498 



NEW YORK STATE MUSEUM 



Minimum flow of Hemlock lake. According to a report made 

 by Henry Tracy, 1 the minimum flow of Hemlock lake is 5 cubic 

 feet per second (catchment, 43 square miles), or 0.116 cubic foot 

 per second per square mile. 



Table No. 49 gives the quantity of water passing out of Hem- 

 lock lake for the period covered and without reference to the 

 natural flow. In order to obtain the approximate natural flow 

 for the year we must take into account the mean elevations of lake 

 surface. Thus, for the water year 1880 the mean elevation of 

 the first month, December, was —1.67, while for the last month, 

 November, it was — 1.24. The difference (0.43 foot) represents 

 the gain in depth of storage for the year. Computing for the 

 value of this storage in inches on the catchment area, we have 

 0.28 inch, which, added to the quantity of water passing out of 

 the lake (3.07 inches), gives as the approximate total runoff for 

 the year 3.35 inches. Since 1880 was a very dry year, we may 

 compute the flow for the entire water year to be 10.3 cubic feet 

 per second, which again amounts to 0.24 cubic foot per second 

 per square mile. 



For the five-year period included in this tabulation the total 

 rainfall and runoff are as follows: 



Rainfall, Run-off, 

 inches inches 



1880 21.99 3.07 



1881 24.27 8.38 



1882 25.46 14.51 



1883 32.24 9.29 



1884 26.74 12.57 



Add for rise in level 0.40 



Total 130.70 48.22 



For the five-year period the total runoff was therefore only 36.9 

 per cent of the rainfall. In 1880 the runoff was only 15.2 per cent 

 of the rainfall. The corrections for rise in lake level arc included 

 in these statements. 



Minimum flow of Oswego river. Previous to 1897 there were 

 no records of any long-continued measurements of the flow of 



1 Report on the Cost and Policy of Constructing Reservoirs on Conesus, 

 Hemlock, Iloneoye and Canadiee lakes. Senate document, No. 40, 1S50. 



