20220301 14322300 1.0 TRUE Snohomish County Responsible Area (MS4) The MS4 is the county-owned storm sewer system. This polygon layer represents the approximate area in which the MS4 operates. The MS4 boundary is derived from a series of other county-maintained GIS layers including:county-owned right-of-way (ROW)county-owned pavement plus 5 ft buffercounty-owned or operated drainage facilitiesThis layer is updated weekly via script to accommodate changes in the GIS layers from which it is derived. Snohomish County Surface Water Management