Water Risk Hotspots for Agriculture: The Case of the Southwest United States

Organisation for Economic Co-operation and Development (OECD) | July 14th, 2016

The Southwest United States – defined here as Arizona, California, Colorado, Nevada, New Mexico, and Utah – is a rapidly growing region that faces major water challe

The Southwest United States – defined here as Arizona, California, Colorado, Nevada, New Mexico, and Utah – is a rapidly growing region that faces major water challenges. It has the fastest growing population and one of the most economically productive regions of the United States. It is also the most arid region and is prone to long-term droughts. These dry conditions, combined with a water allocation system based on prior appropriation — whereby the “first in time” is the “first in line” to access water — generate tension between stable or declining sectors of the economy that hold the majority of the rights to water and the fast-growing sectors of the economy that have more limited water rights. The Southwest provides a case study of the challenges posed by limited water availability and some of the successful methods used to bridge the gap between water supply and demand.

Water Supply Forecasting

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

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

Chapter 7: Part 622 Snow Survey and Water Supply Forecasting from the National Engineering Handbook The U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Snow Survey and Water Supply Forecasting Program issues water supply forecasts for hundreds of points in the Western United States. The primary forecast product is a seasonal volume for a specified period of months (e.g., April–July). These forecasts are issued near the first of the month between January and June. Mid-month updates are also issued for selected forecast points. In addition, daily guidance forecasts are issued for a subset of forecast points using an automated procedure. This chapter describes the essential features of water supply forecasting as practiced in the NRCS. The topics are presented in a roughly chronological sequence of activities, from forecasting point establishment, to data gathering, to model development, to operations, and finally to verification. Citations of foundational professional literature and NRCS technical notes are given to provide sources of details on mathematical procedures and other technical information not explicitly described in this chapter.

Water Surplus and Drought Management Update - Conditions as of 11/29/2022

Metropolitan Water District of Southern California (MWD) | December 13th, 2022

Water Transfers in Water Resource Systems

American Society of Civil Engineers (ASCE) | March 1st, 1995

Water transfers are a common component of many regional water systems and are being increasingly considered for meeting growing water demands and for managing the impacts

Water transfers are a common component of many regional water systems and are being increasingly considered for meeting growing water demands and for managing the impacts of drought.  Water transfers can take many forms and can serve a number of different purposes in the planning and operation of water resource systems. However, to be successful, water transfers must be carefully integrated with traditional water supply augmentation and demand management measures.  This integration requires increased cooperation among different water use sectors and resolution of numerous technical and institutional issues, including impacts to third parties.  This paper identifies the many forms that water transfers can take, some of the benefits they can generate, and the difficulties and constraints which must be overcome in their implementation.

Water Year 2017: What a Difference a Year Makes

California Department of Water Resources (DWR) | October 2nd, 2017

Water year 2017 (October 1, 2016 to September 30, 2017) dramatically illustrated the variability in California’s annual precipitation, ending the state’s 5-year droug

Water year 2017 (October 1, 2016 to September 30, 2017) dramatically illustrated the variability in California’s annual precipitation, ending the state’s 5-year drought and coming in at second place for statewide runoff, behind the wettest year of 1983. Virtually all of the state experienced at least average precipitation, and key Sierra Nevada watersheds were much above average. Governor Brown lifted the proclamation of statewide drought emergency he issued in 2014, although the state-declared emergency remained in selected central California counties experiencing lingering drought impacts. Prior to 2017, California had experienced a decade of largely dry conditions. Eight of the ten preceding water years were dry, and the water years of 2012-15 set a record for the driest consecutive four-year period of statewide precipitation.

