This collection of datasets results from a continuous and high frequency water quality monitoring program in the Mackenzie River close to Inuvik, NT, Canada. The work is carried out by AWI Potsdam's permafrost research section together with the Western Arctic Research Center (WARC). The sampling program aims to observe seasonal variations in organic carbon concentrations and chemistry of the Mackenzie River and thus their fluxes to Arctic coastal waters. The objective is to capture short-term temporal changes, for example those associated with storm or seasonal scale events, against the background of longer-term trends, such as shifts in hydrological regime and permafrost thaw. Weekly to bi-weekly observations cover all phases of the hydrological year (winter under-ice flow, spring break-up and freshet, summer flow, and freeze back in fall) with a focus on the loads and quality of dissolved organic carbon. Datasets record measurements made on water samples taken from the East Channel of the Mackenzie River just south of Inuvik, NT, Canada (68.338°N, 133.705°W). Sampling began May 4, 2023, and continued at approximately weekly frequency during the open water season and biweekly during the ice cover season, with longer gaps during ice cover buildup and breakup seasons. In addition to the samples taken from a dock, two additional samples were occasionally taken from the centre and the other shoreside of the river ("transect").Samples are analyzed for biogeochemical, sedimentological, bio-optical and hydrographical parameters; descriptions of sample handling, processing, transport, storage and analyses are included in the metadata for each dataset.