Datasets supporting the manuscript entitled "Groundwater-stream connections shape the spatial patterns and rates of aquatic metabolism", published in Limnology and Oceanography Letters. Three datasets are available: "Groundwater_Characterization.csv": dissolved organic matter characterization of and heterotrophic activity associated with, the major water sources discharging into a headwater boreal stream during summer 2017. Major water sources are: lake water and five discrete groundwater inflows (here named as discrete riparian inflow points). "Raz_Additions.csv": Constant-rate additions of resazurin performed in a boreal headwater stream (Krycklan catchment, Sweden) during seven dates of summer 2017. Data contains resazurin and resorufin concentrations from the surface and hyporheic water at 18 stations along a 90-m long reach. "Raz_transformation_metric.csv": Hydrologic and metabolic characterization of the 90-m long reach for the seven resazurin additions conducted in summer 2017. More information about the data can be found in the document "Metadata.doc". Information about field and laboratory procedures can be found in the main manuscript or in the document "Supporting_Information.doc".