Water Resources Data for California, Water year 1983, Volume 2, Pacific Slope Basins from Arroyo Grande to Oregon State Line except Central Valley

U.S. Geological Survey (USGS) | January 15th, 1985

Water resources data for the 1983 water year for California consists of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservo

Water resources data for the 1983 water year for California consists of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in wells. Volume 2 contains discharge records for 145 gaging stations; stage and contents for 19 lakes and reservoirs; water quality for 17 stations; water levels for 67 observation wells. Also included are 2 low-flow partial-record stations and 18 water-quality partial-record stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

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 scarcity and fish imperilment driven by beef production

Nature Portfolio (Springer Nature) | March 2nd, 2020

Human consumption of freshwater is now approaching or surpassing the rate at which water sources are being naturally replenished in many regions, creating water s

Human consumption of freshwater is now approaching or surpassing the rate at which water sources are being naturally replenished in many regions, creating water shortage risks for people and ecosystems. Here we assess the impact of human water uses and their connection to water scarcity and ecological damage across the United States, identify primary causes of river dewatering and explore ways to ameliorate them. We find irrigation of cattle-feed crops to be the greatest consumer of river water in the western United States, implicating beef and dairy consumption as the leading driver of water shortages and fish imperilment in the region. We assess opportunities for alleviating water scarcity by reducing cattle-feed production, finding that temporary, rotational fallowing of irrigated feed crops can markedly reduce water shortage risks and improve ecological sustainability. Long-term water security and river ecosystem health will ultimately require Americans to consume less beef that depends on irrigated feed crops.

Water shortage risks from perennial crop expansion in California's Central Valley

Environmental Research Letters (IOP) | October 15th, 2019

California's Central Valley is one of the world's most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from

California's Central Valley is one of the world's most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from a vast network of reservoirs and canals as well as groundwater, which has been substantially overdrafted to support irrigation. The region has undergone a shift to perennial (tree and vine) crops in recent decades, which has increased water demand amid a series of severe droughts and emerging regulations on groundwater pumping. This study quantifies the expansion of perennial crops in the Tulare Lake Basin, the southern region of the Central Valley with limited natural water availability. A gridded crop type dataset is compiled on a 1 mi2 spatial resolution from a historical database of pesticide permits over the period 1974–2016 and validated against aggregated county-level data. This spatial dataset is then analyzed by irrigation district, the primary spatial scale at which surface water supplies are determined, to identify trends in planting decisions and agricultural water demand over time. Perennial crop acreage has nearly tripled over this period, and currently accounts for roughly 60% of planted area and 80% of annual revenue. These trends show little relationship with water availability and have been driven primarily by market demand. From this data, we focus on the increasing minimum irrigation needs each year to sustain perennial crops. Results indicate that under a range of plausible future regulations on groundwater pumping ranging from 10% to 50%, water supplies may fail to consistently meet demands, increasing losses by up to 30% of annual revenues. More broadly, the datasets developed in this work will support the development of dynamic models of the integrated water-agriculture system under uncertain climate and regulatory changes to understand the combined impacts of water supply shortages and intensifying irrigation demand.

Water shortage risks from perennial crop expansion in California’s Central Valley

Environmental Research Letters (IOP) | October 15th, 2019

California’s Central Valley is one of the world’s most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports

California’s Central Valley is one of the world’s most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from a vast network of reservoirs and canals as well as groundwater, which has been substantially overdrafted to support irrigation. The region has undergone a shift to perennial (tree and vine) crops in recent decades, which has increased water demand amid a series of severe droughts and emerging regulations on groundwater pumping. This study quantifies the expansion of perennial crops in the Tulare Lake Basin, the southern region of the Central Valley with limited natural water availability. A gridded crop type dataset is compiled on a 1-square mile spatial resolution from a historical database of pesticide permits over the period 1974–2016 and validated against aggregated county-level data. This spatial dataset is then analyzed by irrigation district, the primary spatial scale at which surface water supplies are determined, to identify trends in planting decisions and agricultural water demand over time. Perennial crop acreage has nearly tripled over this period, and currently accounts for roughly 60% of planted area and 80% of annual revenue. These trends show little relationship with water availability and have been driven primarily by market demand. From this data, we focus on the increasing minimum irrigation needs each year to sustain perennial crops. Results indicate that under a range of plausible future regulations on groundwater pumping ranging from 10% to 50%, water supplies may fail to consistently meet demands, increasing losses by up to 30% of annual revenues. More broadly, the datasets developed in this work will support the development of dynamic models of the integrated water-agriculture system under uncertain climate and regulatory changes to understand the combined impacts of water supply shortages and intensifying irrigation demand.

