IV-435 



The impact of one estuarine use on another may be either "prohibitive" 

 or "restrictive" depending on the kind of use and sometimes on the 

 manner in which it is carried out. 



PROHIBITIVE IMPACTS 



These involve permanent changes in the environment and thereby 

 prohibit all uses unable to cope with such changes. The geo- 

 graphical range of such impacts may be from the limited area in 

 which they occur to an entire estuarine system, depending on the 

 nature and size of the change. The impact may be temporary, if 

 it is possible to return the environment to its original form, 

 or it may be permanent. 



Any use or activity requiring physical modification of the 

 shoreline, marshes, or bottom of an estuarine system may have a 

 prohibitive impact. Modification of water circulation also tends 

 to be prohibitive when it has any conflicting impact. 



Navigation Channel Dredging 



This is probably the most widespread and constant permanent 

 modifying activity in the estuarine system. It is carried out 

 solely to maintain and improve navigation needed for commercial 

 and recreational purposes and for national defense. Dredged 

 navigation channels must be kept clear for navigational purposes, 

 and the bottom is constantly being removed. Both of these 



