HYDROLOGY OF NEW YORK 



513 



mostly deforested, the minimum flows will run as low as from 0.05 

 to 0.1 cubic foot per second per square mile. In extreme cases 

 they may be eyen less than this. In the chapter on the classifica- 

 tion of streams we have shown that Croton riyer properly classi- 

 fies with the Genesee. It is also sIioavii that this stream has 

 low minimum flows. Spring-fed streams in western New York 

 and those with considerable lake surface pondage may be expected 

 to ha ye somewhat greater minimum flows than the preceding. 



In the central part of the State streams flowing from the south 

 side of the Mohawk north into that stream have generally low 

 minimum flows ; they do not differ greatly from the Genesee river 

 and tributaries. To the north of the Mohawk river the conditions 

 are different and the flow of the streams is larger. 



The Mohawk river and upper Hudson may be placed, while their 

 present condition of forestation is maintained, at a minimum of 

 about 0.2 to 0.25 cubic foot per second per square mile. Keser- 

 voirs on the Hoosic river in Massachusetts tend to increase the 

 minimum flow of the Hudson at Mechanicville somewhat. 



Streams issuing from the Catskill mountains, where conditions 

 similar to those on the Genesee river obtain, have minimum flows 

 of from 0.05 to 0.1 cubic foot per second per square mile. 1 



The streams of Long Island, issuing from sand plains, will give 

 larger yields, the available measurements showing minimum run- 

 offs as high as 0.5 cubic foot per second per square mile, but 

 whether these runoffs would be maintained in a minimum dry 

 year is uncertain; at present, it appears somewhat improbable. 

 Moreover, it is proper to say that these measurements were made 

 about fifty years ago and there is some doubt whether they are 

 entirely reliable; probably an extended series would show per- 

 haps 0.35 cubic foot per second per square mile as the minimum. 



The streams of the northern part of the State, issuing from 

 denser forests and with large lake storage, may be expected to 

 give minimum yields somewhat in excess of 0.3 cubic foot per 

 second per square mile, although until definite measurements are 

 made this must be considered an inference merely. 



streams issuing from the Catskill region have not been gaged long enough 

 to entirely settle the question of minimum flows. The difference in forest- 

 ation may be taken into account in estimating these flows. 



