Sacramento River

Future Changes in Global Atmospheric Rivers Projected by CMIP6 Models

American Geophysical Union (AGU) | January 31st, 2024

Future loss of Arctic sea-ice cover could drive a substantial decrease in California’s rainfall

Nature Portfolio (Springer Nature) | December 5th, 2017

From 2012 to 2016, California experienced one of the worst droughts since the start of observational records. As in previous dry periods, precipitation-inducing winter st

From 2012 to 2016, California experienced one of the worst droughts since the start of observational records. As in previous dry periods, precipitation-inducing winter storms were steered away from California by a persistent atmospheric ridging system in the North Pacific. Here we identify a new link between Arctic sea-ice loss and the North Pacific geopotential ridge development. In a two-step teleconnection, sea-ice changes lead to reorganization of tropical convection that in turn triggers an anticyclonic response over the North Pacific, resulting in significant drying over California. These findings suggest that the ability of climate models to accurately estimate future precipitation changes over California is also linked to the fidelity with which future sea-ice changes are simulated. We conclude that sea-ice loss of the magnitude expected in the next decades could substantially impact California’s precipitation, thus highlighting another mechanism by which human-caused climate change could exacerbate future California droughts.

Future precipitation increase from very high resolution ensemble downscaling of extreme atmospheric river storms in California

American Association for the Advancement of Science (AAAS) | July 15th, 2020

Precipitation extremes will likely intensify under climate change. However, much uncertainty surrounds intensification of high-magnitude events that are often i

Precipitation extremes will likely intensify under climate change. However, much uncertainty surrounds intensification of high-magnitude events that are often inadequately resolved by global climate models. In this analysis, we develop a framework involving targeted dynamical downscaling of historical and future extreme precipitation events produced by a large ensemble of a global climate model. This framework is applied to extreme “atmospheric river” storms in California. We find a substantial (10 to 40%) increase in total accumulated precipitation, with the largest relative increases in valleys and mountain lee-side areas. We also report even higher and more spatially uniform increases in hourly maximum precipitation intensity, which exceed Clausius- Clapeyron expectations. Up to 85% of this increase arises from thermodynamically driven increases in water vapor, with a smaller contribution by increased zonal wind strength. These findings imply substantial challenges for water and flood management in California, given future increases in intense atmospheric river-induced precipitation extremes.

FY 2023–2024 Delta Crosscut Budget Report: Transparency in Science and Restoration Funding

Delta Stewardship Council (Delta Council) | December 9th, 2025

How much money is currently being spent on Delta science and restoration? That question drives the analysis herein. State and federal agencies, along with public water ag

How much money is currently being spent on Delta science and restoration? That question drives the analysis herein. State and federal agencies, along with public water agencies, fund and implement science and restoration programs and activities across the Sacramento-San Joaquin Delta. For the past six years, the Delta Crosscut Budget Report has aimed to provide a comprehensive understanding of this funding.

Gage Gap

Nature Conservancy | October 31st, 2018

Following a difficult five-year drought, California just had one of the wettest winters on record. The state is famous for its highly engineered water system, whi

Following a difficult five-year drought, California just had one of the wettest winters on record. The state is famous for its highly engineered water system, which moves millions of gallons of water from north to south and east to west. Thirty-nine million people and our $47 billion agricultural industry rely on that water, not to mention wildlife from the Sierra to the sea. And yet we have surprisingly little data about how much water is moving through our streams at any given time. There are over 3,600 locations in California where stream gages have been active at some point, but only 54% have been active recently. And even fewer of those provide the kind of rich, real-time reporting needed to manage what is arguably our state’s most precious and contentious resource.

Geochemistry of Ground Water in the Sacramento Valley, California

U.S. Geological Survey (USGS) | July 13th, 1984

A geochemical investigation was done to evaluate temporal changes in water quality and to determine the processes that control water chemistry in shallow ground water of

A geochemical investigation was done to evaluate temporal changes in water quality and to determine the processes that control water chemistry in shallow ground water of the Sacramento Valley, California. A total of 671 chemical analyses from 651 wells were used to study the processes controlling water chemistry. Temporal variations in dissolved-solids and nitrate concentrations were studied in 140 and 62 wells, respectively, having multiple observations with time.

