San Francisco Bay

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.

Geohydrological Characterization, Water-Chemistry, and Ground-Water Flow Simulation Model of the Sonoma Valley Area, Sonoma County, California

U.S. Geological Survey (USGS) | December 14th, 2006

Sonoma County is in the northern part of the greater San Francisco Bay region, an area of Northern California that has experienced rapid population growth and accelerated

Sonoma County is in the northern part of the greater San Francisco Bay region, an area of Northern California that has experienced rapid population growth and accelerated urbanization in response to economic expansion over the past few decades. The large increase in population and concomitant changes in land use within Sonoma County require reassessment of the water resources and how best to manage them for optimal utilization over the next few decades. Most basins in the county currently rely on a combination of Russian River water and native ground water to meet demand. Recycled water is used on a limited basis. In addition, water conservation programs have been implemented and are being expanded. The Sonoma Valley is a well-defined hydrologic basin in southeastern Sonoma County. The basin has some areas of declining ground-water levels, potential water-quality problems from seawater intrusion and upwelling of geothermal waters, and ground-water/surface-water interaction. Location of the Study Area The study area is located approximately 30 miles (mi) northeast of San Francisco and includes the entire Sonoma Creek watershed in southeastern Sonoma County, California (fig. 1). The study focused on the area of the valley floor and the adjacent hills where most of the urban development and irrigated agriculture have been occurring. The watershed includes approximately 166 square miles (mi2) of land that drains by way of Sonoma Creek and its tributaries to San Pablo Bay (fig. 2), which is the northern arm of the San Francisco Bay. The Sonoma Mountains form the southwestern side of the watershed and the Mayacmas Mountains form the northeastern side. Between these two mountain ranges lies the northwest trending elongate depression of Sonoma Valley, which extends roughly 20 mi from the shore of San Pablo Bay to near Kenwood (fig. 2). Purpose and Scope: The U.S. Geological Survey (USGS), in cooperation with the Sonoma County Water Agency (SCWA), undertook this study to evaluate the ground-water resources of Sonoma Valley and to develop a tool to better understand and manage the ground-water system. The goals of the study were to update the geohydrologic characterization of the study area; to provide a current assessment of hydrologic conditions, including a description of historical ground-water level and waterquality changes; and to provide water-supply agencies with a ground-water flow model that can be used as a planning tool for water-resources assessment and management. To meet the objectives of this study, four principal tasks were identified: (1) evaluation of existing geohydrologic, geophysical, and geochemical data; (2) collection and analysis of new geohydrologic data, including subsurface lithologic data, gravity measurements, ground-water levels, and streamflow gains and losses; (3) collection and analysis of new water chemistry, temperature, and isotopic data; and (4) development a ground-water flow model. This report provides a geologic and hydrologic description of the area, presents selected hydrologic data collected from the 1970s to 2004, quantifies historical changes in the ground-water system, documents a ground-water flow simulation model, and presents an interpretation of surface geophysical data that help define the geometry of the ground-water reservoir.

Geohydrology, Water Quality, and Estimation of Ground-Water Recharge In San Francisco, California, 1987-92

U.S. Geological Survey (USGS) | January 14th, 1993

The city of San Francisco is considering further development of local ground-water resources as a supplemental source of water for potable or non-potable use. By the y

The city of San Francisco is considering further development of local ground-water resources as a supplemental source of water for potable or non-potable use. By the year 2010, further water demand is projected to exceed the delivery capacity of the existing supply system, from which San Francisco draws most of its water. The existing system is fed by surfacewater sources; thus, supplies are susceptible to drought conditions and damage to conveyance lines by earthquakes. The primary purpose of this study is to describe local geohydrology and water quality, and to estimate ground-water recharge in the area of the city of San Francisco. Seven ground-water basins were identified in San Francisco on the basis of geologic and geophysical data. Basins on the east side of the city are relatively thin and contain a greater percentage of fine-grained sediments than those on the west side. The relatively small capacity of the basins and greater potential for contamination from sewer sources may limit the potential for ground-water development on the east side. Basins on the west side of the city have a relatively large capacity and low density sewer network. Water-level data indicate that the southern part of the largest basin on the west side of the city (Westside basin) probably cannot accommodate additional ground-water development without adversely affecting water levels and water quality in Lake Merced; however, the remainder of the basin, which is largely undeveloped, could be developed further. A hydrologic routing model was developed for estimating ground-water recharge throughout San Francisco. The model takes into account climatic factors, land and water use, irrigation, leakage from underground pipes, rainfall runoff, evapotranspiration, and other factors associated with an urban environment. Results indicate that areal recharge rates for water years 1987-88 for the seven ground-water basins range from 0.32 to 0.78 foot per year. Recharge for the Westside basin was estimated at 0.51 foot per year. Average annual ground-water recharge represents the maximum annual long-term yield of the basin. Attainable yield may be less than the volume of ground-water recharge because interception of all discharge from the basin may not be feasible without inducing seawater intrusion or causing other undesirable effects.

