Federal Register / Vol. 56, No. 157 / Wednesday, August 14. 1991 / Proposed Rules 40461 



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 that 

 have been successfully used to delineate 

 wetlands by the four Federal agencies. If 

 situations require different approaches, 

 the reasons for departing from 

 recommended approaches should be 

 documented. Remember, however, that 

 any method for making a wetland 

 determination must consider the three 

 technical criteria (i.e., hydrophytic 

 vegetation, hydric soils, and wetland 

 hydrology) listed in Part n of this 

 manual. These criteria must be met in 

 order to identify a wetland (unless the 

 area is addressed in this manual as an 

 exception to the criteria). Moreover, 

 procedures for determining the wetland 

 boundary must be consistent with those 

 used in this manual. In applying all 

 methods, relevant available information 

 on wetlands in the area of concern 

 should be collected and reviewed. Table 

 1 lists primary data sources. 



Selection of a Method 



The wetland delineation methods 

 presented in this manual can be grouped 

 into two general types: (1) Offsite 

 preliminary procedures and (2) onsite 

 procedures. The offsite procedures are 

 designed for use in the office for 

 preliminary weUand determinations, 

 while onsite procedures are developed 

 for use in the field for definitive weUand 

 determinations. When an onsite 

 inspection is unnecessary or caimot be 

 undertaken for various reasons, 

 available information can be reviewed 

 in the office to make a preliminary 

 weUand determination. If available 

 information is insufficient to make a 

 preliminary wetland determination or if 

 a definitive wetland determination or 

 wetland boundary must be established, 

 (e.g., for determining whether or not 

 there is jurisdiction or the boundaries of 

 jurisdiction under a Federal weUand 

 regulatory program), an onsite 

 inspection should be conducted. For 

 determining whether or not an area is 

 subject to Clean Water Act jurisdiction, 

 an onsite inspection is usually 

 necessary. Depending on the field 

 information needed or the complexity of 

 the area, one of three basic onsite 

 methods may be employed: (1) Routine, 

 (2) intermediate-level, or (3) 

 comprehensive. 



The routine method is designed for 

 areas equal to or less than five acres in 

 size or larger areas wiUi 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 

 apphed. as necessary. The 

 comprehensive method is applied to 

 situations requiring detailed 

 documentation of vegetation, soils, and 

 hydrology. Assessments of significanUy 

 disturbed sites will often require 

 intermediate-level or comprehensive 

 determinations as weU as some special 

 procedures. WeUand delineators should 

 become well acquainted with common 

 types of weUand disturbances, and with 

 types of weUands that are described in 

 this manual as exceptions to the three 

 criteria. In making weUand 

 determinations, one should select the 

 appropriate method for each individual 

 unit v«thin 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. 



Regardless of the method used, the 

 desired outcome or final product is a 

 weUand/nonweUand determination. 

 Depending on one's expertise, available 

 information, and individual or agency 

 preference, there are two basic 

 approaches to delineating weUand 

 boimdaries. The first approach involves 

 characterizing plant commuinities in the 

 area, identifying plant communities 

 meeting the hydrophytic vegetation 

 criterion, examining the soils in these 

 areas to confirm that the hydric soil 

 criterion is met, and finally looking for 

 evidence of weUand hydrology to verify 

 this criterion. 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 

 approximate boundary of potential 

 hydric soUs, and then verifying the 

 presence of likely hydrophjrtic 

 vegetation and looking for signs of 

 weUand hydrology. This type of 

 approach has been employed by the 

 SCS and to a limited extent by Uie FWS. 

 Since these approaches yield the same 

 result this manual incorporates both 

 approaches into most of the methods 

 presented. 



Table 1.— Primary Sources of Infor- 

 mation That May Be Helpful in Mak- 

 ing A Wetland Determination 



Table 1.— Primary Sources of Infor- 

 mation That May Be Helpful in Mak- 

 ing A Wetland Determination— Con- 

 tinued 



Description of Methods 



Offsite Preliminary Determinations 



When an onsite inspection is not 

 necessary because information on 

 hydrology, hydric soUs. and hydrophytic 

 vegetation is known or an inspection is 

 not possible due to time constraints or 

 other reasons, a preliminary weUand 

 determination can be made in the office. 

 This approach provides an 

 approximation of the presence of 

 weUand and its boundaries based on 

 available information. The accuracy of 

 the determination depends on the 

 quality of the information used and on 

 one's ability and experience in an area 

 to interpret these data. Where reliable, 

 site-specific data have been previously 

 collected, the weUand determination 

 can be reasonably accurate. Where 

 these data do not exist, more 

 generalized information may be used to 

 make a preliminary weUand 

 determination. In either case, however, 

 if a more accurate delineation is 

 required, then onsite procedures must be 

 employed. For the purposes of 



