San Francisco Bay

Significant challenges to the sustainability of the California coast considering climate change

National Academy of Sciences (NAS) | July 29th, 2024

Simplified 1-D Hydrodynamic and Salinity Transport Modeling of the Sacramento–San Joaquin Delta: Sea Level Rise and Water Diversion Effects

University of California, Davis (UC Davis) | December 11th, 2013

Simulating and Evaluating Atmospheric River-Induced Precipitation Extremes along the U.S. Pacific Coast: Case Studies from 1980-2017

American Geophysical Union (AGU) | January 29th, 2020

Atmospheric rivers (ARs) are responsible for a majority of extreme precipitation and flood events along the U.S. West Coast. To better understand the present‐day charac

Atmospheric rivers (ARs) are responsible for a majority of extreme precipitation and flood events along the U.S. West Coast. To better understand the present‐day characteristics of AR‐related precipitation extremes, a selection of nine most intense historical AR events during 1980–2017 is simulated using a dynamical downscaling modeling framework based on the Weather Research and Forecasting Model. We find that the chosen framework and Weather Research and Forecasting Model configuration reproduces both large‐scale atmospheric features—including parent synoptic‐scale cyclones—as well as the filamentary corridors of integrated vapor transport associated with the ARs themselves. The accuracy of simulated extreme precipitation maxima, relative to in situ and interpolated gridded observations, improves notably with increasing model resolution, with improvements as large as 40–60% for fine scale (3 km) relative to coarse‐scale (27 km) simulations. A separate set of simulations using smoothed topography suggests that much of these gains stem from the improved representation of complex terrain. Additionally, using the 12 December 1995 storm in Northern California as an example, we demonstrate that only the highest‐resolution simulations resolve important fine‐scale features—such as localized orographically forced vertical motion and powerful near hurricane‐force boundary layer winds. Given the demonstrated ability of a targeted dynamical downscaling framework to capture both local extreme precipitation and key fine‐scale characteristics of the most intense ARs in the historical record, we argue that such a configuration may be highly conducive to understanding AR‐related extremes and associated changes in a warming climate.

Skarry Removal

California State Lands Commission (SLC) | May 1st, 2025

The Commission’s contractor will remove booms, winches, and other superstructures from the crane barges on site. This equipment will be cut into pieces and placed on a

The Commission’s contractor will remove booms, winches, and other superstructures from the crane barges on site. This equipment will be cut into pieces and placed on a materials barge for recycling. Floating booms will surround the work site and contain any debris. Once lightened of equipment, a crane will remove the two smaller barges directly from the water. The largest barge will be refloated and towed by water to the Mare Island shipyard, where it will be removed from the water and demolished. Scrap metal will be recycled, and other debris will be hauled to a landfill for disposal. Click here for the staff report that accompanied the plan.

Small Populations in Jeopardy: A Delta Smelt Case Study

Social Science Research Network (SSRN) | February 21st, 2021

Under §7 of the federal Endangered Species Act, federal agencies must ensure that actions they authorize, fund, or carry out are “not likely to jeopardize the continue

Under §7 of the federal Endangered Species Act, federal agencies must ensure that actions they authorize, fund, or carry out are “not likely to jeopardize the continued existence of any endangered species or threatened species or result in the destruction or adverse modification of habitat of such species.” For species with low and declining populations, applying this standard is legally and scientifically difficult. The U.S. Fish and Wildlife Service (FWS) faced this problem in its recent biological opinion (BiOp) analyzing impacts to threatened Delta smelt from water project operations in the California Delta. FWS concluded the “species’ recent abundance trends strongly suggest it is in the midst of demographic collapse,” and most recent surveys to locate smelt have failed to find them. Nevertheless, FWS approved agency actions that will likely increase extinction risk for Delta smelt. This Comment illustrates, through a case study of the Delta smelt BiOp, the difficulties in making ESA jeopardy determinations for species on the brink of extinction. We conclude that the myriad challenges inherent in conservation of some small and declining populations make reasoned §7 analysis difficult, bordering on impossible.

Small Tributaries Pollutants of Concern Reconnaissance Monitoring: Application of Storm-event Loads and Yields-Based and Congener-Based PCB Site Prioritization Methodologies

San Francisco Estuary Institute (SFEI) | January 12th, 2022

With RMP funding allocated in 2017 and 2018, a pilot study was completed using a subset of data from watersheds in San Mateo and Santa Clara Counties to build new methods

With RMP funding allocated in 2017 and 2018, a pilot study was completed using a subset of data from watersheds in San Mateo and Santa Clara Counties to build new methods for organizing and analyzing the existing stormwater reconnaissance data that will provide further evidence to support decisions about which watersheds may be of interest for prioritized management focus. The pilot study resulted in two new analysis methodologies outlined in two companion reports: Davis, J.A. and Gilbreath, A.N., 2019. Small Tributaries Pollutants of Concern Reconnaissance Monitoring: Pilot Evaluation of Source Areas Using PCB Congener Data. SFEI Contribution No. 956. San Francisco Estuary Institute, Richmond, California. McKee, L.J., Gilbreath, A.N., Hunt, J.A., Wu, J., Yee, D., and Davis, J.A., 2019. Small tributaries pollutants of concern reconnaissance monitoring: Loads and yields-based prioritization methodology pilot study. SFEI Contribution No. 817. San Francisco Estuary Institute, Richmond, California. In this final report, we describe a few enhancements to the storm-event loads and yields method and then apply both methods to a much larger data set and provide the resulting database to support stormwater management and decision making.

