Peter B McMahon (Former Employee)
Science and Products
Oxidation/Reduction (Redox)
The redox state of groundwater—whether the groundwater is oxic (oxidized) or anoxic (reduced)—has profound implications for groundwater quality. Knowing the redox conditions of groundwater can help determine whether it contains elevated levels of many contaminants, including arsenic, nitrate, and even some manmade contaminants.
Groundwater Quality in Principal Aquifers of the United States, 1991—2010
A new U.S. Geological Survey (USGS) report summarizes the major findings of national and regional assessments of groundwater quality in 40 Principal Aquifers in the United States. Knowledge of contaminant occurrence and the factors that control contaminant concentrations can ensure the availability and quality of this vital natural resource in the future.
Developing the next generation of USGS resource assessments
Resource assessments constitute a key part of the USGS mission, and represent a crucial contribution toward Department of the Interior (DOI) and broader Federal objectives. Current USGS energy and mineral assessment methods evaluate total technically recoverable resources (energy) or economically exploitable materials (minerals); the fiscal year 2010 budget for this work is $82M. To help...
NAWQA High Plains Regional Groundwater Study
As part of the National Water Quality Assessment Program (NAWQA), the USGS has evaluated ground-water quality in the High Plains aquifer system. Beginning in 1999 and continuing for a period of 6 years, the High Plains Regional Groundwater Study intensively investigated the quality of groundwater resources within the study area. Water quality impairment coupled with water-level declines focus...
NAWQA South Platte River Basin Study
The South Platte River Basin study, conducted as part of the U.S. Geological Survey's National Water-Quality Assessment Program, combines information on water chemistry, physical characteristics, stream habitat, and aquatic life to provide science-based insights for current and emerging water issues in surface waters (streams, rivers, reservoirs) and groundwaters of the South Platte River Basin...
Filter Total Items: 14
Produced water chemistry data collected from the Poso Creek, Midway-Sunset, and Buena Vista Oil Fields, 2020-21, Kern County, California
The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board collected produced water and gas samples in the Midway-Sunset, Poso Creek, and Buena Vista Oil Fields in Kern County in 2020 and 2021. Sampled sites included oil wells; injectate from tanks, pipelines, and injection wells where produced water from many wells, after removal of oil, is...
Water Chemistry data for samples collected at groundwater sites in the Poso Creek Oil Field study area, February 2020-December 2021, Kern County, California
The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in...
Oil well annular cement and casing damage data in mature oil fields undergoing hydraulic fracturing, South Belridge and Lost Hills Oil Fields, California
This data release contains oil well annular cement and casing damage data from parts of the South Belridge and Lost Hills Oil Fields in western Kern County, California. The study area coincides with where groundwater with less than 10,000 milligrams per liter total dissolved solids and outside an exempt aquifer are located overlying oil-producing zones in these fields. In the study areas...
Groundwater elevation data and models in and around select California oil fields (ver. 2.0, May 2024)
This data release contains groundwater elevation data and the associated model/code used to create groundwater elevation surfaces in and around select oil fields in California. The data and model provided here are intended to supplement interpretative manuscripts. Specific study areas will be added as Child Items found in this data release. Groundwater elevations are usually collected...
Data for Distribution of Groundwater Age in Aquifers Used for Public Supply in the Continental United States, 2004 - 2017 (Version 1.1: June 2022)
This data release documents seven tables that contain environmental tracer data and lumped parameter model (LPM) results that are used for assessing the distribution of groundwater age in 21 Principal Aquifers of the continental United States. Groundwater samples were collected from 1,279 sites and analyzed for environmental tracers: tritium, tritiogenic helium-3, sulfur hexafluoride...
Geochemical and Geospatial Data for Per- and Polyfluoroalkyl Substances (PFAS) in Groundwater Used As a Source of Drinking Water in the Eastern United States
Concentrations of inorganic constituents, dissolved organic carbon (DOC), tritium, per- and polyfluoroalkyl substances (PFAS), volatile organic compounds (VOCs), and pharmaceuticals were measured in groundwater samples collected from 254 wells in 2019 and 2020. Concentrations of inorganic constituents, DOC, VOCs, and pharmaceuticals were measured at the U.S. Geological Survey (USGS)...
