The data release documents the development of a hybrid (statistical-mechanistic) SPARROW (SPAtially Referenced Regression On Watershed attributes) model of long-term mean annual total nitrogen applied to streams and rivers of the Grande River Basin, Brazil. The model coupled observed long-term average total nitrogen loads at monitoring locations with additional explanatory variables (e.g., landscape sources, wastewater treatment plant inputs, and in-stream nitrogen losses) to estimate nitrogen loading to all reaches in the modeled area. The model was applied to estimate the effects of hypothetical changes in land use and discharge from wastewater treatment on in-stream total nitrogen loading, as described in the journal article. This USGS data release contains all of the input and output files for the execution of all of the models described in the journal article (see Table 1; https://doi.org/10.3390/w12102911). An R script is provided that allows users to execute the model.