Exhibit 99.1 Black Hills Corporation 625 Ninth Street Rapid City, SD 57701 LETTER TO COMMISSION PURSUANT TO TEMPORARY NOTE 3T May 15, 2002 Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 Ladies and Gentlemen: Pursuant to Temporary Note 3T to Article 3 of Regulation S-X, Black Hills Corporation has obtained a letter of representation from Arthur Andersen LLP stating that their review our Form 10-Q was subject to their quality control system for the U.S. accounting and auditing practice to provide reasonable assurance that the engagement was conducted in compliance with professional standards, that there was appropriate continuity of Arthur Andersen LLP personnel working on the review and availability of national office consultation. Availability of personnel at foreign affiliates of Arthur Andersen is not relevant to this review. Very truly yours, Black Hills Corporation /s/ Mark T. Thies Mark T. Thies Senior Vice President and Chief Financial Officer