San Francisco Bay

Waterweed Invasions

Scientific American | October 1st, 1989

Populations of plants and animals ordinarily migrate and multiply slowly over time as a result of the natural interplay among many ecological factors: soils, waters,

Populations of plants and animals ordinarily migrate and multiply slowly over time as a result of the natural interplay among many ecological factors: soils, waters, glaciation, drought, the rise and fall of competitor species. Yet in some regions human activities have quickened the pace of change by dramatically altering the range and abundance of many species. Today plants and animals are shipped, sometimes accidentally, all over the globe to zoos and botanical gardens and for commercial and agricultural purposes. A small minority of the "alien," or introduced, species become ecological as well as economic disasters; although they may have been innocuous in their native region, these species are transformed into aggressive pests or weeds that invade and dominate their new environment.

West False River Drought Salinity Barrier Final EIR

California Department of Water Resources (DWR) | November 8th, 2024

With the proposed project, a temporary drought salinity barrier would be installed in West False River up to two times over 10 years, with each installation remaining in

With the proposed project, a temporary drought salinity barrier would be installed in West False River up to two times over 10 years, with each installation remaining in place for up to 20 months over two consecutive calendar years. The barrier would be installed if a drought were to occur during the 2026–2035 period and the drought conditions indicate that a barrier in West False River would be an effective tool to preserve upstream reservoir storage for health, safety, and regulatory releases, while preventing saltwater intrusion into the central and southern portions of the Sacramento–San Joaquin Delta (Delta). The drought salinity barrier would be constructed only if DWR, in cooperation with other State and federal agencies, determines that drought conditions have reduced water storage in Northern California reservoirs to critical levels, such that projected Delta outflow would be insufficient to control increased salinity intrusion into the Delta. 

West False River Drought Salinity Barrier Project Environmental Impact Report (Draft)

California Department of Water Resources (DWR) | July 7th, 2022

The California Department of Water Resources (DWR) proposes to the install the West False River Drought Salinity Barrier Project (proposed project). During drought condit

The California Department of Water Resources (DWR) proposes to the install the West False River Drought Salinity Barrier Project (proposed project). During drought conditions, water stored in upstream reservoirs may be insufficient to repel salinity moving upstream from San Francisco Bay. Without the protection of the drought salinity barrier in West False River, saltwater intrusions could affect more than 27 million Californians who rely on the Sacramento–San Joaquin Delta (Delta) for at least a portion of their water supply; could render Delta water unusable for agricultural needs; and could reduce the value of habitat for aquatic species. DWR installed emergency drought barriers in West False River in 2015 and 2021–2022 in response to drought conditions to protect water quality in the interior Delta. Installation of a drought salinity barrier in West False River has been shown to be an effective tool for reducing the intrusion of saltwater into the Central and South Delta based on these previous installations (see Section 1.2, “Project Background,” in Chapter 1; California Department of Water Resources 2019).

West Valley Watershed Assessment 2018: Baseline Ecological Condition Assessment of Southwest San Francisco Bay Creeks in Santa Clara County; Calabazas, San Tomas Aquino, Saratoga, Sunnyvale East and West

San Francisco Estuary Institute (SFEI) | May 1st, 2019

This report describes baseline information about the amount and distribution of aquatic resources, and evaluates the overall ecological conditions of streams using the Ca

This report describes baseline information about the amount and distribution of aquatic resources, and evaluates the overall ecological conditions of streams using the California Rapid Assessment Method (CRAM), for the West Valley watershed in Santa Clara County; consisting of Sunnyvale East and West Channels, Calabazas Creek, San Tomas Aquino and Saratoga creeks (subsequently referred to in this document as San Tomas-Saratoga), and many smaller tributaries. 

Western and Traditional Ecological Knowledge in ecocultural restoration

University of California, Davis (UC Davis) | October 1st, 2018

 The Delta Plan (DSC 2013) calls for “protecting and enhancing the unique cultural values” of California’s Sacramento–San Joaquin Delta, a 2,800-km2 (1,100 mi2)

 The Delta Plan (DSC 2013) calls for “protecting and enhancing the unique cultural values” of California’s Sacramento–San Joaquin Delta, a 2,800-km2 (1,100 mi2) region that was occupied by indigenous peoples for ~5,000 years. The legacies of Native Californians need to be included in the Delta Plan, especially Traditional Ecological Knowledge (TEK) of ways to gather, hunt, and fish for food; build shelters; prepare medicines; and perform ceremonies — along with ways to make tools, clothing, baskets, and shelters. Plants were not just collected but also tended, which involved planned burning, digging, planting, weeding, harvesting, and seed dispersal. Populations of plants that have cultural significance and unique values should be enhanced under the Delta Plan. While Western Ecological Knowledge (WEK) offers a strong foundation for restoration of species assemblages and ecosystems, TEK adds culturally-significant species to restoration targets and traditional management practices to achieve ecological resilience. We compare 11 attributes of WEK and TEK that aid ecological restoration; all are complementary or shared by these two ways of knowing. Both WEK and TEK emphasize adaptive approaches for managing natural resources, as mandated in the Delta Plan. We suggest that WEK–TEK restoration sites throughout the Delta can be linked (virtually) to honor cultural integrity and nurture a “Sense of Place” for Native Californians and others. At the same time, such a network could foster ways to achieve sustainability through the TEK ethic of reciprocity, which WEK lacks. A network of WEK–TEK sites could enhance unique cultural values while supporting passive recreation and attracting ecotourists. 

