National Wetland Inventory Classification
Reference Guide

The labels on the National Wetland Inventory Maps are based on a hierarchical classification scheme of System, Subsystem, Class, Subclass, Water Modifier, and Special Modifiers. In WETMAAP, to keep it simple, we are concerned with only the System and Class level identifiers.

 

System Class Water Modifier
E 2 EM 1 P x
Subsystem Subclass Special Modifier

E = Estuarine. Estuarine is tidal, saline content greater than 0.5 parts per thousand. Considered salt water. Considered wetlands.

P = Palustrine. Palustrine is tidal or non-tidal (mostly non-tidal) with a saline content less than 0.5 parts per thousand. Considered fresh water.  Considered wetlands.

U = Upland. Upland is too dry to be considered wetlands.

AB = Aquatic Bed. Seagrass, lily pads, water hyacinth, etc. Because they vary in location and extent from one year to the next. This is considered to be open water.

OW = Open Water

UB = Unconsolidated Bottom. Water covers the surface all the time. Considered as open water.

EM = Emergent Vegetation. Herbaceous vegetation

US = Unconsolidated Shore. Exposed sand or mud at low tide or low water stages. Not vegetated.

FL = Flats. Exposed sand or mud at low tide or low water stages. Not vegetated.

BB = Beaches and Bars. Exposed or flooded sand or mud at low tide or low water stages. Not vegetated.

FO or F = Forested. Woody vegetation over 20 feet in height.

SS = Scrub-Shrub. Woody vegetation less than 20 feet in height.

R = Range. Vegetation dominated by herbaceous plants. Unimproved, fallow, or mowed grass dominated area.

A = Agriculture. Improved pasture and cropland. Planted crops or grass.

U = Urban. Developed areas for residential, industrial, and commercial uses.

B = Barren. Not vegetated. Not developed.

RF = Reef.  Primarily below the water surface features formed by coral, oysters, and worms.

ML = Moss - Lichen.  Areas where substrate is covered by moss - lichen vegetation.

SB = Streambed.  Bed of a stream channel that is occupied by water intermittently.

To see the corresponding WETMAAP to NWI Classification categories