The dataset describes mercury and dissolved organic matter concentration and quality over five synoptic sampling campaigns at 12 stream sites within the 41-hectare (ha) forested W-9 catchment at Sleepers River, Vermont, with an additional site at the downstream W-3 gage (837 ha). The five campaigns included a large (79 millimeter (mm)) fall storm, spring snowmelt, and spring, summer, and fall base flow periods. During the fall storm, the synoptic sampling was augmented with a time series of samples over the hydrograph at the W-9 weir. All samples were filtered and analyzed for mercury, methylmercury, major cations, total dissolved nitrogen, and dissolved organic carbon (DOC). Dissolved organic matter (DOM) was characterized by a full uv-visible absorbance scan and fluorescence excitation emission matrices, and other properties. Conventional DOM quality metrics were derived from these data and reported herein.