A simplified continuous rainfall/runoff/receiving water quality response simulation model is presented. The purpose of this model is to simulate all major urban pollution sources in a simple yet rational manner. Application of the model provides long-term simulation of the total urban system at moderate cost. Processes simulated include rainfall, direct runoff, watershed pollution accumulation and washoff, sewer system infiltration, storage/treatment systems for wet-weather flow, dry-weather WWTP effluent, upstream flow, and receiving water quality response to the combined effects of all the above pollution sources. Pollutants considered are biochemical oxygen demand (BOD), total kjeldahl nitrogen (TKN), suspended solids (SS), and lead (Pb). Receiving water responses simulated included suspended solids concentrations, minimum dissolved oxygen concentrations, and total and dissolved lead concentrations. The simulation provides a planning tool which may be used to evaluate the long-term water quality impacts of various water quality management alternatives including control of combined sewer overflow and/or urban stormwater runoff.