Simulations of Ground-Water Flow and Particle Pathline Analysis in the Zone of Contribution of a Public-Supply Well in Modesto, Eastern San Joaquin Valley, California

U.S. Geological Survey (USGS) | July 1st, 2008

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.

Sociodemographic predictors of PFAS exposure among a combined sample of U.S. pregnant women: an Environmental influences on Child Health Outcomes (ECHO) public-use dataset analysis

Nature Portfolio (Springer Nature) | December 15th, 2025

Compared with White mothers, Black mothers had lower levels of PFOA (−23%; 95% CI −29%, −16%), PFOS (−9%; 95% CI −16%, −1%), and PFHxS (−23%; 95% CI −29%,

Compared with White mothers, Black mothers had lower levels of PFOA (−23%; 95% CI −29%, −16%), PFOS (−9%; 95% CI −16%, −1%), and PFHxS (−23%; 95% CI −29%, −14%) based on linear analysis, and lower detection of PFOSA, EtFOSAA, PFDoDA, and PFPeA and higher detection of PFBS and PFHxA based on logistic analysis. Compared with White mothers, Asian mothers had higher levels of PFNA ( + 26%; 95% CI 13%, 40%), PFDA ( + 60%, 95% CI 36%, 89%), and PFUnDA (+95%; 95% CI 63%, 134%) based on linear analysis and higher detection of PFPeA based on logistic regression. Greater weekly fish consumption was found to be a significant predictor of PFAS concentrations but did not attenuate associations with Asian race. Compared with non-Hispanic mothers, Hispanic mothers had lower levels of most of PFAS analytes studied. Higher levels of maternal education were associated with increased levels of most PFAS analytes.

Socioeconomic Disparities in Exposures to PFAS and Other Unregulated Industrial Drinking Water Contaminants in US Public Water Systems

National Institute of Environmental Health Sciences | January 15th, 2025

Background: Unregulated contaminants in drinking water, such as per- and polyfluoroalkyl substances (PFAS), can contribute to cumulative health risks, particularly in ove

Background: Unregulated contaminants in drinking water, such as per- and polyfluoroalkyl substances (PFAS), can contribute to cumulative health risks, particularly in overburdened and less-advantaged communities. To our knowledge, there has been no nationwide assessment of socioeconomic disparities in exposures to unregulated contaminants in drinking water.Objective: The goals of this study were to identify determinants of unregulated contaminant detection among US public water systems (PWSs) and evaluate disparities related to race, ethnicity, and socioeconomic status.

Sources, Pathways and Loadings: Multi-Year Synthesis with a Focus on PCBs and Hg

San Francisco Estuary Institute (SFEI) | December 15th, 2015

This report provides a synthesis of information gathered since 2000 on sources, pathways, and loadings of pollutants of concern in the San Francisco Bay Area with a focus

This report provides a synthesis of information gathered since 2000 on sources, pathways, and loadings of pollutants of concern in the San Francisco Bay Area with a focus on polychlorinated biphenyls (PCBs) and total mercury (Hg). Concentration and load estimates for other pollutants of concern (POC) are provided in the Appendix tables but not supported by any synthesis or discussion in the main body of the report. The PCB and Hg TMDLs for San Francisco Bay call for implementation of control measures to reduce stormwater PCB loads from 20 kg to 2 kg by 2030 and to reduce stormwater Hg loads from 160 kg to 80 kg by 2028 with an interim milestone of 120 kg by 2018. These are very challenging objectives given that the 2 kg PCB load allocation translates to a mean annual yield of 0.31 g/km2 for the free flowing areas downstream from reservoirs (6,650 km2), a mean annual concentration of 1.33 ng/L (assuming an annual average flow from small tributaries of 1.5 km3), and mean annual particle ratio of 1.4 ng/g of suspended sediment load (assuming an average annual suspended sediment load of 1.4 million metric t). Similarly for Hg, the 80 kg load allocation translates to a mean annual yield of 12 g/km2, a mean annual concentration of 53 ng/L, and mean annual particle ratio of 58 ng/g of suspended sediment load. Concentrations of these low magnitudes have been observed commonly in the Bay Area for Hg and yields of this low magnitude have been observed for PCBs and Hg. However, concentrations of PCBs at these magnitudes have only been observed in Marsh Creek (a more rural watershed) and particle ratios of PCBs and Hg as low as these have never been observed in the region.

