Tetra Tech Acquires Bryan A. Stirrat & Associates

Tetra Tech, Inc. (NASDAQ:TTEK) announced today that it has acquired Bryan A. Stirrat & Associates (BAS), a Southern California-based consulting and engineering firm. BAS provides highly specialized landfill design, leachate and hazardous waste management, energy recovery, and groundwater protection services for municipal and commercial customers. BAS generates revenue of approximately $40 million per year, and has a staff of about 150 located in six offices throughout California and Arizona.

"Protecting groundwater from landfill leachate is critical to many local water supplies,” said Dan Batrack, Tetra Tech’s Chairman and CEO. "The BAS acquisition strengthens Tetra Tech’s technical capabilities in watershed protection and adds new customers throughout the southwestern United States. We welcome all of the employees of BAS.”

Tetra Tech has worked with BAS on many high-profile landfill remediation programs including a 168-acre brownfield redevelopment near Los Angeles, CA. The terms of the acquisition were not disclosed.

About Tetra Tech (www.tetratech.com)

Tetra Tech is a leading provider of consulting, engineering, program management, construction, and technical services addressing the resource management and infrastructure markets. The Company supports government and commercial clients by providing innovative solutions focused on water, the environment, and energy. With more than 10,000 employees worldwide, Tetra Tech’s capabilities span the entire project life cycle.

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.