Small Tributaries Pollutants of Concern Reconnaissance Monitoring: Loads and Yields-based Prioritization Methodology Pilot Study

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

Watershed yields (mass exported per unit watershed area) can be used as an indicator variable to help identify watersheds or source areas of higher management interest i

Watershed yields (mass exported per unit watershed area) can be used as an indicator variable to help identify watersheds or source areas of higher management interest in relation to mass loads that impact the Bay. When prioritization includes an analysis of uncertainty, a recommendation can also be made for priority investigations necessary to reduce uncertainties. A method is presented for generating comparable yield estimates for small industrial watersheds where only a single storm has been sampled and for which a watershed boundary has been generated. The method generates standardized storm-based yields for each sampled site for a 0.5-year annual return frequency storm with 2-hour peak rainfall intensity. No attempt has been made to estimate annual average yields (the metric upon which the TMDL was based).

Small Tributaries Pollutants of Concern Reconnaissance Monitoring: Pilot Evaluation of Source Areas Using PCB Congener Data

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

PCB congener profiles can be used to help identify source areas that contribute most to the PCB mass exported from the watershed via stormwater and to illustrate variabi

PCB congener profiles can be used to help identify source areas that contribute most to the PCB mass exported from the watershed via stormwater and to illustrate variability in PCB mobilization from source areas over time. A method is presented for estimating the contributions of different Aroclor mixtures to the congener profiles of samples of stormwater and sediment. The method is based on the use of indicator congeners that are representative of each of the four most commonly used Aroclors. In this report, the method was applied in three watersheds. In the Pulgas Pump Station watershed, stormwater and sediment had high concentrations with a unique congener profile, dominated by congeners indicative of a combination of Aroclors 1242 and 1260. The concentrations and congener profiles in sediment suggest that there are two distinct source areas in the watershed that combine to create the mix of 1242 and 1260 that is dominant in stormwater at the Pump Station. The data indicate that if PCB flux from one of these areas could be eliminated, loads from the watershed would be reduced by 50% or more. For the Coyote Creek watershed, the similarity in congener profiles for the highest concentration sediment samples and the stormwater samples suggest that the important source areas in the watershed have been identified, and that reduction of loading from an area at the south end of the Charcot Avenue Storm Drain watershed would yield the greatest reduction in export at the Coyote Creek station. The concentrations and congener profiles in stormwater and sediment from the Guadalupe River watershed indicate the presence of one source area that is likely a substantial contributor to PCB export from the watershed, but that all of the significant sources areas may not yet have been identified.

Small Water Systems and Rural Communities Drought and Water Shortage Contingency Planning and Risk Assessment, Part 1

California Department of Water Resources (DWR) | March 25th, 2021

This report is submitted pursuant to California Water Code (CWC) Section 10609.42, which directs the California Department of Water Resources (DWR) to identify small wate

This report is submitted pursuant to California Water Code (CWC) Section 10609.42, which directs the California Department of Water Resources (DWR) to identify small water suppliers and rural communities that may be at risk of drought and water shortage vulnerability, and to propose recommendations and information in support of improving their drought preparedness. The report is published in two parts: Part 1 deals with drought and water shortage contingency planning recommendations, and Part 2 presents a methodology of drought and water shortage vulnerability assessment and risk scoring. Additionally, below are links for Part 1 appendices. Appendix 1: Literature Review Appendix 2: Proposed Water Shortage Contingency Plan Components for Small Water Systems Serving 1,000 to 2,999 Service Connections Appendix 3: Proposed Umbrella Water Shortage Contingency Plan Components Appendix 4: Indian Health Service Template for a Drought Contingency Plan for a Tribal Public Water System Appendix 5: County Drought Advisory Group General Funding and Financing Issues

Small Water Systems and Rural Communities Drought and Water Shortage Contingency Planning and Risk Assessment, Part 2

California Department of Water Resources (DWR) | March 25th, 2021

This report is submitted pursuant to California Water Code (CWC) Section 10609.42 which directs California Department of Water Resources (DWR) to identify small water sup

This report is submitted pursuant to California Water Code (CWC) Section 10609.42 which directs California Department of Water Resources (DWR) to identify small water suppliers and rural communities that may be at risk of drought and water shortage vulnerability and propose recommendations and information in support of improving the drought preparedness of small water suppliers and rural communities. The report is published in two parts: Part 1 dealing with drought and water shortage contingency planning recommendations, and Part 2 presenting a methodology and results of drought and water shortage vulnerability assessment and risk scoring. Additionally, below are links for Part 2 appendices. Appendix 1: Drought and Water Shortage Risk Scoring: California’s Small Water Supplier and Self-Supplied Communities Appendix 2: Drought and Water Shortage Risk Scoring: Risk Score Results of Small Water Suppliers Appendix 3: Drought and Water Shortage Risk Scoring: Risk Score Results of Self-Supplied Communities