A watershed in the coastal Canadian Arctic was sampled for dissolved carbon dioxide and methane concentration and stable carbon (carbon-13) isotopes to trace the transport, production, and consumption of carbon dioxide and methane during the spring thaw across a lake to bay transect. Two field campaigns were conducted in June 2022 and June-July 2023 out of the Canadian High Arctic Research Station (CHARS) in Cambridge Bay, Nunavut, Canada. Gas samples were collected via headspace extraction and transported back to the U.S. Geological Survey (USGS) Woods Hole Coastal and Marine Science Center (WHCMSC), where they were analyzed utilizing the USGS Automated Sample Introduction Module (AutoSIM) interfaced to a Picarro G2201-i CRDS (Cavity Ring-Down Spectrometer) to measure concentrations and stable carbon isotope ratios of methane and carbon dioxide. Field sampling was carried out by researchers from the Woods Hole Oceanographic Institution.