San Joaquin River

Water availability and land subsidence in the Central Valley, California, USA

Hydrogeology Journal (Springer) | November 17th, 2015

The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on sur

The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007–2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use. *Erratum: Water availability and land subsidence in the Central Valley, California, USA, Faunt, C.C., Sneed, M., Traum, J. et al. Hydrogeol J (2017) 25: 2215

Water availability and subsidence in California’s Central Valley

University of California, Davis (UC Davis) | September 5th, 2015

California’s Central Valley covers about 52,000 square kilometers (km2) and is one of the most productive agricultural regions in the world. More than 250 different c

California’s Central Valley covers about 52,000 square kilometers (km2) and is one of the most productive agricultural regions in the world. More than 250 different crops are grown in the broad alluvial filled structural trough, with an estimated value exceeding $20 billion per year (Faunt 2009) (Figure 1). Central Valley agriculture depends on state and federal water systems that divert surface water, predominantly originating from Sierra Nevada snowmelt, to agricultural fields. Because the valley is semi-arid and the availability of surface water varies substantially from year to year, season to season, and from north to south, agriculture, as it grew, developed a reliance on groundwater for irrigation.

Water Available for Replenishment 2018

California Department of Water Resources (DWR) | April 12th, 2018

Water Blueprint for the San Joaquin Valley Economic Impact Analysis: Phase One Results

Water Blueprint for San Joaquin Valley | February 15th, 2020

Water Demand Projection Accuracy and Demand Management Trends in California Cities

American Geophysical Union (AGU) | November 21st, 2025

This study investigates the accuracy of long-term water demand projections and tracks the evolution of water demand management incentives across 61 California water suppl

This study investigates the accuracy of long-term water demand projections and tracks the evolution of water demand management incentives across 61 California water suppliers from 2000 to 2020. Through a systematic analysis of Urban Water Management Plans, we find that water suppliers consistently overestimated future demand by an average of 25% for 5-year projections and 74% for 20-year projections. This overestimation stems primarily from assumptions about per capita water demand rather than population growth estimates. While suppliers generally projected stable or increasing per capita demand, actual water demand per capita declined by 1.9% annually between 2000 and 2020, leading to a decoupling of water demand from population growth. Concurrently, we document a substantial increase in water demand management incentives, with non-voluntary regulations emerging as the dominant demand management approach by 2020, largely driven by state policies like the Model Water Efficient Landscape Ordinance and California Green Building Standards. Demand management efforts have evolved from primarily indoor and educational initiatives toward outdoor-focused non-voluntary regulations and rebates. This shift appears closely linked to the reduction in per capita demand that suppliers failed to fully capture in their water demand projections. Our findings underscore the importance of incorporating dynamic conservation trends into demand projections and suggest that suppliers should develop more sophisticated forecasting methods that account for the continuing evolution of water efficiency incentives. This research provides valuable insights for water resource planners seeking to improve the accuracy of water demand projections in an era of increasing conservation and climate uncertainty.

Water Facilities Including a Peripheral Canal [Proposition 9]

Department of Justice (DOJ) | June 9th, 1982

Water Facilities Including a Peripheral Canal Referendum Statute

State of California | June 1st, 1982

WATER FACILITIES INCLUDING A PERIPHERAL CANAL. REFERENDUM STATUTE. A "yes" vote approves, a "no" vote rejects, a law that will : Designate additional facilities and pr

WATER FACILITIES INCLUDING A PERIPHERAL CANAL. REFERENDUM STATUTE. A "yes" vote approves, a "no" vote rejects, a law that will : Designate additional facilities and programs, including a peripheral canal as units of Central Valley Project. Specify requirements regarding feasibility, environmental impacts, design construction, operation, financing, and protection and enhancement of fish and wildlife for project units. Require Water Resources Department to contract with named Delta agencies regarding users' rights, water quality, and benefit payments; and to immediately proceed with specified prerequisites to construction of peripheral canal . Required compliance with designated water quality standards and conditions . Specify other responsibilities and matters. Summary of Legislative Analyst's estimate of net state and local government fiscal impact: As Project has been planned and operated to be self-supporting, implementation under present policies would not require increase in state taxes or reduce funds for other state programs . Potential construction costs at 1981 prices are in excess of $3 .1 billion plus unknown additional costs, plus interest, to be financed by increased user charges.

