BOARD AGENDA MEMORANDUM
Government Code § 84308 Applies: Yes ☐ No ☒
(If “YES” Complete Attachment A - Gov. Code § 84308)
SUBJECT: Title
Receive an Update on the Anderson Dam Seismic Retrofit Project and Coyote Creek Flood Protection Project.
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RECOMMENDATION: Recommendation
Receive an update on the Anderson Dam Seismic Retrofit Project and Coyote Creek Flood Protection Project.
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SUMMARY:
BACKGROUND
The Anderson Dam Seismic Retrofit Project (ADSRP) will correct dam seismic deficiencies and meet all current Federal Energy Regulatory Commission (FERC) and California Department of Water Resources, Division of Safety of Dams (DSOD) dam safety design standards. The full reservoir capacity will be restored upon completion of the project.
From 2019 to early 2020, project staff and consultants were progressing with the preparation of the 90% design plans and specifications, as well as supporting environmental and permitting documents. On February 20, 2020, Santa Clara Valley Water District (Valley Water) received a letter order from FERC to immediately implement interim risk-reduction measures at Anderson Dam to protect the public from dam failure due to seismic activity.
Valley Water is undertaking the Anderson Dam Federal Energy Regulatory Commission Order Compliance Project (FOCP) to comply with the February 20, 2020, directive from FERC. The construction improvements necessary to complete the FOCP have been grouped into five sub-projects to be completed before the ADSRP construction, including the Anderson Dam Tunnel Project (ADTP) and the Coyote Creek Flood Management Measures Project (CCFMMP). The CCFMMP is considered Phase 1 of the Coyote Creek Flood Protection Project (CCFPP). The CCFPP is funded by the renewed Safe, Clean Water and Natural Flood Protection Program, a special parcel tax overwhelmingly approved by voters in November 2020. The CCFMMP was included as a sub-project in the FOCP to minimize flood risk to downstream urban areas when the larger outlet tunnel constructed by ADTP becomes operational, and in turn was funded by the Water Utility Enterprise Fund. Updates on the ADTP and the CCFPP are provided below. In addition, several other non-construction measures are being implemented as part of the FOCP, including maintaining the reservoir at the lowest level possible, known as “deadpool.”
The Valley Water Board of Directors certified the final Environmental Impact Report (EIR) for ADSRP on February 25, 2025, authorized the advertisement of the project on September 23, 2025, and subsequently invited three prequalified contractors to bid on the ADSRP construction contract. Technical submittals were received on May 20, 2026, and bid price submittals were received on June 24, 2026. The contract was awarded to Flatiron Dragados Sukut ADSRP Joint Venture using the best-value selection method. Notice to Proceed 1 was issued on August 14, 2026, directing the contractor to begin preparing the construction submittal prior to mobilization. Construction is anticipated to begin in January 2027.
The final Environmental Impact Statement was released on February 1, 2026, and the FERC Surrender Order was issued on May 5, 2026.
DISCUSSION
Anderson Dam Tunnel Project
The Anderson Dam Tunnel Project (ADTP) is currently being constructed and includes building a diversion system to augment the existing outlet, consisting of a new diversion tunnel, an outlet structure, a micro-tunnel lake tap, and modifications to Coyote Creek just downstream of the base of the dam. Once completed, the ADTP will serve as the Stage 1 Diversion System, diverting inflows from the reservoir to Coyote Creek at the start of the Anderson Dam Seismic Retrofit Project (ADSRP). All ADTP elements, except for the micro-tunnel lake tap portion, will be incorporated into the final configuration of the ADSRP. Construction of all major elements of the work is planned to be completed by October 2026.
On April 27, 2021, Valley Water Board of Directors awarded the construction contract for the ADTP to the top-ranked best-value proposer, Flatiron West, Inc. (Contractor), in the sum of $161,140,321 and approved a contingency amount of $40,000,000 (25% of the contract price).
On January 28, 2025, the Board of Directors approved an increase of $40,000,000 to the construction contract contingency sum, bringing the total construction contract contingency to $80,000,000.
Several major elements of the ADTP construction have been completed to date, including:
• Tunnel Excavation and Initial Lining
Tunnel excavation and initial lining of the tunnel were completed in April 2024. The Contractor used conventional mining methods, including drilling and blasting the rock to complete the excavation. The initial lining installed to support the excavation consists of an 8-inch thick layer of fiber-reinforced shotcrete (spray-applied concrete) and steel support arches spaced every 3 to 5 feet.
• Microtunnel and Lake tap
Tunneling and tapping into the reservoir were completed in August 2024. A micro-tunnel boring machine (MTBM) drilled through the last 350 feet of tunnel into the reservoir about 30 feet under the water surface. Sections of 8-foot diameter steel pipe were driven into the ground behind the MTBM in this portion of the tunnel.
