CRS-56 



usually the first step in a transition to other uses. If other uses are in- 

 tended, the fill may be stabilized using a variety of engineering techniques, 

 such as planting and sloping embankments to minimize erosion. However, when 

 no other use is anticipated — for instance, if the fill is excess material 

 from a dredge area — often little effort has been made to stablize the fill. 

 This was particularly true in the past. 



Filling destroys the wetland by smothering the habitat and raising the 

 surface elevation. The fill is piled on top of wetlands and develops a dif- 

 ferent, and typically less productive, habitat which is not subject to the 

 periodic saturation or inundation of water. Fills can also alter the functions 

 of adjacent wetlands. If the edges of a fill are not stabilized, sediment may 

 wash into adjacent wetland areas and stream courses. Siting of the fill can 

 alter water flow or change the nature of water movement patterns. This, in 

 turn, can lead to either drier or wetter conditions on adjacent wetlands. 



Dredging 



Dredging may be undertaken in the wetlands themselves or in adjacent 

 strain channels. Dredging In wetlands is often undertaken as the first step in 

 building a firm base for a fill. The soft organic material, which typically 

 lies under a wetland area, is not stable enough to support most structures. 

 It is removed by dredging and the open area is surcharged, or refilled, usually 

 with rock. This process usually provides a satisfactory base for construction. 



Dredging is associated with navigational improvements to stream channels 

 or harbors. Dredging a navigation channel can affect nearby wetlands in several 

 ways. First, the altered river channel changes river flow patterns (including 

 flow velocity and movement), disturbing the relationship between wetlands and 

 water courses. Second, when navigation is made possible, wakes from vessels 

 can erode adjacent streambank areas. This problem has been documented as 



