I 



Part II. 



Mandatory Technical 

 Criteria for Wetland 

 Identification 



2,0. Wetlands possess three essential 

 characteristics: (1) hydrophytic vegeta- 

 tion, (2) hydric soils, and (3) wetland 

 hydrology, which is the driving force 

 creating all wedands. These characteristics and their 

 technical criteria for identificadon purposes are de- 

 scribed in the following sections. The three techni- 

 cal criteria specified are mandatory and must all be 

 met for an area to be identified as wedand. There- 

 fore, areas that meet these criteria are wetlands. 



Hydrophytic Vegetation 



2.1. For purposes of this manual, hydrophytic 

 vegetation is defined as macrophytic plant life 

 growing in water, soil or on a substrate that is at 

 least periodically deficient in oxygen as a result of 

 excessive water content. Nearly 7,000 vascular 

 plant species have been found growing in U.S. 

 wedands (Reed 1988). Out of these, only about 27 

 percent are "obligate wetland" species that nearly 

 always occur in wedands under natural conditions. 

 This means that the majority of plant species grow- 

 ing in wetlands also grow in nonwedands in vary- 

 ing degrees. 



2.2. The FWS in cooperation with CE, EPA, and 

 SCS has published the "National List of Plant Spe- 

 cies That Occur in Wetlands" from a review of the 

 scientific literature and review by wedand experts 

 and botanists (Reed 1988). The list separates vas- 

 cular plants into four basic groups, commonly 

 called "wedand indicator status," based on a plant 

 species' frequency of occurrence in wedands: (1) 

 obligate wetland plants (OBL) that occur almost al- 

 ways (estimated probability >99%) in wedands un- 

 der natural conditions; (2) facultative wetland plants 

 (FACW) that usually occur in wedands (estimated 

 probability 67-99%), but occasionally are found in 

 nonwedands; {3) facultative plants (FAG) that are 

 equally likely to occur in wetlands or nonwetlands 

 (estimated probability 34-66%); and (4) facultative 



upland plants (FACU) that usually occur in non- 

 wetlands (estimated probability 67-99%), but occa- 

 sionally are found in wedands (estimated probabili- 

 ty 1-33%). If a species occurs almost always 

 (estimated probability >99%) in nonwetlands under 

 natural conditions, it is considered an obligate up- 

 land plant (UPL). These latter plants do not usually 

 appear on the wedand plant list; they are listed only 

 when found in wedands with a higher probability 

 in one region of the country. If a species is not on 

 the list, it is presumed to be an obligate upland 

 plant. The "National List of Plant Species That Oc- 

 cur in Wetlands" has been subdivided into regional 

 and state lists. There is a formal procedure to peti- 

 tion the interagency plant review committee for 

 making additions, deletions, and changes in indica- 

 tor status. Since the lists are periodically updated, 

 the U.S. Fish and Wildlife Service should be con- 

 tacted to be sure that the most current version is be- 

 ing used for wetland determinations. The appropri- 

 ate plant list for a specific geographic region should 

 be used when making a wedand determination and 

 evaluating whether the following hydrophytic veg- 

 etation criterion is satisfied. 



Hydrophytic Vegetation Criterion 



2.3. An area has hydrophytic vegetation 

 when, under normal circumstances: (1) 

 more than 50 percent of the composition 

 of the dominant species from ail strata are 

 obligate wetland (OBL), facultative wet- 

 land (FACW), and/or facultative (FAC) 

 species, or (2) a frequency analysis of all 

 species within the community yields a 

 prevalence index value of less than 3.0 

 (where OBL = 1.0, FACW = 2.0, FAC = 

 3.0, FACU = 4.0, and UPL = 5.0). CAU- 

 TION: When a plant community has less 

 than or equal to 50 percent of the domi- 

 nant species from all strata represented by 

 OBL, FACW, and/or FAC species, or a 

 frequency analysis of all species within 

 the community yields a prevalence index 

 value of greater than or equal to 3.0, and 

 hydric soils and wetland hydrology are 

 present, the area also has hydrophytic 

 vegetation. {Note: These areas are consid- 

 ered problem area wetlands.) 



2.4. For each stratum (e.g., tree, shrub, 

 and herb) in the plant community, domi- 

 nant species are the most abundant plant 

 species (when ranked in descending order 