State and green crimes related to water pollution and ecological disorganization: water pollution from publicly owned treatment works (POTW) facilities across US states

Palgrave Communications | August 1st, 2017

Green criminologists often refer to water pollution as an example of a green crime, but have yet to produce much research on this subject. The current article addresses�

Green criminologists often refer to water pollution as an example of a green crime, but have yet to produce much research on this subject. The current article addresses the need for green criminological analyses of water pollution problems, and draws attention to an overlooked issue: water pollution emissions from state owned public water treatment facilities or POTWs. Legally, POTWs may emit certain quantities and kinds of pollutants to waterways following treatment. This does not mean, however, that those emissions have no adverse ecological or public health impacts, or that those emissions cannot also be employed as examples of green crimes or green-state crimes. Indeed, from the perspective of environmental sociology and ecological Marxism, those emissions generate ecological disorganization. Moreover, POTW emissions contain numerous pollutants that generate different forms of ecological disorganization. The current study uses POTW emissions data drawn from the US EPA’s Discharge Monitoring Report system for 2014 to illustrate the extent of pollution emitted by POTWs in and across US states as one dimension of ecological disorganization. To contextualize the meaning of those data, we review US water pollution regulations, review the health and ecological impacts of chemicals emitted by POTWs, and situate those emissions within green criminological discussions of green crime and greenstate crimes.

State of the Estuary, October 2013

San Francisco Estuary Partnership (SFEP) | October 31st, 2013

State of the Salton Sea: A Science and Monitoring Meeting of Scientists for the Salton Sea

U.S. Geological Survey (USGS) | January 19th, 2017

The Salton Sea (Sea) is an ecosystem facing large systemic changes in the near future. Managers and stakeholders are seeking solutions to the decline of the Sea and have

