Guadalupe Dam Seismic Retrofit Project

Location

San Jose

Phase

Design

Schedule

Start: 2028 / Finish: 2032

Cost

$140 million

A 2012 independent engineering study of the Guadalupe Dam found that during a large earthquake, the dam could deform significantly, resulting in an uncontrollable release of reservoir water. In response, the state Division of Safety and Dams (DSOD) imposed storage restrictions for the reservoir of 18-feet below the dam spillway crest, keeping water levels lower than normal to prevent over spilling until the water district assesses and conducts corrective action to restore the dam’s full integrity.

Guadalupe Dam Background
Valley Water plans to upgrade the Guadalupe Dam in South San Jose following regulatory guidance from the State Division of Safety and Dams (DSOD). The Guadalupe Dam Seismic Retrofit Project will ensure the dam’s operational safety and ability to deliver water to Santa Clara County residents. Guadalupe Dam was built in 1936. It is 129 feet high and 650 feet long and has the capacity to store 3,415 acre-feet of drinking water.

Project Objectives
The embankment for Guadalupe Dam was found to have seismic vulnerabilities in withstanding an earthquake with the highest possible magnitude that could occur in the area. The planned improvements for this dam include:

Earthquake Safety: reconstructing and thickening the dam's embankment;
System Upgrades: constructing a new outlet system (releases water from the reservoir);
Flood Protection: constructing a new spillway to current design standards and,
Safety Enhancements: improving maintenance access to the dam and facilities from Hicks Road.

Project Update and Timeline
The planning phase was completed. The dam's embankment and spillway design is 60% complete, with completion scheduled for the summer of 2025. Valley Water is also preparing the environmental documentation. The remaining upgrades to the outlet system and access points will be designed during phase 2 and have their own timeline for completion.

January Public Meeting
The presentation from the January 23 public meeting is available to download, and the meeting recording can be viewed.

For More Information:

Bal Ganjoo, 408-630-3117
Senior Project Manager
Jose Villarreal, 408-630-2879
Neighborhood Liaison

Earthquake Safety: reconstructing and thickening the dam's embankment;
System Upgrades: constructing a new outlet system (releases water from the reservoir);
Flood Protection: constructing a new spillway to current design standards and,
Safety Enhancements: improving maintenance access to the dam and facilities from Hicks Road.

January Public Meeting
The presentation from the January 23 public meeting is available to download, and the meeting recording can be viewed.

For More Information:

Bal Ganjoo, 408-630-3117
Senior Project Manager
Jose Villarreal, 408-630-2879
Neighborhood Liaison

Mercury Assessment

To inform the final design for GDSRP, Valley Water needs to conduct geotechnical investigations and environmental sampling as part of a Mercury Assessment Work Plan, with the purpose of determining subsurface conditions and the concentration of chemical constituents (primarily mercury and other metals) within surficial and subsurface soils. Sampling results will also be used to determine, prioritize, and monitor ongoing maintenance needs for Guadalupe Dam and the appropriate methodologies to implement those maintenance needs over time. An addendum to Valley Water’s Dam Maintenance Program EIR has been prepared in accordance with the California Environmental Quality Act for this work and is included below:

DMP EIR and Addendum

Guadalupe Dam Seismic Retrofit Project Planning Study Report

Notice of Preparation of a Draft Environmental Impact Report

Stabilizes dam embankments

Modifies or replaces outlet works

Modifies or replaces the spillway to increase freeboard

The Santa Clara Valley Water District built the Guadalupe Dam during the Great Depression, completing it in 1935 after acquiring land as the Santa Clara Valley Water Conservation District. The dam and reservoir is one of the six original reservoirs approved for construction by voters in May 1934.

The reservoir’s surface area is 74 acres. Both the dam and reservoir are located along Hicks Creek on Guadalupe Creek, a tributary of the Guadalupe River.

The reservoir primarily stores water for recharging groundwater basins. Groundwater is present beneath the surface in soil pore spaces and in fractures of rock formations and supplies and provides nearly half the drinking water each year for Santa Clara County’s residents.