The Big Water Supply Shift: Groundwater Key to Water Security in California's Changing Climate

Union of Concerned Scientists | November 1st, 2015

For more than a century, California has relied on its snowmelt-fed reservoirs, rivers, and streams for the majority of its water, but drought and climate chang

For more than a century, California has relied on its snowmelt-fed reservoirs, rivers, and streams for the majority of its water, but drought and climate change are depleting those traditional supplies. Snow is already melting as many as 30 days earlier than in the mid-twentieth century, meaning less water is available during the hotter months when water demand is highest. California is increasingly turning to groundwater to meet its water needs. Today, groundwater supplies up to 50 percent of California’s water, but California’s prolonged drought has led to the over-pumping of groundwater, overdrafting the Central Valley’s aquifers. Sustainable groundwater management will allow the state to adapt to climate change while increasing water reliability in the future.

The California Water Atlas

Governor's Office of Planning and Research (OPR) | October 24th, 1979

This book sets out to tell the biggest story in the richest and most populous state in the Union. Water lies at the basis of the modern prosperity of California, and th

This book sets out to tell the biggest story in the richest and most populous state in the Union. Water lies at the basis of the modern prosperity of California, and the history of the state is in large part the history of water development. The problems of water supply and delivery for the future are emerging among the critical issues facing not only California but the entire American Southwest over the next ten years. And yet, at a time when environmental consciousness is high and complex problems of world energy supply and international finance are part of the normal fare in our daily newspapers, water remains probably the least popularly understood of our natural resources.

The California Water Plan: Projected Use and Available Water Supplies to 2010

California Department of Water Resources (DWR) | December 15th, 1983

The case for state-level drinking water affordability programs: Conceptual and empirical evidence from California

Utilities Policy (Elsevier) | April 1st, 2020

Informed by the design of a program in California, we make a three-part argument for why state-level governments might consider implementing direct bill-assistance progra

Informed by the design of a program in California, we make a three-part argument for why state-level governments might consider implementing direct bill-assistance programs for drinking water service to address growing affordability concerns for low-income households. State-level operation of bill-assistance programs represents a departure from the global trend of allowing water utilities to operate bill-assistance programs at their own discretion. We first explain the motivation for enhanced public sector support to help households pay for drinking water service. In state-level contexts such as California, we find that the basic household affordability equation has worsened due to an increase in the numerator of residential retail bills and a stagnation in the denominator of household incomes. We next demonstrate why direct bill assistance to households is necessary even with the presence of other system-level financial support or retail rate structure policies. Finally, we make the case that direct bill-assistance programs are best situated at the state level, due to substantial variation in systems’ capacity and demonstrated willingness to run their own robust affordability programs for vulnerable customers.

The Case of Shifting Snow

Climate Central | February 5th, 2020

Whether you live among palm trees or pine trees, snow plays a critical role in our climate. Snow keeps our planet cooler, significantly affects water resources, and is a

Whether you live among palm trees or pine trees, snow plays a critical role in our climate. Snow keeps our planet cooler, significantly affects water resources, and is a revealing indicator of climate change. Forecasting snowfall and determining long-term trends of snow climatology are inherently challenging, but the research team at Climate Central has produced an analysis of snowfall trends across the United States. While no single overall national trend in snowfall can be discerned from the results, clear regional and seasonal patterns do emerge. In almost all areas of the country, snow is decreasing in the “shoulder” seasons—fall and spring. Results from 145 locations show that 116 stations (80%) had decreased snowfall before December, and 96 stations (66%) had decreased snowfall after March 1. Winter showed a mixed record, with more snow in northern climates, and decreasing snow in the southern regions. We also compared total snowfall from the 1970s to the 2010s and ranked the 20 cities with the biggest percentage gains and losses, using endpoint analysis. The changing patterns of how much, when, and where snow falls have significant impacts on our climate, our economy, and our lives. This report provides a primer on the climatology of snow and includes resources on how to report on snow—or the lack of it—in your area.

The Central Valley Project - Federal or State?

