San Francisco Bay

Status and Understanding of Groundwater Quality in the San Francisco Bay Groundwater Basins, 2007: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | March 29th, 2013

Groundwater quality in the approximately 620-square-mile (1,600-square-kilometer) San Francisco Bay study unit was investigated as part of the Priority Basin Project of t

Groundwater quality in the approximately 620-square-mile (1,600-square-kilometer) San Francisco Bay study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in the Southern Coast Ranges of California, in San Francisco, San Mateo, Santa Clara, Alameda, and Contra Costa Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory.

Status and Understanding of Groundwater Quality in the South Coast Interior Groundwater Basins, 2008: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | May 14th, 2014

Groundwater quality in the approximately 653-square-mile (1,691-square-kilometer) South Coast Interior Basins (SCI) study unit was investigated as part of the Priority Ba

Groundwater quality in the approximately 653-square-mile (1,691-square-kilometer) South Coast Interior Basins (SCI) study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The South Coast Interior Basins study unit contains eight priority groundwater basins grouped into three study areas, Livermore, Gilroy, and Cuyama, in the Southern Coast Ranges hydrogeologic province. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The GAMA South Coast Interior Basins study was designed to provide a spatially unbiased assessment of untreated (raw) groundwater quality within the primary aquifer system, as well as a statistically consistent basis for comparing water quality between basins. The assessment was based on water-quality and ancillary data collected by the USGS from 50 wells in 2008 and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system was defined by the depth intervals of the wells listed in the CDPH database for the SCI study unit. The quality of groundwater in the primary aquifer system may be different from that in the shallower or deeper water-bearing zones; shallow groundwater may be more vulnerable to surficial contamination. The first component of this study, the status of the current quality of the groundwater resource, was assessed by using data from samples analyzed for volatile organic compounds (VOCs), pesticides, and naturally occurring inorganic constituents, such as trace elements and minor ions. This status assessment is intended to characterize the quality of groundwater resources within the primary aquifer system of the SCI study unit, not the treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentration divided by the health- or aesthetic-based benchmark concentration) were used for evaluating groundwater quality for those constituents that have Federal or California regulatory or non-regulatory benchmarks for drinking-water quality. A relative-concentration greater than 1.0 indicates a concentration greater than a benchmark, and a relative-concentration less than or equal to 1.0 indicates a concentration equal to or less than a benchmark. Relative-concentrations of organic constituents and special-interest constituents were classified as “high” (relative-concentration greater than 1.0), “moderate” (relative-concentration greater than 0.1 and less than or equal to 1.0), or “low” (relative-concentration less than or equal to 0.1). Relative-concentrations of inorganic constituents were classified as “high” (relative-concentration greater than 1.0), “moderate” (relative-concentration greater than 0.5 and less than or equal to 1.0), or “low” (relative-concentration less than or equal to 0.5). Aquifer-scale proportion was used as the primary metric in the status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the percentage of the area of the primary aquifer system with a relative-concentration greater than 1.0 for a particular constituent or class of constituents; percentage is based on an areal rather than a volumetric basis. Moderate and low aquifer-scale proportions were defined as the areal percentage of the primary aquifer system with moderate and low relative-concentrations, respectively. Two statistical approaches—grid-based and spatially weighted—were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. Grid-based and spatially weighted estimates were comparable in the SCI study unit (within 90-percent confidence intervals). Inorganic constituents (one or more) with health-based benchmarks were detected at high relative-concentrations in 29 percent of the primary aquifer system, at moderate relative-concentrations in 37 percent, and at low relative-concentrations in 34 percent. High aquifer-scale proportions of inorganic constituents primarily reflected high aquifer-scale proportions of nitrate (14 percent), boron (8.6 percent), molybdenum (8.6 percent), and arsenic (5.7 percent). In contrast, the relative-concentrations of organic constituents (one or more) were high in 1.6 percent, moderate in 2.0 percent, and low or not detected in 96 percent of the primary aquifer system. Of the 207 organic and special-interest constituents analyzed for, 15 constituents were detected. Perchlorate was found at moderate relative-concentrations in 34 percent of the aquifer. Two organic constituents were frequently detected (in greater than 10 percent of samples): the trihalomethane chloroform and the herbicide simazine. The second component of this study, the understanding assessment, identified natural and human factors that may have affected groundwater quality by evaluating land use, physical characteristics of the wells, and geochemical conditions of the aquifer. This evaluation was done by using statistical tests of correlations between these potential explanatory factors and water-quality data. Concentrations of arsenic, molybdenum, and manganese were generally greater in anoxic and pre-modern groundwater than other groundwater. In contrast, concentrations of nitrate and perchlorate were significantly higher in oxic and modern groundwater. Concentrations of simazine were greater in modern than pre-modern groundwater. Chloroform detections were positively correlated with greater urban land use. Boron concentrations and chloroform detections were higher in the Livermore study area than in the other study areas of the SCI; total dissolved solids and sulfate concentrations were greater in the Cuyama study area.

