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



determining whether an area is subject 

 to federal jurisdiction under the Clean 

 Water Act or other Federal wetland 

 regulatory program, onsite 

 determinations are usually necessary. 

 Regardless of the method used, 

 documentation of all three criteria is 

 mandatory. 



Onsite Determinations 



When an qnsite inspection is 

 necessary, always be sure to review 

 pertinent background information (e.g., 

 NWI maps, soil surveys, and site plans) 

 before going to the subject site. This 

 information will be helpful in 

 determining what type of field method 

 should be employed. Also, read the 

 sections of this manual that discuss 

 disturbed area, and exceptions to the 

 three criteria before conducting field 

 work. These situations can pose 

 problems for the inexperienced wedand 

 delineator, so learn the procedures for 

 evaluating these sites. Recommended 

 equipment and materials for conducting 

 onsite determinations are listed in Table 

 2. 



Table 2.— Recommended Equipment 

 AND Materials for Onsite Determi- 

 nations 



'Needed for comprehensive determinatkxv 



For every upcoming field inspection, 

 the followiiig pre-lnspection steps 

 should be imdertaken: 



Step 1. Locate the project area on a 

 map (e.g., U.S. Geological Survey 

 topographic map or SCS soil survey 

 map) or on an aerial photograph and 

 determine the limits of the area of 

 concern. Proceed to Step 2. 



Step 2. Estimate the size of the subject 

 area. Proceed to Step 3. 



Step 3. Review existing background 

 information and determine, to the extent 

 possible, the site's geomorphological 

 setting (e.g., floodplain, isolated 

 depression, or ridge and swale 

 complex), its habitat or vegetative 

 complexity (i.e., the range or habitat or 

 vegetation tjrpes), and its soils. (Note: 

 Depending on available information, it 

 may not be possible to determine the 

 habitat complexity without going on the 

 site; if necessary, do a field 

 reconnaissance.) Proceed to Step 4. 



Step 4. Determine whether a disturbed 

 condition exists. Examine available 

 information and determine whether 

 there is evidence of sufficient natural or 

 hiunan-induced alteration to 

 significantly modify all or a portion of 

 the area's vegetation, soils, and/or 

 hydrology. If such disturbance is noted, 

 identify the limits of affected areas for 

 they should be evaluated separately for 

 wetland determination purposes 

 (usually after evaluating undisturbed 

 areas). The presence of distvirbed areas 

 within the subject area should be 

 considered when selecting an onsite 

 determination method. 



(Note: It may be possible that at any time 

 during this determinatioa, one or more of the 

 three characteristics may be found to be 

 significantly altered. If this happens, follow 

 the disturbed area wetland determination 

 procedures, as necessary). Proceed to Step 5. 



Step 5. Determine the field 

 determination method to be used. 

 Considering the size and complexity of 

 the area and the need for quantification, 

 determine whether a routine, 

 intermediate-level, or comprehensive 

 field determination method should be 

 used. When the area is equal to or less 

 than five acres in size or is larger and 

 appears to be relatively homogeneous 

 with respect to vegetation, soils, and/or 

 hydrology, use the routine method (see 

 below). When the area is greater than 

 five acres in size, or is smaller but 

 appears to be highly diverse with 

 respect to vegetation, use the 

 intermediate-level method (Appendix 3). 

 When detailed quantification of plant 

 commuinities and more extensive 

 documentation of other factors (soils 

 and hydrology) are required, use the 

 comprehensive method regardless of the 

 weUand's size (Appendix 4). 

 Significantly distiirbed sites (e.g., sites 

 that have been filled, hydrologically 

 modified, cleared of vegetation, or had 

 their soils altered) will generally require 

 intermediate-level or comprehensive 

 methods. In these disturbed areas, it 

 usually will be necessary to follow a set 

 of subroutines to determine whether the 

 altered characteristic met the applicable 

 criterion prior to its modification; in the 



case of altered wetland hydrology, it 

 may be necessary to determine whether 

 the area is effectively drained. Because 

 a large area may include a diversity of 

 smaller areas ranging from simple 

 wetlands to vegetatively complex eireas. 

 one may use a combination of the onsite 

 determination methods, as appropriate. 



Disturbed Area Wetland 

 Determina tions 



In the course of field investigations, 

 one often encotmters significantly 

 disturbed or altered areas. Disturbed 

 areas are wetiands that met the 

 mandatory criteria prior to disturbance 

 and have had vegetation, soils, and/or 

 hydrology altered such that the require 

 evidence of the relevant indicators for 

 the affected criteria has been removed. 

 The following sections discuss these 

 situations and present procedures for 

 distinguishing wetlands from 

 nonwedands. If a disturbed area is 

 identified as a wetland, field personnel 

 shall document the reasons for 

 determining that the site would have 

 been a weUand but for the disturbance. 



Disturbed areas have been altered 

 either recently or in the past in some 

 way that makes wetland identification 

 more difficult than it would be in the 

 absence of such changes. Disturbed 

 areas include both weUands and 

 nonwetlands that have been modified to 

 varying degrees by hiunan activities 

 (e.g., filling, excavation, clearing, 

 damming, and building construction) or 

 by natural events (e.g., avalanches, 

 mudslides, fire, volcanic deposition, and 

 beaver dams). Disturbed wetlands 

 include areas subjected to deposition of 

 fill or dredged material, removal or other 

 alteration of vegetation, conversion to 

 agricultural land and silvicultiu^ 

 plantations, and construction of levees, 

 chaimelization and drainage systems, 

 and/or dams (e.g., reservoirs and beaver 

 dams) that significemUy modify an 

 area's hydrology. In considering the 

 effects of natural events (e.g., a weUand 

 buried by a mudslide), the relative 

 permanence of the change eind whether 

 the area is still functioning as a weUand 

 must be considered. If natural events 

 have relatively permanently disturbed 

 an area to the extent that wetiand 

 hydrology is no longer present, and 

 therefore hydric soils and hydrophytic 

 vegetation, even if still present, wotdd 

 not be expected to persist at the site, the 

 area is no longer a wetiand. Detailed 

 investigations of the prior condition of 

 such areas is generally inappropriate. , 



In cases where recent htmian 

 activities have caused these changes, it 

 may be necessary to determine the date 

 of the alteration or conversion for legal 



