Sacramento River

Hydroclimate Report Water Year 2020

California Department of Water Resources (DWR) | August 31st, 2021

Water Year (WY) 2020 continued to demonstrate the climate change narrative of greater variability and more extremes. In both precipitation and temperature, there were ne

Water Year (WY) 2020 continued to demonstrate the climate change narrative of greater variability and more extremes. In both precipitation and temperature, there were new extremes with a very dry February and very hot end to the water year. Late fall precipitation onset continued with the first significant storm of the year arriving in late November. The WY ended with 67 percent of average precipitation statewide and 62 percent of average in the Northern Sierra. For runoff, the Sacramento Basin had 66 percent of average April-July streamflow while the San Joaquin Basin had 58 percent of average. Peak statewide snowpack was 62 percent of average reaching that point in early April with a late season storm providing some offset to the winter’s dryness. February was one of the big stories of WY 2020 with record low precipitation. In a year of extremes, August and September also contributed record warmth for the month including a 130-degree Fahrenheit reading at Death Valley on August 16, 2020. This observation, if verified by the World Meteorological Organization, would be one of the hottest daily temperature maximums recorded on Earth. Several cities set new records for days above 90 degrees as well.

Hydroclimate Report Water Year 2021

California Department of Water Resources (DWR) | December 31st, 2022

Water year (WY) 2021 added to the climate change narrative with extreme dryness leading to record setting drought conditions. In both precipitation and temperature, there

Water year (WY) 2021 added to the climate change narrative with extreme dryness leading to record setting drought conditions. In both precipitation and temperature, there were new extremes with a record dry and warm spring being most notable. Late fall onset occurred again this year arriving in late November starting the seasonal snowpack on very dry soils. The WY ended with 48 percent of average precipitation statewide making it the second driest year in 126 years of record. It was also second warmest for statewide average temperature. For two-year totals, WY 2021 set a record, recording less precipitation than WY 1977. There was only one significant storm in the WY in late January which included low elevation snow and very strong damaging winds. The April 1 statewide snowpack registered 62% of average. Peak snowpack at 64% of average occurred the week before April 1. Runoff from the snowpack was far below expectations due to the dry antecedent conditions and record dry and warm spring. The lack of runoff resulted in the need for emergency drought response measures.

Hydroclimate Report Water Year 2022

California Department of Water Resources (DWR) | October 1st, 2024

Hydroclimate volatility on a warming Earth

Nature Portfolio (Springer Nature) | January 9th, 2025

Hydroclimatic Extremes as Challenges for the Water Management Community: Lessons from Oroville Dam and Hurricane Harvey

American Meteorological Society (AMS) | December 31st, 2018

Record-breaking extreme storms were a hallmark of 2017 in the United States. An extremely wet winter on the West Coast and brutally damaging hurricane season in

Record-breaking extreme storms were a hallmark of 2017 in the United States. An extremely wet winter on the West Coast and brutally damaging hurricane season in the U.S. Southeast and the Caribbean challenged communities and power-, water- and flood-management systems in ways that raised climate change concerns. Among the most severe were two periods of heavy precipitation and high runoff that exposed dangerous weaknesses in water management infrastructure and land use practices in California and Texas. In California, a record-breaking string of atmospheric river landfalls and remarkably wet winter conditions came close to causing a catastrophic failure of the emergency spillway at Oroville Dam (France et al. 2018; Abbott 2018; White et al. 2019) and less publicized concerns elsewhere (Holland et al. 2018; CNRFC 2017). In Texas, near record-doubling rainfall accumulations from Hurricane Harvey led to massive flooding (Blake and Zelinsky 2018) and dam safety challenges in Houston (Wax-Thibodeaux et al. 2017). We use these events as examples to ground the concept that attribution studies, with careful management-focused framing, can help water management better navigate such unprecedented extremes. *Chapter from the American Meteorological Society's Explaining Extreme Events of 2017 from a Climate Perspective.

Hydrodynamic Model Development Report: Sacramento-San Joaquin River Delta and Suisun Bay (Water Year 2016)

San Francisco Estuary Institute (SFEI) | December 13th, 2019

This report describes work related to hydrodynamic model development for the San Francisco Bay-Delta Estuary, undertaken as part of a broader eort to develop and apply co

This report describes work related to hydrodynamic model development for the San Francisco Bay-Delta Estuary, undertaken as part of a broader eort to develop and apply coupled biogeochemical-hydrodynamic models to inform nutrient management decisions. The primary intended application of the hydrodynamic model output is for use as input to an offline coupled biogeochemical model to simulate a wide range of state variables and processes, including: advective and dispersive transport, nutrient transformations, phytoplankton production, benthic and pelagic grazing, sediment diagenesis, and oxygen cycling.

