Knife River Corp. Announces Acquisition of Becker Gravel Company Assets.

BISMARCK, N.D. -- Knife River Corp. announced that the assets of Becker Gravel Company Inc. and a related company have been acquired in a cash purchase. Becker will become an operating division of Fred Carlson Co., a Knife River subsidiary. Financial details of the asset acquisition were not disclosed. Knife River Corp. is the construction materials and mining subsidiary of MDU Resources (NYSE:MDU). MDU Resources anticipates that the acquisition will be accretive to 2004 earnings per share.

Becker is a privately held construction materials company with headquarters in Stratford, Iowa. It is a leading construction materials provider in central and northwestern Iowa, with annual revenues of about $5 million.

Becker's operations include aggregate mining and crushing. The company provides government, commercial, industrial and agricultural customers with crushed stone, sand and gravel, as well as limestone.

Fred Carlson Co. is a ready-mixed concrete producer and concrete and asphalt paving company with headquarters in Decorah, Iowa. It is among the leading construction materials and services providers in Iowa.

"The Becker assets are a great addition to our family of companies," said Terry Hildestad, president and chief executive officer of Knife River. "Becker will integrate nicely with our existing operations at Fred Carlson Co. and our companies in Minnesota, while continuing to provide the same great products and services to its customers."

The information in this release includes certain forward-looking statements, including statements by the president and chief executive officer of Knife River Corp. 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 and MDU Resources' Form 8-K filed July 21.

MDU Resources Group Inc., a member of Standard & Poor's MidCap 400 index, provides value-added natural resource products and related services that are essential to our country's energy and transportation infrastructure. MDU Resources includes electric and natural gas utilities, natural gas pipelines and energy services, utility services, natural gas and oil production, construction materials and mining, 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 Corp. 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 performs integrated construction services, in the central and western United States, and in the states of Alaska and Hawaii. For more information about Knife River, visit the company's Web site at www.kniferiver.com.