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.

The irrigation efficiency trap: rational farm-scale decisions can lead to poor hydrologic outcomes at the basin scale

Frontiers in Environmental Science | August 28th, 2023

Agricultural irrigation practices have changed through time as technology has enabled more efficient conveyance and application. In some agricultural regions, irrigation

Agricultural irrigation practices have changed through time as technology has enabled more efficient conveyance and application. In some agricultural regions, irrigation can contribute to incidental aquifer recharge important for groundwater return flows to streams. The Henrys Fork Snake River, Idaho (United States) overlies a portion of the Eastern Snake Plain Aquifer, where irrigated agriculture has occurred for over a century. Using irrigator interviews, aerial and satellite imagery, and statistical streamflow analysis, we document the impact of farm-scale decisions on basin-scale hydrology. Motivated to improve economic efficiency, irrigators began converting from surface to center-pivot sprinkler irrigation in the 1950s, with rapid adoption of center-pivot sprinklers through 2000. Between 1978–2000 and 2001–2022, annual surface-water diversion decreased by 311 Mm3 (23%) and annual return flow to the river decreased by 299 Mm3 over the same period. Some reaches that gained water during 1978–2000 lost water to the aquifer during the later period. We use an interdisciplinary approach to demonstrate how individual farm-scale improvements in irrigation efficiency can cumulatively affect hydrology at the landscape scale and alter groundwater-surface water relationships. Return flows are an important part of basin hydrology in irrigated landscapes and we discuss how managed and incidental aquifer recharge can be implemented to recover return flows to rivers.

The New Inland Sea

Scientific American | April 13th, 1907

The deep channel in the Alamo River, which passed Holtville in August, was gradually approaching Sharp's Heading, and it was recognized that when this cataract reached

The deep channel in the Alamo River, which passed Holtville in August, was gradually approaching Sharp's Heading, and it was recognized that when this cataract reached the heading it would be very difficult and expensive, and perhaps impossible, to maintain that heading. This, however, was not the only peril to the water supply of the valley. The channel of New River had eroded to such an extent that where the two streams separated it was estimated that four-fifths of the water was running down New River and only one fifth down the Alamo. While this proportion was favorable to the regimen of the Alamo and the safety of Sharp's Heading, it was very threatening in an other respect. It accelerated the cutting of the New River channel, in which was a great cataract four or five miles below the separation of the two streams, and this was, of course, advancing upstream. It was well recognized that when this cataract reached the Alamo the channel would be so deep that all of the water would run down New River and leave Sharp's Heading on dry land, without any water for the irrigation of the Imperial Valley. Threatened first with inundation, and next with the destruction of their entire water supply, the inhabitants of the Imperial Valley have naturally been almost in a state of panic for several months.

The paradox of irrigation efficiency

American Association for the Advancement of Science (AAAS) | August 24th, 2018

Reconciling higher freshwater demands with finite freshwater resources remains one of the great policy dilemmas. Given that crop irrigation constitutes 70% of global wate

Reconciling higher freshwater demands with finite freshwater resources remains one of the great policy dilemmas. Given that crop irrigation constitutes 70% of global water extractions, which contributes up to 40% of globally available calories (1), governments often support increases in irrigation efficiency (IE), promoting advanced technologies to improve the “crop per drop.” This provides private benefits to irrigators and is justified, in part, on the premise that increases in IE “save” water for reallocation to other sectors, including cities and the environment. Yet substantial scientific evidence (2) has long shown that increased IE rarely delivers the presumed public-good benefits of increased water availability. Decision-makers typically have not known or understood the importance of basin-scale water accounting or of the behavioral responses of irrigators to subsidies to increase IE. We show that to mitigate global water scarcity, increases in IE must be accompanied by robust water accounting and measurements, a cap on extractions, an assessment of uncertainties, the valuation of trade-offs, and a better understanding of the incentives and behavior of irrigators.

The San Francisco Bay-Delta Agreement: Principles for Agreement on Bay-Delta Standards Between the State of California and the Federal Government

California State Water Resources Control Board (SWRCB) | December 15th, 1994

The Sustainable Groundwater Management Act challenges the diversity of California farms

California Agriculture (UCANR) | November 16th, 2016

California’s agricultural sector, a major groundwater user, finds itself in the midst of the implementation of the Sustainable Groundwater Management Act (SGMA). The la

California’s agricultural sector, a major groundwater user, finds itself in the midst of the implementation of the Sustainable Groundwater Management Act (SGMA). The law mandates the formation of local groundwater sustainability agencies (GSAs) and adoption of groundwater sustainability plans (GSPs) for all overdrafted groundwater basins across the state by 2020. Each GSA will be unique, with its own governance structures and rules, including the size and composition of the governing board, mechanisms for representing different interests, opportunities for stakeholders to participate, and rules concerning the allocation of pumping “rights” and the use of economic instruments, such as pumping permits, pumping taxes or tiered pricing, to incentivize pumping curtailments (DWR 2016). This new water management landscape may threaten the diversity of the state’s farming operations.

