11-53 



areas have been filled to create more land area for residential and 

 commercial use; channels have been dredged and maintained to permit 

 safer and better navigation; and harbor facilities have been dredged 

 and bridges and causeways have been built. All of this activity has 

 had impact on the coastal zone ecosystem, but the activities having 

 the most impact on water quality are dredging and fil ling . The po- 

 tential for pollution of the system exists in both filling and dredg- 

 ing; both can introduce foreign materials into the water, destroy 

 aquatic habitat, and alter physical circulation patterns. 



The primary source of therma l pollution is from industrial cooling 

 water effluents. Power plants are the major users of cooling water 

 in the estuarine zone, and power generation capacity has approximately 

 aoubled each decade during this century. The impact of this growth 

 on the estuarine areas is evidenced by the fact that, in 1950, 22 

 percent of the power plants were in the coastal zone; it is antici- 

 pated that over 30 percent of the plants will be located there in 

 the late 1970's. 



Estuarine areas are also very important highways of commerce, and 

 thousands of commercial vessels, foreign and domestic, from ocean 

 liners to barges, traverse the coastal waterways each year. Added 

 to this are many of the 1,500 Federal vessels and many nearly eight 

 million recreational vessels. All of these watercraft carry people 

 and/or cargo, and are a real or potential pollution source. 



