State Water Project Report Shows How Water Managers are Preparing for Drought, Extreme Weather, and Future Water Supply Conditions Amidst a Changing Climate
From the Department of Water Resources:
Today, the Department of Water Resources released its final 2023 State Water Project Delivery Capability Report, which presents a new and enhanced analysis of current and future expectations for the SWP water supply if no new adaptation actions are taken. According to the report, SWP delivery capability and reliability could be reduced as much as 23 percent in 20 years due to changing flow patterns and extreme weather shifts – underscoring the need for California to continue addressing the impacts of climate change and upgrading infrastructure.
A 23 percent decline would be equivalent to about 496,000 acre-feet a year, enough to supply 1,736,000 homes for a year. This reinforces the serious need for California to boost water supplies to account for any SWP losses in the coming years, including the Delta Conveyance Project, Sites Reservoir, desalination projects, and more.
“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 amounts to the world’s eighth-largest economy and includes more than 8 million Californians living in disadvantaged communities. Modernizing the State Water Project is critical to delivering on the human right to water in California.”
Built in 1960, the SWP spans more than 700 miles throughout California and consists of canals, dams, reservoirs, pumping plants, and power plants that provide water to 27 million Californians and 750,000 acres of farmland. Several factors impact the SWP’s water delivery capability including California’s population, state legislation, environmental requirements, and potential changing climate resulting in varying hydrologic conditions.
“The SWP was designed for the climate of the 20th century when our precipitation fell as snow more reliably between October and May and we could capture that water effectively for future use,” said SWP Deputy Director John Yarbrough. “We need to continue to adapt and invest in the SWP, so that we can add flexibility and resilience for 21st century conditions and we can avoid these losses in reliability.”
The 2023 Delivery Capability Report introduces two new innovative approaches to characterize current climate change conditions and emphasizes the uncertainty in future climate change projections. The first is an approach to account for changes in operations from the climate change that has already occurred. The second is an approach for developing a range of future climate scenarios. Both additions have undergone independent peer review and are considered significant improvements over previous methods.
The Delivery Capability Report is used widely both within and outside the SWP for water supply planning. The information in these reports is a key component of the drought planning done by the SWP and is fundamental to the drought planning done by the public water agencies that receive SWP and Central Valley Project water. The report provides the information needed by these agencies to develop and manage their own water supply portfolios and is an important input for Sustainable Groundwater Management Plans, Urban Water Management Plans, Agricultural Water Management Plans, and Integrated Regional Water Management Plans.
These decreases in the availability of surface water deliveries can lead to supply shortages, an increase in groundwater demand, and reductions in available supplies to support groundwater replenishment. DWR’s Sustainable Groundwater Management Office will use the information in the report to update its existing climate change data and guidance that many Groundwater Sustainability Agencies used for their initial Plans. Similarly, DWR’s Water Use Efficiency Branch will be advising urban and agricultural water agencies to update their water budget assumptions based on these new assessments.
As part of the State’s long-term planning efforts, the SWP is also proactively developing a Climate Adaption Plan. The Adaptation Plan will incorporate key adaptation strategies, including the Delta Conveyance Project and opportunities for new and expanded storage both above and below ground. It will also build upon the analysis provided in the Delivery Capability Report and will be published later this year.
DWR is committed to supporting the State’s efforts to take an all-of-the-above approach to creating a resilient water supply system in the face of a changing climate. In addition to the Delta Conveyance Project, DWR is supporting efforts to advance Sites Reservoir, groundwater recharge, desalination, water recycling, and promoting continued water conservation.
DWR encourages all SWP water users and local groundwater sustainability agencies to take a collaborative and proactive approach while using the insights from this report for their own planning and adaptation investigations.
For more information, view the report.
Other coverage ….
