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This data release contains input data used in model development and TIF raster files used to predict the probability of high arsenic (As) and high manganese (Mn) in groundwater within the glacial aquifer system in the northern United States. Input data include measured As and Mn concentrations at groundwater wells, and associated predictor variable data. The probability of high As and high Mn was predicted using boosted regression tree methods using the gbm package in R version 4.0.0. The response variables for individual models were the occurrence of: (1) As >10 µg/L, and (2) Mn >300 µg/L. Water-quality data were compiled from three sources, as described in Wilson and others (2019): a compilation of data from numerous...
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This dataset provides aqueous nitrate+nitrite, aqueous manganese, aqueous iron, and total sulfate measurements in groundwater samples from 254 newly constructed private residential wells between 2014 and 2016. The study focuses on three geologically distinct regions of Minnesota: central, northwest, and northeast. These study regions were chosen due to their prevalent elevated As concentrations in drinking water. Each of the 254 wells were sampled in three rounds by the Minnesota Department of Health (MDH). The timing of the three sampling rounds was (1) immediately or shortly after well construction (round 1); (2) 3-6 months after initial sample collection (round 2); and (3) 12 months after initial sample collection...
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This data release contains: (1) ASCII grids of predicted probability of elevated arsenic in groundwater for the Northwest and Central Minnesota regions, (2) input arsenic and predictive variable data used in model development and calculation of predictions, and (3) ASCII files used to predict the probability of elevated arsenic across the two study regions. The probability of elevated arsenic was predicted using Boosted Regression Tree (BRT) modeling methods using the gbm package in R Studio version 3.4.2. The response variable was the presence or absence of arsenic >10 µg/L, the U.S. Environmental Protection Agency’s maximum contaminant level for arsenic, in 3,283 wells located throughout both study regions (1,363...
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This data release provides total and aqueous arsenic (As) determinations and associated field readings collected from groundwater sampled from 254 newly constructed private residential wells between 2014 and 2016. The study focuses on three regions of Minnesota that differ geologically: south-central (herein called central), northwest, and northeast. These study regions were chosen due to their prevalent elevated As concentrations in drinking water. Each of the 254 wells were sampled in three rounds by the Minnesota Department of Health (MDH). The timing of the three sampling rounds was (1) immediately or shortly after well construction (round 1); (2) 3-6 months after initial sample collection (round 2); and (3)...
This data release contains input data used in model development and TIF raster files used to predict the probability of low dissolved oxygen (DO) and high dissolved iron (Fe) in groundwater within the glacial aquifer system in the northern continental United States. Input data include measured DO and Fe concentrations at groundwater wells, and associated predictor variable data. The probability of low DO and high Fe was predicted using boosted regression tree methods using the gbm package in R (v. 4.0.0) in RStudio (v. 1.2.5042). The response variables for individual models were the occurrence of: (1) DO ≤0.5 mg/L, (2) DO ≤2 mg/L, and (3) Fe >100 µg/L. Water-quality data were compiled from three sources, as described...
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A boosted regression tree (BRT) model was developed to predict pH conditions in three-dimensions throughout the glacial aquifer system (GLAC) of the contiguous United States using pH measurements in samples from 18,258 wells and predictor variables that represent aspects of the hydrogeologic setting. Model results indicate that the carbonate content of soils and aquifer materials strongly controls pH and when coupled with long flow paths, results in the most alkaline conditions. Conversely, in areas where glacial sediments are thin and carbonate-poor, pH conditions remain acidic. At depths typical of drinking-water supplies, predicted pH > 7.5 – which is associated with arsenic mobilization – occurs more frequently...
Groundwater-quality data were collected from 648 wells as part of the National Water-Quality Assessment Project of the U.S. Geological Survey National Water-Quality Program and are included in this report. Most of the wells (514) were sampled from January through December 2016 and 60 of them were sampled in 2013 and 74 in 2014. The data were collected from seven types of well networks: principal aquifer study networks, which are used to assess the quality of groundwater used for public water supply; land-use study networks, which are used to assess land-use effects on shallow groundwater quality; major aquifer study networks, which are used to assess the quality of groundwater used for domestic supply; enhanced...
