Los Angeles Department of Public Works Selects Tetra Tech Team for L.A. River Revitalization Master Plan Contract

Business Wire, July 28, 2005

PASADENA, Calif. -- Tetra Tech, Inc. (NASDAQ:TTEK) announced today that the City of Los Angeles Department of Public Works, Bureau of Engineering will be recommending Tetra Tech, Inc. and its subcontractor partners to the Board of Public Works as the team to lead the L.A. River Revitalization Master Plan effort.

The goal of the Los Angeles River Revitalization Master Plan is to provide a comprehensive, 20-year, multi-objective plan that will optimize and enhance a neglected feature within the Los Angeles landscape. The goal is to preserve and enhance the flood control features of the River and at the same time create an amenity that will enrich the quality of life for all City residents. As stated by the Ad Hoc Committee of Council on the Los Angeles River, the goals of the Master Plan include the desire to provide open space, recreational space, wildlife habitat, improved water resources, improved ecological functioning of the Los Angeles River, and in general to identify River adjacent development that will enhance existing communities.

"We are very excited about the prospect of working with the Tetra Tech team as we move forward with the long-awaited master planning process," said Gary Lee Moore, City Engineer.

"This project is one of the most exciting visioning projects happening anywhere in the country," said Li-San Hwang, Tetra Tech's CEO. "We are very proud to be recommended as the winning team - it was a very competitive selection process. The Master Plan is the first phase of what will likely become a several hundred million dollar program overall, and represents a significant opportunity for Tetra Tech."

The project team will work with the City of Los Angeles, which will coordinate with the County of Los Angeles, the Army Corps of Engineers and the many communities, non-profits and governmental entities with an interest in engaging in a long-term visioning process for the future development of the Los Angeles River. The project will encompass a 32-mile stretch of the River and surrounding communities from Canoga Park to Boyle Heights in downtown Los Angeles.

The Tetra Tech team is a multi-faceted partnership encompassing a wide variety of disciplines. The team also includes two nationally recognized urban design, planning and landscape architecture companies that specialize in urban river revitalization and economic development projects, Civitas and Wenk Associates; internationally and locally prominent landscape architect Mia Lehrer and Associates; outreach specialists The Robert Group, the Transportation and Land Use Collaborative (TLUC) and Adan Ortega; HNTB; Urban Partners; Asset Strategies; and legal advisors Latham & Watkins.

About the Los Angeles River Revitalization Program (www.lariver.org)

The L.A. River Revitalization program seeks to re-plan and renew the 32-mile stretch of river flowing through downtown Los Angeles based on the current and future priorities of the River's users.

About Tetra Tech (www.tetratech.com)

Tetra Tech is a leading provider of consulting, engineering and technical services. With nearly 8,000 associates located in the United States and internationally, the Company supports commercial and government clients in the areas of resource management, infrastructure and communications. Tetra Tech's services include research and development, applied science and technology, engineering design, program management, 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.