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

August 23, 2021

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.