King CountyFor more information about this layer please see the GIS Data Catalog . Project was to find, count and map onsite septic system (OSS) served parcels in King County. Additionally, sewer connected parcels were also identified to exclude them from expected OSS parcels. The starting base layer was a parcel layer for all of King County (Plibrary.PROPERTY.parcel_area) from about September of 2015. Project staff used various means to identify and catalogue sewer connected, OSS served, vacant and other identified parcels for all of King County.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/419b260889014a47ad3b134d4b7d71d1_0engKing County GIS Open DataPublicParcels with Onsite Sewage Designations in King County [Washington (State)--King County]Web servicesWashington (State)--King CountyWashington (State)Last Modified: 2025-12-02