California must improve plans to address climate change impacts, state officials say
“California officials say that the state must better prepare for the impending impacts of climate change to avoid potentially devastating losses of water in coming years. The state’s Department of Water Resources on Wednesday released the 2023 State Water Project Delivery Capability Report, analyzing current and future expectations for California’s water supply. Experts reported that the state’s delivery capability and reliability could decrease by as much as 23% within 20 years due to changing flow patterns and extreme weather shifts. That’s equivalent to about 496,000 acre-feet per year, enough to supply more than 1.7 million homes for one year. “The analysis released today underscores the need to modernize and upgrade our aging infrastructure so we can capture water supplies when it’s wet. Modernizing the State Water Project is critical to delivering on the human right to water in California,” Karla Nemeth, Department of Water Resources director, said in a statement Wednesday. … ” Read more from Courthouse News.
State Water Project supplies could fall up to 23% within 20 years due to climate change
“Climate change threatens to dramatically shrink the amount of water California can deliver over the next 20 years and could reduce supplies available from the State Water Project by up to 23%, according to new projections released Wednesday by Gov. Gavin Newsom’s administration. The analysis by the California Department of Water Resources examined a range of climate change scenarios and projected that by 2043 the average amount of water transported through the massive network of reservoirs and canals to more than half the state’s population could decline between 13% and 23%. Such a loss in the State Water Project’s water delivery capacity, if not addressed, could lead to major shortages for much of the state, including Southern California. “The SWP was designed for the climate of the 20th century,” said John Yarbrough, the project’s deputy director. “It’s going to need continued investment to get it in a place where it’s really able to function with the hydrology of the future.” … ” Read more from the LA Times.
SEE ALSO:
- California reservoir levels could drop much more than expected in the future, state report finds, from the San Francisco Chronicle
Reactions …
From Jennifer Pierre, General Manager of the State Water Contractors
“DWR’s final Delivery Capability Report underscores what California’s water managers have known and have been planning for: ongoing shifts in hydrology in California will require newfound investments to ensure we can move and store water when it’s wet for use when it’s dry, for generations to come. The volume of water provided by the SWP cannot easily or affordably be replaced so it is imperative that as part of a suite of actions to shore up water supply portfolios throughout the state, we modernize and upgrade the state’s main water delivery infrastructure and implement science-based regulations.
The report shows that SWP deliveries could drop by between 13%-23% in the next 20 years if no reinvestments in the SWP are made. A 23% drop in supply is a worst-case scenario, built for planning purposes on the assumption that we will do nothing to modernize, adapt, and upgrade our water infrastructure and regulatory structure. That’s good for planning, but thankfully not the case. Water managers are, in fact, proactively analyzing and developing adaptation strategies—including the Delta Conveyance Project, Agreements to Support Healthy Rivers and Landscapes (Agreements), Forecast Informed Reservoir Operations (FIRO), and improved above- and below-ground storage opportunities—to ensure the projected supply reductions never become a reality for California.
While the outlined climate adaptation strategies are critical, needed and long overdue, we need to make sure we can afford their associated costs. Currently, contractors who rely on State Water Project supplies shoulder all the costs, including for public benefits such as flood control, electric grid reliability and significant costs to support important recreation facilities and opportunities throughout the state. Just as the State Water Contractors are prepared to ensure reinvestment in the State Water Project, so too should the state and federal government ensure that all of the benefits continue to accrue to all Californians. The State Water Project’s service area would rank as the eighth largest economy in the world if it were its own nation, and the final DCR shows without question that we must invest in California’s water infrastructure for the millions of people and important farmland that relies on it for California’s continued prosperity.”
From Californians for Water Security:
“The effects of climate change are already upon us. We cannot sit back and do nothing while our water supplies steadily decrease. It is long past time to advance the Delta Conveyance Project to prepare for a more uncertain water future. Time is running out.”
The report finds that our current infrastructure is ill-prepared for the challenges of climate change, including “weather whiplash” of prolonged droughts followed by intense rainy seasons, higher temperatures, and shifting hydrology. The system’s losses can be mitigated by investments in storage and conveyance infrastructure like Sites Reservoir and the Delta Conveyance Project.