Geohydrology and Numerical Model Analysis of Ground-Water Flow in the Goose Lake Basin, Oregon and California

U.S. Geological Survey (USGS) | December 15th, 1988

From the early 1970s until 1981, ground-water development in the Goose Lake basin underwent rapid growth. The number of new wells constructed and total State-perm

From the early 1970s until 1981, ground-water development in the Goose Lake basin underwent rapid growth. The number of new wells constructed and total State-permitted ground-water withdrawals for irrigation reflect the increase in ground-water development that occurred during this period. A strong agricultural economy spurred much of the development by providing incentives to expand irrigated acreage and modernize irrigation methods (from gravity to sprinkler systems). The drought of 1976-77 also encouraged farmers to develop ground water as a supplemental source to less reliable surface-water supplies used in the past. A preliminary assessment of the basin by OWRD staff (R. B. Almy, Oregon Department of Water Resources, written commun., 1981) concluded that, based on rates of water-level decline and increases in withdrawals, further and more detailed study of the basin was warranted. Between 1975 and 1982, water-level declines in some OWRD observation wells ranged from 0.5 to 3 feet per year, while permitted ground- water withdrawals increased at an average rate of 4,000acre-feetperyear(acre-ft/yr). Similarwater-level declines and increases in withdrawals occurred near Davis Creek on the California side of the basin during this period. This prompted a 1982 assessment of ground-water conditions by the California Department of Water Resources (California Department of Water Resources, 1982). At the time of OWRD's assessment it was felt that too little information on the actual rates of ground-water use, recharge, and the geohydrology of the aquifer system was available to allow proper management of the resource. If the rates of water-level decline and ground-water withdrawal that existed prior to 1981 had continued, issuance of new permits for ground-water use potentially could have been halted in order to determine if the Goose Lake basin should be designated as a "criticalground-water area." Sucha designation would allow the State of Oregon to limit the use of ground-water resources in the area. However, overdraft of the ground-water resource became a less urgent issue after 1982, when a downturn in the agricultural economy, combined with rising costs of electrical power (and thus pumping), resulted in a widespread reversion to dryland farming and low-water-use crops. Adverse agricultural market conditions halted the growth of ground-water development in the basin; these trends could conceivably reverse in the future to spur growth again. In recognition of this potential and the need to build an understanding of the basin in order to properly manage future ground-water development, OWRD entered into a joint program of study with the U.S.Geological Survey. The first of a proposed series of ground-water basin assessments, this 1-year study was started in 1986 with the goals of characterizing the nature, extent, and properties of water-bearing rocks within the basin and describing and quantifying the components of recharge to, and discharge from, the basin. Additionally, this study was designed toe valuate the adequacy of available and readily collectable information to quantitatively describe the geohydrology of the basin. If this information was found to be inadequate, the study would also identify the data needed to better describe, understand, and manage the ground-water resource.

Geologic Influences on the Quality of Groundwater Used for Domestic Supply in the Northern Sierra Nevada Foothills

U.S. Geological Survey (USGS) | May 25th, 2021

Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the

Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the U.S. Geological Survey, created the Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) to assess the quality of groundwater used for domestic supply throughout the state and determine regional vulnerabilities to drinking-water resources. Many rural households in the northern Sierra Nevada foothills (hereafter referred to as “the foothills”) use domestic wells that pump water from fractured-bedrock aquifers. In the foothills, complicated and varied regional bedrock geology can cause substantial variation in groundwater chemistry and quality over relatively short distances. This factsheet presents findings from the GAMA-PBP assessment that highlight influences of geologic factors on groundwater quality in the foothills.

Geology of Northern California Bulletin 190

California Division of Mines and Geology | December 1st, 1966

Geology of the Fresh Ground‐water Basin of the Central Valley, California, with Texture Maps and Sections

U.S. Geological Survey (USGS) | December 1st, 1986

The Central Valley of California, which is about 400 miles long and averages about 50 miles wide, comprises about 20,000 square miles. Geologically, the valley is

The Central Valley of California, which is about 400 miles long and averages about 50 miles wide, comprises about 20,000 square miles. Geologically, the valley is a large asymmetric trough that is bounded by granitic, metamorphic, and marine sedimentary rocks of pre-Tertiary age. The trough has been filled with as much as 6 vertical miles of sediment in the San Joaquin Valley and as much as 10 vertical miles of sediment in the Sacramento Valley; these sedi- ments range in age from Jurassic to Holocene. Some volcanic rocks and deposits crop out in the valley, but of those only the Tuscan Formation in the northeastern part of the Sacramento Valley is of major importance to the fresh ground-water basin. Post-Eocene continental rocks and deposits contain most of the fresh water in the Central Valley; they crop out virtually over the whole valley and in most places overlie or contain saline water at depth. Continental rocks and deposits of Tertiary age include the Mehrten Formation. The Mehrten is of great importance to the fresh ground-water basin of the Central Valley and yields large quantities of water to wells.