Electrical Resistivity Imaging of Seawater Intrusion into the Monterey Bay Aquifer System

National Groundwater Association (NGWA) | June 17th, 2015

We use electrical resistivity tomography to obtain a 6.8‐km electrical resistivity image to a depth of approximately 150 m.b.s.l. along the coast of Monterey Bay. The

We use electrical resistivity tomography to obtain a 6.8‐km electrical resistivity image to a depth of approximately 150 m.b.s.l. along the coast of Monterey Bay. The resulting image is used to determine the subsurface distribution of saltwater‐ and freshwater‐saturated sediments and the geologic controls on fluid distributions in the region. Data acquisition took place over two field seasons in 2011 and 2012. To maximize our ability to image both vertical and horizontal variations in the subsurface, a combination of dipole–dipole, Wenner, Wenner‐gamma, and gradient measurements were made, resulting in a large final dataset of approximately 139,000 data points. The resulting resistivity section extends to a depth of 150 m.b.s.l., and is used, in conjunction with the gamma logs from four coastal monitoring wells to identify four dominant lithologic units. From these data, we are able to infer the existence of a contiguous clay layer in the southern portion of our transect, which prevents downward migration of the saltwater observed in the upper 25 m of the subsurface to the underlying freshwater aquifer. The saltwater and brackish water in the northern portion of the transect introduce the potential for seawater intrusion into the hydraulically connected freshwater aquifer to the south, not just from the ocean, but also laterally from north to south.

Electron bifurcation and fluoride efflux systems implicated in defluorination of perfluorinated unsaturated carboxylic acids by Acetobacterium spp

American Association for the Advancement of Science (AAAS) | July 17th, 2024

Emerging PFAS Trends in Water and Sediment from San Francisco Bay

San Francisco Estuary Institute (SFEI) | August 14th, 2025

Per- and polyfluoroalkyl substances (PFAS) are a diverse class of persistent compounds, including several that are bioaccumulative and known or suspected to be toxic. The

Per- and polyfluoroalkyl substances (PFAS) are a diverse class of persistent compounds, including several that are bioaccumulative and known or suspected to be toxic. These unique compounds have widespread uses across consumer, commercial, and industrial products, resulting in widespread occurrence in humans, the environment, and wildlife across the globe. Within San Francisco Bay, the RMP has monitored PFAS across the Bay ecosystem, beginning in 2004 with various biota and since expanding to sediment, surface water, stormwater, and wastewater. These studies found PFAS throughout the Bay, especially in sport fish, where concentrations are of potential concern for human health and led to a classification of PFAS as High Concern for the Bay under the RMP tiered risk-based framework for emerging contaminants.  This study examined Bay sediment and surface water to continue to build our understanding of the occurrence, fate, and risks of PFAS to ecological and human health. Using a targeted method, 40 PFAS were analyzed in Bay sediment collected in three monitoring cruises from 2017 to 2023, and Bay water collected from 2021 to 2023 during both the dry and wet seasons. The Total Oxidizable Precursor (TOP) assay was also used to supplement these findings by indirectly measuring unknown perfluoroalkyl acid (PFAA) precursors of detectable PFAS. This additional information aids in elucidating the broader levels of PFAS present in samples to better evaluate the exposure and risk to the Bay. 

Emerging understanding of the potential role of seagrass and kelp as an ocean acidification management tool in California

California Ocean Science Trust (OST) | January 2nd, 2018

This report was produced by the OPC-SAT working group and Ocean Science Trust on behalf of the Ocean Protection Council (OPC) and the broader community of California man

This report was produced by the OPC-SAT working group and Ocean Science Trust on behalf of the Ocean Protection Council (OPC) and the broader community of California managers with the aim of: • communicating emerging scientific understanding of the ability of seagrass and macroalgae (kelps) to ameliorate ocean acidification (OA) in a California-specific context, • summarizing knowledge gaps and opportunities for filling them through research and monitoring, and • providing guidance on next steps for the State as it considers future nature-based actions to reduce the negative impacts of OA in California and beyond.

