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 Coulée 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 14 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- 
