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Along with over 15,000 lakes, the state has more than 90,000 miles of
watercourses and 10.6 million acres of peatlands, bogs, marshes, and wet
meadows. These highly diverse groups of surface or near-surface water
features are collectively called "wetlands" and cover 24.4 percent of the state.
Technically, wetlands are areas of transition between terrestrial and aquatic
systems where the water is usually at or near the the soil surface.
A three-parameter approach has been developed to define wetlands based on vegetation,
soils, and hydrology. For the purpose of classification wetlands must fit one or more of
the following three attributes as defined by
Cowardin et al.(1979):
- at least periodically, the land supports predominantly hydrophytes (plants that live in water)
- the substrate is predominantly undrained hydric soil
- the substrate is non-soil and is saturated with water or covered
by shallow water at some time during the growing season of each
year
In 1979, the U.S. Fish & Wildlife Service implemented the National
Wetlands Inventory (NWI) program. Wetlands habitats were classified
by observable vegetation types, and extent of water cover, with
a hierarchical classification scheme. The NWI data for Minnesota
was developed from 1974-1984 aerial photographs to identify, characterize,
and map water and wetlands habitats. Digital versions of these maps
were created for use in Geographical Information System (GIS) applications.
Information about obtaining digital and hard copy NWI maps is available
from US Fish and Wildlife
To see the distribution of wetlands in Minnesota and by major drainage
basins and sub-basins from the National Wetland Inventory (Cowardin)
Classification chart, click on table
1.2 of the Minnesota Wetland Guide.
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