Quality-Control Data for Volatile Organic Compounds and Environmental Sulfur-Hexafluoride Data for Groundwater Samples from the Williston Basin, USA
In 2018, groundwater samples were collected from aquifers in the Williston Basin in parts of eastern Montana, western North Dakota, and northwestern South Dakota. This dataset includes quality-control data for volatile organic compounds that include data for source-solution blanks and field blanks. The dataset also includes data for sulfur hexafluoride in environmental samples of...
Data for Fluoride Occurrence in United States Groundwater
Data from 38,105 wells were used to characterize fluoride occurrence in untreated United States groundwater. The data were retrieved from the U.S. Geological Survey (USGS) National Water Information System (NWIS). Groundwater samples were collected from 1988 to 2017 in the conterminous United States. Data for groundwater included in this dataset are pH, water temperature, and...
Data Release for Hydrocarbons in Upland Groundwater, Marcellus Shale Region, Northeastern Pennsylvania and Southern New York, USA
Water samples from 50 domestic wells located 1 km (distal) from shale-gas wells in upland areas of the Marcellus Shale region were analyzed for chemical, isotopic and groundwater-age tracers. Uplands were targeted because natural mixing with brine and hydrocarbons from deep formations is less common in those areas compared to valleys. Methane (CH4) -isotope and pre-drill CH4 data...
Data for Elevated Manganese Concentrations in United States Groundwater, Role of Land Surface-Soil-Aquifer Connections
Chemical data from 43,334 wells were used to examine the role of land surface-soil-aquifer connections in producing elevated manganese concentrations (>300 microgram/L) in United States (U.S.) groundwater. Elevated manganese and dissolved organic carbon (DOC) concentrations were associated with shallow water tables and organic-carbon rich soils, suggesting soil-derived DOC supported...
Well characteristics, water quality and age-date tracer data for wells along two regional flow paths in the Memphis aquifer, southwest Tennessee
In 2013, water-quality and age-date tracer samples were collected at wells located along two flow paths in the Memphis aquifer, southwest Tennessee, as part of the National Water Quality Assessment (NAWQA) Project of the National Water-Quality Program to better understand the vulnerability of the aquifer to contamination.. Each flow path began in the aquifer outcrop area (shallow well...
Data from Methane in Aquifers Used for Public Supply in the United States
In 2013 to 2015, 833 public supply wells in 15 Principal aquifers in the United States were sampled to identify which aquifers contained high methane concentrations (greater than 1 mg/L) and determine the geologic, hydrologic, and geochemical conditions associated with high concentrations. This study represents the first national assessment of methane in aquifers used for public supply...
Filter Total Items: 118
Groundwater quality near the Placerita Oil Field, California, 2018
Groundwater-quality data and potential fluid-migration pathways near the Placerita Oil Field in Los Angeles County, California, were examined by the U.S. Geological Survey to determine if oil-field fluids (water and gas from oil-producing and non-producing zones) have mixed with groundwater resources. Six of the 13 new groundwater samples collected for this study contained petroleum...
Authors
Jennifer S. Stanton, Matthew K. Landon, David H. Schoellhamer, Justin T. Kulongoski, Andrew G. Hunt, Peter B. McMahon, Isabelle M. Cozzarelli, Robert Anders, Theron A. Sowers
Assessing potential effects of oil and gas development activities on groundwater quality near and overlying the Elk Hills and North Coles Levee Oil Fields, San Joaquin Valley, California
Groundwater resources are utilized near areas of intensive oil and gas development in California’s San Joaquin Valley. In this study, we examined chemical and isotopic data to assess if thermogenic gas or saline water from oil producing formations have mixed with groundwater near the Elk Hills and North Coles Levee Oil Fields in the southwestern San Joaquin Valley. Major ion...
