EXHIBIT 23(B) CONSENT OF ENGINEER We hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of our estimates, dated January 31 and 9, 1997, which appear in the MDU Resources Group, Inc. Annual Report on Form 10-K for the year ended December 31, 1996, and to all references to our firm included in this Registration Statement. RALPH E. DAVIS ASSOCIATES, INC. /s/ Joseph Mustacchia Jr. Executive Vice-President Houston, Texas May 27, 1997