Endangered Species Status for the San Francisco Bay-Delta Distinct Population Segment of the Longfin Smelt

U.S. Fish and Wildlife Service (FWS) | July 30th, 2024

We, the U.S. Fish and Wildlife Service (Service), determine endangered species status under the Endangered Species Act of 1973, as amended (Act), for the San Francisco Ba

We, the U.S. Fish and Wildlife Service (Service), determine endangered species status under the Endangered Species Act of 1973, as amended (Act), for the San Francisco Bay-Delta distinct population segment (DPS) of longfin smelt (Spirinchus thaleichthys), a fish species of the Pacific Coast. This rule extends the protections of the Act to this DPS and adds it to the List of Endangered and Threatened Wildlife.... This final rule is available on the internet at https://www.regulations.gov. Comments and materials we received on the proposed rule are available for public inspection at https://www.regulations.gov at Docket No. FWS-R8-ES-2022-0082. Availability of supporting materials: Supporting materials we used in preparing this rule, such as the species status assessment report, are available at https://www.regulations.gov at Docket No. FWS-R8-ES-2022-0082.

Environment California, Inc. v. City of Los Angeles

Holmes, Athey, Cowan & Mermelstein LLP | July 23rd, 2024

Environmental and anthropogenic drivers of contaminants in agricultural watersheds with implications for land management

Science of the Total Environment (Elsevier) | February 17th, 2021

Environmental Health Risks from Abandoned Mines in the Sierra Nevada

Sierra Fund | June 9th, 2014

The widespread pollution from Gold Rush mining activities, including mercury, arsenic and lead, constitutes the oldest and longest neglected environmental justice problem

The widespread pollution from Gold Rush mining activities, including mercury, arsenic and lead, constitutes the oldest and longest neglected environmental justice problem in California. The effects of this pollution on human health and the environment are only now beginning to be addressed. Today, the effects of historic mining pollution are an invisible but very real threat to people who live, work or recreate in the Sierra Nevada. Toxins of concern include mercury, arsenic, lead and asbestos.  There is little information about these potential exposures available to Sierra residents. State-issued fish consumption advisories in the region do not provide site-specific advice for many locations people fish, or the species people eat. In 2006, The Sierra Fund, in partnership with California State University Chico, conducted a survey of Sierra clinics. This study found that not one of 13 surveyed clinics included information on mercury in fish as part of their maternal/infant health programs, whether caught locally or not. Additionally, the study learned that none of the clinics surveyed administer an environmental health history form, so it is difficult to connect current health problems to environmental exposures. In order to address this lack of information and provide a springboard for more research, The Sierra Fund conducted three pilot studies of potential environmental exposures in 2009 and 2010 and a pilot outreach program to present these findings to Sierra communities in 2013-14. This report summarizes findings and recommendations from these efforts, in order to encourage continued research into these potentially serious health exposures.

Environmental justice and drinking water quality: are there socioeconomic disparities in nitrate levels in U.S. drinking water?

Springer Nature | January 17th, 2019

Environmental Justice Program Implementation for Lahontan Region

Lahontan Regional Water Quality Control Board (LRWQCB) | January 30th, 2015

The Lahontan Regional Water Quality Control Board (Lahontan Water Board) reviewed how environmental justice (EJ) is conducted in the region and examined new ways to impro

The Lahontan Regional Water Quality Control Board (Lahontan Water Board) reviewed how environmental justice (EJ) is conducted in the region and examined new ways to improve our efforts to benefit the disadvantaged communities in our region. The challenges faced by disadvantaged communities (DACs) in the Lahontan region are unique and often different than other DACs in more urban regions. This report provides an assessment of existing efforts to help DACs and catalogs EJ concerns. In addition, the report includes recommendations to enhance DACs participation in the regulatory process, expand access to funding and technical assistance, and improve water quality and drinking water.