Authors
John G. Warden, Matthew K. Landon, Michael J. Stephens, Tracy Davis, Janice M. Gillespie, Peter B. McMahon, Justin T. Kulongoski, Andrew G. Hunt, David H. Schoellhamer, Riley Gannon, Lyndsay B. Ball
Land-use interactions, Oil-Field infrastructure, and natural processes control hydrocarbon and arsenic concentrations in groundwater, Poso Creek Oil Field, California, USA
Like many hydrocarbon production areas in the U.S., the Poso Creek Oil Field in California includes and is adjacent to other land uses (agricultural and other developed lands) that affect the hydrology and geochemistry of the aquifer overlying and adjacent to oil development. We hypothesize that the distributions of hydrocarbons and arsenic in groundwater in such areas will be controlled...
Authors
Peter B. McMahon, Matthew K. Landon, Michael J. Stephens, Kimberly A. Taylor, Michael Wright, Angela Hansen, Tamara E. C. Kraus, Isabelle M. Cozzarelli, David H. Schoellhamer, Theron A. Sowers, Justin T. Kulongoski, Andrew G. Hunt, Ruta Karolyte, Darren J. Hillegonds, Chris J. Ballentine
Spectral characterization of dissolved organic matter in groundwater to assess mixing with oil-field water near selected oil fields, southern California
Samples of oil-field water (oil wells, injectate, disposal ponds) and groundwater near selected oil and gas fields in southern California were analyzed for dissolved organic carbon (DOC) concentration and by optical spectroscopic techniques (i.e., absorbance and fluorescence) to assess whether these measurements can be used to distinguish between oil-field water (Oil Field), native...
Authors
Angela Hansen, Tamara E. C. Kraus, Matthew K. Landon, Peter B. McMahon
Fluid migration pathways to groundwater in mature oil fields: Exploring the roles of water injection/production and oil-well integrity in California, USA
Mature oil fields potentially contain multiple fluid migration pathways toward protected groundwater (total dissolved solids, TDS, in nonexempted aquifer
Authors
Peter B. McMahon, Matthew K. Landon, Michael J. Stephens, Kimberly A. Taylor, Janice M. Gillespie, Tracy Davis, David H. Schoellhamer
Multiple-well monitoring site within the Poso Creek Oil Field, Kern County, California
IntroductionThe Poso Creek Oil Field is one of the many fields selected for regional groundwater mapping and monitoring by the California State Water Resources Control Board as part of the Oil and Gas Regional Monitoring Program (RMP; California State Water Resources Control Board, 2015, 2022b; U.S. Geological Survey, 2022a). The U.S. Geological Survey (USGS), in cooperation with the...
Authors
Rhett R. Everett, Peter B. McMahon, Michael J. Stephens, Janice M. Gillespie, Mackenzie M. Shepherd, Nicole C. Fenton
Groundwater quality near the Montebello Oil Field, Los Angeles County, California
Groundwater quality and potential sources and migration pathways of chemical constituents associated with hydrocarbon-bearing formations were assessed by the U.S. Geological Survey for the California State Water Resources Control Board Oil and Gas Regional Monitoring Program (RMP). Groundwater samples were collected as part of the RMP from 21 preexisting wells used for public supply...
Authors
Jennifer S. Stanton, Michael Land, Matthew K. Landon, David H. Schoellhamer, Peter B. McMahon, Tracy Davis, Andrew G. Hunt, Theron A. Sowers
Quality of groundwater used for public supply in the continental United States: A comprehensive assessment
The presence of contaminants in a source water can constrain its suitability for drinking. The quality of groundwater used for public supply was assessed in 25 principal aquifers (PAs) that account for 84% of groundwater pumped for public supply in the U.S. (89.6 million people on a proportional basis). Each PA was sampled across its lateral extent using an equal-area grid, typically...
Authors
Kenneth Belitz, Miranda Fram, Bruce Lindsey, Paul E. Stackelberg, Laura M. Bexfield, Tyler Johnson, Bryant Jurgens, James A. Kingsbury, Peter B. McMahon, Neil Dubrovsky
Over a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination
The distribution of groundwater age is useful for evaluating the susceptibility and sustainability of groundwater resources. Here, we compute the aquifer-scale cumulative distribution function to characterize the age distribution for 21 Principal Aquifers that account for ~80% of public-supply pumping in the United States. The aquifer-scale cumulative distribution function for each...
