EXHIBIT 32.04 --  OFFICER CERTIFICATION

                            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 Annual Report of SPS on Form 10-K for the 2003,
as filed with the Securities and Exchange Commission on the date hereof (Form
10-K), each of the undersigned officers of the SPS certifies, pursuant to 18
U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley
Act of 2002, that, to such officer's knowledge:

(1)  The Form 10-K fully complies with the requirements of Section 13(a) or
     15(d) of the Securities Exchange Act of 1934; and

(2)  The information contained in the Form 10-K fairly presents, in all material
     respects, the financial condition and results of operations of SPS as of
     the dates and for the periods expressed in the Form 10-K.

Date: March 16, 2004

                                         /s/ GARY L. GIBSON
                                         ---------------------------------------
                                         Gary L. Gibson
                                         President and Chief Executive Officer

                                         /s/ BENJAMIN G.S. FOWKE III
                                         ---------------------------------------
                                         Benjamin G.S. Fowke III
                                         Vice President, Chief Financial Officer
                                         and Treasurer

     The foregoing certification is being furnished solely pursuant to 18 U.S.C.
Section 1350 and is not being filed as part of the Report or as a separate
disclosure document.

     A signed original of this written statement required by Section 906, or
other document authenticating, acknowledging or otherwise adopting the signature
that appears in typed form within the electronic version of this written
statement required by Section 906, has been provided to SPS and will be retained
by SPS and furnished to the Securities and Exchange Commission or its staff upon
request.