POWER OF ATTORNEY

     Know all by these presents, that the undersigned hereby constitutes and
appoints each of Paul K. Sandness and Debra S. Anderson, signing singly, the
undersigned's true and lawful attorney-in-fact to:

(1)  execute for and on behalf of the undersigned, in the undersigned's
capacity as an officer and/or director of MDU Resources Group, Inc. (the
"Company"), Forms 3, 4, and 5 in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder;

(2)  do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to complete and execute any such
Form 3, 4, or 5 and timely file such form with the United States Securities
and Exchange Commission and any stock exchange or similar authority; and

(3)  take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit
to, in the best interest of, or legally required by, the undersigned, it
being understood that the documents executed by such attorney-in-fact on
behalf of the undersigned pursuant to this Power of Attorney shall be in
such form and shall contain such terms and conditions as such
attorney-in-fact's discretion.

     The undersigned hereby grants to each such attorney-in-fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the
rights and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and the
rights and powers herein granted.  The undersigned acknowledges that the
foregoing attorneys-in-fact, in serving in such capacity at the request of
the undersigned, are not assuming, nor is the Company assuming, any of the
undersigned's responsibilities to comply with Section 16 of the Securities
Exchange Act of 1934.

     This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to
the undersigned's holdings of and transactions in securities issued by the
Company, unless earlier revoked by the undersigned in a signed writing
delivered to the foregoing attorneys-in-fact.

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of this 6th day of March, 2006.

                                                    /s/Steven L. Bietz
					Signature

					Steven L. Bietz
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