EXHIBIT 32.2

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the combined Annual Report of Sierra Pacific Resources, Nevada Power Company and Sierra Pacific Company (the “Companies”) on Form 10K for the period ended December 31, 2003 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Michael W. Yackira, Chief Financial Officer of the Companies, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that:

(1) the combined Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(2) the information contained in the combined Report fairly presents, in all material respects, the financial condition and results of operations of the Companies.

/s/ Michael W. Yackira

Michael W. Yackira

Chief Financial Officer

March 5, 2004

This Certification accompanies this Report pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 and shall not, except to the extent required by the Sarbanes-Oxley Act of 2002, be deemed filed by the Company for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liability of that section. Such certification will not be deemed to be incorporated by reference into any filing under the Securities Act of the Exchange Act, except to the extent the Companies specifically incorporate it by reference.

A signed original of this written statement required by Section 906 has been provided to the Companies and will be retained by the Companies and furnished to the Securities and Exchange Commission or its staff upon request.