Tetra Tech Wins 2 of 11 Nunn-Perry Awards.

Business Editors

PASADENA, Calif.--(BUSINESS WIRE)--March 26, 2004

Tetra Tech, Inc. (Nasdaq:TTEK) announced today that it was awarded two prestigious Nunn-Perry Awards recognizing the Company's efforts supporting the Department of Defense (DoD) Mentor-Protege program helping

This year eleven Nunn-Perry Awards were announced. In addition to Tetra Tech, winners include teams mentored by Raytheon Company, The Boeing Company, IBM Corporation, and Science Applications International Corporation. A complete list can be found at http://www.acq.osd.mil/sadbu/mentor_protege/.

The DoD Mentor-Protege Program provides incentives for DoD prime contractors to help small disadvantaged businesses develop the technical and business capabilities necessary to become valued defense suppliers. The award is named in honor of former Senator Sam Nunn and former Secretary of Defense William Perry and recognizes outstanding DoD Mentor-Protege teams.

Li-San Hwang, Tetra Tech's CEO, said, "Specialized small businesses can provide unique services that are vital to our federal clients. We would like to thank the DoD for recognizing Tetra Tech's commitment to small business mentoring."

The Tetra Tech-EMAssist team focuses on building EMAssist's technical capabilities and developing corporate QA/QC, health and safety, and subcontract management programs to support the U.S. Air Force. The Tetra Tech-Sullivan Consulting Group team focuses on developing management and technical skills to meet the U.S. Navy's environmental program needs, including contract management, financial administration, corporate QA/QC, and staff technical training. Both small businesses showed substantial increases in staff and revenue last year due in part to DoD contracts.

About Tetra Tech (www.tetratech.com)

Tetra Tech is a leading provider of consulting, engineering and technical services. With over 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.