Wood Rodgers was selected by the Alameda County Flood Control and Water Conservation District to develop a significant flood mitigation analysis and design for the 22-square-mile Flood Control District 3A watershed. The project focused on integrating existing geometry from survey data, as-built construction plans and improvement plans, and extensive field data collection. From this information, a model was created to assess flood reduction measures. GIS played an integral role in the success of the model by managing and querying large volumes of existing geometry data required to create the closed conduit, street network, and open channel hydraulic models; effectively utilizing large volumes of ground surface LiDAR data used in developing the watershed hydrology model; and processing NEXRAD-derived precipitation data grids for use in calibration and validation of the model.