Peter B McMahon
Peter is a Research Hydrologist with the USGS Colorado Water Science Center in Lakewood, CO.
Pete McMahon’s current research interests include understanding the effects of hydrocarbon production activities on groundwater quality and identifying natural and human processes that create regional- and national-scale patterns in the chemistry of groundwater. He uses geochemical, isotope, noble-gas, and groundwater-age tracers to understand the origin and fate of chemicals of concern in groundwater.
Education and Certifications
Ph.D., 1990, Geology, University of South Carolina at Columbia
M.A., 1984, Geology, University of Texas at Austin
B.S., 1981, Geology, University of Missouri at Columbia
Science and Products
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Groundwater chemistry and water-level elevations in bedrock aquifers of the Piceance and Yellow Creek watersheds, Rio Blanco County, Colorado, 2013–16
The Piceance and Yellow Creek watersheds in Rio Blanco County, Colorado, are known to contain important energy resources (oil shale and natural gas) and mineral resources (nahcolite). The primary sources of fresh groundwater in the Piceance and Yellow Creek watersheds are bedrock aquifers in the Uinta and Green River Formations. The aquifers are divided into an upper and lower aquifer separated by
Authors
Judith C. Thomas, Peter B. McMahon
Regional patterns in the geochemistry of oil-field water, southern San Joaquin Valley, California, USA
Chemical and isotopic data for water co-extracted with hydrocarbons in oil and gas fields are commonly used to examine the source of the formation water and possible impacts on groundwater in areas of oil and gas development. Understanding the geochemical variability of oil-field water could help to evaluate its origin and delineate possible contamination of shallow aquifers in cases where oil-fie
Authors
Peter B. McMahon, Justin T. Kulongoski, Avner Vengosh, Isabelle M. Cozzarelli, Matthew K. Landon, Yousif K. Kharaka, Janice M. Gillespie, Tracy Davis
Origin of methane and sources of high concentrations in Los Angeles groundwater
In 2014, samples from 37 monitoring wells at 17 locations, within or near oil fields, and one site >5 km from oil fields, in the Los Angeles Basin, California, were analyzed for dissolved hydrocarbon gas isotopes and abundances. The wells sample a variety of depths of an aquifer system composed of unconsolidated and semiconsolidated sediments under various conditions of confinement. Concentrations
Authors
Justin T. Kulongoski, Peter B. McMahon, Michael Land, Michael Wright, Theodore Johnson, Matthew K. Landon
Methane in groundwater from a leaking gas well, Piceance Basin, Colorado, USA
Site-specific and regional analysis of time-series hydrologic and geochemical data collected from 15 monitoring wells in the Piceance Basin indicated that a leaking gas well contaminated shallow groundwater with thermogenic methane. The gas well was drilled in 1956 and plugged and abandoned in 1990. Chemical and isotopic data showed the thermogenic methane was not from mixing of gas-rich formation
Authors
Peter B. McMahon, Judith C. Thomas, John T. Crawford, Mark M. Dornblaser, Andrew G. Hunt
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 U.S. were sampled to identify which aquifers contained high methane concentrations (>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 in the U.S. and, as such, advanc
Authors
Peter B. McMahon, Kenneth Belitz, Jeannie R. B. Barlow, Bryant C. Jurgens
Fraction of young water as an indicator of aquifer vulnerability along two regional flow paths in the Mississippi embayment aquifer system, southeastern USA
Wells along two regional flow paths were sampled to characterize changes in water quality and the vulnerability to contamination of the Memphis aquifer across a range of hydrologic and land-use conditions in the southeastern United States. The flow paths begin in the aquifer outcrop area and end at public supply wells in the confined parts of the aquifer at Memphis, Tennessee. Age-date tracer (e.g
Authors
James A. Kingsbury, Jeannie R. B. Barlow, Bryant C. Jurgens, Peter B. McMahon, John K. Carmichael
Methane and benzene in drinking-water wells overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas
Water wells (n = 116) overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas were sampled for chemical, isotopic, and groundwater-age tracers to investigate the occurrence and sources of selected hydrocarbons in groundwater. Methane isotopes and hydrocarbon gas compositions indicate most of the methane in the wells was biogenic and produced by the CO2 reduction
Authors
Peter B. McMahon, Jeannie R. B. Barlow, Mark A. Engle, Kenneth Belitz, Patricia B. Ging, Andrew G. Hunt, Bryant C. Jurgens, Yousif K. Kharaka, Roland W. Tollett, Timothy M. Kresse
Preliminary results from exploratory sampling of wells for the California oil, gas, and groundwater program, 2014–15
Introduction
