The GIS Flood Tool (GFT) is a GIS-based flood inundation mapping tool developed by the United States Geological Survey. It using existing medium scale terrain datasets to create estimates of flood inundation boundaries in an area without detailed ground survey information. The tool can also be run with high resolution terrain datasets where available. The tool provides good estimates of the flood inundation extent where flood maps do not otherwise exist. Riverside is working with the USGS to test the tool and train GIS and hydrology professionals on its appropriate use.