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USGS2025

Insights and strategic opportunities from the USGS 2024 Per- and Polyfluoroalkyl Substances (PFAS) Interagency Workshop

Introduction In 2021, the U.S. Geological Survey (USGS) published Circular 1490 titled, “Integrated Science for the Study of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) in the Environment: A Strategic Science Vision for the U.S. Geological Survey” (Tokranov and others, 2021). Circular 1490 was created to be a resource for USGS scientists prioritizing and planning research related to per- and polyfluoroalkyl substances (PFAS) and to be a guide for developing partnerships with other scientists, State and Federal agencies, and stakeholders engaged in PFAS research and management and mitigation of the environmental and human-health effects of PFAS. This USGS PFAS Strategic Science Vision document was intended to be the foundation for a “living strategic vision,” periodically providing updates on the state of USGS PFAS research, emerging PFAS data gaps and needs, and progress on interagency and stakeholder PFAS partnerships and priorities. To meet this objective, the USGS planned to host an Interagency and Stakeholder PFAS Workshop every 2–3 years. During September 10–12, 2024, the USGS hosted the first Interagency and Stakeholder PFAS Workshop in Reston, Virginia. The Workshop brought together experts from other Federal agencies (U.S. Environmental Protection Agency, National Institute of Environmental Health Sciences, Food and Drug Administration, Department of Defense [Air Force, Army]), State agencies (Washington Fish and Wildlife, Virginia Department of Transportation), and academia (Harvard University, University of Maryland) to address key challenges relating to the measurement and modeling of PFAS and the implications for environmental health. Participants engaged in in-depth discussions centered around six pivotal topics related to PFAS: (1) sampling protocols, methods and interpretation; (2) environmental sources, source apportionment, and occurrence; (3) environmental fate and transport; (4) human and wildlife exposure routes and risk; (5) bioconcentration, bioaccumulation, and biomagnification; and (6) ecotoxicology and effects. Each topic had three breakout sessions. A recurrent theme of workshop discussions was how data on a nationwide scale for PFAS occurrence in various environmental matrices, including air, water, food crops, biota, soil, and streambed sediment could help to advance scientific understanding. Participants noted significant geospatial data gaps, particularly in the midwestern and southern United States and the Pacific Northwest. PFAS data collection tends to be more robust along the eastern seaboard and in California. Participants stressed how enhancing the integration of large and small datasets across various agencies could help to support national scale understanding of PFAS. To address these gaps, attendees suggested leveraging datasets from Federal entities like the USGS and the U.S. Department of Defense, State agencies, and municipal utility services to develop predictive contaminant detection and transport models. Improved coordination between water quality programs and USGS research could help to facilitate access to valuable data, leading to comprehensive databases that inform PFAS point (wastewater treatment plants and landfills) and nonpoint (runoff from land, atmospheric deposition, food packaging) sources, environmental transport mechanisms, environmental detection and concentrations, potential exposure routes, and health effects on different biota, including humans. A specific request was made to develop a map demarking the depth of modern (1953 or later) groundwater, which is susceptible to surface-derived anthropogenic (that is, human-made) contamination, based on tritium-age dating. Emphasis was placed on incorporation of hydrology, groundwater flow paths, groundwater–surface water interactions, and landscape factors in predictive statistical models as a step to improve contaminant source identification and tracking. Molecular fingerprinting approaches garnered attention as techniques to link specific PFAS mixtures detected in a sample to environmental sources and levels in biota (Dávila-Santiago and others, 2022). Integrating data from abiotic (that is, water, soil, and air) and biotic (that is, living organisms) systems identified as a research opportunity. For example, understanding the composition of soils and sediments, which include a mixture of mineral, plant, and animal components, could advance understanding of exposure pathways. The discussions highlighted opportunities to explore and understand the potential redistribution and biotic exposures of PFAS from biosolid and wastewater treatment plant effluent land application practices, in addition to atmospheric releases and discharges from landfill and wastewater treatment plants. Participants identified research gaps surrounding how these sources may contribute to contamination and may affect surrounding ecosystems, including a better definition of anthropogenic background concentrations. Moving forward, the collection of co-occurrence data was noted as a means to improve understanding of complex mixtures and to leverage companion modeling efforts focused on areas with high and low contamination levels to identify areas of concern and unaffected resources. Participants emphasized how centralized USGS databases and the establishment of sample-metadata archives can help to ensure that samples are preserved and accessible for future research. In conclusion, the workshop participants identified opportunities to bridge data gaps and improve measurement techniques, modeling frameworks, databases, and communication, to enhance the understanding of PFAS and their effects on environmental and human health. Upon completion of the workshop, participants indicated an interest in developing strategic data collection, modeling, and analytical approaches to address these challenges.

