King CountyFor more information about this layer please see the GIS Data Catalog . Pond/Vault Component Types---Detention (Flow Through): Detention ponds and vaults temporarily store stormwater and typically releases flow over a few hours or a few days. Flow through means that the pond or vault that flow enters the pond through an inlet and exits through an outlet. ---Detention (Backup): Detention ponds and vaults temporarily store stormwater and typically releases flow over a few hours or a few days. Backup means that the pond or vault that flow enters the pond through an inlet and exits through an outlet. ---Stormwater treatment wetland: Stormwater treatment Wetlands use gravity settling, physical, chemical and biological processes of plant uptake and bacterial degradation to remove pollutants. They are similar to wetponds in size, but have a deep cell a shallow cell that promotes plant growth. ---Wet (Water Quality): Drainage facilities for water quality treatment that contain a permanent pool of water. They are designed to optimize water quality by providing long retention times (on the order of a week or more) to settle out particles of fine sediment to which pollutants such as heavy metals adsorb, and to allow biologic activity to occur that metabolizes nutrients and organic pollutants. For wetvaults, the permanent pool of water is covered by a lid which blocks sunlight from entering the facility, limiting light-dependent biologic activity. Depth is >3'. ---Combined (Wet and Detention): Have the appearance of a detention facility but contain a permanent pool of water as well.---Oil Water Separator: A vault, usually underground designed to provide a quiescent environment to separate oil from water. Floatables (e.g., styrofoam) are also removed. ---Infiltration: A Pond or vault that is designed to use the hydrologic process of water soaking into the ground (commonly referred to as percolation) to dispose of surface and storm water runoffArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/2c578a859342423fb5974e819206a901_0engKing County GIS Open DataPublicControl Pond and Vault [Washington (State)--King County]Web servicesWashington (State)--King CountyWashington (State)Last Modified: 2026-01-08