20 New Yoek State 



less, then the greatest effect is noted, and a season of extremely low- 

 water is accompanied by a spread of the polluted area that often is 

 conspicuous enough to attract the attention of the ordinary observer 

 as well as of the trained naturalist. Instances illustrating all of 

 these cases are on record in the office of the Conservation Commis- 

 sion, and are familiar to the public generally in statements concern- 

 ing the conditions of streams at individual points as recorded by 

 residents or inspectors of various kinds. 



It is fortunate that ordinarily the water is highest at that time 

 when one finds the largest migration of fish for spawning purposes, 

 that is, in the months of spring and early summer; for high water 

 results, first, in the maximum dilution of the wastes so that they do 

 the least possible damage, and, in the second place, in washing out 

 the accumulated material so that the bottom is relieved in part, at 

 least, of the accumulated wastes that have been deposited through 

 low water periods, and of the products of decay that have come from 

 the destruction of life by the action of the wastes during the pre- 

 ceding seasons. 



Shad in the Hudson 



If it were not for this seasonal dilution, I imagine that the Hud- 

 son river would have suffered even more seriously than it has in the 

 diminution of the shad run, for the number of shad that return 

 annually to the stream to propagate themselves is directly related to 

 the number of young fish that have been hatched in the river pre- 

 viously and have gone out to the ocean to feed and to grow to 

 maturity. It is perfectly clear that the number of young shad migrat- 

 ing into ocean waters depends upon the success of the reproductive 

 season in which they were hatched. It is only very imperfectly cor- 

 related with the number of eggs deposited, since the character of 

 the bottom and of the water itself will determine pretty largely what 

 per cent of the eggs hatch out successfully and what number of 

 young shad-fry find food and other conditions favorable for exist- 

 ence so that they can complete their development and carry out 

 successfully their movement into the ocean. The shad catch is a 

 matter of large importance to the state and to the nation, and it 

 clearly depends directly upon the condition of the stream. One may 

 maintain confidently that its diminution in recent years is directly 

 connected with the growing pollution of the river, although it would 

 be impossible to say exactly to what degree it is affected thereby. 

 Furthermore, one may prophesy with assurance that if pollution 



