King CountyFor more information about this layer please see the GIS Data Catalog . Control Other Line Component Type---Infiltration Trench: 2-5' wide trench designed to infiltrate stormwater below the ground surface. They feature perforated distribution pipes that is topped with filter fabric to prevent dispersal to the ground surface.---Bioretention Swale: May have rocks in the swale, various plantings with a landscaped feature look. ---Dispersal Trench: 2.5' or greater trench designed to disperse stormwater to the ground surface. They feature perforated distribution pipes and a filter fabric trench liner to prevent infiltration. ---Basic Dispersion: Basic dispersion is the application of dispersion devices that utilize any available capacity of onsite vegetated areas to mitigate the runoff quantity and quality impacts from developed surfaces (i.e., impervious and non-native pervious surfaces). The requirements for basic dispersion are less restrictive than full dispersion in that any type of vegetation cover is allowed, the flowpath lengths through the vegetation are shorter, and there is no requirement to preserve native vegetated surface (e.g., forested surface) or minimize developed surface. As such, its mitigation of runoff impacts is significantly lower than that of full dispersion.---Full Dispersion: Features a native vegetated flowpath segment of at least 100ft (25ft for sheet flow from a non-native pervious surface) along the flowpath that runoff would follow upon discharge. The flowpath segment must be either onsite or in an offsite tract or easement area reserved for dispersion and should be designated as a "native growth retention area" on the flow control BMP site plan attached to the required declaration of covenant and grant of easement. Full dispersion involves use of splash blocks, rock pads, gravel filled trenches or sheet flow.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/ad5b619820dc44188f8b8664d01dd8d4_0engKing County GIS Open DataPublicControl Other Line [Washington (State)--King County]Web servicesWashington (State)--King CountyWashington (State)Last Modified: 2026-01-08