The NWI 2005 was an update to the original 1978 NWI Layer produced by US Fish and Wildlife Service, and utilized 1998 and 2005 imagery to map wetland loss/change over time. Classification of wetlands is based on the Cowardin Wetland Classification system with a minimum mapping unit of 1/10 acre. Wetland data produced by interpreting aerial imagery and digitizing boundaries in a heads up GIS environment. The most current up to date statewide wetland inventory for Michigan available as of 2020. NWI 2015 update is currently in progress in a partnership between EGLE and Ducks Unlimited, with expected statewide completion in 2025.
Michigan Dept. of Environment, Great Lakes, and Energy