Displays areas with 40% steep slope or greater in the City of Seattle.A polygon feature class showing areas with an incline of 40% or more (10 feet of vertical rise over a horizontal distance of 25 feet or less) with a height of at least 10 feet. This layer was produced using a combination of 2001 LIDAR contours (Puget Sound LIDAR Consortium) and the 1993 topographic contours from aerial photos. The Steep Slope layer was most recently updated under SDCI Director's Rule 12-2019. The steep slope area map is called “advisory” because the mapping is used by the Seattle Department of Construction and Inspections for initial information and screening. Whether or not a site is eventually treated as an environmentally critical area is based on the actual topography of the ground surface. For more information about the definition of steep slope erosion hazard areas, see Seattle Municipal Code section 25.09.012, Environmentally Critical Areas (ECA) definitions. Because of the size of this dataset, we do not recommend trying to download it. Please use as a service. If you need a particular area extracted, please use this form to make a request:City of Seattle GIS Data RequestUpdated as needed.