Water Year 2018 Hydrology

Delta Stewardship Council (Delta Council) | November 26th, 2018

Water Year 2021 Compound Precipitation and Temperature Extremes in California and Nevada

American Meteorological Society (AMS) | December 23rd, 2022

The most intense 22-yr drought in the western United States since 800 CE (Williams et al. 2022) was extended by compound dry and hot extremes in Water Year 2021 (October

The most intense 22-yr drought in the western United States since 800 CE (Williams et al. 2022) was extended by compound dry and hot extremes in Water Year 2021 (October 2020–September 2021). Compared to an instrumental record that dates to 1895, low precipitation (Fig. 1a) and high temperatures (Fig. 1b) were widespread across the western United States. The intense and prevalent drought has caused water delivery shortages (U.S. Bureau of Reclamation 2021), damaged ecosystems (Wlostowski et al. 2022), and contributed to extreme wildfires (e.g., Fu et al. 2021; Gutierrez et al. 2021; Abolafia-Rosenzweig et al. 2022). California and Nevada (CA–NV) were once again at the epicenter of drought and heat in Water Year 2021 (California Department of Water Resources 2021). This was the first time since 1895 that precipitation fell below –1.5 standardized departures and temperatures exceeded 1.5 standardized departures concurrently for the two-state average (Fig. 1c). Precipitation and temperatures were individually extreme as well, as the former was the second lowest since 1895 and the latter was the second highest. We examine whether the co-occurrence of anthropogenic climate change and La Niña, two principal climate drivers during Water Year 2021, altered the risk of unprecedented compound dry and hot extremes in CA–NV during Water Year 2021. Our assessment investigates the factors related to compound extremes that lead to heightened societal impacts compared to individual extreme events (e.g., AghaKouchak et al. 2020; Zscheischler et al. 2020; W. Zhang et al. 2021).

Water Year 2023: Weather Whiplash, from Drought to Deluge

California Department of Water Resources (DWR) | October 4th, 2023

Water Year 2023 demonstrated California’s high climate variability, ending the state’s driest consecutive three-year period with one of the snowiest years of record.

Water Year 2023 demonstrated California’s high climate variability, ending the state’s driest consecutive three-year period with one of the snowiest years of record. Even though California has been experiencing a theme of aridity in the 21st century (the statewide droughts of 2007-2009, 2012-2019, and 2020-2022), Water Year 2017 was the state’s second wettest in terms of statewide precipitation. Climate change is expected to amplify naturally occurring variability in the long term, potentially result in a shorter wet season for California but one with more extreme atmospheric river storms and hence potentially greater flood damage risk.

West False River Drought Salinity Barrier Final EIR

California Department of Water Resources (DWR) | November 8th, 2024

With the proposed project, a temporary drought salinity barrier would be installed in West False River up to two times over 10 years, with each installation remaining in

With the proposed project, a temporary drought salinity barrier would be installed in West False River up to two times over 10 years, with each installation remaining in place for up to 20 months over two consecutive calendar years. The barrier would be installed if a drought were to occur during the 2026–2035 period and the drought conditions indicate that a barrier in West False River would be an effective tool to preserve upstream reservoir storage for health, safety, and regulatory releases, while preventing saltwater intrusion into the central and southern portions of the Sacramento–San Joaquin Delta (Delta). The drought salinity barrier would be constructed only if DWR, in cooperation with other State and federal agencies, determines that drought conditions have reduced water storage in Northern California reservoirs to critical levels, such that projected Delta outflow would be insufficient to control increased salinity intrusion into the Delta. 

What Can We Learn From How the State Responded to the Last Major Drought?

Legislative Analyst's Office (LAO) | May 13th, 2021

For the second consecutive year, the state is experiencing extremely low rates of precipitation. As we prepare for what could be an extended period of dry conditions, it

For the second consecutive year, the state is experiencing extremely low rates of precipitation. As we prepare for what could be an extended period of dry conditions, it is helpful to review how the state responded to the last major drought. Such information can inform—and thereby potentially improve—the state’s current and ongoing response to developing conditions. In this report, we summarize the major activities, spending, and policy actions undertaken by the state to respond to the severe drought that occurred from 2012 through 2016. We also describe current conditions, and highlight some key lessons the Legislature can learn from previous efforts to help guide its response to the emerging drought.