MDU Resources Group, Inc. is a diversified natural resource company. Montana-Dakota Utilities Co. (Montana-Dakota), a public utility division of the Company, through the electric and natural gas distribution segments, generates, transmits and distributes electricity and distributes natural gas in Montana, North Dakota, South Dakota and Wyoming. Cascade Natural Gas Corporation (Cascade), an indirect wholly owned subsidiary of MDU Energy Capital, distributes natural gas in Washington and Oregon. Great Plains Natural Gas Co. (Great Plains), a public utility division of the Company, distributes natural gas in western Minnesota and southeastern North Dakota. In May 2008, the Company acquired Amador Transit Mix, Inc. and Yarbrough's Dirt Pit, Inc., doing business as Yarbrough's Material & Construction. On October 1, 2008, the Company acquired Intermountain Gas Company. In August 2009, the Company acquired the assets of Total Corrosion Solutions Inc.