This map service is for the prod version of the county's NWI compliant wetland inventory from 2024.

Wetlands in this dataset were mapped and classified using: the National Wetlands Inventory (NWI) classification system (Cowardin et al., 1979) and the Landscape Position, Landform, Water Flow Path, and Water Body Type (LLWW) classification developed for the Western U.S. (Lemly et al. 2018). King County contracted with Geospatial Services (GSS) at Saint Mary's University of Minnesota to create high-quality National Wetlands Inventory Plus (NWIPlus) level mapping for the county. Program staff conducted some ground truthing of data. NWIPlus is an enhanced NWI product with hydrogeomorphic-type descriptors that can facilitate predicting wetland functions. The enhanced attributes describe wetland landform, water flow path and water body type.

The updated mapping will be used by developers and landowners to avoid wetland impacts, and may be incorporated into other GIS models which would identify potential wetland restoration projects and conservation priorities.