Two key projects are set to begin as part of ongoing modernization work at Castaic Dam in Los Angeles County to reduce risks from a major earthquake. The California Department of Water Resources (DWR) will oversee the installation of new equipment to monitor the dam’s stability and work to strengthen the dam’s intake tower access bridge.
“These projects are important to helping us ensure Castaic Dam continues to operate safely and provides reliable and affordable water supply,” said DWR Deputy Director Ted Craddock, who oversees the State Water Project. “In addition to providing water supply for Southern California, Castaic Lake offers many recreational opportunities for surrounding communities.”
The SWP is a system of 32 storage facilities, 21 pumping plants, four pumping-generating plants, eight conventional hydroelectric plants and about 700 miles of canals and pipelines. Castaic Lake, completed in 1974 and located 45 miles northwest of Los Angeles, provides regulatory storage, water supply and recreational opportunities.
Piezometers will be installed in wells adjacent to the dam’s east side to measure groundwater trends over time to monitor the dam’s stability. DWR will install nine new piezometers and decommission three aging piezometers to improve data collection capabilities for reliable and accurate data. The project should be completed by the end of June 2021.
As the piezometer work wraps up, Castaic Dam’s intake tower access bridge work will begin. It is expected to continue until spring 2022. Bridge work includes strengthening the tower bridge piers, which requires the temporary drawdown of Castaic Lake to access the piers.
During the drawdown that will begin in early May, the reservoir will reach a low elevation of 1,380 feet above mean sea level by fall 2021. The water level will be lowered by over 100 feet during this period. By spring 2022, Castaic Lake will return to normal operations with water levels based on available conditions at that time.
DWR kicked off the Castaic Modernization Program in 2018. The program includes reducing seismic risk to the intake tower and access bridge, evaluation of the spillway to identify and implement necessary modifications, and earthquake monitoring capabilities on various dam components.