In 2014 and 2015, the U.S. Geological Survey (USGS) sampled water wells in the Los Angeles Basin and southern San Joaquin Valley, California, and oil wells in the San Joaquin Valley for analysis of multiple chemical, isotopic, and groundwater-age tracers. The purpose of this reconnaissance sampling was to evaluate the utility of tracers for assessing the effects of oil and gas product
Authors
Peter B. McMahon, Justin T. Kulongoski, Michael T. Wright, Michael T. Land, Matthew K. Landon, Isabelle M. Cozzarelli, Avner Vengosh, George R. Aiken
Response of selenium concentrations in groundwater to seasonal canal leakage, lower Gunnison River Basin, Colorado, 2013
Selenium is a water-quality concern in the lower Gunnison River Basin because irrigation water interacting with seleniferous soils derived from the Mancos Shale Formation has mobilized selenium and increased its concentrations in surface water. Understanding the occurrence of elevated selenium concentrations in groundwater is necessary because groundwater discharge is an important source of seleni
Authors
J.I. Linard, P. B. McMahon, L. R. Arnold, J.C. Thomas
Chemical considerations for an updated National assessment of brackish groundwater resources
Brackish groundwater (BGW) is increasingly used for water supplies where fresh water is scarce, but the distribution and availability of such resources have not been characterized at the national scale in the United States since the 1960s. Apart from its distribution and accessibility, BGW usability is a function of the chemical requirements of the intended use, chemical characteristics of the res
Authors
Peter B. McMahon, John Karl Böhlke, Katharine Dahm, David L. Parkhurst, David W. Anning, Jennifer S. Stanton
The water-energy nexus: an earth science perspective
Water availability and use are closely connected with energy development and use. Water cannot be delivered to homes, businesses, and industries without energy, and most forms of energy development require large amounts of water. The United States faces two significant and sometimes competing challenges: to provide sustainable supplies of freshwater for humans and ecosystems and to ensure adequate
Authors
Richard W. Healy, William M. Alley, Mark A. Engle, Peter B. McMahon, Jerad D. Bales
The quality of our Nation's waters: Water quality in principal aquifers of the United States, 1991-2010
About 130 million people in the United States rely on groundwater for drinking water, and the need for high-quality drinking-water supplies becomes more urgent as our population grows. Although groundwater is a safe, reliable source of drinking water for millions of people nationwide, high concentrations of some chemical constituents can pose potential human-health concerns. Some of these contamin
Authors
Leslie A. DeSimone, Peter B. McMahon, Michael R. Rosen
Science and Products
Filter Total Items: 14
No Result Found
Filter Total Items: 116
Groundwater chemistry and water-level elevations in bedrock aquifers of the Piceance and Yellow Creek watersheds, Rio Blanco County, Colorado, 2013–16
The Piceance and Yellow Creek watersheds in Rio Blanco County, Colorado, are known to contain important energy resources (oil shale and natural gas) and mineral resources (nahcolite). The primary sources of fresh groundwater in the Piceance and Yellow Creek watersheds are bedrock aquifers in the Uinta and Green River Formations. The aquifers are divided into an upper and lower aquifer separated by
Authors
Judith C. Thomas, Peter B. McMahon
Regional patterns in the geochemistry of oil-field water, southern San Joaquin Valley, California, USA
Chemical and isotopic data for water co-extracted with hydrocarbons in oil and gas fields are commonly used to examine the source of the formation water and possible impacts on groundwater in areas of oil and gas development. Understanding the geochemical variability of oil-field water could help to evaluate its origin and delineate possible contamination of shallow aquifers in cases where oil-fie
Authors
Peter B. McMahon, Justin T. Kulongoski, Avner Vengosh, Isabelle M. Cozzarelli, Matthew K. Landon, Yousif K. Kharaka, Janice M. Gillespie, Tracy Davis
Origin of methane and sources of high concentrations in Los Angeles groundwater
In 2014, samples from 37 monitoring wells at 17 locations, within or near oil fields, and one site >5 km from oil fields, in the Los Angeles Basin, California, were analyzed for dissolved hydrocarbon gas isotopes and abundances. The wells sample a variety of depths of an aquifer system composed of unconsolidated and semiconsolidated sediments under various conditions of confinement. Concentrations
Authors
Justin T. Kulongoski, Peter B. McMahon, Michael Land, Michael Wright, Theodore Johnson, Matthew K. Landon
Methane in groundwater from a leaking gas well, Piceance Basin, Colorado, USA
