TYPES OF WETLANDS 
Because of the infinitely varied and intergrading physical and 
chemical conditions that underlie the complex of wetlands in this country, 
it would be impossible to create a useful classification system that 
completely avoids overlapping of types recognized. Some degree of over- 
lapping between types listed here is acknowledged, but it is believed 
that they are sufficiently distinct to serve satisfactorily in svaluations 
of wetlands. 
The 20 types of wetlands described below are listed under the 
following regional categories: Inland Fresh, Inland Saline, Coastal 
Fresh, and Coastal Saline. 
INLAND FRESH AREAS 
Le Seasonally Flooded Basins or Flats. 
Soil covered with water or water- 
logged during variable seasonal 
periods; usually well drained 
during much of the growing 
season. Along river courses, 
flooding ordinarily occurs in 
late fall, winter, or spring; 
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in upland areas, basins or Seasonally flooded basins or flats; type 1. 
. (Cross-hatching denotes where this type 1 
flats may be filled with water SEE Ieael yt conten aca 
during periods of heavy rain or 
melting snow. 
Located on river bottoms in various parts of the country, partic- 
ularly in the Mississippi Valley; and along the borders of 
drawn-down reservoirs and in "dry lakes," shallow potholes, 
and other shallow upland depressions in the West, and elsewhere. 
Vegetation varies greatly, depending mainly on the season and 
duration of flooding. It includes bottomland woods as well as 
herbaceous growths. In marginal zones where the water has 
receded early in the growing season, smartweeds, wild millet, 
fall panicum, tealgrass, chufa, redroot cyperus, and cockleburs 
are likely to occur. Shallow basins that are submerged only 
very temporarily usually develop little or no wetland vegetation. 
Used very much by feeding ducks in bottomlands which become 
reflooded at the right time. Ducks also make considerable use 
of temporarily filled "dry lakes" or other depressions in upland 
