Description of Methods 



Offsite Determinations 



4.4. When an onsite inspection is not necessary 

 because information on hydrology, hydric soils, 

 and hydrophytic vegetation is known or an inspec- 

 tion is not possible due to time constraints or other 

 reasons, a wedand determinadon can be made in 

 t"he office. This approach provides a best approxi- 

 madon of the presence of wedand and its bounda- 

 ries based on available information. The accuracy 

 of the determination depends on the quality of the 

 information used and on one's ability and expen- 

 ence in an area to interpret these data. Where reUa- 

 ble, site-specific data have been previously coUect- 

 ed,'the wedand determination should be reasonably 

 accurate. Where these data do not exist, more gen- 

 eralized information may be used to make a preUm- 

 inary wedand determination. In either case, howev- 

 er, if a more accurate delineation is required, then 

 onsite procedures must be employed. 



Offsite Determination Method 



4.5. The following steps are recommended for 

 conducting an offsite wedand determination: 



Step 1. Locate the area of interest on a 

 U.S. Geological Survey topographic map and 

 delineate the approximate subject area boundary on 

 the map. Note whether marsh or swamp symbols 

 or lakes, ponds, rivers, and other waterbodies are 

 present within the area. If they are, then there is a 

 good likelihood that wedand is present. Proceed to 

 Step 2. 



Step 2. Review appropriate National Wet- 

 lands Inventory (NWl) maps, State wetland maps, 

 or local wetland maps, where available. If these 

 maps designate wetlands in the subject area, there 

 is a high probability that wetlands are present 

 unless there is evidence on hand that the wedands 

 have been effectively drained, filled, excavated, 

 impounded, or otherwise significantiy altered since 

 the effective date of the maps. Proceed to Step 3. 



Step 3. Review SCS soil survey maps 

 where available. In the area of interest, are there 

 any map units listed on the county list of hydric 

 soil map units or are there any soil map units with 

 significant hydric soil inclusions? If YES, then 

 assume that at least a portion of the project area 



may be wetland. If tiiis area is also shown as a 

 wedand on NWI or other wedand maps, then there 

 is a high probability diat the area is wedand unless 

 it has been recendy altered (check recent aenal pho- 

 tos Step 4). Areas without hydric sods or hydnc 

 soil inclusions should in most cases be eliminated 

 from further review, but aerial photos still should 

 be examined for small wedands to be more certam. 

 This is especially true if wedands have been desig- 

 nated on the National Wedands Inventory or other 

 wedand maps. Proceed to Step 4. 



Step 4. Review recent aerial photos of the 

 project area. Before reviewing aerial photos, evalu- 

 ate climatological data to determine whether the 

 photo year had normal or abnormal (high or low) 

 precipitation two to three months, for example, 

 prior to die date of the photo. This will help pro- 

 vide a useful perspective or frame-of -reference for 

 doing photo interpretation. In some cases, aenal 

 photos covering a multi-year penod (e.g., 5-7 

 years) should be reviewed, especially where recent 

 climatic conditions have been abnormal. 



During photo interpretation, look for one or more 

 signs of wedands. For example: 



1) hydrophytic vegetation; 



2) surface water, 



3) saturated soils; 



4) flooded or drowned out crops; 



5) stressed crops due to wemess; 



6) greener crops in dry years; 



7) differences in vegetation patterns due to 

 different planting dates. 



If signs of wedand are observed, proceed to Step 5 

 when site-specific data are available; if site-specific 

 data are not available, proceed to Step 6. 



{CAUTION: Accurate photo interpretation of cer- 

 tain wedand types requires considerable experase. 

 Evergreen forested wedands and temporanly flood- 

 ed wedands, in general, may present considerable 

 difficulty. If not proficient in wetland photo inter- 

 pretation, then one can rely more on the findings of 

 other sources, such as NWI maps and soil sur- 

 veys, or seek help in photo interpretation.) 



Step 5. Review available site-specific infor- 

 mation In some cases, information on vegetation, 

 soils, and hydrology for the project area has been 

 collected during previous visits to the area by agen- 

 cy personnel, environmental consultants or others. 



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