Hydric soil is defined as a soil that is saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part (USDA, 1991). The third edition of Hydric Soils of the United States lists technical criteria which reflect those soils which meet the hydric soil definition. Hydric soils under normal conditions support hydrophytic vegetation. The National Technical Committee for Hydric Soils has developed a list of hydric soils of the United States. However, the presence or absence of hydric soils on the Soil Conservation Service's Soil Survey is not necessarily sufficient to identify hydric soils. A field investigation is also necessary.
Several indicators are available for determining whether a given soil meets the criteria and definition for hydric soils. The following are indications that hydric soils are present:
* Organic soils
Hydric Soils are characteristically organic, mottled or gleyed (a process in which the soil turns grey). Wetland soils are usually black, gray, or mottled with orange in color. Soil colors can be distinguished by using Munsell® Soil Color Charts. A soil is generally considered hydric if the matrix chroma is two (2) or less in mottled soils or a matrix chroma of one (1) or less in unmottled soils.