Tyler Johnson (Former Employee)
Science and Products
Filter Total Items: 21
Data from Decadal Change in Groundwater Quality Web Site, 1988-2022
Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 20
Data from Decadal Change in Groundwater Quality Web Site, 1988-2021
Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 20
Data Release for Secondary Hydrogeologic Regions of the Conterminous United States (ver. 2.0, June 2022)
The U.S. Geological Survey (USGS) previously identified 62 Principal Aquifers (PAs) in the U.S., with 57 located in the conterminous states. The USGS characterized areas outside of PAs as “other rocks;” other rocks account for about 40% of the area of the conterminous states. This paper subdivides the large area identified as other rocks into Secondary Hydrogeologic Regions (SHRs). SHRs are define
Groundwater-quality data in the Coachella Valley Domestic Supply Aquifer Study Unit, 2020: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 38 wells used for domestic and small system drinking water supply in the Coachella Valley of California in 2020. The wells were sampled for the Coachella Valley Basin (CODA) Domestic Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Projec
Groundwater-quality data in the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit, 2020-2021: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 71 wells used for domestic and small system drinking water supplies in Stanislaus and Merced counties of California during 2020-2021. The wells were sampled for the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit of the State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Ba
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) National Wate
Estimated equivalent population using groundwater for public supply domestic use in the conterminous U.S. 2010, hydrogeologic mapping units, and wells used (ver. 2.0, March 2023)
These datasets map the estimated population using public supply drinking water (both groundwater and surface water) using two methods: the census enhanced method (CEM) evenly distributes the population across populated census blocks, and the urban land-use enhanced method (ULUEM) distributes the population only to certain urban land use designations. (See the six Estimated equivalent population us
Data for Machine Learning Predictions of Nitrate in Groundwater Used for Drinking Supply in the Conterminous United States
A three-dimensional extreme gradient boosting (XGB) machine learning model was developed to predict the distribution of nitrate in groundwater across the conterminous United States (CONUS). Nitrate was predicted at a 1-square-kilometer (km) resolution for two drinking water zones, each of variable depth, one for domestic supply and one for public supply. The model used measured nitrate concentrati
Data from Decadal Change in Groundwater Quality Web Site, 1988-2020
Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 20
California Groundwater Ambient Monitoring and Assessment (GAMA) Program Shallow Aquifer Assessment Study Unit Boundaries and Grid Cells for Assessment of Groundwater Resources (ver. 2.0, January 2023)
The California Groundwater Ambient Monitoring and Assessment Program (GAMA) is a statewide assessment of groundwater quality designed to help better understand and identify risks to groundwater resources. GAMA is implemented by the California State Water Resources Control Board. The U.S. Geological Survey (USGS) is the technical lead for the Priority Basin Project (PBP), one of the components of t
Data from Decadal Change in Groundwater Quality Web Site, 1988-2018
Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 20
Groundwater-quality Data in the Redding-Red Bluff Shallow Aquifer Study Unit, 2018-2019: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 50 wells used for domestic and small system drinking water supplies in Shasta and Tehama Counties, California in 2018-2019. The wells were sampled for the Redding-Red Bluff Shallow Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project?
