Hydrological models are integral components of water management and monitoring strategies. In particular, distributed hydrological models allow for detailed description of the hydrological and energy cycle and provide opportunities for dealing with forcing variables that fluctuate strongly in space and time, such as precipitation. Hydrologists and water resources specialists increasingly implement these models as a means to ameliorate the state of knowledge on basins of interest, and provide valuable information regarding hydrological state variables and potentially important distributed information on existing and future streamflow conditions.. Also, there is increasing interest in using spatially distributed meteorological data from diverse sources such as weather radar, Numerical Weather Prediction (NWP) models and traditional rain gauge networks to drive these distributed models. This paper examines the feasibility of implementing a distributed hydrological model for estimating streamflow in unregulated basins and the accuracy of short-term hydrological-forecasting in the Great Lakes Basin of North America. The platform for hydrologic assessment in the Great Lakes Basin is the WATFLOOD hydrological forecasting system. The focus of this study is to provide initial testing of the hydrological model including calibration and validation of the model parameters using historic data. The meteorological forcing data sets include distributed Quantitative Precipitation Estimates (QPE) derived from rain gauge and ground-based radar data. NWP model input from the Canadian Global Environmental Multi-scale (GEM) model and nested high-resolution GEM runs during our initial testing phase (summer of the year 2000) for limited time periods of extreme precipitation also are used as forcing. Initial results to assess the applicability of distributed hydrological modeling and to provide the framework for testing the hydrological aspects of integrated hydrological and atmospheric models, are presented. Routing and regulation considerations including stream network conceptualization and lake routing are also discussed.