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Water Stress and a Changing San Joaquin Valley

Public Policy Institute of California (PPIC) | March 1st, 2017

Summary

The San Joaquin Valley—California’s largest agricultural region, and an important contributor to the nation’s food supply—is in a time of great change and growing

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Water Supply Forecasting

U.S. Department of Agriculture (USDA) | March 9th, 2011

Summary

Chapter 7: Part 622 Snow Survey and Water Supply Forecasting from the National Engineering Handbook The U.S. Department of Agriculture (USDA) Natural Resources Conser

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Water to Supply the Land: Irrigated Agriculture in the Colorado River Basin

Pacific Institute | May 9th, 2013

Summary

The Colorado River, recently named America’s most endangered river, supports millions of people in the American Southwest and northwest Mexico and helps irrigate millio

The Colorado River, recently named America’s most endangered river, supports millions of people in the American Southwest and northwest Mexico and helps irrigate millions of acres of land. Yet demands on the river already exceed the river’s average supply, a situation that is projected to get worse in coming years as climate change reduces runoff at the same time that fast-growing southwest cities demand more water. Irrigated agriculture currently consumes more than 70% of the water supply within the Colorado River basin, making it critical for more efficient water use. For the first time, new research from the Pacific Institute describes the extent of irrigated agriculture throughout the seven Colorado River basin states and two additional states in Mexico, the types of crops grown, and the amount of water used to grow these crops. In addition, the new report – Water to Supply the Land: Irrigated Agriculture in the Colorado River Basin – compares several agricultural management scenarios and the potential water savings and costs associated with each. Importantly, none of the scenarios remove agricultural land from production. More than 90% of pasture and cropland in the 256,000-square-mile Colorado River Basin requires irrigation, with about 60% of the irrigated acreage devoted to pasture, alfalfa, and other forage crops used to feed cattle and horses. These forage crops consume about 5 million acre-feet per year, equivalent to a third of the river’s annual flow. Employing innovative irrigation techniques more strategically and in more places – techniques that many farmers are already using – can help ensure agriculture in the basin states continues in the face of rising demand and climate change’s projected impact on supply. Modeling a series of agricultural water management conservation strategies – including regulated deficit irrigation, crop shifting, and advanced irrigation technologies – the Pacific Institute compared potential water savings and costs associated with individual scenarios. The analysis shows considerable water savings are possible. For example, almost a million acre-feet of water may be generated by irrigating alfalfa less often (a practice known as “regulated deficit irrigation”) throughout the basin in the U.S., at an estimated base cost of approximately $81 per acre-foot. Other scenarios, such as shifting to less water-intensive crops, also yield impressive water savings with relatively low costs and without reducing the total amount of irrigated acreage in the basin. For example, replacing about 10% of the basin’s irrigated alfalfa acreage with cotton and wheat could save about 250,000 acre-feet of consumptive water use each year, with estimated base costs of less than $40 per acre-foot. Total reductions in water withdrawals and applied water would be even greater.

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Water, environment, and socioeconomic justice in California: A multi-benefit framework

Science of the Total Environment (Elsevier) | November 5th, 2022

Summary

Low-income, rural frontline communities of California's Central Valley experience environmental and socioeconomic injustice, water insecurity, extremely poor air quality,

Low-income, rural frontline communities of California's Central Valley experience environmental and socioeconomic injustice, water insecurity, extremely poor air quality, and lack of fundamental infrastructure (sewage, green areas, health services), which makes them less resilient. Many communities depend financially on agriculture, while water scarcity and associated policy may trigger farmland retirement, further hindering socioeconomic opportunities. Here we propose a multi-benefit framework to repurpose cropland in buffers inside and around (400-m and 1600-m buffers) 154 rural disadvantaged communities of the Central Valley to promote socioeconomic opportunities, environmental benefits, and business diversification. We estimate the potential for (1) reductions in water and pesticide use, nitrogen leaching, and nitrogen gas emissions, (2) managed aquifer recharge, and (3) economic and employment impacts associated with clean industries and solar energy. Retiring cropland within 1600-m buffers can result in reductions in annual water use of 2.18 km3/year, nitrate leaching into local aquifers of 105,500 t/year, greenhouse gas emissions of 2,232,000 t CO2-equivalent/year, and 5388 t pesticides/year, with accompanying losses in agricultural revenue of US$4213 million/year and employment of 25,682 positions. Buffer repurposing investments of US$27 million/year per community for ten years show potential to generate US$101 million/year per community (total US$15,578 million/year) for 30 years and 407 new jobs/year (total 62,697 jobs/year) paying 67 % more than prior farmworker jobs. In the San Joaquin Valley (southern Central Valley), where groundwater overdraft averages 2.3 km3/year, potential water use reduction is 1.8 km3/year. We have identified 99 communities with surficial soils adequate for aquifer recharge and canals/rivers within 1600 m. This demonstrates the potential of managed aquifer recharge in buffered zones to substantially reduce overdraft. The buffers framework shows that well-planned land repurposing near disadvantaged communities can create multiple benefits for agriculture and industry stakeholders, while improving quality of life in disadvantaged communities and producing positive externalities for society.

