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Groundwater quality data were collected in 5,000 wells between 1988-2001 by the National Water-Quality Assessment Project. About 1,500 of these wells were sampled again between 2002-2012 to evaluate decadal changes in groundwater quality. Monitoring wells, domestic supply wells, and some public supply wells were included in this study. All water was collected prior to treatment. Groundwater samples used to evaluate decadal change were collected from networks of wells with similar characteristics. Some networks, consisting of domestic or public supply wells, were used to assess changes in the quality of groundwater used for drinking water supply. Other networks, consisting of monitoring wells, assessed changes in...
In many subsurface situations where human health and environmental quality are at risk (e.g., contaminant hydrogeology petroleum extraction, carbon sequestration, etc.),scientists and engineers are being asked by federal agency decision-makers to predict the fate of chemical species under conditions where both reactions and transport are processes of first-order importance.In 2002, a working group (WG) was formed by representatives of the U.S. Geological Survey, Environmental Protection Agency, Department of Energy Nuclear Regulatory Commission, Department of Agriculture, and Army Engineer Research and Development Center to assess the role of reactive transport modeling (RTM) in addressing these situations. Specifically...
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These data sets present results from the analyses of groundwater samples collected from monitoring wells and monitoring intervals in bedrock wells in the mudstone aquifer underlying the former Naval Air Warfare Center (NAWC), West Trenton, NJ. The water samples were collected between 2008 and 2013 and were analyzed for field parameters, inorganic and organic constituents, and the abundances of selected microbes of importance to the evaluation of biological degradation of organic contaminants in groundwater. The collection and analyses of the groundwater samples coincides with conducting a bioaugmentation experiment in a targeted region of the mudstone aquifer. The purpose of the bioaugmentation was to introduce...
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Groundwater residence times were simulated for the major regional aquifers of the Northern Atlantic Coastal Plain aquifer system from New York to North Carolina using particle tracking in a regional groundwater flow model. Millions of particles were distributed throughout the aquifers of the North Atlantic Coastal Plain in a MODFLOW model with a volume-weighted algorithm, then tracked backwards using MODPATH6 (Pollock, 2012) until termination of their paths at their sources of origin, usually the simulated water table. Particles were tracked under simulated transient hydrologic conditions from the reference time of January 1, 2018 backwards to 1900, then under simulated steady-state conditions prior to 1900 until...
This data release contains data used to develop models and maps that estimate the probabilities of exceeding various thresholds of arsenic concentrations in private domestic wells throughout the conterminous United States. Three boosted regression tree (BRT) models were developed separately to estimate the probability of private well arsenic concentrations exceeding 1, 5, and 10 micrograms per liter (µg/L). A random forest (RF) model was developed to estimate the most probable arsenic concentration category (≤5, >5 to ≤10, or >10 µg/L). The models use arsenic concentration data from private domestic wells located throughout the conterminous United States and independent variables that are available as geospatial...
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Groundwater quality data for 472 domestic well-water samples were retrieved from the USGS National Water Information System (NWIS) database and combined with descriptive information on the sampled well locations. The NWIS data for a sample, collected on the selected date, were averaged into a single record (one per well), and rounded according to USGS protocols. For evaluation and reporting, the water-quality data were further combined with physical attributes and classified by lithology, topographic position, physiographic province, region, redox, and pH (as standalone matrix, one row per well). A second data matrix file incorporating minimum reporting levels for censored and low-reported values (set to 0.99X highest...
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Groundwater from the Mississippi River Valley alluvial aquifer (MRVA) is a vital resource for agriculture and drinking-water supplies in the central United States. Water availability can be limited in some areas of the aquifer by high concentrations of trace elements, including manganese and arsenic. Boosted regression trees, a type of ensemble-tree machine-learning method, were used to predict manganese concentration and the probability of arsenic concentration exceeding a 10 µg/L threshold throughout the MRVA. Explanatory variables for the BRT models included attributes associated with well location and construction, surficial variables (such as hydrologic position and recharge), variables extracted from a MODFLOW-2005...
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This child item of the data release contains groundwater-level elevation and water-quality data, both collected by contractors to U.S. Environmental Protection Agency (EPA) and later furnished to U.S. Geological Survey (USGS), and water-quality data collected by USGS during 2020. The USGS sampling and analysis resulted in a diverse dataset including major and trace elements, rare earth elements (REE), stable isotopes, radiogenic isotopes, and environmental tracers. This diverse dataset aids in providing a complete hydrologic and geochemical conceptualization of the processes occurring in the mine workings and adjacent groundwater and serves as an example of applications to other sites.
