A field study was conducted to determine the influences of vegetation composition, buffer width, & infiltration rate on the effectiveness of native vegetation buffer zones as nonstructural treatments of urban runoff with respect to increasing water quality. The soil was a shallow, well-drained clay overlying limestone. 12 constituents were measured, & 4 different vegetation compositions were used as treatments: wooded areas, wooded areas cleared, native grasses mowed, & native grasses unmowed. The mowed & unmowed areas had the lowest concentrations of pollutants. Concentration of the pollutants in the buffer strip was studied.