Water shortages worsened by reservoir effects

Nature Portfolio (Springer Nature) | November 13th, 2018

The expansion of reservoirs to cope with droughts and water shortages is hotly debated in many places around the world. We argue that there are two counterintuiti

The expansion of reservoirs to cope with droughts and water shortages is hotly debated in many places around the world. We argue that there are two counterintuitive dynamics that should be considered in this debate: supply–demand cycles and reservoir effects. Supply–demand cycles describe instances where increasing water supply enables higher water demand, which can quickly offset the initial benefits of reservoirs. Reservoir effects refer to cases where over-reliance on reservoirs increases vulnerability, and therefore increases the potential damage caused by droughts. Here we illustrate these counterintuitive dynamics with global and local examples, and discuss policy and research implications.

Water Stress and a Changing San Joaquin Valley

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

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

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 water stress. Agriculture is a leading economic driver and the predominant water user. The region’s farms and related manufacturing businesses account for 25 percent of the valley’s revenues and 16 percent of local jobs—and 89 percent of annual net water use. The latest drought underscored valley agriculture’s vulnerability to water scarcity and long-term declines in groundwater reserves. The region has a greater abundance of productive farmland than local water supplies for irrigation. In most years since the mid-1980s, groundwater has been used faster than it is being replenished (“groundwater overdraft”). Over the past three decades, overdraft has averaged nearly 2 million acre-feet per year, or 13 percent of net water use. This has contributed to increased pumping costs, dry wells, sinking lands, and declining reliability of this vital drought reserve.

Water Supply Conditions in Southern California during 1958-1959, Volume II, Water Level Data, Central Coastal and Los Angeles Regions

California Department of Water Resources (DWR) | May 1st, 1961

Water Supply in the Conterminous United States, Alaska, Hawaii, and Puerto Rico, Water Years 2010–20, Chapter B of U.S. Geological Survey Integrated Water Availability Assessment—2010–20

U.S. Geological Survey (USGS) | January 17th, 2025

The following are the key points of this chapter: Throughout much of the Great Plains and Northeast through Midwest aggregated hydrologic regions, low precipitation

The following are the key points of this chapter: Throughout much of the Great Plains and Northeast through Midwest aggregated hydrologic regions, low precipitation totals in water years 2011 and 2012 resulted in low streamflow, evapotranspiration, and soil moisture, associated with one of the most substantial droughts since the 1930s. The highest interannual variability in precipitation was in the California–Nevada, Texas, Southern High Plains, and Southwest Desert hydrologic regions, whereas the lowest interannual variability was in the Florida, Tennessee–Missouri, and Northeast hydrologic regions. Among the Western aggregated hydrologic region, where snow is critical for water availability, the California–Nevada hydrologic region had the highest interannual variability in maximum snow accumulation with a coefficient of variation (CV) of 0.60, whereas the Columbia–Snake, Pacific Northwest, and Central Rockies hydrologic regions all had a CV of less than 0.36. Six of 29 unconfined and 6 of 23 confined principal and regional aquifer systems had current water-level percentiles (median 2010–20) of less than 30 percent of historical water levels (that is, median 2000–20 water levels) including the California Coastal Basin aquifers, the Colorado Plateaus aquifers, and the Central and Southern regions of the High Plains aquifer. Hydrologic regions with low precipitation and little storage coincide with aquifer systems that have shown a decline in groundwater levels during water years 2010–20, including the Southern High Plains, Central High Plains, and Texas hydrologic regions. Companion chapters: U.S. Geological Survey Integrated Water Availability Assessment—2010–20, Chapter A Status of Water-Quality Conditions in the United States, 2010–20, Chapter C  Water Use Across the Conterminous United States, Water Years 2010–20, Chapter D  Climate Change and Future Water Availability in the United States, Chapter E  Integrated Water Availability in the Conterminous United States, 2010–20, Chapter F 

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

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