San Francisco Bay

Priorities for California’s Water: Advancing Research During Uncertain Times

Public Policy Institute of California (PPIC) | November 12th, 2025

In California, research underpins all water-related activity. It is vital for coping with too much water, too little water, and rapid changes in hydrology. Whether you ar

In California, research underpins all water-related activity. It is vital for coping with too much water, too little water, and rapid changes in hydrology. Whether you are a farmer managing the precise application of water to your crops, a utility providing clean drinking water supplies to your community, or a restorationist trying to heal a damaged wetland, your actions rely upon decades of applied research that guides your actions and measures your success.  The same reliance on research applies if you are developing policies to reduce the price of water, increase its reliability, regulate its usage, and reduce hazards from floods. None of this works without a vast research enterprise that is regularly updating the science and technology we use to manage water, prepare for the future, inform the public, and address new problems as they arise. 

Priorities for California’s Water: Are We Ready for Climate Change?

Public Policy Institute of California (PPIC) | November 12th, 2024

California faces many immediate challenges around water management, but as the record-breaking heat of 2024 makes clear, temperatures are rising—and Californians are co

California faces many immediate challenges around water management, but as the record-breaking heat of 2024 makes clear, temperatures are rising—and Californians are contending with the consequences. In a PPIC poll earlier this year, residents named climate change, forest fires and wildfires, and water supply and drought as the most important environmental issues facing the state. 

Prioritization of State Investments in Delta Levees and Risk Reduction - Initial Statement of Reasons

Delta Stewardship Council (Delta Council) | August 26th, 2022

Prioritization of State Investments in Delta Levees and Risk Reduction Amendment to Existing Regulation

Delta Stewardship Council (Delta Council) | September 21st, 2023

Priority Margin Unit Stormwater Monitoring to Support Load Estimates of PCBs into San Leandro Bay and the Emeryville Crescent

San Francisco Estuary Institute (SFEI) | July 15th, 2022

The Priority Margin Unit Studies: The 2014 update of the RMP PCB Strategy called for a multi-year effort to implement the recommendations of the  PCB Synthesis Report (D

The Priority Margin Unit Studies: The 2014 update of the RMP PCB Strategy called for a multi-year effort to implement the recommendations of the  PCB Synthesis Report (Davis et al., 2014) including: 1. identifying margin units that are high priorities for management and monitoring, 2. developing conceptual models and mass budgets for margin units downstream of watersheds where management actions will occur, and 3. monitoring in these units as a performance measure. The goal of the effort was to inform the review and possible revision of the PCB TMDL and the reissuance of the Municipal Regional Permit for Stormwater (MRP).

Procedures to evaluate sea-level change: impacts, responses, and adaptation

U.S. Army Corps of Engineers (USACE) | June 30th, 2014

Productive wetlands restored for carbon sequestration quickly become net CO2 sinks with site-level factors driving uptake variability

PLOS | March 25th, 2021

Inundated wetlands can potentially sequester substantial amounts of soil carbon (C) over the long-term because of slow decomposition and high primary productivity, partic

Inundated wetlands can potentially sequester substantial amounts of soil carbon (C) over the long-term because of slow decomposition and high primary productivity, particularly in climates with long growing seasons. Restoring such wetlands may provide one of several effective negative emission technologies to remove atmospheric CO2 and mitigate climate change. However, there remains considerable uncertainty whether these heterogeneous ecotones are consistent net C sinks and to what degree restoration and management methods affect C sequestration. Since wetland C dynamics are largely driven by climate, it is difficult to draw comparisons across regions. With many restored wetlands having different functional outcomes, we need to better understand the importance of site-specific conditions and how they change over time. We report on 21 site-years of C fluxes using eddy covariance measurements from five restored fresh to brackish wetlands in a Mediterranean climate. The wetlands ranged from 3 to 23 years after restoration and showed that several factors related to restoration methods and site conditions altered the magnitude of C sequestration by affecting vegetation cover and structure. Vegetation established within two years of re-flooding but followed different trajectories depending on design aspects, such as bathymetry-determined water levels, planting methods, and soil nutrients. A minimum of 55% vegetation cover was needed to become a net C sink, which most wetlands achieved once vegetation was established. Established wetlands had a high C sequestration efficiency (i.e. the ratio of net to gross ecosystem productivity) comparable to upland ecosystems but varied between years undergoing boom-bust growth cycles and C uptake strength was susceptible to disturbance events. We highlight the large C sequestration potential of productive inundated marshes, aided by restoration design and management targeted to maximise vegetation extent and minimise disturbance. These findings have important implications for wetland restoration, policy, and management practitioners.