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This data release consists of data (in four tables) for assessing the time scales of arsenic variability in three production wells in New Hampshire; tables that describe the data fields in the data tables are also included in the data release. High-frequency (every 5 to 15 minutes) and bi-monthly water-quality monitoring of a bedrock-aquifer domestic well (425651070573701), a bedrock-aquifer public-supply well (425400070545401), and a glacial-aquifer public-supply well (425311070535801) was completed between 2014 and 2018. Concentrations of arsenic and other geochemical constituents and dissolved gases, as tracers of groundwater age, were measured on a bimonthly basis; physicochemical data, including specific conductance,...
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Samples for analysis were selected from 1) archived rotosonic cores drilled by the Minnesota Geological Survey and archived at the Lands and Minerals Drill Core Library, Minnesota Department of Natural Resources, Hibbing, Minnesota, USA; or b) freshly collected rotosonic cores, collected on-site at the time of coring. Cores in the sample archive are stored in wooden core-boxes in ambient air. Cores have supporting geology, stratigraphy, geochemistry, and hydrogeology data as published in County Geologic Atlases, Parts A and B, by the Minnesota Geological Survey (MGS) and the Minnesota Department of Natural Resources (MDNR); or in Regional Hydrogeologic Assessments, MGS. Included in this data release are: Core_Chem_Locations.pdf:...
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This data release contains groundwater-quality data for three parameters of interest (arsenic, manganese, and pH) and well information for sample sites for aquifers in the conterminous U.S. Water-quality data and well information were derived from a dataset compiled from three sources: the U.S. Geological Survey (USGS) National Water Information System (NWIS), the U.S. Environmental Protection Agency (USEPA) Safe Drinking Water Information System (SDWIS), and numerous agencies and organizations at the state, regional, and local level. The data compilation of the National Water Quality Program’s groundwater assessment team is an internal dataset informally referred to as the National Groundwater Aggregation (NGA)....
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This data release includes grids representing the depth and thickness of drinking-water withdrawal zones, polygons of hydrogeologic settings, an inventory of sources of well construction data, and summaries of data comparisons used to assess the depth of groundwater used for drinking-water supplies in the United States. Well construction data sources are documented in Table1_DataSources.xlsx. Data comparisons using the Mann-Whitney test to assess similarity between hydrogeologic settings were used to justify combining data where they were sparse (compare_neighbors_all_domestic.txt and compare_neighbors_all_public.txt). Water-supply-well depth varies geographically by water use and the type of well, which illustrates...
This data release provides total and aqueous arsenic (As) determinations and associated field readings collected from groundwater sampled from 254 newly constructed private residential wells between 2014 and 2016. Also included in this data release is a subset of well construction information provided by the driller's well logs. Included in version 2.0 (June 2018) of this data release is a set of ancillary concentration measurements for aqueous nitrate+nitrite nitrogen, aqueous manganese, aqueous iron, and total sulfate. The study focuses on three regions of Minnesota that differ geologically: south-central (herein called central), northwest, and northeast. These study regions were chosen due to their prevalent...
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This data release contains groundwater-quality data and well information for the glacial aquifer system in the northern USA. Water-quality data and well information were derived from a dataset compiled from three sources: The U.S. Geological Survey (USGS) National Water Information System (NWIS; USGS, 1998, 2002), the U.S. Environmental Protection Agency (USEPA) Safe Drinking Water Information System (SDWIS; USEPA, 2013), and numerous agencies and organizations at the state, regional, and local level. The data compilation of the National Water Quality Program’s groundwater assessment team is an internal dataset informally referred to as the National Groundwater Aggregation (NGA). The current study of groundwater...
