142 



Conservation Department 



At the. 50 meter depth the increase in temperature between June 

 and September was less than 3° C. In Seneca lake, as in Cayuga 

 lake, the decrease in temperature with increase in depth was very 

 slight near the top and the bottom of the lake. The most rapid 

 drop in temperature occurred between the 20 and 25 meter, or 

 between the 15 and 25 meter depths. 



Temperature records show that the water of Oneida lake be- 

 comes relatively warm rather early in the summer. The lake is 

 too shallow to show any vertical stratification. At no time was the 

 bottom temperature more than 4° C. colder than at the surface; 

 in four out of six series of readings the bottom temperature was 

 only about 0.5° C. lower than at the surface. Cayuga and Seneca, 

 both deep lakes, are similar in that they warm up very slowly 

 and show a considerable drop in temperature between the upper 

 and lower water. On the other hand Oneida lake, which is very 

 shallow, warms up much earlier in the summer. 



Transparency of the water. — The transparency of the water 

 was determined in each lake each time when plankton samples 

 were taken. A Secchi disc having a diameter of twenty centi- 

 meters was used for this purpose. The observations were made 

 at noon or as near noon as possible. The depth was determined 

 at which the disc disappeared when lowered in the water and also 

 when it reappeared when raised. The figures in Table 1 repre- 

 sent the averages of these two values recorded in meters. While 

 it must be admitted that this is a crude method for measuring 

 the transparency of the water, the results obtained thereby are 

 sufficient to make possible a rough comparison of the transparency 

 of the water in the three lakes. As shown in the table the water 

 of Seneca lake is much clearer than that of Oneida lake and some- 

 what more so than that of Cayuga lake. 



Table 1. 



Transparency of the Water of Cayuga, Seneca and Oneida 

 Lakes (1927). 



Cayuga lake — south 





Cayuga lake — north 





Date 



Trans- 

 parency 

 in meters 



Date 



Trans- 

 parency 

 in meters 





4.5 

 5.5 



7 

 7 

 5 

 4 

 4 



June 21 . . 





5.5 



June 30 



July 9 



7 



July 13 



July 25 



7 



July 29 



Aug. 17 



5 



Aug. 12 



Aug. 31 



4 



Aug. 26 . 



Sept. 12 



3 



Sept. 14 













Seneca lake — south 





Seneca lake — north 





June 24 . . . 





1 



9.5 

 11 



June 22 



7 



July 16 . . . 







July 17 



8 



Aug. 20 . . . 



Aug. 19 



12 



Sept. 8... 



Sept. 7 



10 











Oneida lake 









June 29 



2.9 



3 



4.1 



4 1 





Juln 12 





July 26 





Aug. 23 . . 