Projected Brackish Water Desalination Projects in California

California Department of Water Resources (DWR) | February 20th, 2024

California’s Water Supply Strategy: Adapting to a Hotter, Drier Future (Water Supply Strategy), adopted by the Newsom Administration in 2022, identifies multiple action

California’s Water Supply Strategy: Adapting to a Hotter, Drier Future (Water Supply Strategy), adopted by the Newsom Administration in 2022, identifies multiple actions necessary to bolster water supply reliability in the face of climate change. The first set of actions drive the development of new water supplies and set explicit goals for expanding the production of both recycled and desalinated water. Action 1.2 includes specific targets for expanded brackish water desalination: 28,000 acre-feet by 2030, and 84,000 acre-feet by 2040. The Water Supply Strategy identifies five steps toward achieving this goal.

Projected responses of the coastal water table for California using present-day and future sea-level rise scenarios

U.S. Geological Survey (USGS) | August 11th, 2020

Coastal groundwater levels (heads) can increase with sea level rise (SLR) where shallow groundwater floats on underlying seawater. In some areas coastal groundwater could

Coastal groundwater levels (heads) can increase with sea level rise (SLR) where shallow groundwater floats on underlying seawater. In some areas coastal groundwater could rise almost as much as SLR, but where rising groundwater intersects surface drainage features, the increase will be less. Numerical modeling can provide insight into coastal areas that may be more or less vulnerable to hazards associated with SLR-driven groundwater shoaling (moving closer to the ground surface) and emergence (flooding the ground surface), providing coastal planners with critical information that can be used to increase public safety, mitigate physical damages, and more effectively manage and allocate resources in complex coastal settings. Seamless unconfined groundwater heads for coastal California groundwater systems were modeled with homogeneous, steady-state MODFLOW simulations. The geographic extent examined was limited primarily to low-elevation (land surface less than approximately 10 m above mean sea level) areas. In areas where coastal elevations increase rapidly (e.g., bluff stretches), the model boundary was set approximately 1 kilometer inland of the present-day shoreline. Steady-state MODFLOW groundwater flow models were used to obtain detailed (10-meter-scale) predictions over large geographic scales (100s of kilometers) of groundwater heads for both current and future sea-level rise (SLR) scenarios (0 to 2 meters (m) in 0.25 m increments, 2.5 m, 3 m, and 5 m) using a range of horizontal hydraulic conductivity (Kh) scenarios (0.1, 1, and 10 m/day). For each SLR/Kh combination, results are provided for two marine boundary conditions; local mean sea level (LMSL) and mean higher-high water (MHHW), and for two model versions. In the first model version, groundwater reaching the land surface is removed from the model, simulating loss via natural drainage. In the second model version, SLR impacts are modeled by simply raising the present-day (SLR 0m) modeled groundwater head by the amount of sea-level rise, simulating the worst-case "linear" response to sea-level rise. Modeled groundwater heads were then subtracted from high-resolution topographic digital elevation model (DEM) data to obtain water table depths. Groundwater head and water table depths are presented in raster GeoTIFF format. Polygon shapefiles also present water table depths by depth range (emergent, 0 to 1, 1 to 2, 2 to 5, and greater than 5 meters depth). All results are presented by County.

Projected U.S. drought extremes through the twenty-first century with vapor pressure deficit

Nature Portfolio (Springer Nature) | May 21st, 2022

Global warming is expected to enhance drought extremes in the United States throughout the twenty-first century. Projecting these changes can be complex in regions with

Global warming is expected to enhance drought extremes in the United States throughout the twenty-first century. Projecting these changes can be complex in regions with large variability in atmospheric and soil moisture on small spatial scales. Vapor Pressure Deficit (VPD) is a valuable measure of evaporative demand as moisture moves from the surface into the atmosphere and a dynamic measure of drought. Here, VPD is used to identify short-term drought with the Standardized VPD Drought Index (SVDI); and used to characterize future extreme droughts using grid-dependent stationary and non-stationary generalized extreme value (GEV) models, and a random sampling technique is developed to quantify multimodel uncertainties. The GEV analysis was performed with projections using the Weather Research and Forecasting model, downscaled from three Global Climate Models based on the Representative Concentration Pathway 8.5 for present, mid-century and late century. Results show the VPD based index (SVDI) accurately identifies the timing and magnitude short-term droughts, and extreme VPD is increasing across the United States and by the end of the twenty first century. The number of days VPD is above 9 kPa increases by 10 days along California’s coastline, 30–40 days in the northwest and Midwest, and 100 days in California’s Central Valley.