Wet Antecedent Soil Moisture Increases Atmospheric River Streamflow Magnitudes Nonlinearly

American Meteorological Society (AMS) | June 4th, 2025

Atmospheric rivers (ARs) drive most riverine floods on the U.S. West Coast. However, estimating flood risk based solely on AR intensity and duration is challenging becaus

Atmospheric rivers (ARs) drive most riverine floods on the U.S. West Coast. However, estimating flood risk based solely on AR intensity and duration is challenging because precipitation phase, antecedent conditions, and physical watershed characteristics (e.g., slope and soil depth) can influence the magnitude of floods. Here, we analyze how antecedent soil moisture (ASM) conditions contribute to variability in streamflow during AR events and how that changes across climatic regimes and physiography in 122 U.S. West Coast watersheds. We identify a robust nonlinear relationship between streamflow and ASM during ARs in 89% of watersheds. The inflection point in this relationship represents a watershed-specific critical ASM threshold, above which event maximum streamflow is, on average, 2–4.5 times larger. Wet ASM conditions amplify the hydrologic impacts of more frequent but weaker, lower moisture transport AR events, while dry ASM conditions attenuate the hydrologic impacts that stronger, higher moisture transport AR events could otherwise cause. Our research shows that watersheds prone to ASM-amplified streamflows have higher evaporation ratios, lower cold-season precipitation, lower snow-to-rain ratios, and shallower, clay-rich soils. Higher evaporation and lower precipitation lead to greater ASM variability during the cold season, increasing streamflow during wet periods and buffering streamflow during dry periods. Lower snow fraction and shallower soils limit the antecedent water storage capacity of a watershed, contributing to greater sensitivity of streamflow peaks to ASM variability. Incorporating ASM thresholds into hydrologic models in these regions prone to AR-amplified streamflow could improve forecasts and decrease uncertainty.

Wetland geomorphology and tidal hydrodynamics drive fine‑scale fish community composition and abundance

Environmental Biology of Fishes (Springer) | January 19th, 2024

What Can We Learn From How the State Responded to the Last Major Drought?

Legislative Analyst's Office (LAO) | May 13th, 2021

For the second consecutive year, the state is experiencing extremely low rates of precipitation. As we prepare for what could be an extended period of dry conditions, it

For the second consecutive year, the state is experiencing extremely low rates of precipitation. As we prepare for what could be an extended period of dry conditions, it is helpful to review how the state responded to the last major drought. Such information can inform—and thereby potentially improve—the state’s current and ongoing response to developing conditions. In this report, we summarize the major activities, spending, and policy actions undertaken by the state to respond to the severe drought that occurred from 2012 through 2016. We also describe current conditions, and highlight some key lessons the Legislature can learn from previous efforts to help guide its response to the emerging drought.

What Threat Does Sea-Level Rise Pose to California?

Legislative Analyst's Office (LAO) | August 10th, 2020

Among Its Other Challenges, California Continues to Face the Looming Impacts of Climate Change and Rising Seas. While the coronavirus disease 2019 (COVID‑19) pandemic a

Among Its Other Challenges, California Continues to Face the Looming Impacts of Climate Change and Rising Seas. While the coronavirus disease 2019 (COVID‑19) pandemic and resulting economic impacts have rightly drawn the focus of the Legislature’s and public’s attention since March 2020, other statewide challenges continue to approach on the horizon. Among these are the impending impacts of climate change, including the hazards that rising seas pose to California’s coast. Scientific estimates suggest the magnitude of sea‑level rise (SLR) in California could be at least half of one foot in 2030 and as much as seven feet by 2100. Moreover, storm surges, exceptionally high “king tides,” or El Niño events could produce notably higher water levels than SLR alone.

When floods hit the road: Resilience to flood-related traffic disruption in the San Francisco Bay Area and beyond

American Association for the Advancement of Science (AAAS) | August 5th, 2020

As sea level rises, urban traffic networks in low-lying coastal areas face increasing risks of flood disruptions. Closure of flooded roads causes employee absen

As sea level rises, urban traffic networks in low-lying coastal areas face increasing risks of flood disruptions. Closure of flooded roads causes employee absences and delays, creating cascading impacts to communities. We integrate a traffic model with flood maps that represent potential combinations of storm surges, tides, seasonal cycles, inter-annual anomalies driven by large-scale climate variability such as the El Niño Southern Oscillation, and sea level rise. When identifying inundated roads, we propose corrections for potential biases arising from model integration. Our results for the San Francisco Bay Area show that employee absences are limited to the homes and workplaces within the areas of inundation, while delays propagate far inland. Communities with limited availability of alternate roads experience long delays irrespective of their proximity to the areas of inundation. We show that metric reach, a measure of road network density, is a better proxy for delays than flood exposure.