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-Editorial
The California Department of Water Resources (DWR) has unveiled its final 2023 State Water Project (SWP) Delivery Capability Report, highlighting an urgent need for infrastructure upgrades amid changing climate conditions. The report provides a comprehensive analysis of current and future expectations for SWP water supply, projecting a potential reduction in delivery capability and reliability by up to 23 percent over the next two decades.
This anticipated decline, equivalent to approximately 496,000 acre-feet per year—enough to supply 1,736,000 homes annually—emphasizes the critical need for California to enhance its water supply strategies. Key projects such as the Delta Conveyance Project, Sites Reservoir, and desalination efforts are crucial to mitigating potential losses.
“The analysis released today underscores the need to modernize and upgrade our aging infrastructure so we can capture water supplies when it’s wet,” said DWR Director Karla Nemeth. “The State Water Project service area is home to more than 8 million Californians in disadvantaged communities. Modernizing the SWP is vital to ensuring the human right to water in California.”
Established in 1960, the SWP stretches over 700 miles and includes canals, dams, reservoirs, and power plants serving 27 million Californians and 750,000 acres of farmland. The system’s delivery capability is influenced by factors such as population growth, legislation, environmental regulations, and changing climate conditions.
“The SWP was designed for a 20th-century climate,” noted SWP Deputy Director John Yarbrough. “To prevent reliability losses, we must adapt and invest in the SWP to meet 21st-century demands.”
The 2023 report introduces two innovative methods to assess climate change impacts: one for existing climate changes and another for future climate scenarios. These improvements, validated through independent peer review, enhance the accuracy of the SWP’s water supply projections.
The report is a critical tool for water supply planning and drought management, informing public water agencies and contributing to Sustainable Groundwater Management Plans, Urban Water Management Plans, and other regional water management strategies.
DWR’s Sustainable Groundwater Management Office will use the report to update climate data and guidance for Groundwater Sustainability Agencies. Similarly, the Water Use Efficiency Branch will advise water agencies on adjusting their water budgets based on these new assessments.
As part of its long-term strategy, the SWP is developing a Climate Adaptation Plan, focusing on key strategies like the Delta Conveyance Project and new storage opportunities. The plan, building on the Delivery Capability Report’s findings, will be published later this year.
The report also emphasizes that SWP delivery capability, impacted by factors like Delta regulations and climate change, is vital for long-term water planning. It includes improved climate modeling and planning scenarios, reflecting changes in hydrology and operations. While the report forecasts a decrease in water availability under future climate conditions, it does not yet incorporate specific adaptation strategies. Future updates will include analyses of adaptation measures and their effectiveness in mitigating these challenges.