Geology and Ground Water in Russian River Valley Areas and in Round, Laytonville and Little Lake Valleys, Sonoma and Mendocino Counties, California

U.S. Geological Survey (USGS) | December 31st, 1965

Geology and Ground Water in the Santa Rosa and Petaluma Valley Areas, Sonoma County, California

U.S. Geological Survey (USGS) | January 31st, 1958

Geology of Northern California Bulletin 190

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

Geology, water resources and usable ground-water storage capacity of part of Solano County, California

U.S. Geological Survey (USGS) | July 1st, 1960

The area described is confined largely to the valley-floor and foothill lands of Solano County, which lies directly between Sacramento, the State capital, and San Franc

The area described is confined largely to the valley-floor and foothill lands of Solano County, which lies directly between Sacramento, the State capital, and San Francisco. The area is considered in two subareas: The Putah area, which extends from Putah Creek southward to the Montezuma Hills and from the foothills of the Coast Ranges eastward to the west edge of the Yolo Bypass; and the Suisun-Fairfield area, which is to the southwest in the notch in the Coast Ranges through which the waters of the Great Central Valley of California reach San Francisco Bay. There are no known hydrologic interconnections between the two subareas, through either surface streams or underground aquifers. The climate of the area is characterized by warm, rainless summers and by cool winters in which temperatures seldom drop much below freezing. The rainfall ranges from about 17 inches per year along the east side to perhaps 24 inches in the foothills to the west, and irrigation is necessary for all crops except dry-farmed grains, pastures, and some orchards.

Gill Net Selectivity for Fifteen Fish Species of the Upper San Francisco Estuary

University of California, Davis (UC Davis) | July 14th, 2022

Gill-net size selectivity for fifteen fish species occurring in the upper San Francisco Estuary was estimated from a data set compiled from multiple studies which togethe

Gill-net size selectivity for fifteen fish species occurring in the upper San Francisco Estuary was estimated from a data set compiled from multiple studies which together contained 7,096 individual fish observations from 882 gill net sets. The gill nets considered in this study closely resembled the American Fisheries Society’s recommended standardized experimental gill nets for sampling inland waters. Relationships between gill-net mesh sizes and the sizes for each fish species retained in them were estimated indirectly using generalized linear modeling and maximum likelihood. Selectivity curves are provided for each species to inform researchers about population characteristics of fishes sampled with similar gill nets.

Global climate mode resonance due to rapidly intensifying El Niño-Southern Oscillation

Publisher not available | October 16th, 2025

Increasing ENSO amplitude and teleconnection patterns imply that remote extratropical precipitation responses, such as in Southern California and the Iberian Peninsula (F

Increasing ENSO amplitude and teleconnection patterns imply that remote extratropical precipitation responses, such as in Southern California and the Iberian Peninsula (Fig. 5), will also become stronger between alternating El Niño and La Niña events. Even though the recurrence of these events may become more predictable due to the increased regularity/periodicity and amplitude (Fig. 1)44, future ENSO teleconnections might generate enhanced whiplash effects on hydroclimate, which requires additional planning and management strategies to minimize the costs of climate damage. While similar increases in ENSO regularity and amplitude can be found in some CMIP6 model projections (Fig. 2), future work needs to assess the detailed dynamics across these models and assess the likelihood of the ENSO regime changes seen in AWI-CM3.