Tyler Johnson (Former Employee)
Science and Products
Filter Total Items: 22
Geochemical and Geospatial Data for Per- and Polyfluoroalkyl Substances (PFAS) in Groundwater Used As a Source of Drinking Water in the Eastern United States 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)...
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) 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...
Data for Machine Learning Predictions of Nitrate in Groundwater Used for Drinking Supply in the Conterminous United States 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
Data from Decadal Change in Groundwater Quality Web Site, 1988-2020 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...
California Groundwater Ambient Monitoring and Assessment (GAMA) Program Domestic-Supply (Shallow) Aquifer Assessment Study Unit Boundaries and Grid Cells for Assessment of Groundwater Resources (ver. 3.0, July 2025) California Groundwater Ambient Monitoring and Assessment (GAMA) Program Domestic-Supply (Shallow) Aquifer Assessment Study Unit Boundaries and Grid Cells for Assessment of Groundwater Resources (ver. 3.0, July 2025)
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...
Data from Decadal Change in Groundwater Quality Web Site, 1988-2018 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...
Filter Total Items: 27
Estimating domestic well locations and populations served in the contiguous U.S. for years 2000 and 2010 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...
Authors
Tyler D. Johnson, Kenneth Belitz, Melissa Lombard
Elevated manganese concentrations in United States groundwater, role of land surface–soil–aquifer connections 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...
Authors
Peter McMahon, Kenneth Belitz, James Reddy, Tyler D. Johnson
Metrics for assessing the quality of groundwater used for public supply, CA, USA: Equivalent-population and area 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)...
Authors
Kenneth Belitz, Miranda Fram, Tyler D. Johnson
Secondary hydrogeologic regions of the conterminous United States 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...
Authors
Kenneth Belitz, Elise Watson, Tyler Johnson, Jennifer Sharpe
Domestic well locations and populations served in the contiguous U.S.: 1990 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...
Authors
Tyler Johnson, Kenneth Belitz
Estimating spatially and temporally varying recharge and runoff from precipitation and urban irrigation in the Los Angeles Basin, California 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...
Authors
Joseph Hevesi, Tyler Johnson
Science and Products
Filter Total Items: 22
Geochemical and Geospatial Data for Per- and Polyfluoroalkyl Substances (PFAS) in Groundwater Used As a Source of Drinking Water in the Eastern United States 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)...
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) 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...
Data for Machine Learning Predictions of Nitrate in Groundwater Used for Drinking Supply in the Conterminous United States 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
Data from Decadal Change in Groundwater Quality Web Site, 1988-2020 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...
California Groundwater Ambient Monitoring and Assessment (GAMA) Program Domestic-Supply (Shallow) Aquifer Assessment Study Unit Boundaries and Grid Cells for Assessment of Groundwater Resources (ver. 3.0, July 2025) California Groundwater Ambient Monitoring and Assessment (GAMA) Program Domestic-Supply (Shallow) Aquifer Assessment Study Unit Boundaries and Grid Cells for Assessment of Groundwater Resources (ver. 3.0, July 2025)
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...
Data from Decadal Change in Groundwater Quality Web Site, 1988-2018 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...
Filter Total Items: 27
Estimating domestic well locations and populations served in the contiguous U.S. for years 2000 and 2010 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...
Authors
Tyler D. Johnson, Kenneth Belitz, Melissa Lombard
Elevated manganese concentrations in United States groundwater, role of land surface–soil–aquifer connections 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...
Authors
Peter McMahon, Kenneth Belitz, James Reddy, Tyler D. Johnson
Metrics for assessing the quality of groundwater used for public supply, CA, USA: Equivalent-population and area 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)...
Authors
Kenneth Belitz, Miranda Fram, Tyler D. Johnson
Secondary hydrogeologic regions of the conterminous United States 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...
Authors
Kenneth Belitz, Elise Watson, Tyler Johnson, Jennifer Sharpe
Domestic well locations and populations served in the contiguous U.S.: 1990 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...
Authors
Tyler Johnson, Kenneth Belitz
Estimating spatially and temporally varying recharge and runoff from precipitation and urban irrigation in the Los Angeles Basin, California 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...
Authors
Joseph Hevesi, Tyler Johnson