Exhibit 99 Office of the Chief Accountant Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 July 7, 2000 Dear Sir/Madam: We have read the paragraphs (a) (i) through (a) (v) of Item 4 included in the Form 8-K dated July 7, 2000 of Central Power and Light Company, Public Service Company of Oklahoma, Southwestern Electric Power Company, and West Texas Utilities Company filed with the Securities and Exchange Commission and are in agreement with the statements concerning our Firm contained therein. Very truly yours, /s/ Arthur Andersen LLP ARTHUR ANDERSEN LLP Copies to: Mr. E. Linn Draper, Chairman/President and Chief Executive Officer American Electric Power Company Mr. E. Richard Brooks, Chairman and Chief Executive Officer Central and South West Corporation Office of the Chief Accountant July 7, 2000 Page 1 of 1