vi-n3 



of present knowledge on bacterial re-growth and the relationship of 

 this indicator organism to the probable presence of disease-producing 

 organisms. 



The Need for Non-harmful Discharges 



Waste water quality criteria should be developed to assure that the 

 discharge of waste to natural receiving waters results in a neutral 

 or beneficial effect upon the biota of the receiving waters. Many 

 estuarine animals are capable of ingesting and eliminating heavy 

 metals without harm when these elements occur in natural ratios. 



Artificially induced imbalances, however, can result in ingestion 

 rates exceeding elimination causing accumulation of heavy metals in 

 the tissues. For examole, in long-term bioassay tests, severe oyster 

 mortalities occurred due to minute amounts of chromium, nickel, and 

 molybdenum originating from a stainless steel water intake line. 

 The gradual increase of heavy metals and other trace elements over 

 background values are an outstanding example of a subtle kind of 

 ecological change in our estuaries. There are many sources of 

 metallic contamination, some of which are known, others not even 

 suspected. One wonders, for example, about the quantity of heavy 

 metals originating from the use of water in households. There are 

 many miles of copper tubing and galvanized water piping in our 

 modern urban dwellings subject to corrosion and leaching, releasing 

 unknown quantities of copper and zinc. 



