Michael J Stephens
Michael J. Stephens is a Research Hydrologist with the USGS California Water Science Center, working in the Groundwater program area.
Michael's research focuses on water resources, particularly groundwater in sedimentary basins. He develops subsurface models of hydrogeologic systems including groundwater salinity, stratigraphy, porosity, temperature, and fault zones which help identify water resources.
Professional Experience
Research Hydrologist, USGS, 2022-present
Hydrologist, USGS, 2017-2022
Education and Certifications
MS, Geology, California State University, Sacramento, 2017
BS, Geology, University of Southern Indiana, 2015
Science and Products
Data and model for mapping groundwater total dissolved solids at the San Ardo Oil Field, Monterey County, California, USA Data and model for mapping groundwater total dissolved solids at the San Ardo Oil Field, Monterey County, California, USA
The U.S. Geological Survey (USGS) compiled and analyzed data for mapping groundwater total dissolved solids (TDS) at the San Ardo Oil Field in Monterey County, California. Data include groundwater TDS and bicarbonate concentration from oil well and groundwater well samples, formation resistivity from borehole geophysical logs, porosity from well logs and rock core samples, temperature...
Groundwater elevation data and models in and around select California oil fields (ver. 3.0, September 2025) Groundwater elevation data and models in and around select California oil fields (ver. 3.0, September 2025)
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...
Idle well fluid measurements for oil and gas wells in California Idle well fluid measurements for oil and gas wells in California
This dataset consists of 119,494 lines of data consisting of idle well fluid level depth, auxiliary measurements, and well parameters from California oil and gas wells that were reported to the California Department of Conservation, Geologic Energy Management Division (CalGEM). The dataset was provided by CalGEM in March 2018 and includes measurements made from 1976 to 2018. There are 5...
Geological, geochemical, and geophysical data from the Lost Hills and Belridge oil fields Geological, geochemical, and geophysical data from the Lost Hills and Belridge oil fields
The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board compiled and analyzed data for mapping groundwater salinity and characterizing aquifer systems in and near selected oil and gas fields in California. Data for the Lost Hills, North Belridge, and South Belridge oil fields include production and injection volumes, oil show data...
Geophysical and geological data for select petroleum wells in North Coles Levee Oil Field, Kern County, California Geophysical and geological data for select petroleum wells in North Coles Levee Oil Field, Kern County, California
This dataset includes geological and geophysical data from petroleum wells located in the North Coles Levee Oil Field, Kern County, California. The purpose of this dataset is to describe groundwater salinity trends and the related geological controls. These data are used in an interpretive manuscript that characterizes a salinity inversion (lower-salinities found below higher-salinities)...
Geophysical, geological, hydrological, and geochemical data for aquifer salinity mapping in the Elk Hills, Buena Vista, and Coles Levee Oil Fields, Kern County, California Geophysical, geological, hydrological, and geochemical data for aquifer salinity mapping in the Elk Hills, Buena Vista, and Coles Levee Oil Fields, Kern County, California
The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (State Water Board) compiled and analyzed data for mapping groundwater salinity, characterizing aquifer systems, and documenting the effects of oil field water injection in the Elk Hills Elk Hills, Buena Vista, and Coles Levee Oil Fields, San Joaquin Valley, California. Data provided...
Filter Total Items: 15
Relations of groundwater quality to long-term surface disposal of produced water near the Midway-Sunset and Buena Vista Oil Fields, California, USA Relations of groundwater quality to long-term surface disposal of produced water near the Midway-Sunset and Buena Vista Oil Fields, California, USA
Contamination of groundwater by oil-field fluids in proximity to oil and gas development has been an issue of concern to water users and regulators given long histories of development and legacy disposal practices. A robust set of geochemical tracers including petroleum hydrocarbon compounds, thermogenic gases, inorganic ion concentrations, stable isotopes, radioactive isotopes, and...
Authors
Riley Gannon, Matthew K. Landon, Justin T. Kulongoski, Michael J. Stephens, Lyndsay B. Ball, John G. Warden, Tracy Davis, Janice M. Gillespie, Isabelle M. Cozzarelli
A joint Gaussian process model of geochemistry, geophysics, and temperature for groundwater TDS in the San Ardo Oil Field, California, USA A joint Gaussian process model of geochemistry, geophysics, and temperature for groundwater TDS in the San Ardo Oil Field, California, USA
Decline in availability of fresh groundwater has expanded interest in brackish groundwater resources; however, the distribution of brackish groundwater is poorly understood. Water resources in sedimentary basins across the United States often overlie oil and gas development. Mapping of groundwater total dissolved solids (TDS) using data from oil well geophysical logs has become an...
Authors
Michael J. Stephens, Will Chang, David H. Shimabukuro, Amanda Howery, Theron Sowers, Janice M. Gillespie
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 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. Shimabukuro, 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 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. Shimabukuro, Theron A. Sowers, Justin T. Kulongoski, Andrew G. Hunt, Ruta Karolyte, Darren J. Hillegonds, Chris J. Ballentine
Fluid migration pathways to groundwater in mature oil fields: Exploring the roles of water injection/production and oil-well integrity in California, USA 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 10 m of uncemented annulus that straddles oil-well casing damage and/or the base of groundwater with TDS
Authors
Peter B. McMahon, Matthew K. Landon, Michael J. Stephens, Kimberly A. Taylor, Janice M. Gillespie, Tracy Davis, David H. Shimabukuro
Multiple-well monitoring site within the Poso Creek Oil Field, Kern County, California Multiple-well monitoring site within the Poso Creek Oil Field, Kern County, California
Introduction The 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
Geostat: Model space-time data with Gaussian processes Geostat: Model space-time data with Gaussian processes
Model space-time data with Gaussian processes. Geostat makes it easy to implement Gaussian Process (GP) models with complex covariance functions and has built-in capabilities for geoscience problems.