Authors
Bryant Jurgens, Kirsten Faulkner, Peter B. McMahon, Andrew G. Hunt, Gerolamo C. Casile, Megan B. Young, Kenneth Belitz
Occurrence of water and thermogenic gas from oil-bearing formations in groundwater near the Orcutt Oil Field, California, USA
Study regionSanta Barbara County, California, USA.Study focusTo analyze a wide array of newly collected chemical, isotopic, dissolved gas, and age dating tracers in conjunction with historical data from groundwater and oil wells to determine if water and/or thermogenic gas from oil-bearing formations have mixed with groundwater in the Orcutt Oil Field and surrounding area.New...
Authors
Robert Anders, Matthew K. Landon, Peter B. McMahon, Justin T. Kulongoski, Andrew G. Hunt, Tracy Davis
Perfluoroalkyl and polyfluoroalkyl substances in groundwater used as a source of drinking water in the eastern United States
In 2019, 254 samples were collected from five aquifer systems to evaluate per- and polyfluoroalkyl substance (PFAS) occurrence in groundwater used as a source of drinking water in the eastern United States. The samples were analyzed for 24 PFAS, major ions, nutrients, trace elements, dissolved organic carbon (DOC), volatile organic compounds (VOCs), pharmaceuticals, and tritium. Fourteen...
Authors
Peter B. McMahon, Andrea K. Tokranov, Laura M. Bexfield, Bruce Lindsey, Tyler Johnson, Melissa Lombard, Elise Watson
Predicting regional fluoride concentrations at public and domestic supply depths in basin-fill aquifers of the western United States using a random forest model
A random forest regression (RFR) model was applied to over 12,000 wells with measured fluoride (F) concentrations in untreated groundwater to predict F concentrations at depths used for domestic and public supply in basin-fill aquifers of the western United States. The model relied on twenty-two regional-scale environmental and surficial predictor variables selected to represent factors...
Authors
Celia Zamora, Kenneth Belitz, Katherine Marie Ransom, Peter B. McMahon, Paul E. Stackelberg
Science and Products
Oxidation/Reduction (Redox)
The redox state of groundwater—whether the groundwater is oxic (oxidized) or anoxic (reduced)—has profound implications for groundwater quality. Knowing the redox conditions of groundwater can help determine whether it contains elevated levels of many contaminants, including arsenic, nitrate, and even some manmade contaminants.
Groundwater Quality in Principal Aquifers of the United States, 1991—2010
A new U.S. Geological Survey (USGS) report summarizes the major findings of national and regional assessments of groundwater quality in 40 Principal Aquifers in the United States. Knowledge of contaminant occurrence and the factors that control contaminant concentrations can ensure the availability and quality of this vital natural resource in the future.
Developing the next generation of USGS resource assessments
Resource assessments constitute a key part of the USGS mission, and represent a crucial contribution toward Department of the Interior (DOI) and broader Federal objectives. Current USGS energy and mineral assessment methods evaluate total technically recoverable resources (energy) or economically exploitable materials (minerals); the fiscal year 2010 budget for this work is $82M. To help...
NAWQA High Plains Regional Groundwater Study
As part of the National Water Quality Assessment Program (NAWQA), the USGS has evaluated ground-water quality in the High Plains aquifer system. Beginning in 1999 and continuing for a period of 6 years, the High Plains Regional Groundwater Study intensively investigated the quality of groundwater resources within the study area. Water quality impairment coupled with water-level declines focus...
NAWQA South Platte River Basin Study
The South Platte River Basin study, conducted as part of the U.S. Geological Survey's National Water-Quality Assessment Program, combines information on water chemistry, physical characteristics, stream habitat, and aquatic life to provide science-based insights for current and emerging water issues in surface waters (streams, rivers, reservoirs) and groundwaters of the South Platte River Basin...
Filter Total Items: 14
Produced water chemistry data collected from the Poso Creek, Midway-Sunset, and Buena Vista Oil Fields, 2020-21, Kern County, California
The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board collected produced water and gas samples in the Midway-Sunset, Poso Creek, and Buena Vista Oil Fields in Kern County in 2020 and 2021. Sampled sites included oil wells; injectate from tanks, pipelines, and injection wells where produced water from many wells, after removal of oil, is...
