EXHIBIT 23 INDEPENDENT AUDITORS' CONSENT We consent to the incorporation by reference in Registration Statements No. 33-36256, No. 33-38534, No. 33-42268, No. 33-45012, and No. 333-12561 of our report dated February 9, 1998 appearing in this Annual Report on Form 10-K for the year ended December 31, 1997. DELOITTE & TOUCHE LLP Minneapolis, Minnesota March 23, 1998