DEVILS LAKE, NORTH DAKOTA. 11 



fully shown by a study of the normal precipitation records, compiled 

 by Mr. E. J. Glass, observer, United States Weather Bureau. From 

 these it may be noted that in 1905 the rainfall amounted to but 18.5 

 inches, and this scanty amount had not been equalled at the close of 

 the present investigations in September, 1907, though May, June, and 

 July are the months of the greatest rainfall. 



From July 20 to September 10, 1907, comprising seven weeks, the 

 level of the lake dropped approximately one-half foot. Observations 

 of the fluctuations of level were made from a tide gauge established 

 by the Geological Survey in 1883. At the beginning of the period 

 mentioned the lake-level reading was 12.3, at the close it was 11.85. 



At the time of the observations at Devils Lake by the Geological 

 Survey a permanent bench mark was established in the yard of Cap- 

 tain Heerman. This consisted of an iron post 3 inches in diameter, 

 with a copper cap, driven into the ground. On the top of the cap 

 was the inscription " U. S. Geological Survey B. M." and in the 

 center a crosscut, as here represented : 



Elevation above 

 sea 



Datum. 



Feet. 



Beside the bench mark a painted wooden tablet reads : " This bench 

 mark is 1,439.08 feet above the sea and represents height of lake in. 

 June, 1883. Zero of gauge 22.90 feet below bench." 



Observations made by the Bureau of Fisheries party in August, 

 1907, disclose the fact that this bench mark was situated 143 feet from 

 the present shore line and the level of the lake was found to be 1,428.6, 

 approximately 10^ feet below that of 1883. 



The following quotation from the monograph ^ on the Glacial Lake 

 Agassiz by Warren Upham, pages 594-595, describes the fluctuations 

 in level common to lakes of this region : 



Through the itast hundred years maximum and minimum stages of the great 

 Laurentiau lakes have alternated in cycles of about a dozen years, during 

 which comparatively scanty average rainfall for several years was followed 

 by unusually abundant rainfall. These fluctuations are similar with those just 

 noted in the rainfall of North Dakota. Besides such short cycles important 

 secular changes of the mean annual i)recipitation in this State, occupying con- 

 siderably longer periods, have caused remarkable changes in the levels of 

 numerous lakes which have no outlets. 



Devils Lake thus shows evidence of having attained, about the year 1830^ 

 a level of 16 feet higher than its low stage in 1889, reaching at or near the 

 former date to the line that limits the large and dense timber of its bordering 



"U. S. Geological Survey Monograph XXV. The Glacial Lake Agassiz by 

 Warren Upham. Washinjgton, 1895. 



