If sufficient data on hydrology that existed prior to 

 site alteration are not available to determine whether 

 wedand hydrology was previously present, then 

 use the other wedand identificanon criteria (i.e., 

 hydrophytic vegetation and hydric soils) to make a 

 wetland determination. 



5) Determine whether wetland hydrology 

 previously occurred. Examine available data. If no 

 indicators of wedand hydrology are found, and 

 other evidence of wedand hydrology is lacking, the 

 original hydrology of the area is not considered 

 wedand hydrology. If wetland hydrology indica- 

 tors and other evidence of wedand hydrology are 

 found, the area meets the wetland hydrology criter- 

 ion. Record decision and return to the applicable 

 step of the onsite determination method being used. 



Step 6. Determine whether wetland hydrology 

 still exists. Many wedands have a single ditch dis- 

 secting them, while others may have an extensive 

 network of ditches. A single ditch through a wet- 

 land may not be sufficient to effectively drain it; in 

 other words, the wetland hydrology criterion still 

 may be met under these circumstances. Undoubt- 

 edly, when ditches are observed, questions as to 

 the extent of drainage arise, especially if the ditches 

 are part of a more elaborate stream channelization 

 or other drainage project. In these cases and other 

 situations where the hydrology of an area has been 

 significantly altered (e.g., dams, levees, ground- 

 water withdrawals, and water diversions), one 

 must determine whether wedand hydrology still 

 exists. If it is present, the area is not effectively 

 drained. To determine whether wedand hydrology 

 still exists: 



1) Describe the type or nature of the altera- 

 tion. Look for evidence of: 



A) dams; 



B) levees, dikes, and similar structures; 



C) ditches; 



D) channelization; 



E) filling of channels and/or depressions; 



F) diversion of water; and 



G) groundwater withdrawal. 



(See Step 5 above for discussion of these factors.) 



2) Determine the approximate date when the 

 alteration occurred, if necessary. Check aerial pho- 

 tographs, consult with local officials, and review 

 other possible sources of information. 



3) Characterize the hydrology that presently 

 exists at the area. The following sequence of ^- 

 actions is recommended: ( 



A) Review existing information (e.g., 

 stream gauge data, groundwater well data, and 

 recent observations) to leam if data provide evi- 

 dence that wedand hydrology is still present. 



B) Examine early spring or wet growing 

 season aerial photographs for several recent years 

 and look for signs of inundation and/or soil satura- 

 tion. {Note: Large-scale aerial photographs, 

 1:24,000 and larger, are preferred.) These signs of 

 wetness indicate that the area still meets the wetland 

 hydrology criterion. If these signs are observed, 

 return to the applicable step of the onsite determina- 

 tion method being used. If such signs are not 

 present, then one should conduct an onsite inspec- 

 tion as follows. 



C) Inspect the site on the ground, look 

 for field indicators of wetland hydrology, and 

 assess changes in the plant community, if neces- 

 sary. If field indicators of wetland hydrology 

 (excluding hydric soil morphological characteris- 

 tics) are present, then wetland hydrology exists; 

 return to the applicable step of the onsite determina- /* 

 tion method being used. If such indicators are lack- ^ 

 ing, then examine the vegetation following an 

 appropriate onsite determination method. If OBL 

 and FACW plant species (especially in the herb 

 stratum) are dominant or scattered throughout the 

 site and UPL species are absent or not dominant, 

 the area is considered to meet the wedand hydrolo- 

 gy criterion and remains wedand. If UPL species 

 predominate one or more strata (i.e., diey represent 

 more than 50 percent of the dominants in a given 

 stratum) and no OBL species are present, then the 

 area is considered effectively drained and no longer 

 wedand. If the vegetation differs from the above 

 situations, then the vegetation at this site should be 

 compared if possible with a nearby undisturbed 

 reference area, so proceed to substep 3D; if it is not 

 possible to evaluate a reference site and the area is 

 ditched, channelized or tile-drained, go to substep 

 3E, or else go to substep 3F. 



D) Locate a nearby undisturbed reference 

 site with vegetation, soils, hydrology, and topogra- 

 phy similar to the subject area prior to its alteration, 

 examine the vegetation (following an appropriate 

 onsite delineation method), and compare it with the , 

 vegetation at the project site. If the vegetation is 



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