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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 Water Quality Laboratory in Lakewood, Colorado. Concentrations of tritium were measured at the USGS Tritium Laboratory in Menlo Park, California. Concentrations of PFAS were measured at SGS Laboratory in Orlando, Florida. In addition, several geospatial parameters were determined, including: percentages of selected land uses...
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This data release documents nine Microsoft Excel tables that contain data for understanding groundwater ages in the Glacial aquifer system. Results for the three sample networks (PAS, principal aquifer study; MSS, modeling support study; FPS, flow path study) are described by three tables each: dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), and results for the mean age and age distribution. Tables are labeled by network and data type (as described below) separated by an underscore (_). For example, dissolved gas modeling results from the PAS network is label ‘PAS_NGmodel’. Dissolved gas modeling results...
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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Continuous monitoring and discrete water-quality sampling were coupled in a karst aquifer to assess drivers and timescales of water-quality change. Water-quality data included environmental tracers of groundwater age (tritium [3H], tritiogenic helium-3 [3He-trit], sulfur hexafluoride [SF6], carbon-14 [14C], and radiogenic helium-4 [4He-rad]). All water quality data is available from the U.S. Geological Survey NWIS database (U.S. Geological Survey, 2019). Groundwater ages were estimated by calibration of environmental tracers to lumped parameter models of groundwater age for multiple samples collected at six groundwater wells using the program TracerLPM (Jurgens and others, 2012). The final estimates for mean groundwater...
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The U.S. Geological Survey (USGS), in cooperation with the Illinois Center for Transportation and the Illinois Department of Transportation, prepared hydro-conditioned geographic information systems (GIS) layers for use in the Illinois StreamStats application. These data were used to delineate drainage basins and compute basin characteristics for updated peak flow and flow duration regression equations for Illinois. This dataset consists of raster grid files for elevation (dem), flow accumulation (fac), flow direction (fdr), and stream definition (str900) for each 8-digit Hydrologic Unit Code (HUC) area in Illinois merged into a single dataset. There are 51 full or partial HUC 8s represented by this data set: 04040002,...
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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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Residence time distribution (RTD) is a critically important characteristic of groundwater flow systems; however, it cannot be measured directly. RTD can be inferred from tracer data with analytical models (few parameters) or with numerical models (many parameters). The second approach permits more variation in system properties but is used less frequently than the first because large-scale numerical models can be resource intensive. With the data and computer codes in this data release users can (1) reconstruct and run 115 General Simulation Models (GSMs) of groundwater flow, (2) calculate groundwater age metrics at selected GSM cells, (3) train a boosted regression tree model using the provided data, (4) predict...
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Lithium concentrations in untreated groundwater from 1,464 public-supply wells, 1,676 domestic-supply wells, and 1,560 monitoring wells distributed across 33 principal aquifers in the United States were evaluated for spatial variations and possible explanatory factors. For context, lithium concentrations are compared to a drinking-water only threshold (60 micrograms per liter) and a Health-Based Screening Level (HBSL, 10 micrograms per liter). These thresholds were exceeded in 9% and 45% of samples from public-supply wells and in 6% and 37% from domestic-supply wells, respectively. Exceedances were most frequent for arid regions and older groundwater. Groundwater lithium concentrations were highest in unconsolidated...
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Categorical classification of groundwater age based on concentrations of tritium (3H) in groundwater can provide useful information for the assessment and understanding of groundwater resources. These data present a three-part groundwater age classification system for the continental United States based on tritium thresholds that vary in space and time: modern (recharged after 1952), if the measured value is larger than an upper threshold; premodern (recharged prior to 1953) if the measured value is smaller than a lower threshold; or mixed if the measured value is between the two thresholds. Inclusion of spatially-varying that vary geographically on the basis of the location of the sample rather than a single threshold...
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Evaluating Decadal Changes in Groundwater Quality: Groundwater quality data were collected from 5,000 wells between 1988-2001 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 about 10 years later between 2002-2012 (second sampling event) to evaluate decadal changes in groundwater quality. Between 2012 and 2016 (third sampling event), a subset of these networks has been sampled again, allowing additional results to be displayed on the web page: Decadal changes in groundwater quality. This is the third iteration of data added to the website, so this data release is referred...