Open-File Report↗
USGS1975

Configuration of water table and distribution of downward leakage to the Prairie du Chien-Jordan Aquifer in the Minneapolis-Saint Paul metropolitan area, Minnesota

The configuration of the water table as plotted at a contour interval of 20 feet (6 metres) on quadrangle maps (scale 1:2,500) of the Minneapolis-Saint Paul metropolitan area. Control points used for mapping were water levels in wells, lakes and sloughs, and places where topographic contours cross perennial streams. A computer program, using a variation of Darcy's law, was developed to determine distribution of 1) downward leakage to the Prairie du Chien-Jordan aquifer under steady-state conditions, using estimated vertical-hydraulic conductivity values for overlying materials; 2) calculated vertical hydraulic conductivity values, assuming uniform leakage to the aquifer; and 3) additional leakage to the aquifer resulting from increased pumpage during the summer. For data determination and data input to the computer program, the area was gridded into units of 1-minute longitude by 1-minute latitude, about 600 acres (243 hectares) per unit. Previous work estimated the increased summer pumpage (1971) of ground water to be 127 million gallons (481x106 litres) per day. Calculations, made Within the limits of governing assumptions, indicate that 10 to 20 percent of increased summer pumpage is derived from increased leakage. Most of the remainder is probably from captured natural discharge and induced recharge from major streams within the influence of summer cones of depression. Based on available data and estimates of vertical hydraulic conductivity for geologic units, major leakage to the Prairie du Chien-Jordan aquifer is indicated to occur in formation subcrop areas, especially where these areas are. overlain by the most permeable glacial drift.

Minnesota↗
USGS1979

Water resources of the Santa Rosa Indian Reservation and vicinity, Riverside County, California

The Santa Rosa Indian Reservation is a 17-square-mile area located between the Santa Rosa and San Jacinto Mountains in south-central Riverside County, Calif. The source of water in most of the study area is precipitation on the three topographic subbasins that nearly surround the reservation. Precipitation averages about 12 inches annually (18,000 acre-feet per year), with 10 inches (15,000 acre-feet per year) of it returning to the air by evapotranspiration, 1 inch (1,500 acre-feet per year) running off from the area, and 1 inch (1,500 acre-feet per year) going to ground-water recharge. Local geology and the shape of the ground-water basin, as defined by a gravity survey, indicate that the area receives no ground-water inflow from outside the study area. Production of a dry-farm crop is planned for the 800-acre area west of Vandeventer Flat on the reservation's main section. Additional water supplies are needed for crop irrigation. At present (1979), water is obtained from a supply well that taps the saturated section of the sandy material overlying the basement complex of Cretaceous age or older. Existing data indicate that the aquifer may not yield large volumes of water to individual wells. A specific capacity of about 0.4 gallon per minute per foot of drawdown was measured at the supply well. Estimates of specific yield for the material encountered during the drilling of three wells and a test hole were 5 to 10 percent. The thickest section of the aquifer in the Vandeventer Flat area was outlined by a gravity survey. Test wells should provide information on thickness of the aquifer, aquifer properties, and potential well yield. Damming of area streams could also supply irrigation water. Average runoff totals about 1,500 acre-feet per year, with greater volumes lost during periods of heavy precipitation and flooding. Peak discharge from the central and southern subbasins totaled about 160 acre-feet per hour during the January-March period of 1978. Water-quality analyses for the supply well and five major springs indicate that the ground water is suitable for irrigation everywhere except at Sulphur Spring, where the percent sodium of 97 is above recommended maximum levels, and at Bull Canyon Spring, where water of 1,300 micromhos specific conductance is considered a high salinity hazard. The sulfate concentration of 290 milligrams per liter in Bull Canyon Spring is above the recommended maximum level for drinking water.

California↗
USGS1979

Physical and chemical properties of San Francisco Bay waters, 1969-1976

Basic data on the physical and chemical properties of San Francisco Bay are presented here. Samples were collected over the period 1969-1976 at approximately six-week intervals at 36 stations. The stations were located along the axis of the Bay from Calaveras Point in South San Francisco Bay to the town of Rio Vista on the Sacramento River. On most cruises vertical profiles of the water properties were taken at 12 of the 36 stations. The samples were analyzed for the following core parameters: salinity, temperature, light transmission, chlorophyll a fluorescence, dissolved oxygen, orthophosphate, nitrate+nitrite, nitrite, ammonia, and silicate. Other analyses performed on selected samples included: particulate organic carbon, alkalinity, pH, pCO 2 , and suspended particulate weight. The results of these analyses and the analytical methods used are documented in this report.