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This data release provides a comprehensive dataset of sampling-site characteristics and baseline groundwater-quality data collected from a network of multilevel sampling wells installed in a densely developed coastal neighborhood undergoing a conversion from onsite septic systems to municipal sewering. Groundwater samples were collected during multiple events from a total of 227 well screens at 15 locations using a peristaltic pump between June 2016 and September 2021. Samples were collected and preserved following methods documented in the U.S. Geological Survey National Field Manual (variously dated) and Savoie and others (2012). This dataset provides well construction information, groundwater levels, water-quality...
Groundwater age distributions and susceptibility to natural and anthropogenic contaminants were assessed for selected wells, streambed piezometers, and springs in southeastern Minnesota. The data provide information to understand how long it will take to observe groundwater quality improvements from best management practices implemented at land surface to reduce losses of nitrate (and other chemicals) from agricultural practices. A total of eleven water samples were collected from four wells, three streambed piezometers, and four springs between October 2020 and May 2021. One field replicate sample was collected from one of the spring sites. Groundwater ages were estimated from dissolved gas (neon, argon, krypton,...
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Groundwater is a vital resource to the Mississippi embayment region of the central United States. Regional and integrated assessments of water availability that link physical flow models and water quality in principal aquifer systems provide context for the long-term availability of these water resources. An innovative approach using machine learning was employed to predict groundwater pH across drinking water aquifers of the Mississippi embayment. The region includes two principal regional aquifer systems; the Mississippi River Valley alluvial (MRVA) aquifer and the Mississippi embayment aquifer system that includes several regional aquifers and confining units. Based on the distribution of groundwater use for...
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Groundwater is a vital resource in the Mississippi embayment of the central United States. An innovative approach using machine learning (ML) was employed to predict groundwater salinity—including specific conductance (SC), total dissolved solids (TDS), and chloride (Cl) concentrations—across three drinking-water aquifers of the Mississippi embayment. A ML approach was used because it accommodates a large and diverse set of explanatory variables, does not assume monotonic relations between predictors and response data, and results can be extrapolated to areas of the aquifer not sampled. These aspects of ML allowed potential drivers and sources of high salinity water that have been hypothesized in other studies to...


map background search result map search result map Biogeochemical analyses of water samples collected in the mudstone aquifer underlying the Naval Air Warfare Center, West Trenton, NJ (2008-2013) Data from Decadal Change in Groundwater Quality Web Site, 1988-2012 Baseline groundwater-quality data from a densely developed coastal neighborhood, Falmouth, Massachusetts (2016 - 2021) (ver. 4.0, February 2022) Machine-learning model predictions and groundwater-quality rasters of specific conductance, total dissolved solids, and chloride in aquifers of the Mississippi embayment Statistical summaries of simulated groundwater residence times for the 10 regional aquifers of the Northern Atlantic Coastal Plain aquifer system, at a 1 square-mile grid resolution Prediction grids of pH Machine-learning model predictions and rasters of arsenic and manganese in groundwater in the Mississippi River Valley alluvial aquifer Data compilation for regional synthesis of chemical characteristics of groundwater used for domestic supply in north-east and north-central Pennsylvania Hydrologic and geochemical data Groundwater data and age information from samples collected in Minnesota Biogeochemical analyses of water samples collected in the mudstone aquifer underlying the Naval Air Warfare Center, West Trenton, NJ (2008-2013) Baseline groundwater-quality data from a densely developed coastal neighborhood, Falmouth, Massachusetts (2016 - 2021) (ver. 4.0, February 2022) Hydrologic and geochemical data Groundwater data and age information from samples collected in Minnesota Data compilation for regional synthesis of chemical characteristics of groundwater used for domestic supply in north-east and north-central Pennsylvania Machine-learning model predictions and groundwater-quality rasters of specific conductance, total dissolved solids, and chloride in aquifers of the Mississippi embayment Prediction grids of pH Machine-learning model predictions and rasters of arsenic and manganese in groundwater in the Mississippi River Valley alluvial aquifer Statistical summaries of simulated groundwater residence times for the 10 regional aquifers of the Northern Atlantic Coastal Plain aquifer system, at a 1 square-mile grid resolution Data from Decadal Change in Groundwater Quality Web Site, 1988-2012