CE-QUAL-W2, a mechanistic, two-dimensional model of hydrodynamics and water quality (Portland State University, 2021), was developed and calibrated for J. Percy Priest Reservoir, Tennessee, a U.S. Army Corps of Engineers (USACE) reservoir on the Stones River, southeast of Nashville, Tennessee. The J. Percy Priest CE-QUAL-W2 model was simulated and calibrated using USACE data collected from January 2012 through May 2019. Constituent loads were developed for the model using the LOAD ESTimator (LOADEST; U.S. Geological Survey, 2016) and were based on water-quality data collected by the USACE from January 2005 through May 2019. The calibrated model will be used by the Tennessee Department of Environmental Conservation and others as a water-quality diagnostic and predictive tool for water-resources management.