Wetlands have physical, ecological, and legal definitions. The term describes those places in the landscape where water naturally collects or emerges on the surface. Legal definitions depend on the presence of water, the seasonal depletion of oxygen in soils, and the presence of biota adapted to those conditions.
Our wet climate, undulating glacial plateau with its compacted till soils, and broad floodplains, large historical population of beaver resulted in a landscape with vast wetlands, providing summer stream flow for salmon and migrating waterfowl along the pacific flyway.
Wetlands are a large complex topic with a vast literature that hasn't been well developed on this wiki.