University of California, Berkeley (UC Berkeley) | June 1st, 1955

The Delta Plan

Delta Stewardship Council (Delta Council) | May 16th, 2013

The Delta Plan is a comprehensive, long-term management plan for the Delta. Required by the 2009 Delta Reform Act, it creates new rules and recommendations to further the

The Delta Plan is a comprehensive, long-term management plan for the Delta. Required by the 2009 Delta Reform Act, it creates new rules and recommendations to further the state’s coequal goals for the Delta: Improve statewide water supply reliability, and protect and restore a vibrant and healthy Delta ecosystem, all in a manner that preserves, protects and enhances the unique agricultural, cultural, and recreational characteristics of the Delta. Now the Council is considering updates to the Delta Plan. For information about the amendment process, please click here. Developed through eights drafts, hundreds of hours of public meetings and thousands of public comments over two years, the Delta Plan is guided by the best available science and is founded on cooperation and coordination among federal, State and local agencies. The Delta Plan is enforceable through regulatory authority in the Delta Reform Act that requires state and local agencies to be consistent with the Delta Plan. The Delta Plan was unanimously adopted by the Delta Stewardship Council on May 16, 2013. Subsequently its 14 regulatory policies were approved by the Office of Administrative Law, a state agency that ensures the regulations are clear, necessary, legally valid, and available to the public. The Delta Plan became effective with legally-enforceable regulations on September 1, 2013.

The Delta Plan: Ensuring a reliable water supply for California, a healthy Delta ecosystem, and a place of enduring value

Delta Stewardship Council (Delta Council) | May 16th, 2013

The Sacramento-San Joaquin River Delta is the grand confluence of California’s waters, the place where the state’s largest rivers merge in a web of channels—and in

The Sacramento-San Joaquin River Delta is the grand confluence of California’s waters, the place where the state’s largest rivers merge in a web of channels—and in a maze of controversy. The Delta is a zone where the wants of a modern society come into collision with each other and with the stubborn limitations of a natural system. In 2009, seeking an end to decades of conflict over water, the Legislature established the Delta Stewardship Council with a mandate to resolve long-standing issues. The first step toward that resolution is the document you have before you, the Delta Plan.

The disappearing Salton Sea: A critical reflection on the emerging environmental threat of disappearing saline lakes and potential impacts on children's health

Science of the Total Environment (Elsevier) | February 6th, 2019

Changing weather patterns, droughts and competing water demands are dramatically altering the landscape and creating conditions conducive to the production of wind-blown

Changing weather patterns, droughts and competing water demands are dramatically altering the landscape and creating conditions conducive to the production of wind-blown dust and dust storms. In California, such factors are leading to the rapid shrinking of the Salton Sea, a 345 mile2 land-locked “sea” situated near the southeastern rural border region known as the Imperial Valley. The region is anticipated to experience a dramatic increase in wind-blown dust and existing studies suggest a significant impact on the health and quality of life for nearby residents of this predominantly low-income, Mexican-American community. The discussion calls attention to the public health dimensions of the Salton Sea crisis. We know little about the possible long-term health effects of exposure to mobilized lakebed sediments or the numerous toxic contaminants that may become respirable on entrained particles. We draw on existing epidemiological literature of other known sources of wind-blown dust, such as desert dust storms, and related health effects to begin to understand the potential public health impact of wind-blown dust exposure. The increased production of wind-blown dust and environmental exposures to such non-combustion related sources of particulate matter are a growing health threat, due in part to drought coupled with increasing pressures on limited water resources. Recent population-based studies have linked dust storms with cardiovascular mortality, asthma hospitalization and decrease in pulmonary function in both adults and children. A growing number of studies provide evidence of the acute health effects of wind-blown dust exposures among children, which with repeated insults have the potential to influence respiratory health over time. The shrinking of the Salton Sea illustrates a public health and environmental justice crisis that requires action and attention to protect the health and well-being of local communities.

The Draft State Water Project Delivery Capability Report 2021

California Department of Water Resources (DWR) | December 31st, 2021

The California Department of Water Resources (DWR) has authority under state law to construct, operate, and maintain the State Water Project (SWP) to manage, store and de