Filter Total Items: 27
Predicting redox conditions in groundwater at a national scale using random forest classification
Redox conditions in groundwater may markedly affect the fate and transport of nutrients, volatile organic compounds, and trace metals, with significant implications for human health. While many local assessments of redox conditions have been made, the spatial variability of redox reaction rates makes the determination of redox conditions at regional or national scales problematic. In this study, r
Authors
Anthony J. Tesoriero, Susan Wherry, Danielle Dupuy, Tyler D. Johnson
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 with 60 wells
Authors
Kenneth Belitz, Miranda S. Fram, Bruce D. Lindsey, Paul Stackelberg, Laura M. Bexfield, Tyler D. Johnson, Bryant Jurgens, James A. Kingsbury, Peter B. McMahon, Neil M. Dubrovsky
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 of the 24
Authors
Peter B. McMahon, Andrea K. Tokranov, Laura M. Bexfield, Bruce D. Lindsey, Tyler D. Johnson, Melissa Lombard, Elise Watson
Populations using public-supply groundwater in the conterminous U.S. 2010; Identifying the wells, hydrogeologic regions, and hydrogeologic mapping units
Most Americans receive their drinking water from publicly supplied sources, a large portion of it from groundwater. Mapping these populations consistently and at a high resolution is important for understanding where the resource is used and needs to be protected. The results show that 269 million people are supplied by public supply, 107 million are supplied by groundwater and 162 million are sup
Authors
Tyler D. Johnson, Kenneth Belitz, Leon J. Kauffman, Elise Watson, John T. Wilson
Geochemistry and age of groundwater in the Williston Basin, USA: Assessing potential effects of shale-oil production on groundwater quality
Thirty water wells were sampled in 2018 to understand the geochemistry and age of groundwater in the Williston Basin and assess potential effects of shale-oil production from the Three Forks-Bakken petroleum system (TBPS) on groundwater quality. Two geochemical groups are identified using hierarchical cluster analysis. Group 1 represents the younger (median 4He = 21.49 × 10−8 cm3 STP/g), less chem
Authors
Peter B. McMahon, Joel M. Galloway, Andrew G. Hunt, Kenneth Belitz, Bryant Jurgens, Tyler D. Johnson
Fluoride occurrence in United States groundwater
Data from 38,105 wells were used to characterize fluoride (F) occurrence in untreated United States (U.S.) groundwater. For domestic wells (n = 11,032), water from which is generally not purposely fluoridated or monitored for quality, 10.9% of the samples have F concentrations >0.7 mg/L (U.S. Public Health Service recommended optimal F concentration in drinking water for preventing tooth decay) (8
Authors
Peter B. McMahon, Craig J. Brown, Tyler D. Johnson, Kenneth Belitz, Bruce D. Lindsey
Estimating domestic well locations and populations served in the contiguous U.S. for years 2000 and 2010
Domestic wells provide drinking water supply for approximately 40 million people in the United States. Knowing the location of these wells, and the populations they serve, is important for identifying heavily used aquifers, locations susceptible to contamination, and populations potentially impacted by poor-quality groundwater. The 1990 census was the last nationally consistent survey of a home’s
Authors
Tyler D. Johnson, Kenneth Belitz, Melissa Lombard
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 μg/L) in United States (U.S.) groundwater. Elevated concentrations of manganese and dissolved organic carbon (DOC) in groundwater are associated with shallow, anoxic water tables and soils enriched in organic carbon, suggesting soil-derived DOC
Authors
Peter B. McMahon, Kenneth Belitz, James E. Reddy, Tyler D. Johnson
Metrics for assessing the quality of groundwater used for public supply, CA, USA: Equivalent-population and area
Data from 11 000 public supply wells in 87 study areas were used to assess the quality of nearly all of the groundwater used for public supply in California. Two metrics were developed for quantifying groundwater quality: area with high concentrations (km2 or proportion) and equivalent-population relying upon groundwater with high concentrations (number of people or proportion). Concentrations are
Authors
Kenneth Belitz, Miranda S. Fram, Tyler D. Johnson
Secondary hydrogeologic regions of the conterminous United States
The U.S. Geological Survey (USGS) previously identified and mapped 62 Principal Aquifers (PAs) in the U.S., with 57 located in the conterminous states. Areas outside of PAs, which account for about 40% of the conterminous U.S., were collectively identified as “other rocks.” This paper, for the first time, subdivides this large area into internally-consistent features, defined here as Secondary H
Authors
Kenneth Belitz, Elise Watson, Tyler D. Johnson, Jennifer B. Sharpe
Domestic well locations and populations served in the contiguous U.S.: 1990
