This model is designed to assist University researchers with understanding the freshwater component of the Saco River outlet area where tidal and freshwater flows meet and interact. The model was developed using ArcGIS, Geo HMS and HECHMS to create a simulation of the Saco River Basin. The model can be used to simulate design storms such as a 100-year, 24-hour rainfall event or can simulate the impacts of actual recorded NEXRAD data from real storm events. The model incorporates GIS based land use, watershed, soils, and topographic information, as well as river sections, reservoir information and gage locations. The model is still under development, and is in the calibration stage for annual type of storms incorporating NEXRAD gridded rain data. The model currently accurately simulates large storm events using historical rainfall data at selected gages.