Water for a Growing Bay Area: How the region can grow without increasing water demand

Pacific Institute | October 21st, 2021

The San Francisco Bay Area is at a crossroads. The region, blessed with a beautiful natural setting, multiple shipping ports and world-class universities, is a driver of

The San Francisco Bay Area is at a crossroads. The region, blessed with a beautiful natural setting, multiple shipping ports and world-class universities, is a driver of global economic growth. But the region’s housing supply has not kept up with population growth. Many low-income households, disproportionately made up of people of color, have been forced into overcrowded and substandard housing or displaced from the urban center to new neighborhoods far from their jobs, friends and families. The most vulnerable have lost their homes entirely and are among the region’s 35,000 unhoused people. Over the next half-century, the Bay Area’s need to add housing will only grow more intense. The region is projected to add 2 million new jobs by 2070, which would attract as many as 6.8 million people, and needs to build at least 2.2 million new housing units just to prevent housing affordability from worsening. This represents 83% more people, 74% more housing units and 38% more jobs over the next 50 years.

Water Partnerships between Cities and Farms in Southern California and the San Joaquin Valley

Public Policy Institute of California (PPIC) | October 29th, 2020

The San Joaquin Valley and urban Southern California are worlds apart in many ways. Yet each face growing water challenges and a shared interest in ensuring reliable, aff

The San Joaquin Valley and urban Southern California are worlds apart in many ways. Yet each face growing water challenges and a shared interest in ensuring reliable, affordable water supplies to safeguard their people and economies. Both regions’ water futures could be more secure if they take advantage of shared water infrastructure to jointly develop and manage some water supplies.  Increasing climate volatility is heightening concerns about droughts of the future. And two major shifts in California’s water landscape have generated new opportunities for collaboration between urban and agricultural interests. For urban areas, significant declines in water demand have reduced pressure on supplies during normal and wet years for many agencies, making reliability for future droughts the primary concern. For the overdrafted San Joaquin Valley, the requirement to manage groundwater sustainably has heightened interest in expanding water supplies and underground storage.  Partnerships between Southern California cities and San Joaquin Valley farms could help alleviate groundwater overdraft in the valley while building drought resilience in Southern California. More flexible supplies can help agencies adapt to changing conditions. By coordinating the location of infrastructure investments, agencies can use partnerships to bring the water where and when it is most needed, at least cost.  This report explores a variety of solutions that could benefit both regions. For the San Joaquin Valley, we look for ways to augment water supplies to ease the transition to groundwater sustainability, while for Southern California we explore options that would increase cities’ ability to deal effectively with extended droughts. By diversifying water supplies, building connections to share water more flexibly, and preparing for the extreme events to come, such partnerships would support Governor Newsom’s Water Resilience Portfolio, and pave the way for a shared effort to make the state’s water system more resilient to a changing climate. 

Water Quality Conditions in the Sacramento-San Joaquin Delta and Suisun and San Pablo Bays during 2009

California Department of Water Resources (DWR) | December 28th, 2010

This report summarizes the results of water quality monitoring and special  studies conducted by the Environmental Monitoring Program (EMP) within the Sacramento-San Joa

This report summarizes the results of water quality monitoring and special  studies conducted by the Environmental Monitoring Program (EMP) within the Sacramento-San Joaquin Delta (Delta) and Suisun and San Pablo bays (the upper San Francisco estuary) during calendar year 2009. This monitoring is mandated by Water Right Decision 1641 (D-1641) and this report is being submitted to fulfill the reporting requirements of this decision. The EMP monitored water quality using a protocol implemented in 1996. Under this monitoring protocol, 13 sampling sites—2 of which were added after 1996—representing 8 regions of the upper San Francisco estuary (estuary) were monitored for 15 physical and chemical water quality parameters. The results gathered from the sampling of these 15 parameters are described in this report. Parameters such as water temperature, Secchi disk depth, dissolved oxygen (DO) concentration, specific conductance, dissolved inorganic nitrogen, orthophosphate, and volatile suspended solids were within their historical range. Measured parameters exhibited seasonal variation as well as changes in response to significant rainfall events and in flow rates. In addition to monitoring physical and chemical water quality parameters, biological sampling was conducted to monitor the productivity and community composition of phytoplankton, zooplankton, and benthic communities.