Impervious Surface Analysis Tool
The Impervious Surface Analysis Tool (ISAT) is used to calculate the percentage of impervious surface area of user-selected geographic areas (e.g., watersheds, municipalities, subdivisions). ISAT is available as an ArcView® 3.x, ArcGIS 8.x or an ArcGIS 9.x extension.
The link address is: http://www.csc.noaa.gov/crs/cwq/isat.html