IV-383 



(3) The settleable material 1n municipal wastes may be 

 deposited on the bottom, resulting in large sludge banks 

 of organic content. These sludge banks can also deplete 

 the oxygen resources through biochemical reactions. The 

 suspended materials, if sufficient in quantity, can 

 reduce the depth to which sunlight penetrates, altering 

 that portion of the ecosystem dependent upon photo- 

 synthetic activity. 



(4) Dissolved salts can make the water less desirable 

 for other uses and the fertilizer or nutrient portions 

 are sometimes implicated in stimulating nuisance growths 

 of algae and other aquatic plants. These aquatic growths 

 in an enriched stream can cause severe fluctuations 1n 

 dissolved oxygen concentrations and can interfere with 

 other legitimate uses. 



Table IV. 5. 5 summarizes municipal waste discharge volumes into 

 the biophysical regions. While the Middle Atlantic region has by 

 far the largest volume of municipal waste discharge, the potential 

 impact on the estuarine zone is greatest in both the Pacific 

 Southwest and in the Pacific Islands because of the small estuarine 

 water areas in these two regions. This potential impact is les- 

 sened by the ability to use deep ocean outfalls, an approach made 

 practicable by the narrow continental shelf in these regions. 



