This data was produced as part of a subsurface tracer experiment performed on a boreal hillslope in July, 2015. The data is separated into three files: 'subsurfaceFlow_bromideTracer_well_wTwinCr_koch.csv' includes the location and depth of well screens, concentrations of the bromide tracer in time, saturation state of the subsurface at the wells, ground cover at the wells, and depth of the organic-mineral boundary which controls shallow flow. 'subsurfaceFlow_bromideTracer_probe_wTwinCr_koch.csv' includes thaw depth, gravel presence, and vegetation type within the well field. 'subsurfaceFlow_bromideTracer_breakthroughs_wTwinCr_koch.csv' includes solute concentrations in time from wells that displayed robust breakthroughs. The data includes electrical conductivity and bromide measurements, and a column that combines these two solutes based on a significant linear relationship between the two.