Water Chemistry data for samples collected at groundwater sites in the Poso Creek Oil Field study area, February 2020-December 2021, Kern County, California
The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in...
Oil well annular cement and casing damage data in mature oil fields undergoing hydraulic fracturing, South Belridge and Lost Hills Oil Fields, California
This data release contains oil well annular cement and casing damage data from parts of the South Belridge and Lost Hills Oil Fields in western Kern County, California. The study area coincides with where groundwater with less than 10,000 milligrams per liter total dissolved solids and outside an exempt aquifer are located overlying oil-producing zones in these fields. In the study areas...
Groundwater elevation data and models in and around select California oil fields (ver. 2.0, May 2024)
This data release contains groundwater elevation data and the associated model/code used to create groundwater elevation surfaces in and around select oil fields in California. The data and model provided here are intended to supplement interpretative manuscripts. Specific study areas will be added as Child Items found in this data release. Groundwater elevations are usually collected...
Data for Distribution of Groundwater Age in Aquifers Used for Public Supply in the Continental United States, 2004 - 2017 (Version 1.1: June 2022)
This data release documents seven tables that contain environmental tracer data and lumped parameter model (LPM) results that are used for assessing the distribution of groundwater age in 21 Principal Aquifers of the continental United States. Groundwater samples were collected from 1,279 sites and analyzed for environmental tracers: tritium, tritiogenic helium-3, sulfur hexafluoride...
Geochemical and Geospatial Data for Per- and Polyfluoroalkyl Substances (PFAS) in Groundwater Used As a Source of Drinking Water in the Eastern United States
Concentrations of inorganic constituents, dissolved organic carbon (DOC), tritium, per- and polyfluoroalkyl substances (PFAS), volatile organic compounds (VOCs), and pharmaceuticals were measured in groundwater samples collected from 254 wells in 2019 and 2020. Concentrations of inorganic constituents, DOC, VOCs, and pharmaceuticals were measured at the U.S. Geological Survey (USGS)...
Quality-Control Data for Volatile Organic Compounds and Environmental Sulfur-Hexafluoride Data for Groundwater Samples from the Williston Basin, USA
In 2018, groundwater samples were collected from aquifers in the Williston Basin in parts of eastern Montana, western North Dakota, and northwestern South Dakota. This dataset includes quality-control data for volatile organic compounds that include data for source-solution blanks and field blanks. The dataset also includes data for sulfur hexafluoride in environmental samples of...
Data for Fluoride Occurrence in United States Groundwater
Data from 38,105 wells were used to characterize fluoride occurrence in untreated United States groundwater. The data were retrieved from the U.S. Geological Survey (USGS) National Water Information System (NWIS). Groundwater samples were collected from 1988 to 2017 in the conterminous United States. Data for groundwater included in this dataset are pH, water temperature, and...
Data Release for Hydrocarbons in Upland Groundwater, Marcellus Shale Region, Northeastern Pennsylvania and Southern New York, USA
Water samples from 50 domestic wells located 1 km (distal) from shale-gas wells in upland areas of the Marcellus Shale region were analyzed for chemical, isotopic and groundwater-age tracers. Uplands were targeted because natural mixing with brine and hydrocarbons from deep formations is less common in those areas compared to valleys. Methane (CH4) -isotope and pre-drill CH4 data...
Data for Elevated Manganese Concentrations in United States Groundwater, Role of Land Surface-Soil-Aquifer Connections
Chemical data from 43,334 wells were used to examine the role of land surface-soil-aquifer connections in producing elevated manganese concentrations (>300 microgram/L) in United States (U.S.) groundwater. Elevated manganese and dissolved organic carbon (DOC) concentrations were associated with shallow water tables and organic-carbon rich soils, suggesting soil-derived DOC supported...
