38 



LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL 



downstream. All sampling was done by boat, since the river is not other- 

 wise accessible. Samples were collected for data on B.O.D., apparent color, 

 physical character of stream bed, aerobic and anaerobic plate counts, B. 

 coll index, plankton and benthos. Not all of these data, although available, 

 will be reported here. 



In the region under study, available bacterial foods are waste sulphite 

 liquor, wood fiber, domestic sewage and other organic substances of natural 

 origin. Graph 1 shows that the food supply, expressed as B.O.D., increases 

 abruptly as a result of the entry of waste sulphite liquor at level zero. 

 Bacterial oxidation plus a non-biological affinity of this trade waste for 



Graph 1. o Five day biochemical oxygen demand ppm at 20" 



C. • Dissolved oxygen in ppm. Average for August 8, 9, 10. 



oxygen reduces the supply to less than 1 ppm within 10 miles. A correla- 

 tive relationship will be shown between these environmental conditions, 

 high food and low oxygen, and the biotic density and distribution. It goes 

 without saying, of course, that other factors also are influential. 



Twenty-four hour, 22° C aerobic plate counts are plotted as log of 

 the count per milliliter in Graph 2. Field conditions necessitated storage 

 of the samples just above the freezing point for 48 hours before plating, 

 so the dependability of the data is questionable. At the same time, they 

 do suggest an inhibitory influence of waste sulphite liquor. Anaerobic 

 counts tended to increase erratically downstream but are not considered 

 significant. As would be expected, the B. coli index reached a peak of 

 100,000 below Park Falls and gradually decreased to 1,000 twenty-seven 

 miles downstream. 



