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.

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.

The Captain Jack Superfund site near Ward, Colorado hosts extensive interconnected underground mine workings, which drain via the Big Five Adit. Drainage from the adit has historically been acidic with elevated concentrations of metals. In 2018 the U.S. Environmental Protection Agency (EPA) utilized a subsurface remediation strategy consisting of the installation of a hydraulic bulkhead within the workings to preclude drainage out of the mine. To understand the processes occurring during water impoundment within the mine workings, the U.S. Geological Survey (USGS), in cooperation with EPA, completed water-quality sampling and analysis during 2020 as water was again impounded within the mine workings. 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. This data release contains data pertaining to groundwater-level elevations and water-quality data furnished to USGS by EPA and collected by USGS. Also included are geochemical model input files to simulate aqueous speciation, mineral equilibrium, and groundwater age and mixing as well as output files. Data are provided in child item "Hydrologic and geochemical data" and model input and output files are provided in child item "Geochemical and environmental tracer models".

The Captain Jack Superfund site near Ward, Colorado hosts extensive interconnected underground mine workings, which drain via the Big Five Adit. Drainage from the adit has historically been acidic with elevated concentrations of metals. In 2018 the U.S. Environmental Protection Agency (EPA) utilized a subsurface remediation strategy consisting of the installation of a hydraulic bulkhead within the workings to preclude drainage out of the mine. To understand the processes occurring during water impoundment within the mine workings, the U.S. Geological Survey (USGS), in cooperation with EPA, completed water-quality sampling and analysis during 2020 as water was again impounded within the mine workings. 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. This data release contains data pertaining to groundwater-level elevations and water-quality data furnished to USGS by EPA and collected by USGS. Also included are geochemical model input files to simulate aqueous speciation, mineral equilibrium, and groundwater age and mixing as well as output files. Data are provided in child item "Hydrologic and geochemical data" and model input and output files are provided in child item "Geochemical and environmental tracer models".

This child item of the data release contains geochemical and environmental-tracer model inputs, outputs, model results, and a full model archive (model code). Dataset includes environmental-tracer concentrations, modeled recharge conditions (water temperature, excess air), resulting estimated groundwater residence times, and geochemical modeling simulations of aqueous speciation and water-rock interaction. This dataset supports an integrated hydrogeochemical investigation of solute sources, groundwater recharge processes, and groundwater flow in the vicinity of the Captain Jack Superfund Site, Boulder County, Colorado. Data were collected by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency.

This child item of the data release contains geochemical and environmental-tracer model inputs, outputs, model results, and a full model archive (model code). Dataset includes environmental-tracer concentrations, modeled recharge conditions (water temperature, excess air), resulting estimated groundwater residence times, and geochemical modeling simulations of aqueous speciation and water-rock interaction. This dataset supports an integrated hydrogeochemical investigation of solute sources, groundwater recharge processes, and groundwater flow in the vicinity of the Captain Jack Superfund Site, Boulder County, Colorado. Data were collected by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency.

This child item of the data release contains geochemical and environmental-tracer model inputs, outputs, model results, and a full model archive (model code). Dataset includes environmental-tracer concentrations, modeled recharge conditions (water temperature, excess air), resulting estimated groundwater residence times, and geochemical modeling simulations of aqueous speciation and water-rock interaction. This dataset supports an integrated hydrogeochemical investigation of solute sources, groundwater recharge processes, and groundwater flow in the vicinity of the Captain Jack Superfund Site, Boulder County, Colorado. Data were collected by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency.

The U.S. Geological Survey (USGS) used an analytic-element method (AEM) modeling approach to quantitatively understand groundwater dynamics at the Captain Jack Superfund Site, located in Boulder County, Colorado. The Captain Jack Superfund Site hosts extensive interconnected underground mine workings.The U.S. Environmental Protection Agency has instituted a remedial strategy of impounding water within the mine workings behind a hydraulic bulkhead in May 2018. The AEM is a grid-less modeling framework where multiple hydrologic stressors may be superimposed upon one another, resulting in a prediction of the bulk system response. This screening-level model could be used for evaluation of boundary conditions, hydraulic properties, and hydrologic compartmentalization and uses a probabilistic approach wherein uncertainty in multiple boundary conditions and hydraulic properties may be tested. The model is not expected to reproduce all observed water levels exactly, but instead is used to provide a framework for future data collection and modeling. This model archive contains model code, inputs, and example outputs for a single simulated scenario. The AEM for the Captain Jack Superfund Site was constructed in the Python programming language. This USGS data release contains all of the input and output files for the simulations described in the associated journal article (https://doi.org/10.1007/s12665-023-10797-3)

The U.S. Geological Survey (USGS) used an analytic-element method (AEM) modeling approach to quantitatively understand groundwater dynamics at the Captain Jack Superfund Site, located in Boulder County, Colorado. The Captain Jack Superfund Site hosts extensive interconnected underground mine workings.The U.S. Environmental Protection Agency has instituted a remedial strategy of impounding water within the mine workings behind a hydraulic bulkhead in May 2018. The AEM is a grid-less modeling framework where multiple hydrologic stressors may be superimposed upon one another, resulting in a prediction of the bulk system response. This screening-level model could be used for evaluation of boundary conditions, hydraulic properties, and hydrologic compartmentalization and uses a probabilistic approach wherein uncertainty in multiple boundary conditions and hydraulic properties may be tested. The model is not expected to reproduce all observed water levels exactly, but instead is used to provide a framework for future data collection and modeling. This model archive contains model code, inputs, and example outputs for a single simulated scenario. The AEM for the Captain Jack Superfund Site was constructed in the Python programming language. This USGS data release contains all of the input and output files for the simulations described in the associated journal article (https://doi.org/10.1007/s12665-023-10797-3)

This U.S. Geological Survey (USGS) data release contains stream water chemistry and streamflow data collected in late August and early September, 2021 from 28 sites located throughout Colorado, USA. The sampled streams all drain high-elevation mountain watersheds in areas where the bedrock is hydrothermally altered and contains abundant sulfide minerals. Most sampled streams are therefore affected by natural acid-rock drainage. All sites had been sampled in prior years so that the 2021 data could be used to evaluate potential changes in stream water chemistry in recent decades. Streamflow was also quantified at most sites using data from a sodium chloride slug addition wherein specific conductivity readings were used as a surrogate for the tracer concentration.