HYDROLOGY OF NEW YORK 



495 



the storage period. 12.59 inches; growing period, 4.82 inches; re- 

 plenishing period, 8.60 inches; total for the year, 26.01 inches. 

 The record for the rear 1846 at Middlebury is not given. It is 

 clear, therefore, so far as we have any definite meterological 

 record, that the measurements made by Mr Marsh in 1846 were at 

 a time of very low water. 



A number of years ago gagings of the minimum flow of the 

 Genesee were kept at the raceAvay of the Genesee Paper Company, 

 in the north part of the city of Rochester, where it is possible to 

 turn the entire flow of the river through the raceway. These 

 gagings showed that for several months the minimum flow did not 

 exceed about 160 cubic feet per second, and as this included per- 

 haps 10 cubic feet per second flow of sewage, we may conclude 

 that the minimum flow of this stream at Rochester is as low as 

 150 cubic feet per second (catchment, 2365 square miles), or at 

 the rate of 0.064 cubic foot per second per square mile. These 

 measurements were verified during the summer of 1903, when at 

 Elmwood avenue bridge in the south part of the city the flow was 

 even somewhat less than this, as determined by current-meter 

 measurement. 



These statements apparently indicate that the minimum sum- 

 mer flow of the Genesee river has decreased from 412 cubic feet per 

 second in 1846 to about 150 cubic feet per second in 1903. As to 

 the reason for this decrease, it is believed that the extensive de- 

 forestation of the catchment area which has taken place since 

 1846 offers full explanation. In 1846 the upper Genesee catch- 

 ment was still very largely in forest. Probably of the entire area 

 above Rochester the virgin forest was from 65 per cent to 70 per- 

 cent of the whole. We have therefore apparently a marked case 

 where the deforestation of a large area has materially reduced the 

 minimum runoff. 



The foregoing minimum flows of Genesee river show conclusively 

 that in its present condition it is not a good mill stream. The 

 great variation in runoff is conclusive on this point. The figures 

 show that the runoff of the stream may be exceedingly slack for 

 several months during the summer and fall. 



Minimum flow of Oatka creek. The catchment area of this 

 stream above the point of measurement is 27.5 square miles. The 

 mean flow for the month of August, 1891, was 6 cubic feet per 



