IV-392 



artificial changes being made in its physical structure. Shore- 

 line areas have been filled to create more land area for residen- 

 tial and commercial use; channels have been dredged and maintained 

 to permit safer and better navigation; harbor facilities have been 

 dredged; bridges and causeways have been built. All of these 

 activities have impact on the coastal zone ecosystem, but the activ- 

 ities having the most impact on water quality are dredging and 

 filling. The potential for pollution of the system exists in both 

 filling and dredging; both can introduce foreign materials into 

 the water, destroy aquatic habitat, and alter physical circulation 

 patterns. In the case of dredging, exposed bottom materials, if 

 sufficiently high in organic content, can adversely affect oxygen 

 resources. Disposal of dredged materials often creates another 

 problem — unless the materials are used for land fill, dredged 

 material creates water quality problems in the disposal area. 



The general magnitudes of dredging and filling activities are 

 shown in Tables IV. 2. 9 and IV. 2. 10. These generalities hide the 

 slow attrition of estuarine areas by the small bulkheading, fill- 

 ing, and dredging activities associated with statistically small 

 operations such as those associated with improvement of numerous 

 private residences. Probably few such operations create notice- 

 able habitat damage, but the total effect in local areas may be 

 severe over an extended period. 



