4 DEVILS LAKE, NORTH DAKOTA. 



standpoint is the larger and deeper portion — called the Main Lake — 

 lying in the central portion of the present lake system, extending 

 from Grahams Island on the west to the highway at the southern 

 extremity of Roque Island on the east. This occupied the attention 

 of the party for the major part of the investigations, though all sec- 

 tions and surrounding waters were inspected and observations made 

 thereon. 



A brief hydrographic survey of the Main Lake was made, a num- 

 ber of triangulation points being established along its shores and 

 signals erected at favorable sites. The projection of range lines to 

 the water's edge and the location of section corners near the lake 

 shore were of great value in this connection, photolithographic copies 

 of township plats bordering upon the lake being furnished by the 

 United States General Land Office. The lines of soundings con- 

 sisted of a system of transverse zigzags from shore to shore with a 

 few lines along the axis of the lake and occasional diagonals to 

 check results. The lines were run with the aid of small gasoline 

 launches, soundings being taken by lead line and positions ascertained 

 by sextant observations at about five-minute intervals. At each 

 station temperature and density observations, water specimens, and 

 plankton hauls were taken and recorded. The biological features 

 of the lake received careful consideration, and collections repre- 

 sentative of the fauna and flora were made. 



The lake is located in a district of small rainfall and the excess 

 of evaporation over precipitation has reduced the area and caused 

 the desiccation of many shallow tributary bays. It has so decreased 

 the depth that across the narrower portions of the lake highways 

 have been constructed, thus anticipating the natural isolation of its 

 component portions. Lamoreau Bay is isolated by a highway at its 

 western extremity; from the southern point of Roque Island an- 

 other public road and railroad trestle have been constructed, and 

 these with the shallow across the narrows at La Rose Ferry divide 

 the lake into four sections. Of these the middle section, lying be- 

 tween the Great Northern Railroad trestle and La Rose Ferry, is 

 the deepest and most important. The entire western end of the old 

 lake is now converted into barren, weed-grown tracts of land, the 

 alkaline deposit on the soil and rocks that once formed its shores 

 outlining its former area, and Mauvaise Coulee opens into a de- 

 tached pond, the narrow irregular tributary formerly leading to it 

 being cut off. Devils Lake city, formerly touched by the northern 

 end of Creel Bay, is at present 1^ miles distant from the shore. The 

 major portion of Mission Bay, an arm extending into the Sioux 

 Indian Reservation, on the southern shore of the lake, has been 

 entirely cut off from the parent body and is now known as Mission 

 Lake; another portion. Large Mission Bay, is dried up; while an- 