The tradeoff between water savings and salinization prevention in dryland irrigation

Advances in Water Resources (Elsevier) | December 7th, 2023

Soil salinization is a global phenomenon that affects large tracts of arid farmland worldwide. It contributes to the loss of soil fertility, declining yields, and – in

Soil salinization is a global phenomenon that affects large tracts of arid farmland worldwide. It contributes to the loss of soil fertility, declining yields, and – in the most severe cases – land unsuitability for cultivation. Irrigation water applications are both the main cause of and the solution to, anthropogenic (or ‘secondary’) salinization because salt typically enters the soil column as dissolved in irrigation water and leaves it through excess water applications (e.g., leaching). Excess leaching, which places additional water costs in areas affected by water scarcity, can be achieved with different irrigation techniques and practices. Here, by complementing a process-based crop water model with a salt balance of the shallow soil, we investigate the tradeoff between root zone salinization and water conservation to limit withdrawals from the water source. We evaluate how such a tradeoff is achieved under different irrigation technology and excess leaching practices. Considering as a case study the cultivation of tomatoes in Egypt, we find that drip and furrow irrigation allows for better control of salt accumulation, thus preventing crop exposure to salt stress. Drip irrigation achieves this goal with minimal water applications because it maintains the soil wetter. Thus, the (rare) rainfall events find more suitable conditions to drain the excess moisture. Conversely, by using more irrigation water (and ‘less efficiently’), furrow irrigation allows for higher rates of soil drainage and salt leaching. The irrigation schedule typically adopted with sprinkler irrigation allows for soil drying, thus limiting the ability of rainfall events to drain the soil and leach its salts. Collectively, these results highlight the key role of irrigation technology and practices in the management of secondary salinity in dryland agriculture. Specifically, there is a tradeoff between minimizing water use and preventing salt accumulation in the root zone. Drip irrigation exhibits the co-benefit of achieving both goals, while furrow irrigation limits soil salinity at the cost of requiring greater volumes of applied irrigation water.

The Well Fixer's Warning

The Atlantic | August 17th, 2021

The well fixer and I were standing at the edge of an almond orchard in the exhausted middle of California. It was late July, and so many wells on the farms of Madera Co

The well fixer and I were standing at the edge of an almond orchard in the exhausted middle of California. It was late July, and so many wells on the farms of Madera County were coming up dry that he was running out of parts to fix them. In this latest round of western drought, desperate voices were calling him at six in the morning and again at midnight. They were puzzled why their pumps were coughing up sand, the water’s flow to their orchards now a trickle.

Thirstwaves: Prolonged Periods of Agricultural Exposure to Extreme Atmospheric Evaporative Demand for Water

American Geophysical Union (AGU) | March 20th, 2025

Global atmospheric evaporative demand has increased, impacting agricultural productivity and water use. Traditionally, trend assessments have been limited to total evapor

Global atmospheric evaporative demand has increased, impacting agricultural productivity and water use. Traditionally, trend assessments have been limited to total evaporative demand, overlooking shifts in daily extremes, which are meaningful for agrohydrological outcomes yet largely unknown. Here, using a fully physical metric of evaporative demand, that is, standardized short crop reference evapotranspiration, we introduce the concept of thirstwaves—prolonged periods of extremely high evaporative demand—and analyze their characteristics during 1981–2021 growing seasons for the conterminous US. Findings show that long-term mean spatial patterns demonstrated by thirstwave characteristics do not follow that of total or mean evaporative demand. Weighted for cropland area harvested, thirstwave intensity, duration, and frequency have increased by 0.06 mm d−1 decade−1, 0.10 days decade−1, and 0.39 events decade−1, respectively during 1981–2021. Statistically significant trends appear across 17%, 7%, and 23% of cropland area for intensity, frequency, and duration. Not only have thirstwaves increased in severity, but the likelihood of no thirstwaves occurring during the growing season has significantly decreased. Our work proposes a novel metric to describe periods of extremely elevated evaporative demand and presents a systematic analysis of such conditions historically for US croplands.

Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China

Nature Portfolio (Springer Nature) | June 21st, 2016

Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are wi

Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr. Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery and Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr and cumulative subsidence as much as 155 cm.