266 



and they are a real or potential pollution source. Just based on an 

 occupancy rate alone, the waterways of this Nation received untreated 

 wastes from vessels equivalent to a city of 500,000. Added to these 

 wastes are the many gallons of oils, bilge water, ballast water, wash 

 water, chemicals, and accidental cargo spills. 



Recreational boat usage creates a somewhat different waste impact 

 from that of commercial traffic. These craft are generally congregated 

 near large population centers, and boat usage is most intense on the 

 weekends when the boatowners have free time. In addition to the 

 human waste and garbage, there are large quantities of unburnt fuel 

 products exhausted from boats, particularly from the two-stroke cycle 

 outboard motors (fig. IV.5.16). 



Figure IV.5.16 



INFLUENCE OF THE USE OF THE 

 INTERNAL COMBUSTION ENGINE ON 

 DIFFERENT MEDIA AND ON THE ESTUARIES 



_ Chemical Change 

 Gaseous .——^——— "*"~"~Tk 



I Exhaust and 



Aquatic 



Estuaries 



Terrestrial 



