A simulation model was used to assess how agricultural practices used to reduce soil erosion, such as no-till cropping, affect the plant nutrient and suspended sediment levels in streams. The model is based on principles developed by the Soil Conservation Service, such as the Universal Soil Loss Equation and the Hydrologic Curve Number Equation. Annual model predictions for discharge and the mass loadings of phosphorus, nitrogen, and suspended sediment compare favorably to actual data collected for Irondequoit Creek, in western New York State during 1980 and 1981. The model was then run, driven by 20 years of meterological data, in order to assess various agricultural Best Management Practices. The effect of selected practices on discharge, nutrient loadings, and sediment loadings is presented.