Well characteristics, water quality and age-date tracer data for wells along two regional flow paths in the Memphis aquifer, southwest Tennessee
In 2013, water-quality and age-date tracer samples were collected at wells located along two flow paths in the Memphis aquifer, southwest Tennessee, as part of the National Water Quality Assessment (NAWQA) Project of the National Water-Quality Program to better understand the vulnerability of the aquifer to contamination.. Each flow path began in the aquifer outcrop area (shallow well...
Data from Methane in Aquifers Used for Public Supply in the United States
In 2013 to 2015, 833 public supply wells in 15 Principal aquifers in the United States were sampled to identify which aquifers contained high methane concentrations (greater than 1 mg/L) and determine the geologic, hydrologic, and geochemical conditions associated with high concentrations. This study represents the first national assessment of methane in aquifers used for public supply...
Filter Total Items: 118
Groundwater quality near the Placerita Oil Field, California, 2018
Groundwater-quality data and potential fluid-migration pathways near the Placerita Oil Field in Los Angeles County, California, were examined by the U.S. Geological Survey to determine if oil-field fluids (water and gas from oil-producing and non-producing zones) have mixed with groundwater resources. Six of the 13 new groundwater samples collected for this study contained petroleum...
Authors
Jennifer S. Stanton, Matthew K. Landon, David H. Schoellhamer, Justin T. Kulongoski, Andrew G. Hunt, Peter B. McMahon, Isabelle M. Cozzarelli, Robert Anders, Theron A. Sowers
Assessing potential effects of oil and gas development activities on groundwater quality near and overlying the Elk Hills and North Coles Levee Oil Fields, San Joaquin Valley, California
Groundwater resources are utilized near areas of intensive oil and gas development in California’s San Joaquin Valley. In this study, we examined chemical and isotopic data to assess if thermogenic gas or saline water from oil producing formations have mixed with groundwater near the Elk Hills and North Coles Levee Oil Fields in the southwestern San Joaquin Valley. Major ion...
Authors
John G. Warden, Matthew K. Landon, Michael J. Stephens, Tracy Davis, Janice M. Gillespie, Peter B. McMahon, Justin T. Kulongoski, Andrew G. Hunt, David H. Schoellhamer, Riley Gannon, Lyndsay B. Ball
Land-use interactions, Oil-Field infrastructure, and natural processes control hydrocarbon and arsenic concentrations in groundwater, Poso Creek Oil Field, California, USA
Like many hydrocarbon production areas in the U.S., the Poso Creek Oil Field in California includes and is adjacent to other land uses (agricultural and other developed lands) that affect the hydrology and geochemistry of the aquifer overlying and adjacent to oil development. We hypothesize that the distributions of hydrocarbons and arsenic in groundwater in such areas will be controlled...
Authors
Peter B. McMahon, Matthew K. Landon, Michael J. Stephens, Kimberly A. Taylor, Michael Wright, Angela Hansen, Tamara E. C. Kraus, Isabelle M. Cozzarelli, David H. Schoellhamer, Theron A. Sowers, Justin T. Kulongoski, Andrew G. Hunt, Ruta Karolyte, Darren J. Hillegonds, Chris J. Ballentine
Spectral characterization of dissolved organic matter in groundwater to assess mixing with oil-field water near selected oil fields, southern California
Samples of oil-field water (oil wells, injectate, disposal ponds) and groundwater near selected oil and gas fields in southern California were analyzed for dissolved organic carbon (DOC) concentration and by optical spectroscopic techniques (i.e., absorbance and fluorescence) to assess whether these measurements can be used to distinguish between oil-field water (Oil Field), native...
Authors
Angela Hansen, Tamara E. C. Kraus, Matthew K. Landon, Peter B. McMahon
Fluid migration pathways to groundwater in mature oil fields: Exploring the roles of water injection/production and oil-well integrity in California, USA
Mature oil fields potentially contain multiple fluid migration pathways toward protected groundwater (total dissolved solids, TDS, in nonexempted aquifer
Authors
Peter B. McMahon, Matthew K. Landon, Michael J. Stephens, Kimberly A. Taylor, Janice M. Gillespie, Tracy Davis, David H. Schoellhamer
Multiple-well monitoring site within the Poso Creek Oil Field, Kern County, California
IntroductionThe Poso Creek Oil Field is one of the many fields selected for regional groundwater mapping and monitoring by the California State Water Resources Control Board as part of the Oil and Gas Regional Monitoring Program (RMP; California State Water Resources Control Board, 2015, 2022b; U.S. Geological Survey, 2022a). The U.S. Geological Survey (USGS), in cooperation with the...