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This data release contains groundwater-quality data for nitrate and chloride, and well information for sample sites for aquifers in the Great Lakes Basin within the United States. Water-quality data and well information were derived from a dataset compiled from the U.S. Geological Survey (USGS) National Water Information System and numerous agencies and organizations at the state, regional, and local level. The data presented in this data release are data pulled from the USGS National Water Quality Program groundwater assessment team’s internal dataset, informally referred to as the National Groundwater aggregation (NGA). Data collected in the Great Lakes Basin by the U.S. and Canada augment the NGA. Specifically,...
This dataset includes data collected to validate a method of analysis for arsenic species As(III), As(V), dimethylarsinate (DMA), and monomethylarsonate (MMA) in surface water and groundwater samples. It also includes site information and water chemistry for samples used in the validation and used for other studies of arsenic species in groundwater. It includes speciation data measured at multiple time points to establish or verify hold times and stability of As species in surface water and groundwater samples.
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Groundwater-quality data were collected from 983 wells as part of the National Water-Quality Assessment Project of the U.S. Geological Survey National Water-Quality Program and are included in this report. The data were collected from six types of well networks: principal aquifer study networks, which are used to assess the quality of groundwater used for public water supply; land-use study networks, which are used to assess land-use effects on shallow groundwater quality; major aquifer study networks, which are used to assess the quality of groundwater used for domestic supply; enhanced trends networks, which are used to evaluate the time scales during which groundwater quality changes; vertical flow-path study...
    map background search result map search result map Groundwater arsenic data and ASCII grids for predicting elevated arsenic in northwestern and central Minnesota using boosted regression tree methods Arsenic and field parameter data Aqueous nitrate+nitrite, aqueous manganese, aqueous iron, and total sulfate data Data used to evaluate drinking water quality in the glacial aquifer system, northern USA Data for Time Scales of Arsenic Variability and the Role of High-Frequency Monitoring at Three Water-Supply Wells in New Hampshire, USA Data for depth of groundwater used for drinking-water supplies in the United States Till geochemistry from rotosonic cores in Minnesota, USA Groundwater data, predictor variables, and rasters used for predicting redox conditions in the glacial aquifer, northern continental United States Datasets of Groundwater-Quality and Select Quality-Control Data from the National Water-Quality Assessment Project, January 2017 through December 2019 (ver. 1.1, January 2021) Data for machine learning predictions of pH in the glacial aquifer system, northern USA Groundwater data, predictor variables, and rasters used for predicting the probability of high arsenic and high manganese in the Glacial Aquifer System, northern continental United States Arsenic, manganese, and pH groundwater quality data, selected well construction characteristics, and aquifer assignments for wells in the conterminous U.S. Nitrate and chloride groundwater quality data, selected well construction characteristics, and aquifer assignments for wells in the Great Lakes Watershed, United States Data for Time Scales of Arsenic Variability and the Role of High-Frequency Monitoring at Three Water-Supply Wells in New Hampshire, USA Groundwater arsenic data and ASCII grids for predicting elevated arsenic in northwestern and central Minnesota using boosted regression tree methods Arsenic and field parameter data Aqueous nitrate+nitrite, aqueous manganese, aqueous iron, and total sulfate data Till geochemistry from rotosonic cores in Minnesota, USA Nitrate and chloride groundwater quality data, selected well construction characteristics, and aquifer assignments for wells in the Great Lakes Watershed, United States Data for machine learning predictions of pH in the glacial aquifer system, northern USA Groundwater data, predictor variables, and rasters used for predicting redox conditions in the glacial aquifer, northern continental United States Groundwater data, predictor variables, and rasters used for predicting the probability of high arsenic and high manganese in the Glacial Aquifer System, northern continental United States Data used to evaluate drinking water quality in the glacial aquifer system, northern USA Datasets of Groundwater-Quality and Select Quality-Control Data from the National Water-Quality Assessment Project, January 2017 through December 2019 (ver. 1.1, January 2021) Arsenic, manganese, and pH groundwater quality data, selected well construction characteristics, and aquifer assignments for wells in the conterminous U.S. Data for depth of groundwater used for drinking-water supplies in the United States