110 Conservation Department 



screening while a big" aid is not sufficient in itself to render a waste 

 effluent harmless. 



Milk product factories and condensaries were relatively un- 

 important from the standpoint of numbers, but in at least one 

 case, to be discussed later, the pollution made up in severity for 

 the absence of a greater number of instances. Other sources of 

 pollution encountered were gas and tar works, varnish and enamel- 

 ware factories, insulator works, Solvay works, rope, shade, shoe, 

 carpet and button factories, typewriter works, foundries, machine 

 shops and feed mills. 



Methods Employed and Effects of Pollution. — For a dis- 

 cussion of the effects of pollution the reader is referred to "A 

 Biological Survey of the Genesee River System," supplemental to 

 sixteenth annual Conservation report, 1926. Analytical methods 

 employed were substantially the same, being those outlined in 

 "Standard Methods of Water Analysis," 6th edition, 1925, Ameri- 

 can Public Health Association. The values for dissolved oxygen 

 listed in the accompanying tables and represented graphically in 

 several instances have been calculated to percentage of saturation 

 based upon Whipple's values, and the barometric pressures of the 

 regions have been taken into consideration. The heavy horizontal 

 lines across the graphs represent 100 per cent saturation. The 

 values for carbon dioxide refer to free carbon dioxide in all cases 

 unless otherwise indicated. 



It is noteworthy that waters which have assimilated quantities 

 of organic and nitrogenous matter and have consequently become 

 abundantly supplied with plant food often support luxurious 

 oxygen producing growths, and give values for dissolved oxygen 

 far in excess of those required for 100 per cent saturation, which 

 figures, as pointed out in the past, refer to water in equilibrium 

 with the atmosphere, about one-fifth of which is oxygen. Excellent 

 examples of such are offered by Canandaigua outlet as shown by 

 the tabulated data in Series I, and by Owasco outlet, data of 

 Series I and Fig. 2. 



The Canals. — The State barge canal system forces itself so fre- 

 quently upon the attention of an investigator that some considera- 

 tion had to be given it, though a study of such an extensive system 

 offers a weighty problem in itself. Hence where closely linked up 

 with other waters studied the canals have been to some extent in- 

 cluded in the investigation. 



The effect of wash from passing boats in keeping the water roiled 

 and turbid can only be referred to in passing, as can the consider- 

 able quantities of oil which escape or are discharged at times upon 

 the waters. 



A fairly continuous canal section is that starting with Seneca 

 lake as a westerly terminus and extending eastward and northward 

 for a stream length of about ninety miles to Lake Ontario at 

 Oswego, joined en route by the Cayuga lake section from the south, 

 the Clyde river section from the west, and Oneida river section 



