The 2800 square km Etowah River Basin forms the watershed of Lake Allatoona in North Georgia. Lake Allatoona is classified as in transition to eutrophic and the state has placed a cap on annual phosphorus (P) loads to the lake. Our objective was to develop a watershed-scale model of P transport to Lake Allatoona using the Soil Water Assessment Tool (SWAT). We used the Parameter Estimator (PEST) software for auto-calibration of daily water flow and manual calibration for monthly Suspended Sediment (SS) and P concentrations. PEST did an excellent job of calibrating flow, although peak flows during storms were slightly under-predicted. There was a tendency to under-predict base-flow concentrations of SS and P and it was difficult to judge how well the model was calibrated for storm SS and P predictions due to the sparse observed data set. SWAT predictions of annual load of Total P (TP) to Lake Allatoona agreed well with observed data. Point sources accounted for only 10.4% of the TP load. Export coefficients for TP were highest from pasture landuse in the Etowah River basin (7 kg TP/ha/yr) where poultry operations are common. These results indicate that non-point sources of TP loading to Lake Allatoona are significant and there is a potential for trading P credits between point and nonpoint sources.