The Nelson Reservoir, located 19 miles northeast of Malta, MT, provides offstream storage for irrigation of Malta Division lands in the Saco and Hinsdale areas. A series of dikes, with a maximum structural height of 28 feet, crest length of 9,900 feet, and total volume of 233,000 cubic yards, provide for storage of 79,200 acre-feet of water. The reservoir does not have a spillway. Slide gates installed in the Nelson North Canal outlet works permit releases of water to Milk River for use in the Glasgow Division. Slide gates installed in the Nelson South Canal outlet works permit releases of water for irrigation of project lands.
Preconstruction subsurface investigation efforts for the Nelson Dikes were limited to hand-dug pits along the footprint of the proposed structures. Investigations conducted since construction indicate all the structures were founded in unconsolidated and potentially liquefiable materials.