1909.] THE CAYUGA LAKE BASIN, N. Y. 375 



The following is a table of the elevations, and area of water and 

 of catchment basins of the Finger Lakes taken from Rafter :^ 



Elevation in 

 Lake. Feet. 



Canandaigua 686 



Keuka 720 



Seneca 444 



Cayuga 381 



Owasco 710 



Skaneateles 867 



Otisco 7S4 



Thus it appears that Cayuga has a slightly greater water area,® 

 a decidedly greater catchment basin and a lower level (PI. XIX) 

 than any of the other Finger Lakes. The catchment basin is larger 

 than the combined basins of the other six lakes. The usual fluctua- 

 tion between high and low water in Cayuga is not great. Upon 

 this point Rafter observes (p. 112) : 



According to figures given in the Eleventh Annual Report of the State 

 Board of Health of New York it appears that the maximum fluctuation of 

 Cayuga Lake for a long series of years has been 7.56 feet, although this large 

 fluctuation may be possibly partly due to work done by the state in cutting 

 out the channel of the Seneca River for the purpose of draining the Mon- 

 tezuma marsh. Ordinarily, the fluctuation of Cayuga Lake does not exceed 

 between 2 and 3 feet. From March 4, 1887, to December 2 of that year, the 

 lake fell 2.93 feet. By way of illustrating how these great natural reservoirs 

 tend to prevent floods, it may be mentioned that the configuration of Cayuga 

 outlet with relation to Clyde River is such that frequently, when there are 

 heavy rainfalls in the catchment area of the Clyde River, Cayuga Lake being 

 at the same time at a low level, the entire flood flow of Clyde River is dis- 

 charged into Cayuga Lake without affecting Seneca River below the mouth 

 of the Clyde River at all. It is undoubtedly due to this fact that fall floods 

 on Oswego River are almost entirely unknown. 



The evaporation of the Oswego River catchment area is exceedingly 

 large — about 28 inches — whence it results that the run-off from a mean annual 

 rainfall of from z'^ to 37 inches does not exceed about 9 or 10 inches. 



During the winter of 1908-9 the lake level fell 1.25 feet below the 

 mean level (383 feet), the lowest it had been for twenty years. 



''Rafter, George W., "Hydrology of the State of New York," Bull. 85 

 of the New York State Museum, 190S, p. 216. 



' Much greater if the forty-five square miles of the Montezuma marshes 

 are included. 