Hydrodynamics and habitat interact to structure fish communities within terminal channels of a tidal freshwater delta

Ecological Society of America (Wiley) | January 13th, 2023

Terminal channels were historically a common feature of tidal delta ecosystems but have become increasingly rare as landscapes have been modified. Tidal hydrodynamics are

Terminal channels were historically a common feature of tidal delta ecosystems but have become increasingly rare as landscapes have been modified. Tidal hydrodynamics are a defining feature in tidal terminal channel ecosystems from which native aquatic communities have evolved. However, few studies have explored the relationship between fish community structure and hydrodynamics in these tidal terminal channel ecosystems. We sampled fish communities throughout a network of terminal channels within the northeasternmost region of the San Francisco Estuary to determine the relationship between fish community structure and hydrodynamics within these environments. We collected two years (2017 and 2018) of fish community samples using gill nets and analyzed data using multivariate community analyses and count models. We found metrics of fish diversity and counts of native fishes to be greatest upstream (farthest from tidal influence) of the tidal excursion within terminal channels. Counts of non-native fishes were less affected by this hydrodynamic feature of terminal channels and more tightly correlated to local habitat conditions (e.g., water temperature, depth). Our results suggest that channel hydrodynamics plays a role in structuring fish communities within terminal channels, particularly native fishes. These results indicate that hydrodynamics in tidal delta ecosystems may be able to be altered in ways that benefit native fishes without the cost of water pumping.

Hydrogeology of the Sutter Basin, Sacramento Valley, California

University of Arizona | March 23rd, 1971

A mound of saline water exists in continental sediments between two fresh water rivers in the Sutter Basin of the Sacramento Valley, California. This saline water has mov

A mound of saline water exists in continental sediments between two fresh water rivers in the Sutter Basin of the Sacramento Valley, California. This saline water has moved from the marine sediments, at depth, upward along the Sutter Basin Fault and then through 2,000 feet of alluvium.

Hydrologic Modeling Goals and Objectives for Yolo County

Water Resources Association of Yolo County, California Department of Water Resources (DWR) | May 16th, 2002

The Water Resources Association of Yolo County (WRA) has entered into a Memorandum of Understanding (MOU) with the California Department of Water Resources (DWR) to coo

The Water Resources Association of Yolo County (WRA) has entered into a Memorandum of Understanding (MOU) with the California Department of Water Resources (DWR) to cooperatively investigate conjunctive use opportunities in Yolo County. As part of the MOU, DWR is assisting the WRA to develop goals and objectives for a combined groundwater and surface water model of Yolo County, including a modeling strategy. As DWR’s contractor, WRIME, Inc., in collaboration with the DWR, WRA, and other consultants with modeling experience/knowledge about Yolo County, conducted the modeling assessment study.

Hydrology and Hydrodynamics on the Sacramento River Near the Fremont Weir, California—Implications for Juvenile Salmon Entrainment Estimates

U.S. Geological Survey (USGS) | November 9th, 2018

Estimates of fish entrainment on the Sacramento River near the Fremont Weir are a critical component in determining the feasibility and design of a proposed notch in the

Estimates of fish entrainment on the Sacramento River near the Fremont Weir are a critical component in determining the feasibility and design of a proposed notch in the weir to increase access to the Yolo Bypass, a seasonal floodplain of the Sacramento River. Detailed hydrodynamic and velocity measurements were made at a river bend near the Fremont Weir in the winter and spring of 2016 to examine backwater conditions and estimate the hydraulic entrainment zone, a zone where fish would be predicted to be entrained into the notch. Secondary circulation near the river bend was shown to shift the velocity and discharge distributions toward the outside of the bend. Variability in the stage-discharge relation was shown to be the biggest source of uncertainty in determining the location of the hydraulic entrainment zone. Outflow from the Sutter Bypass and high flow on the Feather River resulted in backwater conditions near the Fremont Weir about 25 percent of the time over the 27-year period from April 1990–April 2017. Velocity measurements used to estimate the critical streakline position (the outer edge of the hydraulic entrainment zone) were not made over a sufficient range of conditions to explicitly quantify the variability in the location of the critical streakline. The variability in the critical streakline position was therefore represented stochastically with a random effects model. The estimated position of the critical streakline and the random effects model are input parameters used in a simulation designed to estimate fish entrainment over a 15-year period. The estimates of the critical streakline and likely fish entrainment could be much improved with velocity measurements over a broader range of stage and discharge conditions.