CH2M Hill Companies 10-Q 2004 Q2 Quarterly report

Exhibit 32.1

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 Quarterly Report of CH2M HILL Companies, Ltd. (the Company) on Form 10-Q for the quarterly period ended June 30, 2004 as filed with the Securities and Exchange Commission on the date hereof (the Report), I, Ralph R. Peterson, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

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

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

/s/Ralph R. Peterson

Ralph R. Peterson

Chief Executive Officer

August 6, 2004

This certification accompanies the 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 the purposes of Section 18 of the Securities Exchange Act, as amended.  A signed original of this written statement required by Section 906 has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.