18 THE LIFE OF DEVILS LAKE 



water approximately 130 sq. km. in extent and at present** of about 

 5 m. maximum depth. It has two main arms extending north — 

 Creel Bay, about 5 km., and Six Mile Bay about 6 km. long, each 

 averaging from 0.8 to 1.2 km. in width. At the eastern end Main 

 Lake is cut off from East Lake by a highway across the Narrows, 

 while to the southeast Mission Lake was cut off by a dam in 1908, 

 The floor of Main Lake is mostly covered with a very fine, impalpa- 

 ble, black, foul smelling ooze, but in places sandy or gravelly bottom 

 is found, with occasional glacial boulders scattered over the lake 

 floor. The greater part of the lake bottom is nearly level, with 

 a gradual rise about the shores, which in places are covered with 

 glacial boulders, and in others are low, muddy flats. 



PHYSICS 



The physics and chemistry of the water naturally varies with 

 the changing level of the lake, and with the seasons of the year. 



The specific gravity in 1907, as given by Pope (1908) was 

 1.006, while in 1912 this* had increased to 1.0099. 



The color of the water, determined by the platinum-cobalt 

 standard of the IT. S. Geological Survey, usually ranges from 15 to 

 70, the lower figure representing conditions in winter, when chem- 

 ical and physical changes are at a minimum, while the higher rep- 

 resents the condition in spring, accompanying the run-off from the 

 melting snow, with its large amount of dissolved material from the 

 humus in the soil. There is no appreciable difference in color be- 

 tween the surface and the bottom of the lake. 



On March 11, 1923, the water from a hole cut in the ice near 

 the shore was a deep wine color, which faded very markedly after 

 standing a few days. Not having any color standard solutions 

 available at the time a color reading was impossible. The color 

 moreover was not comparable with the platinum-cobalt standard, 

 being distinctly pinkish, so much so, in fact that an alkalinity read- 

 ing with phenolthalein was impossible. The ice in the neighbor- 

 hood of the hole was thickly filled with Ruppia, and the color was 

 apparently due to an extract of the latter. That this should have 

 occurred to such an extent at a temperature of about 0° C. seems 

 remarkable. 



Comparative analysis of the water from the shore hole and from 

 one some distance out in the lake, made on March 22, when the 

 color had nearly disappeared, showed, as was to be expected, a 

 much higher amount of both free and albuminoid ammonia in the 

 shore sample.* 



**1924 



•Mid lake — free NHa 0.52, albuminoid Nils 2.71 ppin. 



Shore — free NH^ 3.56, albuminoid Nil,, 7.24 ppm. 



