14 New York State 



extended the areas in which life has been destroyed or highly modi- 

 fied until they extend for miles along the stream and involve entire 

 rivers. In fact, in the most densely populated portions of the state 

 and on the greater river systems, one source of pollution overlaps 

 the one next lower down on the watershed to such an extent that 

 the entire stream is seriously affected. 



A new danger confronts us in considering modifications that have 

 come over even the small village communities and towns in their 

 relation to this problem. The sewage which they formerly turned 

 out into a convenient stream was composed almost exclusively 

 of organic wastes. It was subject to rapid transformation under 

 natural conditions, and the stream flowing, as such streams do in 

 most cases in this state, over a broken, stony or rocky bed, tended 

 to accumulate oxygen and thereby to assist in the rapidity of the 

 changes which led to the ultimate transformation of the domestic 

 sewage into materials that could be utilized by living organisms. 



Modification of Domestic Wastes 



At the present time even in small villages it is not possible to 

 find domestic sewage of an unmodified type. What is designated 

 under that name is really a mixture containing often much trade 

 waste. The existence of small factories, or at least machine shops 

 with oil and gasoline waste that is turned into the sewer system, 

 has transformed the original easily handled sewage material into 

 that which resists the ordinary methods of self purification in flow- 

 ing waters, and constitutes a lasting menace to the life that normally 

 would be found in the streams. 



It is an unfortunate fact that whatever may be the average yearly 

 run off there has been in connection with these changes a distinct 

 and considerable reduction at certain seasons in the volume of 

 stream flow, so that even if sewage conditions had not been changed 

 the amount of dilution would be much less at the present time than 

 it was formerly. Thus the process has been unfavorably modified at 

 both ends and at present the situation is changing conspicuously for 

 the worse, so that it is necessary to look for some means of improv- 

 ing matters before the point is reached where all the life of our 

 streams will have been destroyed. 



Canalization Lessens Purification 



In some regions another factor has been annmportant element in 

 increasing the difficulties of the situation, and that is the modifica- 

 tion of the stream itself through canalization. Water flowing over 



