Snohomish County Public Works Surface Water ManagementClosed detention features are designed to retain storm water and allow outflow over time. They mapped to allow for inspection and maintenance as part of Snohomish County's National Pollutant Discharge Elimination System (NPDES) permit.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/47e40e0f92fe489aaa20d66f726e165a_0engSnohomish County Open Data PortalPublicClosed Detention [Washington (State)--Snohomish County]Web servicesWashington (State)--Snohomish CountyWashington (State)Last Modified: 2022-11-09