Project–At–A–Glance

WSIP Region
Peninsula

Location
San Mateo County

Construction Start
September, 2010

Construction Finish
October, 2011

Current Status:
Design, Environmental

Project Cost
$31M

The Lower Crystal Springs Reservoir System (Upper and Lower Crystal Springs Reservoirs) is the primary water storage facility on the San Francisco Peninsula. Water stored in this reservoir is pumped to the San Andreas Reservoir, which subsequently provides raw water to the area’s water treatment facility. The project is provided in response to the Delivery Reliability and Water Supply level of service goals

In 1983, California Department of Water Resources – Division of Safety of Dams dictated that the maximum allowable water surface elevation of the reservoir be lowered by 8 feet because the dam’s spillway was inadequate to safely pass a Probable Maximum Flood event. The lower maximum operating elevation reduces the storage capacity of the reservoir by 2.6 billion gallons. The purpose of this project is to make the necessary improvements so that the dam can safely pass the Probable Maximum Flood event, and thereby restore the maximum operating elevation of the reservoir.

Description

The project would consist of:

• Widening the spillway, constructing two bridge piers within the spillway to accommodate rebuilding of a San Mateo County Bridge, removing the existing timber stop-log system, constructing a new weir system within the spillway, installing access cat-walks for operation and maintenance, and eliminating water ponding on top of the dam.
  
• Raising the parapet wall that is located on top of the upstream face of the dam and raising the approach walls to the spillway.
  
• Removing the existing stilling basin, constructing a new larger basin, and adding downstream riprap protection at the toe of the basin.

Note: Schedule and cost information shown may vary from the 2007 Approved WSIP Schedule and Budget. The information shown reflects the current forecast information published in the latest WSIP Quarterly Report.