HYDROLOGY OF NEW YORK 



451 



25,000 to 30,000 cubic feet per second nearly every year, while at 

 Rochester 30.000 cubic feet per second is quite rare, even the great 

 flood of 1865 probably did not materially exceed 45,000 to 54,000 

 cubic feet per second. About 30,000 to 35,000 cubic feet per sec- 

 ond at Rochester gives a full river, and anything much beyond 

 that figure will produce a disastrous flood. The flats then act to 

 decrease in a very marked degree the violence of the spring fresher 

 at Rochester. With the river in its natural state, and with the 

 same character of catchment area throughout its whole course 

 that we find to exist above Mount Morris, what is now the chief 

 business portion of the city of Rochester would probably be sub- 

 merged nearly every year. 



This immunity of the city of Rochester is, however, purchased 

 at the expense of the flats which act as an immense storage reser 

 voir for the spring floods of the upper river. 



From an economic point of view one marked effect of the 

 annual inundation is largely to prevent the use of these flats for 

 any agricultural purpose other than grazing. If they can be cer- 

 tainly relieved of the burden of that portion of the annual overflow 

 which occurs in May, they will immediately become the most fer- 

 tile agricultural lands in the State, and their value will be doubled. 

 It is in line with the policy of all civilized governments to estab- 

 lish works for river conservancy wherever results are to be gained 

 such as these, and the precedent of similar works by other gov- 

 ernments is in view of the benefits to be derived by the Common- 

 wealth in the way of increased valuation of property, the strongest 

 possible argument that can be urged in favor of the Genesee river 

 storage. 



The question may be asked whether the annual inundation is 

 not really a benefit rather than an injury, by reason of carrying a 

 large amount of valuable silt fertilizing material over the entire 

 submerged area, as in the case of the river Nile and other irri- 

 gating streams. The answer is that, by reason of a heavy May 

 rainfall, occurring at a time when the ground water is high and 

 before vegetation has become active, there is likely to be an over- 

 flow just at the planting season, which effectually prevents the 

 putting in of crops. Frequently, too. the May overflow extends 

 over into the early days of June. In May, 1803. the discharge at 

 Rochester was at the rate of over 14,500 cubic feet per second, 



