channels (rhizospheres) are present around living 

 roots and rhizomes of any plants, or if water- 

 staip'='d leaves caused by inundation are present, 

 then uiese areas are considered to meet the wetland 

 hydrology criteria and are wetlands. If direct evi- 

 dence or these field indicators are not present, then 

 one must use best professional judgement to make 

 the wetland determination. In doing so, one should 

 review the problem area wetland discussion (p. 

 55), consider other hydrologic indicators that may 

 be present (see pp. 17-19), and perhaps even con- 

 sult with a wetland expert to assist in the determi- 

 nation. 



Disturbed Area and Problem Area Wetland 

 Determination Procedures 



4.20. In the course of field investigations, one 

 will undoubtedly encounter significantly disturbed 

 or altered areas, or natural areas where making a 

 wetland determination is not easy. Disturbed areas 

 include situations where field indicators of one or 

 more of the three wetland identification criteria are 

 obliterated or not present due to recent change. In 

 contrast, there are other wetlands that, under natu- 

 ral conditions, are simply difficult to identify, such 

 as wetlands dominated by FACU species, wetlands 

 lacking field indicators for one or more of the tech- 

 nical criteria for wetlands, and wetlands occurring 

 on difficult to identify hydric soils. These wetlands 

 are considered problem area wetiands. The follow- 

 ing sections discuss these difficult, confounding 

 situations and present procedures for distinguish- 

 ing wetiands from nonwetiands. 



Disturbed Areas 



4.21. Disturbed areas have been altered either 

 recendy or in the past in some way that makes wet- 

 land identification more difficult than it would be in 

 the absence of such changes. Disturbed areas 

 include both wetiands and nonwetiands that have 

 been modified to varying degrees by human activi- 

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

 and building construction) or by natural events 

 (e.g., avalanches, mudslides, fu-e, volcanic deposi- 

 tion, and beaver dams). Such activities and events 

 change the character of the area often making it dif- 

 ficult to identify field characteristics of one or more 

 of tile wetiand identification criteria (i.e., hydro- 

 phytic vegetation, hydric soils, and wetland 

 hydrology). Disturbed wetiands include areas sub- 

 jected to deposition of fill or dredged material. 



removal or other alteration of vegetation, conver- 

 sion to agricultural land and silviculture planta- 

 tions, and construction of levees, channelization 

 and drainage systems, and/or dams (e.g., reser- 

 voirs and beaver dams) that significantiy modify an 

 area's hydrology. In cases where recent human 

 activities have caused these changes, it may be 

 necessary to determine the date of the alteration or 

 conversion for legal purposes. {Note: If the activity 

 occurred prior to the effective date of regulation or 

 other jurisdiction, it may not be necessary to make 

 a wetiand determination for regulatory purposes.) 

 In considering the effects of natural events (e.g., a 

 wetiand buried by a mudslide), the relative perma- 

 nence of the change and whether the area is still 

 functioning as a wetiand must be considered. 



4.22. In disturbed wetiands, field indicators for 

 one or more of the three technical criteria for wet- 

 land identification are usually absent. It may be 

 necessary to determine whether the "missing" indi- 

 cator(s) (especially wetland hydrology) existed 

 prior to alteration. To do this requires review of 

 aerial photographs, existing maps, and other avail- 

 able information about the site, and may involve 

 evaluating a nearby reference site (similar to the 

 original character of the one altered) for indicator(s) 

 of the "altered" characteristic. 



4.23. When a significantiy disturbed condition is 

 detected during an onsite determination, the follow- 

 ing steps should be taken to determine if the "miss- 

 ing" indicator(s) was present before alteration and 

 whether the criterion in question was originally 

 met. Be sure to record findings on the appropriate 

 data form. After completing the necessary steps 

 below, return to the applicable step of the onsite 

 determination method being used and continue 

 evaluating the site's characteristics. 



Step 1. Determine whether vegetation, soils, 

 and/or hydrology have been significantly altered at 

 the site. Proceed to Step 2. 



Step 2. Determine whether the "altered" charac- 

 teristic met the wetland criterion in question prior to 

 site alteration. Review existing information for the 

 area (e.g., aerial photos, NWI maps, soil surveys, 

 hydrologic data, and previous site inspection 

 reports) contact knowledgeable persons familiar 

 with the area, and conduct an onsite inspection to 

 build supportive evidence. The strongest evidence 

 involves considering all of the above plus evaluat- 

 ing a nearby reference site (an area similar to the 



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