We estimate the location and population served by domestic wells in the contiguous United States in two ways: (1) the “Block Group Method” or BGM, uses data from the 1990 census, and (2) the “Road-Enhanced Method” or REM, refines the locations by using a buffer expansion and shrinkage technique along roadways to define areas where domestic wells exist. The fundamental assumption is that houses (an
Authors
Tyler Johnson, Kenneth Belitz
Estimating spatially and temporally varying recharge and runoff from precipitation and urban irrigation in the Los Angeles Basin, California
A daily precipitation-runoff model, referred to as the Los Angeles Basin watershed model (LABWM), was used to estimate recharge and runoff for a 5,047 square kilometer study area that included the greater Los Angeles area and all surface-water drainages potentially contributing recharge to a 1,450 square kilometer groundwater-study area underlying the greater Los Angeles area, referred to as the L
Authors
Joseph A. Hevesi, Tyler D. Johnson
Science and Products
Filter Total Items: 21
Data from Decadal Change in Groundwater Quality Web Site, 1988-2022
Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 20
Data from Decadal Change in Groundwater Quality Web Site, 1988-2021
Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 20
Data Release for Secondary Hydrogeologic Regions of the Conterminous United States (ver. 2.0, June 2022)
The U.S. Geological Survey (USGS) previously identified 62 Principal Aquifers (PAs) in the U.S., with 57 located in the conterminous states. The USGS characterized areas outside of PAs as “other rocks;” other rocks account for about 40% of the area of the conterminous states. This paper subdivides the large area identified as other rocks into Secondary Hydrogeologic Regions (SHRs). SHRs are define
Groundwater-quality data in the Coachella Valley Domestic Supply Aquifer Study Unit, 2020: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 38 wells used for domestic and small system drinking water supply in the Coachella Valley of California in 2020. The wells were sampled for the Coachella Valley Basin (CODA) Domestic Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Projec
Groundwater-quality data in the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit, 2020-2021: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 71 wells used for domestic and small system drinking water supplies in Stanislaus and Merced counties of California during 2020-2021. The wells were sampled for the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit of the State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Ba
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) National Wate
Estimated equivalent population using groundwater for public supply domestic use in the conterminous U.S. 2010, hydrogeologic mapping units, and wells used (ver. 2.0, March 2023)
These datasets map the estimated population using public supply drinking water (both groundwater and surface water) using two methods: the census enhanced method (CEM) evenly distributes the population across populated census blocks, and the urban land-use enhanced method (ULUEM) distributes the population only to certain urban land use designations. (See the six Estimated equivalent population us
Data for Machine Learning Predictions of Nitrate in Groundwater Used for Drinking Supply in the Conterminous United States
A three-dimensional extreme gradient boosting (XGB) machine learning model was developed to predict the distribution of nitrate in groundwater across the conterminous United States (CONUS). Nitrate was predicted at a 1-square-kilometer (km) resolution for two drinking water zones, each of variable depth, one for domestic supply and one for public supply. The model used measured nitrate concentrati
Data from Decadal Change in Groundwater Quality Web Site, 1988-2020
Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 20
California Groundwater Ambient Monitoring and Assessment (GAMA) Program Shallow Aquifer Assessment Study Unit Boundaries and Grid Cells for Assessment of Groundwater Resources (ver. 2.0, January 2023)
The California Groundwater Ambient Monitoring and Assessment Program (GAMA) is a statewide assessment of groundwater quality designed to help better understand and identify risks to groundwater resources. GAMA is implemented by the California State Water Resources Control Board. The U.S. Geological Survey (USGS) is the technical lead for the Priority Basin Project (PBP), one of the components of t
Data from Decadal Change in Groundwater Quality Web Site, 1988-2018
Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 20
Groundwater-quality Data in the Redding-Red Bluff Shallow Aquifer Study Unit, 2018-2019: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 50 wells used for domestic and small system drinking water supplies in Shasta and Tehama Counties, California in 2018-2019. The wells were sampled for the Redding-Red Bluff Shallow Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project?
