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deeper navigation channels, building of causeways of jetties, and 

 even construction of pier bridges can cause subtle changes in water 

 movement that can change the balance of environmental conditions in 

 an estuarine system and result in gradual undesirable changes in the 

 ecosystem in addition to direct habitat damage. 



SOURCES OF POLLUTION 



Nearly all of man's activities can result in environmental degrada- 

 tion. Pollutants and polluting conditions are very rarely unique to 

 a particular use or specific activity, but may result from man's 

 existence in the estuarine zone as well as his use of it. The major 

 sources of pollution. 



(1) Those sources associated with the extent of development 

 of the estuarine zone, including waste discharges from 

 municipalities and industries, and land runoff from these 



as well as agriculture; 



(2) Those sources associated with particular activities of 

 great pollutional significance, specifically dredging and 

 filling, watercraft operation, underwater mining, and heated 

 effluent discharges; 



(3) External sources having impact derived through flow 

 regulation and upitream water quality. 



Over eight billion gallons of muni cipal wastes are discharged daily 

 into the waters of the estuarine zone. While most of this volume is 



