Tetra Tech Appoints PricewaterhouseCoopers As Its New Independent Auditor.

Business Editors

PASADENA, Calif.--(BUSINESS WIRE)--Jan. 12, 2004

Tetra Tech, Inc. (Nasdaq:TTEK) announced today that the Audit Committee of its Board of Directors has appointed PricewaterhouseCoopers LLP (PwC) as the Company's new independent auditor for fiscal year 2004. The

PwC will replace Deloitte & Touche, LLP (D&T), which completed Tetra Tech's fiscal year 2003 audit. The decision was not the result of any disagreement between the Company and D&T on any matter, including accounting principles or practices, financial statement disclosure, or auditing scope or procedures.

"As Tetra Tech continues to emerge as a leading provider of consulting, engineering and technical services, our audit requirements are evolving as well," said Li-San Hwang, Tetra Tech's Chairman and CEO. "PwC is a leading provider of audit services to our industry, and we believe that PwC is well equipped to work with us in the future. Meanwhile, we appreciate D&T for its many years of support and service."

About Tetra Tech (www.tetratech.com)

Tetra Tech is a leading provider of consulting, engineering and technical services. With nearly 9,000 associates located in the United States and internationally, the Company supports commercial and government clients in the areas of resource management and infrastructure. Tetra Tech's services include research and development, applied science and technology, engineering design, construction management, and operations and maintenance.

Any statements made in this release that are not based on historical fact are forward-looking statements. Any forward-looking statements made in this release represent management's best judgment as to what may occur in the future. However, Tetra Tech's actual outcome and results are not guaranteed and are subject to certain risks, uncertainties and assumptions ("Future Factors"), and may differ materially from what is expressed. For a description of Future Factors that could cause actual results to differ materially from such forward-looking statements, see the discussion under the section "Risk Factors" included in the Company's Form 10-K and 10-Q filings with the Securities and Exchange Commission.