The first step in understanding Illinois' wetlands is to define what a wetland is. In general terms, a wetland may be described as an area that is both part land and part water. The legal definition of a wetland, however, is more technical. The State of Illinois defines a wetland as, "land that has a predominance of hydric soils and that is inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances does support, a prevalence of hydrophytic vegetation typically adapted for life in saturated soil conditions" (Interagency Wetlands Policy Act of 1989).

In the federal government, there are several different legal definitions of the term "wetland". The differences between the definitions are relatively minor. Every definition includes the same three major attributes: hydric soils, wetland hydrology, and hydrophytic vegetation. It is how each of these three attributes are defined and the combinations in which they must be present that separates the various definitions.

Because there are variations in the legal wetland definition it is difficult to determine under what conditions an area may be considered wetland. To help define and identify the presence of the three wetland attributes on a piece of property, some highly technical and very specific nationwide guidance and delineation manuals have been developed. These manuals and their applications are discussed in more detail in the delineation section of this webpage. The remaining sections are designed to further help simplify the process of identifying and classifying wetlands.

[Introduction | Delineations | Hydric Soils|Wetland Hydrology| Hydrophytic Vegetation|
Wetland Classification |Summary]

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