Science and Products
Data and model for mapping groundwater total dissolved solids at the San Ardo Oil Field, Monterey County, California, USA Data and model for mapping groundwater total dissolved solids at the San Ardo Oil Field, Monterey County, California, USA
The U.S. Geological Survey (USGS) compiled and analyzed data for mapping groundwater total dissolved solids (TDS) at the San Ardo Oil Field in Monterey County, California. Data include groundwater TDS and bicarbonate concentration from oil well and groundwater well samples, formation resistivity from borehole geophysical logs, porosity from well logs and rock core samples, temperature...
Groundwater elevation data and models in and around select California oil fields (ver. 3.0, September 2025) Groundwater elevation data and models in and around select California oil fields (ver. 3.0, September 2025)
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...
Idle well fluid measurements for oil and gas wells in California Idle well fluid measurements for oil and gas wells in California
This dataset consists of 119,494 lines of data consisting of idle well fluid level depth, auxiliary measurements, and well parameters from California oil and gas wells that were reported to the California Department of Conservation, Geologic Energy Management Division (CalGEM). The dataset was provided by CalGEM in March 2018 and includes measurements made from 1976 to 2018. There are 5...
Geological, geochemical, and geophysical data from the Lost Hills and Belridge oil fields Geological, geochemical, and geophysical data from the Lost Hills and Belridge oil fields
The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board compiled and analyzed data for mapping groundwater salinity and characterizing aquifer systems in and near selected oil and gas fields in California. Data for the Lost Hills, North Belridge, and South Belridge oil fields include production and injection volumes, oil show data...
Geophysical and geological data for select petroleum wells in North Coles Levee Oil Field, Kern County, California Geophysical and geological data for select petroleum wells in North Coles Levee Oil Field, Kern County, California
This dataset includes geological and geophysical data from petroleum wells located in the North Coles Levee Oil Field, Kern County, California. The purpose of this dataset is to describe groundwater salinity trends and the related geological controls. These data are used in an interpretive manuscript that characterizes a salinity inversion (lower-salinities found below higher-salinities)...
Geophysical, geological, hydrological, and geochemical data for aquifer salinity mapping in the Elk Hills, Buena Vista, and Coles Levee Oil Fields, Kern County, California Geophysical, geological, hydrological, and geochemical data for aquifer salinity mapping in the Elk Hills, Buena Vista, and Coles Levee Oil Fields, Kern County, California
The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (State Water Board) compiled and analyzed data for mapping groundwater salinity, characterizing aquifer systems, and documenting the effects of oil field water injection in the Elk Hills Elk Hills, Buena Vista, and Coles Levee Oil Fields, San Joaquin Valley, California. Data provided...
Filter Total Items: 15
Relations of groundwater quality to long-term surface disposal of produced water near the Midway-Sunset and Buena Vista Oil Fields, California, USA Relations of groundwater quality to long-term surface disposal of produced water near the Midway-Sunset and Buena Vista Oil Fields, California, USA
Contamination of groundwater by oil-field fluids in proximity to oil and gas development has been an issue of concern to water users and regulators given long histories of development and legacy disposal practices. A robust set of geochemical tracers including petroleum hydrocarbon compounds, thermogenic gases, inorganic ion concentrations, stable isotopes, radioactive isotopes, and...
Authors
Riley Gannon, Matthew K. Landon, Justin T. Kulongoski, Michael J. Stephens, Lyndsay B. Ball, John G. Warden, Tracy Davis, Janice M. Gillespie, Isabelle M. Cozzarelli
A joint Gaussian process model of geochemistry, geophysics, and temperature for groundwater TDS in the San Ardo Oil Field, California, USA A joint Gaussian process model of geochemistry, geophysics, and temperature for groundwater TDS in the San Ardo Oil Field, California, USA
Decline in availability of fresh groundwater has expanded interest in brackish groundwater resources; however, the distribution of brackish groundwater is poorly understood. Water resources in sedimentary basins across the United States often overlie oil and gas development. Mapping of groundwater total dissolved solids (TDS) using data from oil well geophysical logs has become an...
Authors
Michael J. Stephens, Will Chang, David H. Shimabukuro, Amanda Howery, Theron Sowers, Janice M. Gillespie
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 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. Shimabukuro, 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 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. Shimabukuro, Theron A. Sowers, Justin T. Kulongoski, Andrew G. Hunt, Ruta Karolyte, Darren J. Hillegonds, Chris J. Ballentine
Fluid migration pathways to groundwater in mature oil fields: Exploring the roles of water injection/production and oil-well integrity in California, USA 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 10 m of uncemented annulus that straddles oil-well casing damage and/or the base of groundwater with TDS
Authors
Peter B. McMahon, Matthew K. Landon, Michael J. Stephens, Kimberly A. Taylor, Janice M. Gillespie, Tracy Davis, David H. Shimabukuro
Multiple-well monitoring site within the Poso Creek Oil Field, Kern County, California Multiple-well monitoring site within the Poso Creek Oil Field, Kern County, California
Introduction The 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
Geostat: Model space-time data with Gaussian processes Geostat: Model space-time data with Gaussian processes
Model space-time data with Gaussian processes. Geostat makes it easy to implement Gaussian Process (GP) models with complex covariance functions and has built-in capabilities for geoscience problems.