84 
BULLETIN" OF THE BUREAU OF FISHERIES. 
DEER LAKE, WASH. 
Deer Lake is surrounded on three sides by hills; the fourth side looks out onto 
an open plain. The lake is not deep, 25 m. in the deepest part, and has a great 
deal of very shallow water around its borders. 
The shallowness of the water gives the upper stratum a chance to become 
warmer than in lakes that are more uniform in depth. The surface water had a 
temperature of 22.2° C. There was a distinct thermocline, oxygen was present at 
the bottom, and free carbon dioxide was found in the lower strata and was absent 
in the upper. The Cladocera and the Copepoda were more abundant near the sur- 
face, a condition that was noticed in several other lakes. The nauplii, however, 
were found in their regular position near the thermocline. (See fig. 10.) 
HAYDEN LAKE, IDAHO. 
This beautiful little lake, irregular in outline, lies between Lake Pend Oreille and 
Lake Coeur d’Alene, 8.8 km. (5J miles) north of Coeur d’Alene City. Its north, 
south, and east shores rise abruptly to mountains from 915 to 1,464 m. (3,000 to 
