Sustainability of irrigated agriculture in the San Joaquin Valley, California

National Academy of Sciences (NAS) | October 25th, 2005

The sustainability of irrigated agriculture in many arid and semiarid areas of the world is at risk because of a combination of several interrelated factors, including

The sustainability of irrigated agriculture in many arid and semiarid areas of the world is at risk because of a combination of several interrelated factors, including lack of fresh water, lack of drainage, the presence of high water tables, and salinization of soil and groundwater resources. Nowhere in the United States are these issues more apparent than in the San Joaquin Valley of California. A solid understanding of salinization processes at regional spatial and decadal time scales is required to evaluate the sustainability of irrigated agriculture. A hydro-salinity model was developed to integrate subsurface hydrology with reactive salt transport for a 1,400-km2 study area in the San Joaquin Valley. The model was used to reconstruct historical changes in salt storage by irrigated agriculture over the past 60 years. We show that patterns in soil and groundwater salinity were caused by spatial variations in soil hydrology, the change from local groundwater to snowmelt water as the main irrigation water supply, and by occasional droughts. Gypsum dissolution was a critical component of the regional salt balance. Although results show that the total salt input and output were about equal for the past 20 years, the model also predicts salinization of the deeper aquifers, thereby questioning the sustainability of irrigated agriculture.

Sustainable Groundwater Management Act Governance Strategies Summary Report

California State University, Fresno (CSUF) | September 15th, 2021

A three-bill legislative package, referred to as the Sustainable Groundwater Management Act (SGMA), created a fundamental change in the governance of California’s groun

A three-bill legislative package, referred to as the Sustainable Groundwater Management Act (SGMA), created a fundamental change in the governance of California’s groundwater. SGMA requires, with some exceptions, the formation of groundwater sustainability agencies (GSAs) for identified groundwater subbasins. Signed into law in 2014 by Governor Jerry Brown, it set forth a long-term, statewide framework to protect groundwater resources. This report outlines the initial implementation of these new laws by the GSAs in 21 critically overdrafted groundwater subbasins2. Based on a review of multiple statutes, regulations, early research, official government documents and interviews with individuals involved in the process, the authors explain how these first GSAs were created and the organizational and governance challenges they navigated. Once formed, the GSAs were charged with the development and implementation of groundwater sustainability plans (GSPs). The purpose of a GSP is to avoid the undesirable results of groundwater depletion and mitigate overdraft within 20 years. A review of the formation process for this set of GSAs was particularly instructive as they were required to meet a set of SGMA requirements two years earlier than the remaining legislatively identified basins. Presented in an approach that moves from the general to the specific, this report documents the historic process of how 125 GSAs began to implement SGMA. In addition, this report provides important baseline information to help researchers, regulators, policy makers and GSAs themselves, in the development and evaluation of governance and future governance strategies, statutes and regulatory actions. The report is organized into two major topics. 1. Governance structure choices available to GSAs and the GSA formation process set forth in SGMA, including: Specific examples of GSA governance choices. How governance choices were influenced by the preparation and financing of GSPs. 2. Summary findings and observations from interviews of policymakers, technical experts, and thought leaders on their perception of the GSA governance decision-making process and the improvements they believe would benefit SGMA outcomes.The interviewees’ insights reflect the experience they gained during the formation of the critically overdrafted basins GSAs. They identified key elements they felt would be helpful when forming future GSAs, most notably: Providing simplified groundwater science education information for managers, leaders, and groundwaters users. Implementing agency leadership training so the organizational structures and efforts of GSAs can be fully responsive to constituents. Heightening attention relative to some of the beneficial uses of groundwater that were not adequately addressed by GSPs, such as small domestic wells and environmental needs. These experts also observed that implementation of SGMA is an iterative process and that time will be needed to develop, implement, measure, and improve the results of groundwater management strategies. A variety of additional sources of information are offered throughout this report. In addition, Appendix A includes searchable links and information on GSAs, GSPs and other governance elements found in DWR’s (Department of Water Resources) SGMA Portal.

Sustained groundwater loss in California's Central Valley exacerbated by intense drought periods

American Geophysical Union (AGU) | July 4th, 2018

The accelerated rate of decline in groundwater levels across California’s Central Valley resultsfrom overdrafting and low rates of natural recharge and is exacerbated b

The accelerated rate of decline in groundwater levels across California’s Central Valley resultsfrom overdrafting and low rates of natural recharge and is exacerbated by droughts. The lack of observations with an adequate spatiotemporal resolution to constrain the evolution of groundwater resources poses severe challenges to water management efforts. Here we present SAR interferometric measurements of high-resolution vertical land motion across the valley, revealing multiscale patterns of aquifer hydrogeological properties and groundwater storage change. Investigating the depletion and degradation of the aquifer-system during 2007–2010, when the entire valley experienced a severe drought, we find that ~2% of total aquifer-system storage was permanently lost, owing to irreversible compaction of the system. Over this period, the seasonal groundwater storage change amplitude of10.11 ± 2.5 km3modulates a long-term groundwater storage decline of 21.32 ± 7.2 km3. Estimates for subbasins show more complex patterns, most likely associated with local hydrogeology, recharge, demand, and underground flow. Presented measurements of aquifer-system compaction provide a more complete understanding of groundwater dynamics and can potentially be used to improve water security.