The Salton Sea (Sea) is an ecosystem facing large systemic changes in the near future. Managers and stakeholders are seeking solutions to the decline of the Sea and have turned to the scientific community for answers. In response, scientists gathered in Irvine, California, to review existing science and propose scientific studies and monitoring needs required for understanding how to retain the Sea as a functional ecosystem. This document summarizes the proceedings of this gathering of approximately 50 scientists at a September 8–10, 2014, workshop on the State of the Salton Sea (SoSS).  In 1997, a similar gathering of nearly 100 scientists and others in Palm Springs, Calif., yielded a number of scientific proposals establishing a foundation for a program of integrated science investigations. The 1997 workshop results were combined with recommendations from a U.S. Geological Survey (USGS) Tiger Team (Shipley and others, 1999), resulting in the eventual creation of a Strategic Science Plan (SSP) for the Salton Sea (Salton Sea Science Subcommittee, 2000). The vision from the 1997 workshop of an integrated and coordinated program of scientific investigations, embraced by the SSP, was implemented through the SSC and the USGS Salton Sea Science Office (Science Office). The integrated science program, mandated by the Salton Sea Reclamation Act of 1998 (Public Law 105–372) and spelled out in the SSP, directly led to an increased scientific understanding of the Salton Sea ecosystem. The workshop concluded that “rehabilitation of the Sea is essential and requires that current ills be rectified in a manner that allows the Sea to sustain social values of importance to the human populations of the Imperial and Coachella Valleys, as well as society in general” (U.S. Fish and Wildlife Service, 1997). The 2014 SoSS workshop built upon the foundations of the 1997 workshop, with particular emphasis on changes in the condition of the Sea and its environment in the intervening years. Over the past five decades, investigations of the Salton Sea have addressed water quality, biological, recreation, and (or) economic issues at the Salton Sea (California Resources Agency, 2006, chap. 8). Many stakeholders believe that the Salton Sea has been “studied to death” (Claiborne, 1996). Although it is true that a great deal of research has been completed at the Salton Sea, much of it has been short term and focused on specific topics with little or no integration across science disciplines, time, and space. Additionally, there have been numerous attempts at resource management of the Salton Sea (previously referred to as restoration planning).  Study objectives have differed, but the main focus has generally been on methods to control the salinity and elevation of the Salton Sea (California Resources Agency, 2006, chaps. 1 and 4). Most investigations resulted in proposed plans to preserve the Salton Sea as a thriving fishery and recreational destination, and most of these plans addressed methods to preserve the “whole Sea.” More recently, however, studies have recognized that maintaining a smaller Salton Sea should be considered, owing to declining inflows to the Salton Sea (California Resources Agency, 2006).  Prior investigations considered hundreds of alternatives for managing Salton Sea salinity, nutrients, and water elevation. Some alternatives generated revenue to help pay for rehabilitating the Sea. These alternatives have been addressed in multiple studies, as summarized in chapters 1 and 4 of the “Salton Sea Ecosystem Restoration Program Draft Programmatic Environmental Impact Report” (California Resources Agency, 2006).  Although there have been multiple efforts to characterize the Salton Sea ecosystem and develop management plans, it was not until 1996 that a comprehensive and integrated research needs assessment was developed (U.S. Fish and Wildlife Service, 1997). The 1997 report captured the combined thinking of scientists and managers and identified several areas of scientific research that would be required for a fuller, more complete understanding of the Salton Sea necessary to undertake any management project. The report defined these broad categories of science as physical environment, biological environment, cultural resources, pathogens and diseases, and contaminants. These categories form the basic framework for all scientific investigations at the Salton Sea. Some science categories continue to receive greater emphasis because limited funding has required the prioritization of projects.  A Salton Sea Science Subcommittee (SSC) authorized by Public Law 105–372, representing a broad range of Federal, State, local, and other stakeholder interests, endorsed a long-range Strategic Science Plan for the Salton Sea (Salton Sea Science Subcommittee, 2000). Whereas the U.S. Fish and Wildlife Service 1997 report established the types of science needed, the SSP further established the governing processes and expectations of how this science program should be conducted. The SSP provided the framework for scientific investigations and remains the source for identifying how scientific studies should be undertaken to better understand the Salton Sea ecosystem. Based substantially on the U.S. Fish and Wildlife Service (1997) analysis of science needs, and in consultation with many stakeholders, the SSC authorized and funded a number of initial reconnaissance-level projects. The structure of this SoSS document follows the basic framework of the U.S. Fish and Wildlife Service 1997 report, placing emphasis on physical environment (air and water quality), biological environment (birds, fish, invertebrates, carbon, and algae), contaminants, and socioeconomics.  The SoSS meeting in 2014 was convened to build upon previous scientific efforts and to provide guidance to managers on what experts believe are the most critical science needs going forward. Experts were invited to participate in the SoSS meeting based on a review by the organizing committee of individuals with subject area expertise and experience working at the Salton Sea or in similar environments. The SoSS organizing committee presented a synopsis of known science to the gathered scientists, who were then tasked to evaluate the completeness of that science and make recommendations for science needs to fill information gaps. Participants were challenged to think and act independently of their organizational affiliation in order to generate conceptual proposals designed to address scientific and monitoring concerns identified by the managerial meeting participants.

Statistical Methods Development and Sampling Design Optimization to Support Trends Analysis for Loads of Polychlorinated Biphenyls from the Guadalupe River in San Jose, California, USA

San Francisco Estuary Institute (SFEI) | September 3rd, 2018

The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP), with guidance from its Small Tributaries Loading Strategy (STLS) Team, has been conducting s

The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP), with guidance from its Small Tributaries Loading Strategy (STLS) Team, has been conducting small tributary loading studies at several sites in the Bay Area since 2003. A current priority for the STLS is developing a strategy for measuring trends in pollutant loadings from small tributaries to the Bay.  This technical report presents the work to develop a statistical model for trends in loads of polychlorinated biphenyls (PCBs), and estimate the power for proposed monitoring designs as a basis for detecting trends for the Guadalupe River watershed (San Jose, California). The statistical approach builds upon the turbidity surrogate methodology that has been employed in the STLS since 2003. A novel, two-stage statistical modeling approach was used to incorporate the significant turbidity-PCB relationships that exist, and evaluate climatic, seasonal, and inter-annual factors as additional potential drivers of PCB loads. The longest-running time series of tributary monitoring by the STLS on the Guadalupe River was selected as the case study for developing and testing the statistical approach. As a result of this effort, a multiple linear regression model for detecting trends in PCB loads in the Guadalupe River was developed.