Stormwater runoff can cause both flooding and the spread of pollutants, so it is important that it be managed effectively. This project investigates the watershed scale implementation of green infrastructure: technologies that reduce the imperviousness and promote the retention and treatment of the runoff at the source, rather than move the water to centralized locations for treatment and release. The aim of the project is to create a modeling framework to be used in transportation planning. It will model the effect of green infrastructure on flooding and water quality, and assess their life cycle costs and environmental and health impacts. The project is conducted in phases. Phase I work is completed, which is to develop a method for creating a GIS layer of existing green infrastructure that can be overlaid with transportation and grey stormwater infrastructure network. Phase II aims to integrate hydrological and water quality modeling for scenario analysis of combination of transportation planning and green infrastructure design.