CASTAIC DAM MODERNIZATION CASTAIC DAM, LAKE AND LAGOON are located 45 miles northwest of Los Angeles and provide water for the greater LA area. The dam was built between 1965 and 1974 as part of the CALIFORNIA STATE California Department of Water Resources (DWR) State Water Project (SWP). WATER PROJECT DWR is modernizing its SWP facilities across the state, including Castaic Dam. This consists of Begun in earnest in the identifying and proactively addressing any issues that could impact the delivery of water or the safety of 1950s, the California surrounding communities. In Fall of 2019, DWR initiated field work for the Castaic Dam Modernization State Water Project (SWP) is a water storage Program. Over the next several years, DWR will conduct assessments of the dam and associated and delivery system that structures, and undertake construction activities to ensure the dam continues to function safely. supplies water to more than 27 million people and provides irrigation Based on DSOD findings and DWR’s Status of Castaic Dam for about 750,000 acres inspections, the initial focus of the Castaic In its most recent inspection, the California of farmland. The SWP Dam modernization effort will be to explore the spans two-thirds of the Division of Safety of Dams (DSOD) rated conditions of the spillway, left abutment (where length of California and Castaic Dam as fair – meaning there are no the dam meets the valley wall), water supply includes 26 dams and existing dam safety deficiencies that will impact outlet structures, and the tower access bridge reservoirs; 705 miles of the dam’s functions under normal conditions. canals, tunnels, and to the water outlets. However, improvements can be made to pipelines; and nine prevent serious impacts after either an extreme hydroelectric power plants. In addition to weather or earthquake event. Spillway Condition and Extreme water supply, the SWP Weather Assessments provides many benefits, n Over the years, DWR has carefully and including flood control, power generation, consistently managed the reservoir’s recreation, and fish and water levels so as to not use the spillway. wildlife habitat. However, changes in weather patterns introduce new uncertainties for future The SWP collects rainfall extreme weather events. Climate models and snowmelt runoff, show that increased temperatures in transports the water California will result in more precipitation through the California Aqueduct, and stores falling as rain rather than snow, which water in one of the will alter river flows throughout the state. many storage facilities DWR wants to ensure that the spillway will like Castaic Lake. The function appropriately if it is activated to SWP works as a system release water in the future. to manage water supply throughout the n Dam safety engineers have identified that SWP, which can vary some of the concrete wall and floor panels both seasonally and in the spillway have shifted, which could from year to year. lead to erosion if the spillway were used SWP water travels to 29 water contracting to release water. DWR is investigating the agencies that deliver causes and impacts to target rehabilitation the water to their work and ensure the spillway will work customers. appropriately if a need ever arises. Earthquake Resiliency Assessments What to Expect? n DWR conducted a stability analysis in n During the modernization process, as 2018, which indicated the dam structure a cautionary measure, DWR lowers will continue to perform safely, even in the the water level of Castaic Lake slightly event of a major earthquake. during the winter months to provide more capacity in the reservoir to buffer winter n However, other studies indicate that the run-off, reducing the likelihood that the outlet structures (the large towers that spillway would need to be employed. allow DWR to release water from the Additionally, temporarily reduced water reservoir) are vulnerable to collapse in a levels may be necessary to conduct major earthquake. While this would not various repair efforts of the outlet towers cause the dam to fail, it would significantly and access bridge. These slightly lower reduce DWR’s ability to release water water levels will not impact water supply. reliably resulting in potential impacts to DWR is working closely with its state water deliveries. partners and local organizations to n DWR is currently conducting seismic minimize the extent of recreation impacts. retrofits of the access bridge to the outlet n structures to ensure that personnel can DWR will be operating construction access the outlet structures should an equipment in all phases of the earthquake occur. modernization program. Some localized noise and increased activity may be expected, particularly during rehabilitation construction efforts. n DWR anticipates that the modernization efforts of the Program will take about 10 years to complete. How to Contact Us For more information on the Castaic Dam Modernization Program, contact: [email protected].