NORTHWESTERN LAKES OF THE UNITED STATES. 
79 
confined to the 0-5 m. stratum of the lake. Taking the Crustacea as a whole, 
23,000 individuals per cubic meter of water were in the 0-5 m. stratum of the lake, 
as contrasted with only about 6,000 in the 5-10 m. stratum. 
The contrary was noted for the nauplii, for 79 per cent of them were in the 
lower 5 m. of the lake. There were only about 2,500 nauplii per cubic meter 
of water in the upper stratum of the lake and 8,900 in the lower. The rotifers 
varied somewhat in their general distribution. Anuraea aculeata and Notholca 
longispina were found in very small numbers entirely in the 5-10 m. stratum of 
the lake. Polyarthra platyptera, which comprised a large percentage of the rotifers, 
was found throughout the lake, but 61 per cent were found in the lower water. 
Asplanchna was distributed uniformly throughout the depth of the lake, and 
Mastigocerca was confined almost entirely to the 0-5 m. stratum. Taking Rotifera 
as a whole, they were rather uniformly distributed. There were 5,970 per cubic 
meter of water in the 0-5 m. stratum of the lake, and 6,220 in the 5-10 m. stratum. 
Phytoplankton was present in very large quantities. The number of green 
and blue-green algse ran as high as 683,000 per cubic meter of water in the 0-5 m. 
stratum and 405,000 in the 5-10 m. stratum. The diatoms numbered 480,000 
per cubic meter of water in the 0-5 m. stratum, and 100,000 in the 5-10 m. stratum 
of the lake; 70 per cent of the algse were in the 0-5 m. stratum of the lake. 
LAKE CHELAN, WASH. 
This magnificent body of water in north central Washington is located between 
high mountains and occupies a glacial valley extending south by east from the 
Cascade range. It is 76 km. (47 miles) long and has an average width of about 
2 km. (If miles). The shores on the upper portions are very precipitous, rising in 
many places to snowcapped peaks. At the south end the mountains are lower, 
and near the city of Chelan they open out into a level valley noted for its orchards. 
The lake has an elevatioh of 329.2 m. (1,080 feet) and a depth of 458 m. (1,500 feet). 
The bottom is therefore 128.8 m. (420 feet) below sea level. The greatest depth is 
off Falls Creek, which is very near the center. The deep area is small, the bottom 
rising toward the ends of the lake. 
The largest inlets are Stehekin River, which enters at Stehekin, situated at the 
extreme north end of the lake, and Railroad Creek, at Lucerne 13 km. (8 miles) 
below. These, together with many small mountain streams, supply the lake with 
a large amount of cold water, which, with the small surface, largely shaded by moun- 
tains, accounts for the low temperature of the surface water and the almost imper- 
ceptible thermocline. 
Since the bottom temperatures, 5.9° C. at 458 m., determined in August, 
1911, were higher than in the other deep lakes, a special trip was made to the lake 
September 11, 1913, for taking a series of temperatures with the standardized 
thermometers used on Crater Lake. Two determinations, one with each ther- 
mometer, of the bottom temperature at 440 m. showed it to be 4° C., the two read- 
ings agreeing within 0.1° C. It should be stated that in 1911 we did not anchor 
the launch. The series of samples and temperatures were taken during calms on 
three different days. The temperatures were taken August 10. The 458 m. 
temperature was checked and the chemical samples were taken August 14. 