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The U.S. Geological Survey (USGS), in cooperation with the Cook County Bureau of Technology (BOT), prioritized waterbodies (lakes, rivers, and canals) of interest within Cook County to survey in 2022. These surveys describe the bathymetry and basic water-quality conditions observed, and could be used by the BOT to assist with resource management decisions and uses, as well as build an inventory that could be shared with other local governmental agencies. Waterbodies surveyed in 2022 and included in this data release are: Arrowhead Lake, Axehead Lake, Baker's Lake, Belly Deep Slough, Bode Lake North, Bode Lake South, Bull Frog Lake, Busse Lake Main Pool, Busse Lake North Pool, Busse Lake South Pool, Busse Woods...
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Three wells in New Hampshire were sampled bimonthly over three years to evaluate the temporal variability of arsenic concentrations and groundwater age. All samples had measurable concentrations of arsenic throughout the entire sampling period and concentrations in individual wells varied, on average, by more than 7 µg/L. High arsenic concentrations (>10 µg/L) were measured in wells KFW-87 and SGW-93, consistent with the high pH and low dissolved oxygen typically found in bedrock wells. Lower arsenic concentrations (< 10 µg/L) at well SGW-65 were consistent with lower pH typical of the glacial aquifer. The well producing the oldest water, public bedrock well SGW-93, was not the well with the highest arsenic concentrations;...
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This data release includes tables and plots of results for pesticide compounds (pesticides and degradates) analyzed in groundwater samples collected by the USGS National Water-Quality Assessment Project during water years 2013-18 and in associated quality-control samples that are used to assess the quality of the reported pesticide results. All samples were analyzed by the USGS National Water Quality Laboratory (NWQL) using laboratory schedule 2437. The table of groundwater data includes pesticide results as reported by the laboratory, along with results that represent the application of censoring levels at the 90-percent upper confidence limit of the 95th percentile of laboratory blank concentrations determined...
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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 2002-2012 (second sampling event) to evaluate decadal changes in groundwater quality. Between 2012 and 2020 (third sampling event), a subset of these networks was sampled again, allowing additional results to be displayed on the web page: Decadal changes in groundwater quality (https://nawqatrends.wim.usgs.gov/decadal/)....
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Ensemble-tree machine learning (ML) regression models can be prone to systematic bias: small values are overestimated and large values are underestimated. Additional bias can be introduced if the dependent variable is a transform of the original data. Six methods were evaluated for their ability to correct systematic and introduced bias: (1) empirical distribution matching (EDM); (2) regression of observed on estimated values (ROE); (3) linear transfer function (LTF); (4) linear equation based on Z-score transform (ZZ); (5) second machine learning model used to estimate residuals (ML2-RES); and (6) Duan smearing estimate applied after ROE is implemented (ROE-Duan). The performance of the methods was evaluated using...
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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...
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This dataset provides analytical and other data in support of an analysis of lead and manganese in untreated drinking water from Atlantic and Gulf Coastal Plain aquifers, eastern United States. The occurrence of dissolved lead and manganese in sampled groundwater, prior to its distribution or treatment, is related to the potential presence of source minerals and specific environmental factors including hydrologic position along the flow path, water-rock interactions, and associated geochemical conditions such as pH and dissolved oxygen (DO) concentrations. A DO/pH framework is proposed as a screening tool for evaluating risk of elevated lead or manganese, based on the occurrence of elevated lead and manganese concentrations...
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Groundwater samples were collected from 60 public supply wells in the Colorado Plateaus principal aquifer. Water quality evaluations of groundwater for drinking water at public supply depths were made with the purpose of summarizing the current quality of source water (that is, untreated water) from public supply wells using two types of assessments; (1) status: an assessment that describes the current quality of the groundwater resource, and (2) understanding: an evaluation of the natural and human factors affecting the quality of groundwater, including an explanation of statistically significant associations between water quality and selected explanatory factors. To provide context for water-quality data, constituent...
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This data release includes tables and time-series plots of results for volatile organic compounds (VOCs) analyzed in samples of groundwater used for public supply that were collected by the USGS National Water-Quality Assessment (NAWQA) Project and the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) during 2013-19; results for associated quality-control samples also are included. All samples were analyzed by the USGS National Water Quality Laboratory (NWQL) using laboratory schedules 4436 and 4437. The table of groundwater data includes VOC results as reported by the laboratory, along with results that represent the application...
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The location of a point (or pixel) within the conterminous U.S. can be assigned based on its position relative to the Nation’s stream network. Two metrics are recognized: lateral position (LP) and distance from stream to divide (DSD). And given that a point can have different positions in different hydrologic orders the term multi-order hydrologic position (MOHP) is used to describe the ensemble of hydrologic positions. LP and DSD were developed for nine hydrologic orders across the conterminous U.S. (Belitz and others, 2019; Moore and others, 2019). Four case studies are presented here that were used for evaluating the utility of MOHP in the context of random forest machine learning (Belitz and others, 2019)....


