542 
BULLETIN OF THE BUREAU OF FISHERIES. 
(8 feet) above its natural low level of 70 years ago. The water of this lake, with that 
from Otisco Lake, is also used for the water supply of the city of Syracuse, which lies 
some 27 kilometers to the northeast. 
Our observations in 1910 were made otf Carpenters Point. The later temperature 
observations were taken off Mandana. 
For the details of the hydrography, see page 599. 
Otisco Lake (pi. cxi). — Otisco Lake is quite similar in situation and form to the six 
major lakes, but is wholly different in area, depth, and biological character. The lake 
is used as a source of water supply for the city of Syracuse, which lies about 27 kilo- 
meters to the northeast. The height of the water is controlled by a dam, which may 
raise the water 3 meters or more above its original level. This dam is placed some 1.5 
kilometers below the original outlet and has thus caused a shallow extension of the 
lake at the south end. The sides of the original lake are steep, and the increase in height 
of the water adds little to its breadth. At the south end of the lake the floor of the 
valley slopes very gradually and here the dam has caused a broad, shallow expanse 
which varies greatly in area with the rise and fall of the water as it is drawn upon for 
the use of the city. 
Across this shallow expanse and close to the original south end of the lake there runs 
a causeway pierced only by a narrow opening. There is thus a considerable area of 
shallow water which is practically separated from the main body of the lake. 
In the general table of the lakes the statistics for Otisco Lake are based on the 
Cornell survey and include the entire lake. The level of the water shown by this survey 
was not correlated with the level of the crest of the dam, or if such measurements were 
made (as they probably were) the records have disappeared. The water was probably 
about I meter below the spillway at the time the soundings were taken. They there- 
fore do not represent the maximum possible depth of the lake, but are probably quite 
as great as the ordinary depth. 
For all purposes of limnology the southern extension of the lake beyond the cause- 
way has no significance, however valuable it may be as a storage for water supply. 
For the purposes of our discussion, the dimensions of the lake must be recalculated, 
including that part of the lake which lies between the dam and the causeway. The 
results are as follows; Length, 7.33 kilometers; breadth, maximum, 1.22 kilometers; 
mean, 0.93 kilometers; area, 6.84 square kilometers; depth, maximum, 20.1 meters; 
mean, 11.2 meters; volume, 76,440,000 cubic meters; shore development, 1.76; volume 
development, 1.64; mean slope, 2.41 per cent, 1° 23'. These measurements are 
employed in the table of hydrography, page 597. 
Otisco Lake occupies only a small part of its valley, which extends far beyond the 
lake both to the north and the south. Its steepest slopes begin at about the same 
point as do those of the Skaneateles valley, and since the lake is little more than one- 
third as long, they lie wholly to the south of the water. In general they are more 
broken and diversified than are those of the other eastern lakes. There is hardly a 
view in this picturesque and beautiful region finer than is that which the Otisco Valley 
