MDU Resources Announces Acquisition of Fred Carlson Company, Inc. and Roverud Construction, Inc.

Business Editors

BISMARCK, N.D.--(BUSINESS WIRE)--Feb. 6, 2004

MDU Resources Group, Inc. (NYSE:MDU) announced that Fred Carlson Company, Inc. and Roverud Construction, Inc. have been acquired for a combination of cash and MDU Resources common stock. The companies have been merged into Knife River Corporation, the construction materials and mining subsidiary of MDU Resources. Financial details of the merger were not disclosed. MDU Resources anticipates that the acquisition will be accretive to 2004 earnings per share.

Fred Carlson Co. is a privately held ready-mixed concrete producer and concrete and asphalt paving company with headquarters in Decorah, Iowa. Roverud Construction is a privately held aggregate mining and production company with headquarters in Spring Grove, Minn. These companies are among the leading construction materials providers in southeastern Minnesota and northeastern Iowa. The companies have combined annual revenues of about $90 million.

Fred Carlson Co. performs concrete paving throughout Iowa and in surrounding states. It also operates seven ready-mixed concrete plants serving communities in northeast Iowa and southeast Minnesota and one asphalt plant in Decorah. Roverud Construction owns and mines significant aggregate reserves in southeastern Minnesota and northeastern Iowa, and supplies sand, gravel and limestone to commercial, agricultural and residential customers.

"Fred Carlson Company has been in business for more than 100 years, and Roverud Construction also has a significant history in the aggregate business," said Terry Hildestad, president and chief executive officer of Knife River Corporation. "These companies are a good fit with Knife River's long-standing tradition of supplying high-quality products and services to our customers for more than 80 years."

Hildestad said the companies will collectively operate under the name Fred Carlson Company, LLC.

The information in this release includes certain forward-looking statements, including statements by the president and chief executive officer of Knife River Corporation and statements concerning accretive earnings per share, within the meaning of Section 21E of the Securities Exchange Act of 1934. Although the company believes that its expectations are based on reasonable assumptions, actual results may differ materially. Important factors that could cause actual results to differ materially from those in the forward-looking statements include the effects of competition and the ability to effectively integrate acquired operations. For a discussion of other important factors, refer to the Introduction and Item 2 - Management's Discussion and Analysis of Financial Condition and Results of Operations - Risk Factors and Cautionary Statements that May Affect Future Results in MDU Resources' most recent Form 10-Q.

MDU Resources Group, Inc. provides energy, value-added natural resource products and related services that are essential to our country's energy, transportation and communication infrastructure. MDU Resources includes electric and natural gas utilities, a natural gas pipeline, utility services, natural gas and oil production, construction materials and mining, energy services, and domestic and international independent power production. For more information about MDU Resources, see the company's Web site at www.mdu.com or contact the investor relations department at [e-mail]. Knife River Corporation mines aggregates and markets crushed stone, sand, gravel and related construction materials, including ready-mixed concrete, cement, asphalt and other value-added products, as well as performing integrated construction services, in the north central and western United States and in the states of Alaska and Hawaii. For more information about Knife River Corporation, visit the company's Web site at www.kniferiver.com.