Data from tracer injection tests related to investigations of the Captain Jack mine site, Boulder County, Colorado

Acid mine drainage originating from underground mine workings discharge to surface water within the Lefthand Creek watershed and may adversely affect downstream aquatic ecosystems and habitats. The U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency (EPA), conducted a series of tracer injection tests to study groundwater transport and mixing dynamics near the Captain Jack mine superfund site in Boulder County, CO. Tracer injection tests consisted of the placement of liquid and solid tracers into collapsed mine shafts, waste rock piles, and groundwater wells. These datasets can be used to understand connectivity and quantify travel times in the underground mine workings, as well as support site characterization and potential remediation efforts.

This data release includes: (1) records of tracer dye injections, including tracer type, injection locations, masses injected, and injection timing; (2) laboratory results from activated charcoal packets and dye vials deployed and collected throughout the study area to detect the presence or absence of fluorescent tracers; (3) time-series and synoptic measurements of fluorescein concentrations in water samples collected following tracer injections; (4) chemical analyses of water samples, including dissolved metals and major anions collected from groundwater, surface-water, blank, and replicate samples; and (5) Synoptic measurements of streamflow along a lower stream reach, bounding associated inflows. The release also includes a photographic image documenting visible fluorescein transport and mixing within the study area.