This U.S. Geological Survey (USGS) data release contains data from stream water, groundwater, and soil samples collected in 2019 and 2020 in the North Quartz Creek watershed in central Colorado. Fourteen streambank wells were installed in pairs at seven locations in August 2020 to capture the emerging groundwater from the left bank and right banks (relative to downstream-facing direction) and a synoptic sampling campaign was conducted to quantify metal contributions to the stream. A continuous, instream injection of sodium bromide (NaBr) was initiated at the head of the 5 km study reach several days prior to the synoptic sampling campaign and maintained throughout the duration of the study. Bromide concentrations were subsequently used to determine streamflow in the primary study reach (upper 1.3 km) using the tracer-dilution method, and as an indicator of hydrologic connections between North Quartz Creek and subsurface water. Streamflow was quantified in a secondary study reach (lower 3.7 km) using data from a series of sodium chloride slug additions wherein specific conductivity readings were used as a surrogate for the tracer concentration. Surface water samples were collected along North Quartz Creek including inflows from the left (LBI) and right (RBI) banks. Soil and sediment samples were collected along the transport path from source material (natural weathering and mine tailings/mine drainage) to the stream.

This U.S. Geological Survey (USGS) data release contains data from stream water, groundwater, and stream sediment samples collected in August 2023 in the East Mancos River watershed in southwestern Colorado. Data were collected as part of a study aimed at identifying sources of elevated metal concentrations in the stream. Eighteen streambank wells were installed in pairs at nine locations to capture the emerging groundwater from the left and right banks (relative to downstream-facing direction) and a synoptic sampling campaign was conducted to quantify stream metal loads. A continuous, instream injection of sodium bromide (NaBr) was initiated at the head of the ~17 km study reach prior to the synoptic sampling campaign and maintained throughout the duration of the study. Bromide concentrations were subsequently used to determine streamflow in the upper ~2.7 km of the stream using the tracer-dilution method. Streamflow was quantified for tributaries and locations farther downstream using data from a series of sodium chloride slug additions wherein specific conductivity readings were used as a surrogate for the tracer concentration. Stream and groundwater samples, including the wells and inflows from the left (LBI) and right (RBI) banks, were collected mainly in the upper ~0.9 km of the stream course (primary study reach). Environmental tracer data were collected to better understand groundwater flowpaths to the stream. Stream sediment samples, including some ferricrete samples, were also collected to help identify potential instream and near-stream metal sources.

This dataset contains environmental tracer data from surface water and groundwater samples collected by the U.S. Geological Survey in Redwell Basin, an alpine watershed in the Elk Mountains near the town of Crested Butte, Colorado. The basin is underlain by interbedded shale and sandstone that have been variably hydrothermally altered and silicified by local magmatic intrusions. Samples were collected from 2017 to 2019 from bedrock monitoring wells completed at multiple depths, shallow hand-installed piezometers and mini boreholes, springs, mine adits, and streams. The tracer data include stable isotopes of water (oxygen-18 and deuterium), tritium, dissolved noble gases (He, Ne, Ar, Kr, Xe, and helium-3/helium-4 ratio), sulfur hexafluoride, and other dissolved atmospheric gases.

This dataset contains environmental tracer data from surface water and groundwater samples collected by the U.S. Geological Survey in Redwell Basin, an alpine watershed in the Elk Mountains near the town of Crested Butte, Colorado. The basin is underlain by interbedded shale and sandstone that have been variably hydrothermally altered and silicified by local magmatic intrusions. Samples were collected from 2017 to 2019 from bedrock monitoring wells completed at multiple depths, shallow hand-installed piezometers and mini boreholes, springs, mine adits, and streams. The tracer data include stable isotopes of water (oxygen-18 and deuterium), tritium, dissolved noble gases (He, Ne, Ar, Kr, Xe, and helium-3/helium-4 ratio), sulfur hexafluoride, and other dissolved atmospheric gases.

This data release is part of a study examining the use of near-stream groundwater discharge as a tool for Geochemical Exploration. Handcart Gulch is an unmined alpine watershed in Montezuma Mining District in the Colorado Front Range. The streambed is cemented by deep ferricrete deposits. Stream water, groundwater, and ferricrete samples were collected and analyzed to constrain the location of a possible concealed mineral occurrence identified by previous stream water sampling. Nineteen, near stream mini-boreholes were drilled through ferricrete using a portable, handheld, gasoline powered, rock coring drill manufactured by Shaw Tool. Boreholes were drilled within 2 meters of the stream on the east and west banks to constrain local-scale groundwater variations on either side of the stream. Ferricrete samples were logged and collected during drilling. A subset of ferricrete samples were analyzed for bulk chemistry and a deionized water leach quantified the water-soluble fraction from the ferricrete samples. Groundwater levels and field parameters (temperature, pH, specific conductance, and dissolved oxygen) were measured and groundwater samples were collected using a peristaltic pump for major and trace element chemistry. Environmental tracer samples (stable water isotopes, dissolved noble gases, helium isotopes, and tritium) were collected using a submersible double-valve pump manufactured by Solinst Canada Ltd. Stream water samples were collected adjacent to mini-boreholes over a period of two days with no major precipitation events.

