committee, the entity created by the DCA that has been meeting twice monthly to provide input to the DCA on tunnel siting, construction, design, and potential mitigation for Project impacts.  The Stakeholder Engagement Committee meets again on March 11, 2020 in Hood, California.

DWR is accepting written comments on the NOP until 5:00 p.m. on March 20, 2020 by both mail and email.  If submitting comments by mail, address them to:  Renee Rodriguez, Department of Water Resources, P.O. Box 942836, Sacramento, CA 94236.  If submitting comments by email, address them to

Click here to review the Independent Technical Review Panel’s Report from the DCA’s Board packet.

Click here to review the NOP.

For further information on this topic, please contact Alyson E. Ackerman at or Kelley M. Taber at

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