San Francisco Bay

River Floods Under Wetter Antecedent Conditions Deliver Coarser Sediment to the Coast

American Geophysical Union (AGU) | April 13th, 2025

Increasing hydrologic volatility—more extreme rain, and larger variations between wet and dry years—has become apparent in some regions, but few data exist to determi

Increasing hydrologic volatility—more extreme rain, and larger variations between wet and dry years—has become apparent in some regions, but few data exist to determine how intensifying hydrologic extremes affect sedimentary systems. Using uniquely high-resolution records of fluvial suspended sediment and coastal morphology, we quantify sedimentary responses from a steep, 357-km2 watershed in California under extreme wet and dry hydrologic conditions. In years with multiple 2- to 10-year floods, fluvial sediment coarsened significantly as the wet season progressed, with late-season floods delivering dominantly sand-sized material to the coast. Greater and coarser sediment supply under wetter antecedent conditions affected nearshore geomorphic evolution for 4–5 years. The watershed and coastal changes we documented point to an increasing role of sediment-related hazards (flooding and hillslope erosion) and resources (nearshore accretion) as wet seasons intensify.

Rivers of California

Pacific Gas & Electric Company (PG&E) | July 1st, 1962

Ruling on Motions for Preliminary Injunction in Tulare Lake Basin Water Storage District v. California Department of Water Resources

Superior Court of California, County of Sacramento | June 20th, 2024

Sacramento and San Joaquin River Basins Comprehensive Study Technical Studies Documentation: Reservoir Operations Modeling - Existing Design Operations and Re-operation Analyses

U.S. Army Corps of Engineers (USACE) | December 1st, 2002

In response to extensive flooding and damages experienced in 1997, the United States Congress authorized the U.S. Army Corps of Engineers, Sacramento District (USACE) to

In response to extensive flooding and damages experienced in 1997, the United States Congress authorized the U.S. Army Corps of Engineers, Sacramento District (USACE) to provide a comprehensive analysis of the Sacramento and San Joaquin river basin flood management systems and to partner with the State of California to develop master plans for flood damage reduction. The USACE and the State Reclamation Board of California are leading this Comprehensive Study to improve flood management and integrate ecosystem restoration in the Sacramento and San Joaquin river basins. The authorization for the Comprehensive Study directed the development of hydrologic and hydraulic models for both river basins that will allow systematic evaluation. These models incorporate reservoir operations and flow along the major river systems to evaluate the performance of the flood management systems. The models can be used to assess the performance of the current systems or modified systems under a wide range of hydrologic conditions. This report documents the work conducted for the Sacramento and San Joaquin River Basins Comprehensive Study to develop reservoir operation models, specifically Phase II – Model Refinement and Simulation of both existing operational conditions and evaluation of flood management alternatives. The main product components of this effort include: HEC-5 Reservoir Operation Models for the Sacramento and San Joaquin River basins, which will include headwater and major flood management reservoirs. The first part of this document is limited to the use of reservoir models to identify and describe baseline conditions. It does not include the formulation or evaluation of flood management alternatives. The performance of modified flood management strategies is addressed within subsequent sections of this document. Future work will continue to use these models in the analysis of alternatives for reducing flood damages in California’s Central Valley.

Sacramento River Temperature Task Group Annual Report of Activities October 1, 2013 through September 30, 2014

Delta Stewardship Council (Delta Council) | October 6th, 2014

Sacramento-San Joaquin Delta Historical Ecology Investigation: Exploring Pattern and Process

San Francisco Estuary Institute (SFEI) | September 12th, 2012

In 2012, SFEI researchers (in collaboration with the CA Department of Fish and Wildlife) completed a historical ecology study of the Sacramento-San Joaquin Delta. The

In 2012, SFEI researchers (in collaboration with the CA Department of Fish and Wildlife) completed a historical ecology study of the Sacramento-San Joaquin Delta. The project improves understanding of what the Delta looked like and how it functioned prior to the significant modification that has occurred over the last 160 years. This historical reconstruction documents patterns of variation and extent of habitat types throughout the Delta for improved understanding of species support functions and controlling physical processes within the native landscape. Knowing how different parts of the vast historical Delta looked and functioned provides needed information for future restoration strategies.

Sacramento/San Joaquin Delta Dilemma

Assembly Office of Research (AOR) | January 1st, 1982

Sailing the Salt Line

Bay Nature | July 2nd, 2024

A strait is a place of motion. Change is a constant in our universe, a fact we humans often struggle with, but certain places are especially good at reminding us of it. T

A strait is a place of motion. Change is a constant in our universe, a fact we humans often struggle with, but certain places are especially good at reminding us of it. The Carquinez Strait itself was only just born, some 560,000 years ago—explosively, according to one theory—when a giant inland lake forced a path to the ocean. This created the unusual inverted river delta (with the fan pointing inland, instead of spreading out onto the coast) that is the San Francisco Bay.

Salinity Changes the Dynamics of Pyrethroid Toxicity in Terms of Behavioral Effects on Newly Hatched Delta Smelt Larvae

Toxics (MDPI) | February 20th, 2021

Salinity can interact with organic compounds and modulate their toxicity. Studies have shown that the fraction of pyrethroid insecticides in the aqueous phase increases w

Salinity can interact with organic compounds and modulate their toxicity. Studies have shown that the fraction of pyrethroid insecticides in the aqueous phase increases with increasing salinity, potentially increasing the risk of exposure for aquatic organisms at higher salinities. In the San Francisco Bay Delta (SFBD) estuary, pyrethroid concentrations increase during the rainy season, coinciding with the spawning season of Delta Smelt (Hypomesus transpacificus), an endangered, endemic fish. Furthermore, salinity intrusion in the SFBD is exacerbated by global climate change, which may change the dynamics of pyrethroid toxicity on aquatic animals. Therefore, examining the effect of salinity on the sublethal toxicity of pyrethroids is essential for risk assessments, especially during the early life stages of estuarine fishes. To address this, we investigated behavioral effects of permethrin and bifenthrin at three environmentally relevant concentrations across a salinity gradient (0.5, 2 and 6 PSU) on Delta Smelt yolk-sac larvae. Our results suggest that environmentally relevant concentrations of pyrethroids can perturb Delta Smelt larvae behavior even at the lowest concentrations (<1 ng/L) and that salinity can change the dynamic of pyrethroid toxicity in terms of behavioral effects, especially for bifenthrin, where salinity was positively correlated with anti-thigmotaxis at each concentration.

Salinity Incursion and Water Resources, Appendix to Bulletin No. 76, Delta Water Facilities

California Department of Water Resources (DWR) | April 16th, 1962

Data and analyses contained in this appendix were utilized to determine the present and future quantity and quality of water supplies within the Delta and to determine

Data and analyses contained in this appendix were utilized to determine the present and future quantity and quality of water supplies within the Delta and to determine the conditions under which the State Water Facilities must operate within the Delta with the various facilities proposed in Bulletin No. 76 constructed therein. In general, the conditions imposed result from conservative assumptions of available water supply and Delta channel hydraulics.