Status of 2020 Agricultural Water Management Plans and Implementation of Efficient Water Management Practices Report

California Department of Water Resources (DWR) | January 25th, 2024

As required by the California Water Code (CWC), Agricultural Water Suppliers (AWS) must implement Efficient Water Management Practices (EWMPs) and submit an Agricultural

As required by the California Water Code (CWC), Agricultural Water Suppliers (AWS) must implement Efficient Water Management Practices (EWMPs) and submit an Agricultural Water Management Plan (AWMP) to the Department of Water Resources (DWR) every five years. Agricultural Water Suppliers subject to United States Bureau of Reclamation (Reclamation) requirements for a Water Conservation Plan (Reclamation Plan) may submit those plans to DWR in lieu of an AWMP. DWR then reports to the Legislature on the status of AWMPs, including outstanding elements, and implementation of EWMPs or Reclamation Best Management Practices (EWMPs/BMPs). This legislative report addresses the requirements for reporting on AWMPs and EWMPs in a single report that documents the status of AWMP submittals and the implementation of associated EWMPs. This report is the final Legislative report on EWMPs under CWC Section 10608.48(g).

Status of 2020 Urban Water Management Plans

California Department of Water Resources (DWR) | July 25th, 2023

As required by the California Water Code (CWC), every five years Urban Water Suppliers must submit an Urban Water Management Plan (UWMP) to the Department of Water Resour

As required by the California Water Code (CWC), every five years Urban Water Suppliers must submit an Urban Water Management Plan (UWMP) to the Department of Water Resources (DWR). DWR then reports to the Legislature on the status of UWMPs and Water Shortage Contingency Plans (WSCPs) and exemplary elements. Key Findings: * 95% (417 of 438) of Urban Water Suppliers submitted plans. * 97% (374 of 386) of Urban Retail Suppliers that submitted UWMPs met their water use reduction targets. * Statewide per capita urban water use was down 32% by 2020 from baseline period (suppliers identify a continuous 10-year or 15-year baseline period between 1995 and 2010). * 94% (393 of 417) of Urban Water Suppliers anticipate being able to manage any water shortages by implementing their Water Shortage Contingency Plans.

Still Imperilled, Still Important: The Little Hoover Commission’s Review of the CALFED Program

Little Hoover Commission | November 17th, 2005

The Sacramento-San Joaquin River Delta is a treasured and imperiled resource. And CALFED has been the best hope to restore it. The ambitious state-federal partnership is

The Sacramento-San Joaquin River Delta is a treasured and imperiled resource. And CALFED has been the best hope to restore it. The ambitious state-federal partnership is proof that political will and leadership can resolve seemingly intractable conflicts. And yet in recent years, the program also has demonstrated the propensity for rudderless bureaucracies to get caught in inescapable eddies. It is not too late for the Delta, or for CALFED. But restoring the estuary and managing the resource in a sustainable manner will require continuous political support, expert leadership, and smart management.

Storage Capacity and Sedimentation Characteristics of the San Antonio Reservoir, California, 2018

U.S. Geological Survey (USGS) | January 15th, 2020

Storage in California’s reservoirs and snowpack in this time of drought

University of California, Davis (UC Davis) | June 30th, 2015

The San Francisco Bay and Sacramento–San Joaquin Delta (Delta) are the recipients of inflows from a watershed that spans much of California and that has ties to nearly

The San Francisco Bay and Sacramento–San Joaquin Delta (Delta) are the recipients of inflows from a watershed that spans much of California and that has ties to nearly the entire state. Historically, California has buffered its water supplies and flood risks both within—and beyond—the Delta’s catchment by devel-oping many reservoirs, large and small, high and low. Most of these reservoirs carry water from wet winter seasons—when water demands are low and flood risks are high—to dry, warm seasons (and years) when demands are high and little precipitation falls. Many reservoirs are also used to catch and delay (or spread in time) flood flows that otherwise might cause damage to communities and floodplains. This essay describes the status of surface-water and snow-pack storage conditions in California in spring 2015, providing context for better understanding where the state’s water stores stand as we enter summer 2015. 

Storing and managing water for the environment is more efficient than mimicking natural flows

Nature Portfolio (Springer Nature) | June 27th, 2024

Storing Water for the Environment: Operating Reservoirs to Improve California’s Freshwater Ecosystems

Public Policy Institute of California (PPIC) | August 23rd, 2022

Large reservoirs like those that rim the Central Valley are essential for managing water in California’s highly variable climate. They provide multiple benefits includi

Large reservoirs like those that rim the Central Valley are essential for managing water in California’s highly variable climate. They provide multiple benefits including water supply, hydropower, flood management, and recreation. However, construction and operation of these reservoirs have also imposed significant environmental costs, including native fishes’ loss of access to high-quality habitat above dams and degradation of freshwater ecosystems below them. Moreover, regulatory uncertainty for water users is rising as these ecosystems decline. California needs a new approach for managing environmental water in its large reservoirs, particularly as the climate warms and droughts become more intense.

Stormquakes

American Geophysical Union (AGU) | October 14th, 2019

Seismic signals from ocean-solid Earth interactions are ubiquitously recorded on our planet. However, these wavefields are typically incoherent in the time domain limiti

Seismic signals from ocean-solid Earth interactions are ubiquitously recorded on our planet. However, these wavefields are typically incoherent in the time domain limiting their utilization for understanding ocean dynamics or solid Earth properties. In contrast, we find that during large storms such as hurricanes and Nor’easters the interaction of long-period ocean waves with shallow seafloor features located near the edge of continental shelves, known as ocean banks, excites coherent transcontinental Rayleigh wave packets in the 20 to 50 s period band. These “stormquakes” migrate coincident with the storms, but are effectively spatiotemporally focused seismic point sources with equivalent earthquake magnitudes that can be greater than 3.5. Stormquakes thus provide new coherent sources to investigate Earth structure in locations that typically lack both seismic instrumentation and earthquakes. Moreover, they provide a new geophysical observable with high spatial and temporal resolution with which to investigate ocean wave dynamics during large storms.