1) Describe the type of alteration. Examine 

 the area and describe the type of alteration that 

 occurred. Look for evidence of: 



A) dams - Has recent construction of a 

 dam or some natural event (e.g., beaver activity or 

 landslide) caused the area to become increasingly 

 wetter or drier? {Note: This activity could have 

 occurred at a considerable distance from the site in 

 question, so be aware of and consider the impacts 

 of major dams in the watershed above the project 

 area.) 



B) levees, dikes, and similar structures - 

 Have levees or dikes been recently constructed that 

 prevent the area from periodic overbank flooding? 



C) ditches - Have ditches been recently 

 constructed causing the area to drain more rapidly? 



D) channelization - Have feeder streams 

 recently been channelized sufficiently to alter the 

 frequency and/or duration of inundation? 



E) filling of channels and! or depressions 

 (land-leveling) - Have natural channels or depres- 

 sions been recendy filled? 



F) diversion of water - Has an upstream 

 drainage pattern been altered that results in water 

 being diverted from the area? 



G) groundwater withdrawal - Has pro- 

 longed and intensive pumping of groundwater for 

 irrigation or other purposes significantiy lowered 

 the water table and/or altered drainage patterns? 



2) Determine the approximate date when the 

 alteration occurred, if necessary. Check aerial pho- 

 tographs, consult with local individuals, and 

 review other possible sources of information. 



3) Describe the effects of the alteration on 

 the area's hydrology. Consider the following and 

 generally describe how the observed alteration 

 affected the project area: 



A) Is the area more frequendy or less fre- 

 quendy inundated than prior to alteration? To what 

 degree and why? 



B) Is the duration of inundation and soil 

 saturation different than prior to alteration? How 

 much different and why? 



4) Characterize the hydrology that previous- 

 ly existed at the area. Obtain and record all possible 

 evidence that may be useful for characterizing the 

 previous hydrology. Consider the following: 



A) stream or tidal gauge data - If a stream 

 or tidal gauging station is located near the area, it 

 may be possible to calculate elevations representing 

 the upper limit of wetland hydrology based on 

 duration of inundation. Consult SCS district offic- 

 es, hydrologists from the local CE district offices 

 or other agencies for assistance. If fill material has 

 not been placed on the area, survey this elevation 

 from the nearest USGS benchmark. If fill material 

 has been placed on the area, compare the calculated 

 elevation with elevations shown on a USGS topo- 

 graphic map or any other survey map^at predates 

 site alteration. ^ 



B) field hydrologic indicators onsite or in 

 a neighboring reference area - Cenain field indica- 

 tors of wetiand hydrology may still be present. 

 Look for water marks on trees or other structures, 

 drift lines, and debris deposits (see pp. 17-19 for 

 additional hydrology indicators). If adjacent undis- 

 turbed areas are in the same topographic position, 

 have the same soils (check soil survey map), and 

 are similarly influenced by the same sources of 

 inundation, look for wetiand hydrology indicators 

 in these areas. 



C) aerial photographs - Examine aerial 

 photographs and determine whether the area has 

 been inundated or saturated during the growing 

 season. Consider the time of the year that the aerial 

 photographs were taken and use only photographs 

 taken prior to site alteration. 



D) historical records - Examine historical 

 records for evidence that the area has been periodi- 

 cally inundated. Obtain copies of any such infor- 

 mation. 



E) National Flood Insurance Agency 

 flood maps - Determine the previous frequency of 

 inundation of the area from national floods maps (if 

 available). 



F) local government officials or other 

 knowledgeable individuals - Contact individuals 

 who might have knowledge that the area was peri- 

 odically inundated or saturated. 



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