This data release is part of a study examining the use of near-stream groundwater discharge as a tool for Geochemical Exploration. Handcart Gulch is an unmined alpine watershed in Montezuma Mining District in the Colorado Front Range. The streambed is cemented by deep ferricrete deposits. Stream water, groundwater, and ferricrete samples were collected and analyzed to constrain the location of a possible concealed mineral occurrence identified by previous stream water sampling. Nineteen, near stream mini-boreholes were drilled through ferricrete using a portable, handheld, gasoline powered, rock coring drill manufactured by Shaw Tool. Boreholes were drilled within 2 meters of the stream on the east and west banks to constrain local-scale groundwater variations on either side of the stream. Ferricrete samples were logged and collected during drilling. A subset of ferricrete samples were analyzed for bulk chemistry and a deionized water leach quantified the water-soluble fraction from the ferricrete samples. Groundwater levels and field parameters (temperature, pH, specific conductance, and dissolved oxygen) were measured and groundwater samples were collected using a peristaltic pump for major and trace element chemistry. Environmental tracer samples (stable water isotopes, dissolved noble gases, helium isotopes, and tritium) were collected using a submersible double-valve pump manufactured by Solinst Canada Ltd. Stream water samples were collected adjacent to mini-boreholes over a period of two days with no major precipitation events.

This U.S. Geological Survey (USGS) data release contains data from stream water, groundwater/springs, and sediment samples collected from legacy mine land (LML) sites in central Colorado. The sites were selected using a GIS-based approach that integrated regional geological and geochemical datasets with known mine features and satellite data identifying hydrothermal alteration (ASTER) to identify LML-impacted watersheds with low natural background or metal concentrations slightly above aquatic life standards. The central Colorado watersheds selected for preliminary investigation included 1) McNasser Gulch, 2) upper South Fork Lake Creek, 3) Saints John Creek, and 4) Hall Valley (north fork of South Platte River). Reconnaissance sampling of surface water, groundwater, and sediment (August 2019) to identify sources of trace element contamination in each watershed. Follow-up sampling in the Hall Valley watershed (August 2020) provided flow and concentration data for the four largest surface inflows to a headwater pond and additional locations below the pond outlet. Metal loads at these locations were calculated as the product of flow and concentration.

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.

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.

This data release is part of a study designed to test geochemical methods that best delineate known mineral deposits in the northeast part of the Tanacross 1° x 3° quadrangle, within the Yukon-Tanana Upland region, Alaska. The total area sampled is about 3,200 km2. Extensive tundra cover and patchy spruce/alder vegetation and very limited outcrop exposure characterize the area. Soils and stream sediments contain mixtures of weathered bedrock, sand derived from dunes developed during the Pleistocene, and volcanic ash deposits from the 1.2 Ky eruption of the nearby Mount Churchill volcano. Several mineral deposits are known in the area, including the Late Cretaceous to earliest Tertiary porphyry Cu (+/-Mo-Au) deposits at Taurus, Bluff, and Oreo; and poorly understood epithermal(?) Cu-Au (+/- Pb-Zn) deposits at Pika, Fishhook, and Pushbush. Stream water and sediment samples were collected near these occurrences, as well as in surrounding areas, to determine methods that most effectively enhance geochemical signals related to mineralization. Sediment samples were collected during two sampling campaigns (2017 and 2018). Each sample was dried, homogenized, and split into multiple aliquots. One aliquot of sediment was subsequently sieved to recover the minus-80 mesh portion of the sample, whereas a second was sieved to recover the minus-230 mesh portion of the sample. Both aliquots were analyzed by three techniques, all of which included ICP-OES/ICP-MS analysis following (1) sodium peroxide fusion, 2) leaching by aqua regia; and 3) leaching by cold hydroxylamine-HCL. Stream water samples were collected from select sites in August 2018 and analyzed for cation and anion concentrations using high-resolution ICP-MS for cations and Ion Chromatography (IC) for anions.