The California Department of Water Resources (DWR) has authority under state law to construct, operate, and maintain the State Water Project (SWP) to manage, store and deliver water for the benefit of the State. This report is intended to provide information about the key factors affecting the operation of the SWP in California, its long-term capability as a source of water for beneficial use, and an estimate of its current delivery capability. This report meets the requirements of Attachment B to the Monterey Plus Settlement Agreement of May 2003. Water provided by the SWP is a major source of the water supplies available to many SWP contractors. SWP contractors consist of 29 public entities that include cities, counties, urban water agencies, and agricultural irrigation districts. SWP contractors’ local/-regional water users have long-term contracts with the DWR for all, or a portion of their water supply needs. Thus, the delivery capability of water from the SWP system is an important component in the water supply planning of its recipients, and ultimately affects the amount of water available for beneficial use in California. The availability of these water supplies may be highly variable. A sequence of relatively wet water years1 may be followed by a varying sequence of dry or critically dry years. Having good and reliable estimates on how much water each contractor will receive each year —- whether it be a wet water year, a critical year, or somewhere in between -- gives contractors a better sense of the degree to which they may need to implement increased conservation measures, or plan for new facilities or back up sources of water to meet their needs. The geography of California and the infrastructure of water transfer from the source areas, located in the Sierra Mountain Range, to areas of demand for water, makes the Sacramento-San Joaquin Delta a key feature of the SWP’s ability to deliver water to its agricultural and urban contractors in the North Bay, the South Bay, California Central Valley, and Southern California. All but five of the 29 SWP contractors receive water deliveries by diversions from the Delta. These water diversions are pumped by either the Harvey O. Banks or Barker Slough pumping plants. DWR and the United States Bureau of Reclamation (USBR), the managing entities of the two statewide systems of water transfer in California, face numerous challenges in the operation of their diversion facilities in the Delta, and are regulated by several state and federal agencies to maintain, and enhance the Delta’s long-term sustainability. Maintaining suitable quality of water flowing in the channels of the Delta for the numerous in-basin beneficial uses, and the protection of endangered and threatened fish species are important factors of concern for the operators of the Delta export diversion facilities. Ongoing regulatory restrictions, such as those aimed at protecting the estuary’s resident and migratory fish species, are major challenges to a reliable and sustainable water delivery capability of both, SWP and the Central Valley Project (CVP) systems. Complications induced by climate change also pose the threat of increased variability in the frequency and magnitude of floods and droughts. The projected sea level rise caused by the increase in average temperature complicate efforts to manage salinity levels in the channels affected by tides. Additionally, higher ocean levels could result in more frequent water quality degradation in the Delta channels requiring additional Delta outflow to maintain water quality objectives. The 2021 Final Main Report (released at the end of March 2022) may include further information on climate change. Previously, the climate change scenario results were only discussed and presented in the Technical Addendum which is not published during the draft phase of the Delivery Capability Report (DCR). Other challenges include continued subsidence of Delta islands, many of which are already below sea level and supported by relatively unstable levee systems. Thus, the threat of a catastrophic levee failure becomes more significant as water pressure increases against the already fragile levees. The analyses in this report factor in all the current regulations governing SWP and CVP operations in the Delta and assumptions about water uses upstream in the Sacramento River and San Joaquin River watersheds. Analyses were conducted that determined the amounts of water that SWP contractors receive and the amounts of water they choose to hold for use in a subsequent year. SWP Delta exports have decreased since 2005, although the bulk of the change occurred between 2005 and 2009 and in 2019. The former reduction is due to the Delta regulations which constrained exports that culminated in the federal Biological Opinions (BiOps) which went into effect in 2008-2009. These BiOps restricted operations of the CVP and SWP diversion pumps. The later reduction is due to two main factors: 1) the amended Coordinated Operation Agreement (COA) with accompanying project operation changes which reduced SWP exports and increased CVP exports, and (2) a more conservative operation of Lake Oroville by the SWP. Many of the same assumptions on SWP operations described in the 2019 Report remains the same in this update for 2021, however, there were a few notable changes. These include the transition from CalSim II to CalSim 3 and CVP and SWP operational refinements. As a result, the differences between the 2019 and 2021 Reports can be attributed primarily to differences in hydrology, spatial and temporal expansion, more explicit groundwater and surface water interaction representation, and operational refinements. The most salient findings in this report are: Under existing conditions, the estimated average annual delivery of Table A water for this 2021 Report is 2,309 thousand acre-feet (TAF)/year, 105 TAF less than the 2,414 TAF/year estimated for the 2019 Report (Table 5-2). The likelihood of existing condition SWP Article 21 deliveries (supplemental deliveries to Table A water) being greater than 20 TAF/year has decreased by 20% relative to the likelihood presented in the 2019 Report (Figure 5-7).