Site-specific and regional analysis of time-series hydrologic and geochemical data collected from 15 monitoring wells in the Piceance Basin indicated that a leaking gas well contaminated shallow groundwater with thermogenic methane. The gas well was drilled in 1956 and plugged and abandoned in 1990. Chemical and isotopic data showed the thermogenic methane was not from mixing of gas-rich formation
Authors
Peter B. McMahon, Judith C. Thomas, John T. Crawford, Mark M. Dornblaser, Andrew G. Hunt
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 U.S. were sampled to identify which aquifers contained high methane concentrations (>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 in the U.S. and, as such, advanc
Authors
Peter B. McMahon, Kenneth Belitz, Jeannie R. B. Barlow, Bryant C. Jurgens
Fraction of young water as an indicator of aquifer vulnerability along two regional flow paths in the Mississippi embayment aquifer system, southeastern USA
Wells along two regional flow paths were sampled to characterize changes in water quality and the vulnerability to contamination of the Memphis aquifer across a range of hydrologic and land-use conditions in the southeastern United States. The flow paths begin in the aquifer outcrop area and end at public supply wells in the confined parts of the aquifer at Memphis, Tennessee. Age-date tracer (e.g
Authors
James A. Kingsbury, Jeannie R. B. Barlow, Bryant C. Jurgens, Peter B. McMahon, John K. Carmichael
Methane and benzene in drinking-water wells overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas
Water wells (n = 116) overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas were sampled for chemical, isotopic, and groundwater-age tracers to investigate the occurrence and sources of selected hydrocarbons in groundwater. Methane isotopes and hydrocarbon gas compositions indicate most of the methane in the wells was biogenic and produced by the CO2 reduction
Authors
Peter B. McMahon, Jeannie R. B. Barlow, Mark A. Engle, Kenneth Belitz, Patricia B. Ging, Andrew G. Hunt, Bryant C. Jurgens, Yousif K. Kharaka, Roland W. Tollett, Timothy M. Kresse
Preliminary results from exploratory sampling of wells for the California oil, gas, and groundwater program, 2014–15
Introduction
In 2014 and 2015, the U.S. Geological Survey (USGS) sampled water wells in the Los Angeles Basin and southern San Joaquin Valley, California, and oil wells in the San Joaquin Valley for analysis of multiple chemical, isotopic, and groundwater-age tracers. The purpose of this reconnaissance sampling was to evaluate the utility of tracers for assessing the effects of oil and gas product
Authors
Peter B. McMahon, Justin T. Kulongoski, Michael T. Wright, Michael T. Land, Matthew K. Landon, Isabelle M. Cozzarelli, Avner Vengosh, George R. Aiken
Response of selenium concentrations in groundwater to seasonal canal leakage, lower Gunnison River Basin, Colorado, 2013
Selenium is a water-quality concern in the lower Gunnison River Basin because irrigation water interacting with seleniferous soils derived from the Mancos Shale Formation has mobilized selenium and increased its concentrations in surface water. Understanding the occurrence of elevated selenium concentrations in groundwater is necessary because groundwater discharge is an important source of seleni
Authors
J.I. Linard, P. B. McMahon, L. R. Arnold, J.C. Thomas
Chemical considerations for an updated National assessment of brackish groundwater resources
Brackish groundwater (BGW) is increasingly used for water supplies where fresh water is scarce, but the distribution and availability of such resources have not been characterized at the national scale in the United States since the 1960s. Apart from its distribution and accessibility, BGW usability is a function of the chemical requirements of the intended use, chemical characteristics of the res
Authors
Peter B. McMahon, John Karl Böhlke, Katharine Dahm, David L. Parkhurst, David W. Anning, Jennifer S. Stanton
The water-energy nexus: an earth science perspective
Water availability and use are closely connected with energy development and use. Water cannot be delivered to homes, businesses, and industries without energy, and most forms of energy development require large amounts of water. The United States faces two significant and sometimes competing challenges: to provide sustainable supplies of freshwater for humans and ecosystems and to ensure adequate
Authors
Richard W. Healy, William M. Alley, Mark A. Engle, Peter B. McMahon, Jerad D. Bales
The quality of our Nation's waters: Water quality in principal aquifers of the United States, 1991-2010
About 130 million people in the United States rely on groundwater for drinking water, and the need for high-quality drinking-water supplies becomes more urgent as our population grows. Although groundwater is a safe, reliable source of drinking water for millions of people nationwide, high concentrations of some chemical constituents can pose potential human-health concerns. Some of these contamin
Authors
Leslie A. DeSimone, Peter B. McMahon, Michael R. Rosen