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Wells of Southern California

Scientific American | March 22nd, 1902

Summary

In the Series of Water Supply Irrigation Papers, the United States Geological Survey has in press, but not yet published, the “Wells of Southern California" (Nos. 59

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West-Wide Climate Risk Assessments: Irrigation Demand and Reservoir Evaporation Projections

U.S. Bureau of Reclamation (USBR) | February 5th, 2015

Summary

Section 9503 of the SECURE Water Act, Subtitle F of Title IX of P.L. 111-11 (2009) (SECURE Water Act), authorizes the Bureau of Reclamation (Reclamation) to evaluate the

Section 9503 of the SECURE Water Act, Subtitle F of Title IX of P.L. 111-11 (2009) (SECURE Water Act), authorizes the Bureau of Reclamation (Reclamation) to evaluate the risks and impacts of climate change in each of the eight major Reclamation river basins identified in the Act, and to work with stakeholders to identify climate adaptation strategies. Reclamation implements Section 9503 of the SWA through the Department of Interior’s WaterSMART Program1, which is working to achieve a sustainable water strategy to meet the Nation’s water needs now and for the future. Through Basin Studies, part of WaterSMART, Reclamation works with State and local partners to evaluate the ability to meet future water demands within a river basin and to identify adaptation and mitigation strategies of the potential impacts of climate change. Through another activity, West-Wide Climate Risk Assessments (WWCRA), Reclamation is working to provide projections of future changes in water supplies, water demands, and river system operations that could result from changes in climate. As part of WWCRA, Reclamation has conducted an analysis of the potential changes in crop irrigation demand in eight major river basins in the West and projections of evaporation for 12 reservoirs within those river basins when considering observed and projected impacts of climate change. This report contains the results of that analysis. The findings presented in this report are intended to be used for future basin-specific WWCRA impact assessments and Basin Studies conducted under WaterSMART if the teams conducting those studies elect to do so. This technical assessment report provides: (1) an analysis of changes in irrigation demand, and (2) an analysis of changes in evaporation for selected reservoirs across the major Reclamation river basins with respect to presently observed and projected future impacts of global climate change. The analysis involved developing irrigation demand and reservoir evaporation projections associated with World Climate Research Programme Coupled Model Intercomparison Project3 (WCRP CMIP3) climate projections that have been bias-corrected and spatially downscaled (BCSD) and served at the following Web site: http://gdo-dcp.ucllnl.org/downscaled_cmip_projections/dcpInterface.html. For the purposes of this study, CMIP3 climate projections were used because they represented the best available collection of climate projections at the onset of this effort (summer 2011 which was begun prior to the release of CMIP5). Although the CMIP3 and CMIP5 projections are considered equally likely potential climate futures at this time, there is significant variability in the two sets of projections. This is especially true with regard to precipitation projections, and it is significant to note the potential impact of this variability on future irrigation demand and net evaporation estimates. Changes to irrigation demand (model, described below) were analyzed for five climate change scenarios (warm-dry, warm-wet, hot-dry, hot-wet, and central tendency – ensemble median) that were informed by 112 BCSD-CMIP3 projections at three future periods: 2020s (years 2010-2039), 2050s (years 2040–2069), and 2080s (2070-2099) with 1950–1999 as the baseline period. The reservoir evaporation modeling (described below) was performed as transient simulations using the individual 112 BCSD-CMIP3 projections. Both the irrigation demands modeling and the reservoir evaporation modeling used observed data from weather stations representative of irrigated land areas and reservoir sites in a secondary bias correction step to account for local scale climate conditions in the climate change scenarios. Although it would be ideal to calculate future irrigation demands for all 112 projections using the transient method as was done for the future reservoir evaporation estimates, such calculations were not feasible given the multiple crops and numerous locations modeled.

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Yolo Bypass Salmon Habitat Restoration and Fish Passage Analytical Tool Review

Delta Stewardship Council (Delta Council) | October 1st, 2017

Summary

NOAA’s National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS) have issued a Biological Opinion (BiOp) on the long-term operat

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Page : 19

Water Stress and a Changing San Joaquin Valley

Water Supply Forecasting

Water to Supply the Land: Irrigated Agriculture in the Colorado River Basin

Water, environment, and socioeconomic justice in California: A multi-benefit framework

Wells of Southern California

West-Wide Climate Risk Assessments: Irrigation Demand and Reservoir Evaporation Projections

Yolo Bypass Salmon Habitat Restoration and Fish Passage Analytical Tool Review

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