EXHIBIT 15 Sierra Pacific Power Company 6100 Neil Road Reno, Nevada 89511 We have made a review, in accordance with standards established by the American Institute of Certified Public Accountants, of the unaudited condensed interim financial information of Sierra Pacific Power Company and subsidiaries for the period ended September 30, 1997, as indicated in our report dated November 4, 1997; because we did not perform an audit, we expressed no opinion on that information. We are aware that our report referred to above, which is included in your Quarterly Report on Form 10-Q for the quarter ended September 30, 1997, is incorporated by reference in Registration Statement No. 333-17041 on Form S-3. We also are aware that the aforementioned report, pursuant to Rule 436(c) under the Securities Act of 1933, is not considered a part of the Registration Statement prepared or certified by an accountant or a report prepared or certified by an accountant within the meaning of Sections 7 and 11 of that Act. DELOITTE & TOUCHE LLP Reno, Nevada November 11, 1997 19