• Diversion Outlet Structure (DOS) Construction
Construction of the DOS outside the downstream tunnel portal was completed in June 2024. The DOS will be used to house the two large fixed-cone valves that control flow through the tunnel and dissipate the energy of the releases by reducing the water velocity. The foundation, walls, and roof of the structure are made of thick, reinforced concrete sections cast in multiple stages.
• North Channel Extension
Work to reopen the North Channel was completed in November 2024. The work included excavation, grading, and rock placement over 1,600 linear feet, starting outside the DOS to reconnect this historic creek channel to Coyote Creek. A concrete labyrinth weir was also installed in the channel to dissipate energy and control high flows to be released from Anderson Reservoir.
The remaining major construction elements to be completed by the end of 2026 include:
• South Channel Weir Construction
Improvement of the South Channel by constructing a new concrete weir, with a notch for low-flow passage. This weir will work in conjunction with the North Channel Weir to control flow releases from Anderson Reservoir in this reach of Coyote Creek.
• Final Tunnel Lining Installation
Construction of the final tunnel lining. There are three distinct structural systems that will be used for the final tunnel lining:
o Continuous Reinforced Concrete - a 24-inch thick, horseshoe-shaped arch, walls, and floor
o Articulating Joint Concrete Sections - a similar 24-inch -thick reinforced concrete structure with heavier reinforcement and gaps between sections every five or ten feet designed to independently displace if ground movements occur.
o Steel Pipe with Concrete Backfill - about 450 linear feet of 13-foot diameter steel pipe will be installed at the downstream end of the tunnel that exits the portal. The annular space will be backfilled with concrete.
• Diversion Outlet Structure (DOS) Large Diameter Pipe and Valve Installation
Installation of the large-diameter steel pipes and valves in the DOS. As the 13-foot diameter steel pipe exits the tunnel, it bifurcates into two 11-foot diameter steel pipes. Each of the 11-foot diameter pipes have a butterfly valve and fixed cone valve to control flow releases and dissipate energy into the DOS.
Coyote Creek Flood Protection Project
Before the FERC order in 2020, Valley Water was planning and designing a project to provide flood protection against a 20-year flood event along Coyote Creek, referred to as the Coyote Creek Flood Protection Project (CCFPP). The February 20, 2020 FERC order stipulated that Valley Water must include measures to protect residents and properties downstream of the dam during implementation of FOCP. To comply with the FERC order, Valley Water accelerated a portion of the original CCFPP elements and incorporated them as part of FOCP. These prioritized elements are now referred to as the Coyote Creek Flood Management Measures Project (CCFMMP). The remaining original CCFPP elements not included in the FOCP are now in the construction phase, and the CCFPP project name is retained.
The CCFMMP and CCFPP, collectively referred to as “Project”, represent Phase 1 and Phase 2, respectively, of a 9-mile flood protection project along Coyote Creek between Montague Expressway and Tully Road in the City of San Jose. The overall flood risk reduction objective of the Project is to protect areas of Coyote Creek against a flood equivalent to the February 2017 flood or approximately a 20-year flood event.
Phase 1, CCFMMP, which is the expedited portion of the Project to meet FERC order requirements, completed construction and Valley Water Board of Directors accepted the work as complete on June 24, 2025.
Phase 2, CCFPP, is planned for completion before the Anderson Dam Seismic Retrofit Project Stage 2 Diversion is in operation (estimated in 2028). In total, the CCFPP includes constructing approximately 17,060 feet (3.2 miles) of improvements along the 9-mile stretch of Coyote Creek from Montague Expressway to Tully Road. On March 11, 2025, Valley Water Board certified the Final Environmental Impact Report for the CCFPP. On July 24, 2026, Valley Water Board awarded the construction contract for the CCFPP to Shimmick Construction Company Inc., in the sum of $124,378,309, and approved a contingency amount of $18,656,746 (15% of the contract price).
Valley Water staff worked closely with the City of San Jose parks staff on the CCFPP elements to be constructed at Watson Park, William Street Park, and Selma Olinder Park. Valley Water staff is also working closely with City of San Jose staff on plans for improvements to the storm drain system for backflow prevention.
ENVIRONMENTAL JUSTICE IMPACT:
There is no environmental justice impact associated with this item.
FINANCIAL IMPACT:
There is no financial impact associated with this item.
CEQA:
The recommended action does not constitute a project under CEQA because it does not have the potential to result in direct or reasonably foreseeable indirect physical change in the environment.
ATTACHMENTS:
Attachment 1: PowerPoint
Handout 2.2-A: M. Schroeder Letter
UNCLASSIFIED MANAGER: Manager
Ryan McCarter, 408-630-2983