Section G - Problem Areas 



77. There are certain wetland types and/or conditions that may make 

 application of Indicators of one or more parameters difficult, at least at 

 certain times of the year. These are not considered to be atypical situa- 

 tions. Instead, they are wetland types in which wetland indicators of one or 

 more parameters may be periodically lacking due to normal seasonal or annual 

 variations in environmental conditions that result from causes other than 

 human activities or catastrophic natural events. 



Types of problem areas 



78. Representative examples of potential problem areas, types of varia- 

 tions that occur, and their effects on wetland indicators are presented in the 

 following subparagraphs. Similar situations may sometimes occur in other wet- 

 land types. Note: This section is not intended to bring nonwetland areas 

 having wetland indicators of two, but not all three, -parameters into Sec- 

 tion 404 jurisdiction. 



a. Wetlands on drumlins. Slope wetlands occur in glaciated areas 

 in which thin soils cover relatively impermeable glacial till 

 or in which layers of glacial till have different hydraulic 

 conditions that produce a broad zone of ground-water seepage. 

 Such areas are seldom, if ever, flooded, but downslope ground- 

 water movement keeps the soils saturated for a sufficient por- 

 tion of the growing season to produce anaerobic and reducing 

 soil conditions. This fosters development of hydric soil char- 

 acteristics and selects for hydrophytic vegetation. Indicators 

 of wetland hydrology may be lacking during the drier portion of 

 the growing season. 



b. Seasonal wetlands. In many regions (especially in western 

 states) , depression areas occur that have wetland indicators of 

 all three parameters during the wetter portion of the growing 

 season, but normally lack wetland indicators of hydrology 

 and/or vegetation during the drier portion of the growing sea- 

 son. Obligate hydrophytes and facultative wetland plant spe- 

 cies (Appendix C, Section 1 or 2) normally are dominant during 

 the wetter portion of the growing season, while upland species 

 (annuals) may be dominant during the drier portion of the grow- 

 ing season. These areas may be inundated during the wetter 

 portion of the growing season, but wetland hydrology indicators 

 may be totally lacking during the drier portion of the growing 

 season. It is important to establish that an area truly is a 

 water body. Water in a depression normally must be suffi- 

 ciently persistent to exhibit an ordinary high-water mark or 

 the presence of wetland characteristics before it can be con- 

 sidered as a water body potentially subject to Clean Water Act 

 jurisdiction. The determination that an area exhibits wetland 



93 



