Extent of available data.
This data layer depicts the Circular 39 classification system of the original National Wetland Inventory. It was developed by the United States Fish and Wildlife Service between 1980 and 1986. The Circular 39 system divides wetlands predominantly based on depth and vegetation. Wetlands were primarily identified through aerial photo interpretation. Limited field verification and the use of supplemental spatial data, primarily USGS Quadrangle Maps and soil surveys, aided the process. Wetlands are highly valued for their ecological contributions. They provide habitat for a variety of plants and animals and improve water quality. Minnesota's wetlands are also legally protected - any loss of wetlands in the state must be mitigated through an associated restoration project.