Near-surface geophysical data collected along French Gulch near Breckenridge, Colorado, USA, September 2020

Near-surface geophysical surveys were completed in September 2020 in a mine-affected drainage near Breckenridge, Colorado, known as French Gulch. The study area was along a 0.3 mile (0.5 kilometer [km]) reach of French Gulch, approximately 2 river miles upstream from its confluence with the Blue River. This data release presents data from three geophysical surveys that used fiber-optic distributed temperature sensing (FO-DTS), forward-looking infrared (FLIR) imagery, and frequency domain electromagnetic induction (FDEM). The FO-DTS data were collected from September 14 to 17, 2020, using a Silixa XT-DTS system (Silixa, 2021) in single-ended mode. The FO-DTS cable was placed along the right and left banks of the French Gulch study reach. Within the zipped folder "DTS.zip," two comma-separated (.csv) files contain FO-DTS data collected along the right bank ('rb') and left bank ('lb') of the stream channel, as well as coordinates of the cable position collected using a Trimble Global Positioning System (GPS). Beyond georeferencing and time-correction, the FO-DTS data were not processed. All associated FLIR files are within the folder named “FLIR.zip”. The FLIR data were collected using a FLIR E8 camera (FLIR Systems, Inc., 2021) during a pre-dawn survey on September 17, 2020. The survey traveled along the FO-DTS cable (going downstream along the right bank and then returning upstream along the left bank). The GPS coordinates for the images are provided in a separate .csv file (flir_data_summary.csv). All associated FDEM files are within the folder named “FDEM.zip".The FDEM data were collected with a portable GEM-2 instrument (Geophex Ltd., 2021) carried at a height of 3.28 feet (1 meter) above ground surface during walking surveys on September 14-17, 2020. Multi-frequency quadrature data ranging from 1,530 to 47,970 hertz (Hz) were recorded by the instrument in horizontal coplanar mode. The gem.csv files contain the raw FDEM data and coordinate information extracted from the instrument and converted to a tabular format. Within each dataset's folder is a readme.txt that provides additional data-collection and data-use details.