Exhibit 99(a) AVISTA CORPORATION --------------- STATEMENTS OF CORPORATE OFFICERS (Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002) -------------- Each of the undersigned, Gary G. Ely, Chairman of the Board, President and Chief Executive Officer of Avista Corporation (the "Company"), and Jon E. Eliassen, Senior Vice President and Chief Financial Officer of the Company, hereby certifies, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2002 fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934, as amended, and that the information contained therein fairly presents, in all material respects, the financial condition and results of operations of the Company. August 12, 2002 /s/ Gary G. Ely ------------------------------------ Gary G. Ely Chairman of the Board, President and Chief Executive Officer /s/ Jon E. Eliassen ------------------------------------ Jon E. Eliassen Senior Vice President and Chief Financial officer