of abundance and cumulatively totaled) 

 that immediately exceed 50 percent of the 

 total dominance measure (e.g., basal area 

 or areal coverage) for the stratum, plus 

 any additional species comprising 20 per- 

 cent or more of the total dominance meas- 

 ure for the stratum. All dominants are 

 treated equally in determining the presence 

 of hydrophytic vegetation. 



2.5. {Note: The "National List of Plant Species 

 that Occur in Wetlands" uses a plus (+) sign or a 

 minus (-) sign to specify a higher or lower portion 

 of a particular wetland indicator frequency for the 

 three facultative-type indicators; for purposes of 

 identifying hydrophytic vegetation according to this 

 manual, however, FACW+, FACW-, FAC+, and 

 FAC are included as FACW and FAC, respective- 

 ly, in the hydrophytic vegetation criterion.) 



Hydric Soils 



2.6. Hydric soils are defined as soils that are satu- 

 rated, flooded, or ponded long enough during the 

 growing season to develop anaerobic conditions in 

 the upper part (U.S.D.A. Soil Conservation Serv- 

 ice 1987). In general, hydric soils are flooded, 

 ponded, or saturated for usually one week or more 

 during the period when soil temperatures are above 

 biologic zero 41° F as defined by "Soil Taxonomy" 

 (U.S.D.A. Soil Survey Staff 1975). These soils 

 usually suppon hydrophytic vegetation. The Na- 

 tional Technical Committee for Hydric Soils has 

 developed criteria for hydric soils and a list of the 

 Nation's hydric soils (U.S.D.A. Soil Conservation 

 Service 1987). {Note: Caution must be exercised in 

 using the hydric soils list for determining the pres- 

 ence of hydric soil at specific sites; see p. 12.) 



Hydric Soil Criterion 



2.7. An area has hydric soils when the 

 National Technical Committee for Hydric 

 Soils (NTCHS) criteria for hydric soils 

 are met. 



NTCHS Criteria for Hydric Soils 

 (U.S.D.A. Soil Conservation Service 

 1987): 



2. Soils in Aquic suborders, Aquic sub- 

 groups, Albolls suborder, Salorthids 

 great group, or Pell great groups of 

 Vertisols that are: 



a. somewhat poorly drained and have 

 water table less than 0.5 feet from 

 the surface for a significant period 

 (usually a week or more) during 

 the growing season, or 



b. poorly drained or very poorly 

 drained and have either: 



(1) water table at less than 1.0 

 feet from the surface for a sig- 

 nificant period (usually a week 

 or more) during the growing 

 season if permeability is equal 

 to or greater than 6.0 inches/ 

 hour in all layers within 20 

 inches, or 



(2) water table at less than 1.5 

 feet from the surface for a sig- 

 nificant period (usually a week 

 or more) during the growing 

 season if permeability is less 

 than 6.0 inches/hour in any 

 layer within 20 inches; or 



3. Soils that are ponded for long dura- 

 tion or very long duration during the 

 growing season; or 



4. Soils that are frequently flooded for 

 long duration or very long duration 

 during the growing season." 



{Note: Long duration is defined as inundation for a 

 single event that ranges from seven days to one 

 month; very long duration is defined as inundation 

 for a single event that is greater than one month; tre- 

 quendy flooded is defined as flooding likely to occur 

 often under usual weather conditions - more than 50 

 percent chance of flooding in any year or more than 

 50 times in 100 years. Other technical terms in the 

 NTCHS criteria for hydric soils are generally de- 

 fined in the glossary.) 



"1. All Histosols except Folists; or 



