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Project Information
August 2011
Mid 2019
Cost $810 Million
Project Phase Construction
Additional Information

The information shown reflects the current forecast information published in the latest WSIP Quarterly Report.

Project Materials

Project Factsheet - Summer 2016
Spillway Media Fact Sheet

Naturally Occurring Asbestos Information and Data

Naturally Occurring Asbestos Questions and Answers
Air Monitoring Results


Environmental Impact Report

Volume 1      • Volume 5-6
Volume 2      • Volume 5-7
Volume 3      • Volume 5-8
Volume 4      • Volume 6
Volume 5-1   • Addendum 1
Volume 5-2   • Addendum 2
Volume 5-3   • Addendum 3
Volume 5-4  
Volume 5-5  

Summary Data Reports from
Air Monitoring Events

August 2008 through August 2009
September 2009 through July 2010
August 2010 through November 2010


Need more information? Contact:

Maria Le
Phone: 925.493.4535

Betsy L. Rhodes
Phone: 415.554.3240

Sign up for our Sunol Valley Regional Blog to follow the projects in that area.



Project Update

As of July 5, 2016, Calaveras Road between Geary Road and Oakridge Road has been closed to vehicle, pedestrian, and bicycle traffic on weekdays for 18 months. This is due to large truck traffic on the narrow portions of Calaveras Road for dam construction.

Calaveras Road will be closed on WEEKDAYS ONLY between Geary Road and Oakridge Road – near the Santa Clara/Alameda County Line. Entrance to Sunol Regional Wilderness will be open at all times.

Calaveras Road opens Saturday mornings 6 a.m. and closes Sunday evenings at 11:00 p.m.

To stay updated, please join our road closure notification mailing list by emailing For more details on the upcoming Calaveras road closure at

What's New at Calaveras Dam?

Construction began in 2011 to build a new earth and rock fill dam adjacent to the existing dam. To date, the Contractor has moved over six million cubic yards of earth and rock materials and started to construct the new dam. Crews have constructed a new shaft and five adits (tunnels) which connect outlet pipelines to the reservoir. We have completed grouting operations on the right abutment and continue grouting on the left abutment. Completion of the new spillway is expected sometime in Spring 2016. A new 78 inch diameter pipe has been installed and encased in concrete, which will be connected to existing lines to deliver water. Dam embankment work is scheduled to begin in late 2016. As of June 2016, the project is over 75% complete.

Calaveras Road Advisory:

  • Construction haul trucks are expected on Calaveras Road from 6:00 a.m. to 4:00 a.m. Monday through Friday
  • Please drive slowly and bike safely on the narrow portions of Calaveras Road
  • Speed limit is 25 mph in construction zones
  • Bicyclists traveling in groups are encouraged to ride in single file,
    to share the road with oncoming trucks and vehicles
  • This affects the portion of Calaveras Road from the Highway 680 entrance in Sunol to the dam site south of Geary Road

Project Description

The project consists of building a new zoned earth and rock fill dam immediately downstream of the existing dam. The replacement dam will have a structural height of 220-feet high and is designed to accommodate a maximum credible earthquake on the Calaveras Fault. The dam will have a crest length of 1,210 feet, a base thickness of 1,180 feet, and crest thickness of 80 feet. The total volume of the dam will be approximately 3.5 million cubic yards. The replacement dam will restore the original reservoir capacity of 96,850 acre-feet, or 31 billion gallons of water. The storage is crucial to providing adequate water to our 2.6 million customers in the Bay Area.

Last updated: 7/26/2016 12:13:41 PM