“…The influence of land cover and anthropogenic activity on NDMA UFC at each sampling site was assessed for circles with different radii (2.5, 5, 7.5, 8.5, 10, 12.5, and 15 km) and drawn around a point upstream of each sampling site at various distances (1, 2, 3, 4, 5, 6, 7, 8, 10, and 12 km). Previous work evaluating anthropogenic chemical inputs has used a similar protocol. − Within each circle, land cover and anthropogenic activity information were extracted, processed, and analyzed via R and ArcGIS online. − All anthropogenic activities within each circle, including the number of WWTPs, the WWTP design flow, the number of feedlots, the total weight of livestock, the number of brownfields, and the number of septic tanks, were extracted from the Minnesota Geospatial Commons of the Minnesota Department of Health using R . The land cover within each circle, including forest, cropland, pasture, open water, and urban area, was obtained from the National Agricultural Statistics Service provided by the United States Department of Agriculture .…”