37 



The largest percentage contributions by weight of these contaminants of 

 concern are generally those associated with discharges from the Hudson 

 estuary. The ocean dumping of municipal and industrial wastes and dredged 

 materials is the second major class of pollutant input. The remaining 

 sources, atmospheric and other direct inputs, provide relatively minor 

 contributions to the Apex. All of these estimates are based on assumptions 

 and extrapolations, particularly with regard to estuarine inputs to the 

 Apex. They also represent the amount of material inputted by each source, 

 and not necessarily the relative environmental impact. 



Pollution-control requirements on discharges to the Hudson estuary are 

 governed mainly by provisions of the Clean Water Act. This Act establishes 

 a dual system of technology-based controls supplemented with water-quality 

 limits to assure adequate protection of our Nation's waters. The Act 

 provides for: 



secondary treatment of municipal wastewaters; 



imposition of "best available technology" for industrial 

 discharges; 



V 



imposition of pretreatment requirements for industrial users of 

 municipal treatment plants; 



establishment and implementation of water-quality standards; 