California↗
USGS1982

Mineralogy and autoradiography of selected mineral-spring precipitates in the Western United States

X-ray diffaction analysis of 236 precipitate or sediment samples from 97 mineral-spring sites in nine Western States showed the presence of 25 minerals, some precipitated and some detrital. Calcite and (or) aragonite are the most common of all the precipitated minerals. Gypsum and (or) anhydrite, as well as barite and native sulfur, are less common but are also believed to be precipitated minerals. Precipitated manganese and iron oxides, including romanechite, manganite, pyrolusite, goethite, and hematite, were found in some of the samples. Various salts of sodium, including halite and thenardite, were also identified. Dolomite and an unknown type of siliceous material are present in some of the samples and were possibly precipitated at the spring sites. Quartz, feldspar, and mica are present in many of the samples and are believed to be detrital contaminants. An autoradiographic and thin section study of 11 samples from nine of the most radioactive spring sites showed the radioactivity, which is due primarily to radium, to be directly associated with mineral phases containing barium, manganese, iron, and (or) calcium as major constituents. Furthermore, the radioactivity has an exclusive affinity for the manganese-bearing minerals, which in these samples contain a substantial amount of barium, even if calcite or iron oxides are present. Where calcite predominates and manganese- and barium-bearing minerals are absent, the radioactivity shows a close association with the iron oxides present, especially hematite, but also shows a moderate association with the calcite and (or) aragonite cementing phases. In other samples composed predominantly of calcite but lacking iron oxides, the radioactivity is preferentially associated with an early stage of calcite development and is considerably lower in the later cementing stages. The radioactivity observed in all these samples is believed to be caused by radium substituting for barium in mineral lattices, filling irregularities in other crystal structures, or adsorbing on the surfaces of precipitated molecules.

Open-File Report↗
USGS1986

Physical and chemical data for the Sacramento River at Rio Vista, California, January through May, 1983

Physical and chemical data for the Sacramento River at Rio Vista , California, for the period of January to May, 1983 are presented in this report. Measurements include specific conductance, alkalinity, suspended particulate matter, and the dissolved inorganic nutrients; nitrite, nitrate plus nitrite, ammonium, dissolved silica, and ortho-phosphate. Numerical results are tabulated and details of the methods are described.

California↗
USGS1989

Approximate altitude of water levels in wells in the Chicot and Evangeline aquifers in the Houston area, Texas, spring 1989

This report shows the altitudes of water levels in the Chicot and Evangeline aquifers in the Houston metropolitan area, Texas. Of the 425 wells measured, 307 were used to construct the maps of potentiometric surface. The Chicot and Evangeline aquifers are composed of several sand layers, each with a separate potentiometric surface. These maps, however, show a single potentiometric surface which represents the collective water levels for the sand layers comprising each aquifer. Maps showing the altitudes of water levels have been published in many reports on ground-water development in the Houston area, the most recent of which (Gabrysch and others, 1988) presented maps of the altitudes of potentiometric surfaces for 1988.

Texas↗
USGS1989

Approximate water-level changes in wells completed in the Chicot and Evangeline aquifers, 1977-89 and 1988-89, and measured compaction, 1973-89, in the Houston-Galveston region, Texas

This report presents data on water-level changes in the Chinot and Evangeline aquifers during 1977-89 and 1988-89 and data on measured compaction during 1973-89. Measurements of water level in 307 wells were used to construct the maps showing water-level changes. Compaction data were obtained from 12 wells equipped with compaction monitors at 11 sites.

Texas↗
USGS1990

Approximate water-level changes in wells completed in the Chicot and Evangeline aquifers, 1977-90 and 1989-90, and measured compaction, 1973-December 1989, in the Houston-Galveston region, Texas

This report is one in a series of reports that depict water-level changes since 1977 and compaction of subsurface material since 1973. The report was prepared in cooperation with the City of Houston and the Harris-Galveston Coastal Subsidence District, and presents approximate water-level changes in wells in the Chicot and Evangeline aquifers, 1977-90 and 1989-90 (figs. 1-4), and measured compaction, 1973-December 1989 (figs. 5 and 6), in the Houston-Galveston region.

Texas↗
USGS1991

Approximate altitude of water levels in wells in the Chicot and Evangeline aquifers in the Houston area, Texas, January-February 1990

This report is one in a series of reports that depict altitudes of water levels since 1977, the most recent of which (Barbie and other, 1989) presented maps of the altitudes of water levels for 1989. This report was prepared in cooperation with the City of Houston and the Harris-Galveston Coastal Subsidence District, and presents approximate altitudes of water levels in wells in the Chicot and Evangeline aquifers in the Houston area, Texas, January-February 1990.

Open-File Report↗
USGS1991

Approximate water-level changes in wells completed in the Chicot and Evangeline aquifers, 1977-91 and 1990-91, and measured compaction, 1973-90, in the Houston-Galveston region, Texas

This report is one in a series of reports that depict water-level changes and compaction of subsurface material in the Houston-Galveston region. The maps present approximate water-level changes in wells in the Chicot and Evangeline aquifers, 1977-91 and 1990-91 (figs. 1-4). The location of borehole extensometers is shown in figure 5, and graphs present measured compation for 1973-90 (fig. 6).

Texas↗