Tehachapi Reclaimed Water Project

City of Tehachapi | September 24th, 2024

As part of the proposed project, the City would change the location of application of the secondary treated effluent produced at the Tehachapi WWTP from the agricultural

As part of the proposed project, the City would change the location of application of the secondary treated effluent produced at the Tehachapi WWTP from the agricultural fields near the Tehachapi Municipal Airport to a new location south of the Borrow Pit. Overall WWTP effluent production and WWTP throughput capacity would remain unchanged as would the time of year of application (from April to October).

Ten Rivers in America's Future, No. 2. The Central Valley of California

U.S. Water Resources Policy Commission | July 1st, 1950

Tentative Ruling, Friant Water Authority vs. Eastern Tule Groundwater Sustainability Agency

Superior Court of California, County of Tulare | June 25th, 2024

The Economic Impact of the Westlands Water District on the Local and Regional Economy

Westlands Water District | October 11th, 2016

To anyone who visits the Westlands Water District (the District), the one reality that is most obvious to the observer is that agriculture IS the economy in the communiti

To anyone who visits the Westlands Water District (the District), the one reality that is most obvious to the observer is that agriculture IS the economy in the communities within and immediately surrounding the Westlands Water District. It is an area characterized by wide open fields-often populated with crops and occasional small pockets of residential and (rarer) retail-usually at the intersections of roads. Not only is agriculture the primary employer, but government, agricultural support industries and the limited general retail sector comprise the full course of jobs within the district and its immediate environs. Nearly every business in the district is related to agriculture or supporting the needs of the workers who support those working in agriculture. Westlands Water District is perched on the eastern side of Interstate 5 in the Central Valley covering the geography between roughly Kettleman City in the south and Firebaugh in the north. As the largest agricultural water district in the nation, it plays a central role in the economies of both Fresno and Kings Counties. This analysis unravels the story of Westlands' contributions to the local economy, exploring the demographics and economy of the region, agriculture's major role in that economy, estimating the economic contributions of growers within the District's boundaries, and providing a preliminary assessment of the consequences of current water policies on crop production, and giving a preview of what some of the implications of those changes may be.

The Effect of Declining Groundwater Levels on Supply Well Operations

University of California, Davis (UC Davis) | August 15th, 2016

This report explores the impact of droughts on domestic and irrigation well operations. Well completion reports and groundwater depth data obtained from the Department of

This report explores the impact of droughts on domestic and irrigation well operations. Well completion reports and groundwater depth data obtained from the Department of Water Resources were used in the analysis. The percentages of wells in which the top, middle or bottom of the screened interval became exposed above the pumping water level were calculated and implied maintenance or replacement costs were estimated. Increases in pumping costs from greater depths to groundwater were estimated as well. For our case study, we selected a 27 square mile area in Tulare County, where the California Department of Water Resources has determined that groundwater is in a state of critical overdraft and designated the basin as High Priority under the Sustainable Groundwater Management Act. Results indicate that for the 2015 drought, there was significant potential for incurring well maintenance and replacement costs as a result of drought conditions and water levels approaching critical points in the screened intervals. While the assumptions associated with the current method appear to result in overestimation of impacts, the current drought may have resulted in several million dollars in well maintenance and replacement costs. For irrigation wells that remained in operation, increased depths to groundwater would increase overall pumping costs. About $5.31 per acre ($1.7 per acre-foot) were estimated as increased pumping costs in the recent 2012-2015 drought. While these costs are not large on a per acre basis, they may be significant when incurred across large agricultural areas. This proof of concept analysis highlights the value of information on groundwater levels and well constructions for estimating impacts of droughts on long term groundwater pumping capacity and operation. This analysis can be extended for the entire Central Valley in an effort to quantify the impacts of drought and the importance of groundwater management.