Filter Total Items: 27
Predicting redox conditions in groundwater at a national scale using random forest classification
Redox conditions in groundwater may markedly affect the fate and transport of nutrients, volatile organic compounds, and trace metals, with significant implications for human health. While many local assessments of redox conditions have been made, the spatial variability of redox reaction rates makes the determination of redox conditions at regional or national scales problematic. In this study, r
Authors
Anthony J. Tesoriero, Susan Wherry, Danielle Dupuy, Tyler D. Johnson
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 with 60 wells
Authors
Kenneth Belitz, Miranda S. Fram, Bruce D. Lindsey, Paul Stackelberg, Laura M. Bexfield, Tyler D. Johnson, Bryant Jurgens, James A. Kingsbury, Peter B. McMahon, Neil M. Dubrovsky
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 of the 24
Authors
Peter B. McMahon, Andrea K. Tokranov, Laura M. Bexfield, Bruce D. Lindsey, Tyler D. Johnson, Melissa Lombard, Elise Watson
Populations using public-supply groundwater in the conterminous U.S. 2010; Identifying the wells, hydrogeologic regions, and hydrogeologic mapping units
Most Americans receive their drinking water from publicly supplied sources, a large portion of it from groundwater. Mapping these populations consistently and at a high resolution is important for understanding where the resource is used and needs to be protected. The results show that 269 million people are supplied by public supply, 107 million are supplied by groundwater and 162 million are sup
Authors
Tyler D. Johnson, Kenneth Belitz, Leon J. Kauffman, Elise Watson, John T. Wilson
Geochemistry and age of groundwater in the Williston Basin, USA: Assessing potential effects of shale-oil production on groundwater quality
Thirty water wells were sampled in 2018 to understand the geochemistry and age of groundwater in the Williston Basin and assess potential effects of shale-oil production from the Three Forks-Bakken petroleum system (TBPS) on groundwater quality. Two geochemical groups are identified using hierarchical cluster analysis. Group 1 represents the younger (median 4He = 21.49 × 10−8 cm3 STP/g), less chem
Authors
Peter B. McMahon, Joel M. Galloway, Andrew G. Hunt, Kenneth Belitz, Bryant Jurgens, Tyler D. Johnson
Fluoride occurrence in United States groundwater
Data from 38,105 wells were used to characterize fluoride (F) occurrence in untreated United States (U.S.) groundwater. For domestic wells (n = 11,032), water from which is generally not purposely fluoridated or monitored for quality, 10.9% of the samples have F concentrations >0.7 mg/L (U.S. Public Health Service recommended optimal F concentration in drinking water for preventing tooth decay) (8
Authors
Peter B. McMahon, Craig J. Brown, Tyler D. Johnson, Kenneth Belitz, Bruce D. Lindsey
Estimating domestic well locations and populations served in the contiguous U.S. for years 2000 and 2010
Domestic wells provide drinking water supply for approximately 40 million people in the United States. Knowing the location of these wells, and the populations they serve, is important for identifying heavily used aquifers, locations susceptible to contamination, and populations potentially impacted by poor-quality groundwater. The 1990 census was the last nationally consistent survey of a home’s
Authors
Tyler D. Johnson, Kenneth Belitz, Melissa Lombard
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 μg/L) in United States (U.S.) groundwater. Elevated concentrations of manganese and dissolved organic carbon (DOC) in groundwater are associated with shallow, anoxic water tables and soils enriched in organic carbon, suggesting soil-derived DOC
Authors
Peter B. McMahon, Kenneth Belitz, James E. Reddy, Tyler D. Johnson
Metrics for assessing the quality of groundwater used for public supply, CA, USA: Equivalent-population and area
Data from 11 000 public supply wells in 87 study areas were used to assess the quality of nearly all of the groundwater used for public supply in California. Two metrics were developed for quantifying groundwater quality: area with high concentrations (km2 or proportion) and equivalent-population relying upon groundwater with high concentrations (number of people or proportion). Concentrations are
Authors
Kenneth Belitz, Miranda S. Fram, Tyler D. Johnson
Secondary hydrogeologic regions of the conterminous United States
The U.S. Geological Survey (USGS) previously identified and mapped 62 Principal Aquifers (PAs) in the U.S., with 57 located in the conterminous states. Areas outside of PAs, which account for about 40% of the conterminous U.S., were collectively identified as “other rocks.” This paper, for the first time, subdivides this large area into internally-consistent features, defined here as Secondary H
Authors
Kenneth Belitz, Elise Watson, Tyler D. Johnson, Jennifer B. Sharpe
Domestic well locations and populations served in the contiguous U.S.: 1990
We estimate the location and population served by domestic wells in the contiguous United States in two ways: (1) the “Block Group Method” or BGM, uses data from the 1990 census, and (2) the “Road-Enhanced Method” or REM, refines the locations by using a buffer expansion and shrinkage technique along roadways to define areas where domestic wells exist. The fundamental assumption is that houses (an
Authors
Tyler Johnson, Kenneth Belitz
Estimating spatially and temporally varying recharge and runoff from precipitation and urban irrigation in the Los Angeles Basin, California
A daily precipitation-runoff model, referred to as the Los Angeles Basin watershed model (LABWM), was used to estimate recharge and runoff for a 5,047 square kilometer study area that included the greater Los Angeles area and all surface-water drainages potentially contributing recharge to a 1,450 square kilometer groundwater-study area underlying the greater Los Angeles area, referred to as the L
Authors
Joseph A. Hevesi, Tyler D. Johnson