Authors
Rhett R. Everett, Peter B. McMahon, Michael J. Stephens, Janice M. Gillespie, Mackenzie M. Shepherd, Nicole C. Fenton
Groundwater quality near the Montebello Oil Field, Los Angeles County, California
Groundwater quality and potential sources and migration pathways of chemical constituents associated with hydrocarbon-bearing formations were assessed by the U.S. Geological Survey for the California State Water Resources Control Board Oil and Gas Regional Monitoring Program (RMP). Groundwater samples were collected as part of the RMP from 21 preexisting wells used for public supply...
Authors
Jennifer S. Stanton, Michael Land, Matthew K. Landon, David H. Schoellhamer, Peter B. McMahon, Tracy Davis, Andrew G. Hunt, Theron A. Sowers
Quality of groundwater used for public supply in the continental United States: A comprehensive assessment
The presence of contaminants in a source water can constrain its suitability for drinking. The quality of groundwater used for public supply was assessed in 25 principal aquifers (PAs) that account for 84% of groundwater pumped for public supply in the U.S. (89.6 million people on a proportional basis). Each PA was sampled across its lateral extent using an equal-area grid, typically...
Authors
Kenneth Belitz, Miranda Fram, Bruce Lindsey, Paul E. Stackelberg, Laura M. Bexfield, Tyler Johnson, Bryant Jurgens, James A. Kingsbury, Peter B. McMahon, Neil Dubrovsky
Over a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination
The distribution of groundwater age is useful for evaluating the susceptibility and sustainability of groundwater resources. Here, we compute the aquifer-scale cumulative distribution function to characterize the age distribution for 21 Principal Aquifers that account for ~80% of public-supply pumping in the United States. The aquifer-scale cumulative distribution function for each...
Authors
Bryant Jurgens, Kirsten Faulkner, Peter B. McMahon, Andrew G. Hunt, Gerolamo C. Casile, Megan B. Young, Kenneth Belitz
Occurrence of water and thermogenic gas from oil-bearing formations in groundwater near the Orcutt Oil Field, California, USA
Study regionSanta Barbara County, California, USA.Study focusTo analyze a wide array of newly collected chemical, isotopic, dissolved gas, and age dating tracers in conjunction with historical data from groundwater and oil wells to determine if water and/or thermogenic gas from oil-bearing formations have mixed with groundwater in the Orcutt Oil Field and surrounding area.New...
Authors
Robert Anders, Matthew K. Landon, Peter B. McMahon, Justin T. Kulongoski, Andrew G. Hunt, Tracy Davis
Perfluoroalkyl and polyfluoroalkyl substances in groundwater used as a source of drinking water in the eastern United States
In 2019, 254 samples were collected from five aquifer systems to evaluate per- and polyfluoroalkyl substance (PFAS) occurrence in groundwater used as a source of drinking water in the eastern United States. The samples were analyzed for 24 PFAS, major ions, nutrients, trace elements, dissolved organic carbon (DOC), volatile organic compounds (VOCs), pharmaceuticals, and tritium. Fourteen...
Authors
Peter B. McMahon, Andrea K. Tokranov, Laura M. Bexfield, Bruce Lindsey, Tyler Johnson, Melissa Lombard, Elise Watson
Predicting regional fluoride concentrations at public and domestic supply depths in basin-fill aquifers of the western United States using a random forest model
A random forest regression (RFR) model was applied to over 12,000 wells with measured fluoride (F) concentrations in untreated groundwater to predict F concentrations at depths used for domestic and public supply in basin-fill aquifers of the western United States. The model relied on twenty-two regional-scale environmental and surficial predictor variables selected to represent factors...
Authors
Celia Zamora, Kenneth Belitz, Katherine Marie Ransom, Peter B. McMahon, Paul E. Stackelberg