265 



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 bulklieading, filling, and dredging 

 activities associated with statistically small operations such as those 

 associated with improvement of numerous private residences. Prob- 

 ably few such operations create noticeable habitat damage, but the 

 total effect in local areas may be severe over an extended period. 



HEATED WASTE DISCHARGES 



Waste heat is another type of pollutant that is discharged to the 

 water environment as an expediency. Heat energy can be equally as 

 dangerous to aquatic environment as the other more obvious forms of 

 pollution. The primary source of heat energy is from industrial cool- 

 ing water effluents. Table IV.5.9 is a summary of the cooling water 

 use by industry for the United States. Power plants are the major 

 users of cooling water in the estuarine zone as shown in table IV.2.7. 



Power generation capacity has approximately doubled 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 powerplants 

 were in the coastal zone ; it is anticipated that over 30 percent of the 

 plants will be located there in the late 1970's. 



The existing cooling water use and waste heat discharges are sum- 

 marized in table IV.2.T. The contrasts among the various regions are 

 related to differences in factors such as the degree of urbanization and 

 industrialization and the availability of hydroelectric power. 



TABLE IV.5.9.— INDUSTRIAL USE OF COOLING WATER DURING 1964i 



Cooling water 

 intake (billions 

 Industry of gallons) Percent of tota I 



Electric power 



Primary metals 



Chemicals and allied products .:_ 



Petroleum and coal products.. 



Paper and allied products 



Food and kindred products ,.. 



Machinery 



Rubber and plastics 



Transportation equipment 



Another 



Total 50,065 100.0 



» Data from U.S. Dept. of Commerce, Bureau of the Census, "Census of Manufactures, Industrial Water Use," 1964. 

 WATERCRAPT OPERATIGN" 



Estuarine areas are important highways of commerce; thousands 

 of commercial vessels, foreign and domestic, from oceanliners to 

 barges, traverse the coastal waterways each year. Added to this traffic 

 are many of the 1,500 Federal vessels and many of nearly 8 million 

 recreational vessels. All of these watercraft carry people and/or cargo. 



