The Crosby-Mohall area covers about 2,700 square miles in the north-western part of North Dakota. This area is included in the 2,500,000-acre Missouri-Souris and Garrison Diversion irrigation projects,which are important units in the general plans for development of the water resources of the Missouri River Basin. Although the Crosby-Mohall area lies outside the drainage basin of the Missouri River, plans have been made for the irrigation of about 1,000,0)0 acres (equivalent to 1,560 square miles) of the most suitable land, with water brought by canal from the Missouri River in Montana.
The studies that have been undertaken in the area by the Division of Ground Water of the United States Geological Survey form a part of the investigations which have been initiated by the Survey and several other bureaus of the Department of the Interior, especially the Bureau of Reclamation. The studies on which the present report is bas2 were made during the field seasons of 1945, 1946 and 1947, to obtain information on the occurrence, movement, quantity, and quality of the ground water. The report contains data on the several kinds of water-bearing materials, water analyses, and well logs; the records of fluctuation of water level in about 400 wells; and an inventory of 4,636 wells and test holes.
Later studies for the whole of the Missouri-Souris Unit will supply additional data on ground-water levels and piezometric surfaces, more extensive information on quality of water, a complete inventory of wells, and further geologic information relating to ground-water supplies. Other work that is planned also includes the drilling of additional test holes and the analysis of water samples from representative wells throughout the area.
