INDEPENDENT AUDITOR'S CONSENT We consent to the incorporation by reference in Registration Statement Nos. 33-39208 and 33-58372 on Form S-8 of our report dated June 23, 1999 appearing in this Annual Report on Form 11-K of The Savings Plan for Union Employees of Arizona Public Service Company and The Savings Plan for Employees of Arizona Public Service Company for the year ended December 31, 1998. DELOITTE & TOUCHE LLP DELOITTE & TOUCHE LLP Phoenix, Arizona June 25, 1999 EXHIBIT 23.1