Exhibit 32.1
Certification of Chief Executive Officer Pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002
In connection with the Quarterly Report of Tetra Tech, Inc. (the “Company”) on Form 10-Q for the quarterly period ended July 3, 2005 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Li-San Hwang, Chairman and Chief Executive Officer of the Company, hereby certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to my knowledge:
1. The Report fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934; and
2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.
/s/ Li-San Hwang |
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Li-San Hwang | |
Chairman and Chief Executive Officer | |
August 12, 2005 | |