Stormwater Open Conveyance Ditch and Natural Drainage

For more information about this layer please see the GIS Data Catalog. Components of Open Conveyance (Ditch and Natural Drainage)--Ditch: A long narrow constructed channel.--Natural Drainage: Non-engineered, non-constructed flow paths following existing land contours. When a stream isn’t mapped and the natural drainage system (stream) may be confused with a ditch that is part of King County’s MS4, the stream is mapped as Natural Drainage to prevent future confusion.