The futures market for water rights trading in California: Analyzing the emergence of a controversial experiment

Environmental Challenges (Elsevier) | March 29th, 2025

This paper presents a qualitative case study of the world's first water futures contract in California, a market that enables hedgers and speculators to bet on water pric

This paper presents a qualitative case study of the world's first water futures contract in California, a market that enables hedgers and speculators to bet on water prices. It is attempted to explain which factors shaped the emergence of the unique market by applying the Political Process Inherent Dynamics Approach (PIDA), an analytical framework from the field of environmental policy analysis. In addition, the topics of heated debate that have surrounded the new market are summarized and contextualized. To obtain the relevant information, expert interviews, complemented by online sources, were subjected to a Qualitative Content Analysis. It is concluded that the launch of the contract is an extreme case of private business actors shaping water governance, made possible by a longstanding market philosophy in the US, that gives leeway for actors of financialization to create facts. In the political-administrative realm, a lack of accountability and will to interfere seems to prevail. However, nongovernmental organizations (NGOs) and other actors have led efforts to abolish the market, criticizing water futures in ways that resonate with broader debates about privatization and food futures.

The Implications of Agricultural Water for the Central Valley

Westlands Water District | September 6th, 2017

This report is the companion report to last summer’s publication The Economic Impact of the Westlands Water District on the Local and Regional Economy. That study had m

This report is the companion report to last summer’s publication The Economic Impact of the Westlands Water District on the Local and Regional Economy. That study had many important findings, including: Westlands Water District (WWD) directly accounts for nearly 29,000 jobs and $3.6 billion of economic activity. The state’s continued failure to provide the contracted water levels has resulted in an 18 percent loss of economic output within the district; Economic pressures coupled with the prolonged shortfall in water availability have driven growers to shift to less labor-intensive crops; Westlands growers provide significant shares of the national supplies of many key fresh fruit, produce, and nuts; and Sustaining domestic production of fresh fruit, produce and nuts serve critical national priorities, including National security, environmental protection, worker protection, providing workers with reasonable wages, and using scarce water resources efficiently. In this analysis, the research focuses on the implications to the local economy and communities of the agriculture-driven jobs that Westlands and other water districts in the region foster. Among its most important findings are: Consistent and ongoing provision of the full allocation of water to WWD would result in a 19.9 percent increase in employment and more than a 17 percent increase in economic output from WWD alone. Providing none of the allocation to the growers in the WWD (through either policy choices or a long-term drought) would result in an 80 to 86 percent decrease in both employment and economic output in the district. This would represent 25,000 to 27,000 jobs and more than $3.0 billion of economic output in the local economy. In the presence of a long-term water crisis in the region, the economic impacts for Fresno and Kings Counties would be major. Agriculture directly contributes to (conservatively) one in six jobs in Fresno County and one in five jobs in Kings County. It accounts for at least one-sixth of the economic output of Fresno County and nearly one-fourth of the economy in Kings County. For solar construction to replace this level of employment in the county, more than $6.24 billion dollars a year would have to be invested in new solar projects within the county’s boundaries. Agriculture provides employment, income and opportunity to a wide range of workers in the region with extremely limited education and training. More than half of agricultural workers have less than a high school education and 95 percent have no college. Agriculture does provide a path for social mobility with opportunities to advance and earn significantly higher wages, even for these low skilled workers. Almost 90 percent of the workers who would be displaced by disruptions to the agricultural sector in the Central Valley are Hispanic. Communities that show success in attracting manufacturing have much better educated labor pools. The disappearance or significant reduction of agriculture as a major employer in the region, could have severe consequences for the local economy, including: o The loss of billions in public revenues; o Major migration from the region could turn local communities into ghost towns; o For those that remain behind, they would change from being net contributors to the local economy to recipients of public resources through the social safety net. In its final section, the study identifies four action items needed to ensure that the region experiences more of the benefits that can be reaped from a vibrant agricultural sector in the region and to avoid the major challenges that would arise if it shrank significantly. These recommendations include: Devise a statewide plan for water and water policy in California; Expand storage capacities significantly and improve the state’s ability to move water between systems and projects; Reprioritize the use of available water resources toward agriculture; and Expand the water resources available in the state through conservation, desalinization, and recycling. Agricultural production is a national security asset—especially in today’s uncertain global trade climate, it is essential to have a reliable and accessible domestic food supply. There are a limited number of places where the climate, soil and space overlap as they do in the California Central Valley to produce an ideal climate for agriculture. Not surprisingly, California’s irrigation technologies are increasingly among the best in the world. Add to that the state’s stringent environmental regulations on the use of pesticides, worker protections, and food handling regulations, and the state’s food supply is among the safest in the world. Once the land that supports this critical national asset is dedicated to other purposes, and once the industrial infrastructure that supports the processing and distribution of these crops are gone, they are almost impossible to rebuild. All it takes is enough water to make it work—a problem that humans have been solving since the first patch of crops were planted in prehistoric times. With the technologies available, we should be able to solve it today.