The U.S. Geological Survey’s (USGS) SPAtially Referenced Regression On Watershed attributes (SPARROW) model was used to aid in the interpretation of monitoring data and simulate nutrient loads in streams across the Midwest Region of the United States. SPARROW is a hybrid empirical/process-based mass balance model that can be used to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in streams. The spatially explicit model structure is defined by a river reach network coupled with contributing catchments. The model is calibrated by statistically relating watershed sources and transport-related properties to monitoring-based water-quality load estimates. This USGS data release includes input, output, control, model coefficient and summary statistic files associated with 2012 SPARROW simulations of total phosphorus load in streams of the Midwest and represents a variation of a similar model described in Robertson and Saad (2019, https://doi.org/10.3133/sir20195114). This version of the model utilizes cover crops as a land-to-water delivery term in place of the phosphorus loss rate term included in the original model. The impacts of cover crops on total phosphorus load in streams was evaluated by increasing and decreasing the percent of cover crop in catchments of the Midwest. The results of this evaluation are described in Roland and others (2022, https://doi.org/10.2489/jswc.2022.00162).