Part IV. 



Methods for Identifica- 

 tion and Delineation of 

 Wetlands 



4.0. Four basic approaches for identify- 

 ing and delineating wetlands have been 

 developed to cover situations ranging 

 from desk-top or office determinations 

 to highly complex field determinations 

 for regulatory purposes. These methods 

 are the recommended approaches and the reasons 

 for departing from them should be documented. 

 Remember, however, that any method for making a 

 wetland determination must consider the three tech- 

 nical criteria (i.e., hydrophytic vegetation, hydric 

 soils, and wetland hydrology) listed in Part II of 

 this manual. These criteria must be met in order to 

 identify a wetland. In applying all methods, rele- 

 vant available information on wedands in the area 

 of concern should be collected and reviewed. Table 

 2 lists primary data sources. 



Selection of a Method 



4.1, The wetland delineation methods presented in 

 this manual can be grouped into two general types: 

 (1) off site procedures and (2) onsite procedures. 

 The offsite procedures are designed for use in the 

 office, while onsite procedures are developed for 

 use in the field. When an onsite inspection is unne- 

 cessary or cannot be undertaken for various rea- 

 sons, available information can be reviewed in the 

 office to make a wetland determination. If available 

 information is insufficient to make a wedand deter- 

 mination or if a precise wedand boundary must be 

 established, an onsite inspecrion should be con- 

 ducted. Depending on the field information needed 

 or the complexity of the area, one of three basic 

 onsite methods may be employed: (1) roudne, (2) 

 intermediate-level, or (3) comprehensive. 



4.2. The routine method is designed for areas 

 equal to or less than five acres in size or larger are- 

 as with homogeneous vegetation. For areas greater 

 than five acres in size or other areas of any size that 

 are highly diverse in vegetation, the intermediate- 

 level method or the comprehensive method should 

 be applied, as necessary. The comprehensive meth- 

 od is applied to situations requiring detailed docu- 

 mentation of vegetation, soils, and hydrology. 

 Assessments of significantiy disturbed sites will 

 often require intermediate-level or comprehensive 

 determinations as well as some special procedures. 

 In other cases where natural conditions make wet- 

 land identification difficult, special procedures for 

 problem area wetland determinations have been 

 developed. These procedures are subroutines of the 

 three onsite determination methods. In making wet- 

 land determinations, one should select the appro- 

 priate method for each individual unit within the 

 area of concern and not necessarily employ one 

 method for the entire site. Thus, a combination of 

 determination methods may be used for a given 

 site. 



4.3. Regardless of the method used, the desired 

 outcome or final product is a wetiand/nonwetland 

 determination. Depending on one's expertise, 

 available information, and individual or agency 

 preference, there are two basic approaches to delin- 

 eating wetland boundaries. The first approach 

 involves characterizing plant communities in the 

 area, identifying hydrophytic plant communities, 

 examining the soils in these areas to confirm the 

 presence of hydric soil, and finally looking for evi- 

 dence of wetland hydrology. This approach has 

 been widely used by the CE and EPA and to a large 

 extent by the FWS. A second approach involves 

 first delineating the boundary of hydric soils, and 

 then verifying the presence of hydrophytic vegeta- 

 tion and looking for signs of wetiand hydrology. 

 This type of approach has been employed by the 

 SCS and to a limited extent by the FWS. Since 

 these approaches yield the same result, this manual 

 incorporates both approaches into most of the 

 methods presented. 



21 