map background search result map search result map Inventory of well-construction data, water-quality and quality control data, statistical data, and geochemical modeling data for wells in Atlantic and Gulf Coastal Plain aquifers, eastern United States, 2012 and 2013 Dissolved Gas, Environmental Tracer Concentrations, and Lumped Parameter Modeling Results for Groundwater Age Dating in the Glacial Aquifer System, Conterminous United States Data for Arsenic Variability and Groundwater Age in Three Water-Supply Wells in Southeast New Hampshire Data for Tritium as an Indicator of Modern, Mixed and Premodern Groundwater Age Data for timescales of water-quality change in a karst aquifer, south-central Texas Data from Decadal Change in Groundwater Quality Web Site, 1988-2016 Point data for four case studies related to testing of multi-order hydrologic position Field, laboratory, and third-party data for assessment of the quality of pesticide results reported by the National Water Quality Laboratory for groundwater samples collected by the National Water-Quality Assessment Project, 2013-18 Data for Groundwater-Quality and Select Quality-Control Data for the Colorado Plateaus Principal Aquifer 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 Data for three-dimensional distribution of groundwater residence time metrics in the glaciated United States using metamodels trained on general numerical simulation models Inorganic Constituent and Ancillary Data for Evaluation of Lithium in Groundwater in the United States, 1991-2018 Data Release for Evaluation of Six Methods for Correcting Bias in Estimates from Ensemble Tree Machine Learning Regression Models Geochemical and Geospatial Data for Per- and Polyfluoroalkyl Substances (PFAS) in Groundwater Used as a Source of Drinking Water in the Eastern United States Data from Decadal Change in Groundwater Quality Web Site, 1988-2020 Data for volatile organic compounds in groundwater used for public supply across the United States, 2013-19, and data for associated quality-control samples Elevation, Flow Accumulation, Flow Direction, and Stream Definition Data in Support of the Illinois StreamStats Upgrade to the Basin Delineation Database Bathymetry and Water-Quality Data of Surface Waterbodies in Cook County, Illinois, 2022 Data for Arsenic Variability and Groundwater Age in Three Water-Supply Wells in Southeast New Hampshire Bathymetry and Water-Quality Data of Surface Waterbodies in Cook County, Illinois, 2022 Data for timescales of water-quality change in a karst aquifer, south-central Texas Elevation, Flow Accumulation, Flow Direction, and Stream Definition Data in Support of the Illinois StreamStats Upgrade to the Basin Delineation Database Till geochemistry from rotosonic cores in Minnesota, USA Data for Groundwater-Quality and Select Quality-Control Data for the Colorado Plateaus Principal Aquifer Geochemical and Geospatial Data for Per- and Polyfluoroalkyl Substances (PFAS) in Groundwater Used as a Source of Drinking Water in the Eastern United States Inventory of well-construction data, water-quality and quality control data, statistical data, and geochemical modeling data for wells in Atlantic and Gulf Coastal Plain aquifers, eastern United States, 2012 and 2013 Dissolved Gas, Environmental Tracer Concentrations, and Lumped Parameter Modeling Results for Groundwater Age Dating in the Glacial Aquifer System, Conterminous United States Data for three-dimensional distribution of groundwater residence time metrics in the glaciated United States using metamodels trained on general numerical simulation models Groundwater data, predictor variables, and rasters used for predicting redox conditions in the glacial aquifer, northern continental United States Data Release for Evaluation of Six Methods for Correcting Bias in Estimates from Ensemble Tree Machine Learning Regression Models Data for Tritium as an Indicator of Modern, Mixed and Premodern Groundwater Age Point data for four case studies related to testing of multi-order hydrologic position Field, laboratory, and third-party data for assessment of the quality of pesticide results reported by the National Water Quality Laboratory for groundwater samples collected by the National Water-Quality Assessment Project, 2013-18 Data for volatile organic compounds in groundwater used for public supply across the United States, 2013-19, and data for associated quality-control samples Data for depth of groundwater used for drinking-water supplies in the United States Data from Decadal Change in Groundwater Quality Web Site, 1988-2016 Data from Decadal Change in Groundwater Quality Web Site, 1988-2020 Inorganic Constituent and Ancillary Data for Evaluation of Lithium in Groundwater in the United States, 1991-2018