The successful testing of a two-dimensional hydrothermal/hydrodynamic model, CE-QUAL-W2(t), for Cannonsville Reservoir is documented. The model is calibrated to the detailed temperature data collected in the reservoir (depth-profiles at six locations) over the April-November interval (weekly) of 1995, using comprehensive hydrologic and on-site meteorological forcing data. Further, the frequency of current oscillations predicted for the lower layers matched results of independent determinations made from thermistor chain deployments (two locations). The model is verified through the successful continuous simulation of the observed thermal stratification regime of the reservoir for the 1988–1994 interval, a period in which wide interannual differences were observed related to variations in meteorology and operations. The model performs well in simulating: 1) the timing of stratification and turnover, 2) the duration of stratification, 3) the dimensions of the epilimnion and hypolimnion, 4) the temperature of the layers, and 5) longitudinal variations in these features. The tested model is applied to characterize longitudinal transport of a conservative substance input at the mouth of the principal tributary as a pulse event (e.g., spill).