NORTHWESTERN LAKES OF THE UNITED STATES. 
81 
sediment from both rivers. The depth of water gradually increases from the head 
of the lake to within 3 miles of the outlet, where it begins to decrease. The deepest 
place, 56 m., is at one of the narrowest parts of the lake. The temperature recorded 
here indicates that there may be a slight current even at the bottom of the lake. 
For instance, the bottom temperature, which was taken July 11, 1911, when the 
lake was high, was 0.7° higher than that read August 21, 1912, when the lake was 
2 m. lower and the surface temperature 2.7° higher than July 11, 1911. 
31177°— 23 3 
