The purpose of the project was to study urban watersheds as a complex system. The approach was to use mathematical models that could adjust for the major causes of variation in the system. The models used had been developed earlier using hydrologic data obtained from rural watersheds. These models were designed to be used in planning and regionalized so that model parameters can be predicted based upon site characteristics and thus the models applied at ungaged sites. A goal of this project was to extend the capabilities of these hydrologic models to include the effects of urbanization and to include water quality as a component.