2020-103 - Approving the Water Supply Assessment

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41" AND CABRILLO WATER SUPPLY ASSESSMENT AUGUST 21, 2020 Over the past 16 years (2000-2015), there have only been three years when the Colorado River flow has been above average.b The long-term imbalance in future supply and demand is projected to be approximately 3.2 MAF by the year 2060. Actions are currently being taken and planned in the future to resolve the imbalance between water supply and demand in areas that use Colorado River water. Such actions include the resolution of uncertainties related to water conservation, reuse, water banking, and weather modification concepts.7 State Water Proiect The State Water Project (SWP) collects water from rivers in Northern California and redistributes it to the water -scarce but populous central and southern portions of California through a network of aqueducts, pumping stations and power plants. Approximately 70% of the water provided by the SWP is used for urban areas and industry in Southern California and the San Francisco Bay Area, and 30% is used for irrigation in the Central Valley. The availability of water supplies from the SWP can be highly variable. A wet water year may be followed by a dry water year which restricts the amount of water that can be delivered throughout California. Metropolitan's SWP imported water is stored at Castaic Lake on the western side of Metropolitan's service area and at Silverwood Lake near San Bernardino, as well as in Diamond Valley Lake. The Sacramento -San Joaquin River Delta (Delta) is key to the SWP's ability to deliver water to its agricultural and urban contractors. The Delta faces many challenges concerning its long- term sustainability such as climate change posing a threat of increased variability in floods and droughts. Sea level rise complicates efforts in managing salinity levels and preserving water quality in the Delta to ensure a suitable water supply for urban and agricultural use. Furthermore, other challenges include continued subsidence of Delta islands, many of which are below sea level, and the related threat of a catastrophic levee failure as the water pressure increases, or as a result of a major seismic event. Metropolitan's Board approved a Delta Action Plan in June 2007 that provides a framework for staff to pursue actions with other agencies and stakeholders to build a sustainable Delta and reduce conflicts between water supply conveyance and the environment. The Delta action plan aims to prioritize immediate short-term actions to stabilize the Delta while an ultimate solution is selected, and mid-term steps to maintain the Delta while a long-term solution is implemented. Currently, Metropolitan is working towards addressing three basic elements: Delta ecosystem restoration, water supply conveyance, and flood control protection and storage development. In April 2015, the Brown Administration announced California WaterFix, as well as a separate ecosystem restoration effort called California EcoRestore (formerly known as the Bay Delta Conservation Plan). Together, the California WaterFix and California EcoRestore would make significant contributions toward achieving the coequal goals of providing a more reliable water supply for California and protecting, restoring, and enhancing the Delta ecosystem. The WaterFix was aimed at making physical and operational improvements to the SWP system in the Delta necessary to restore and protect ecosystem health, south -of -Delta SWP water supplies, and water quality. 6 2015 Metropolitan UWMP. 7 2012 USBR Colorado River Basin Water Supply and Demand Study. FUSCOE ENGINEERING, INC. 17