Tetra Tech Wins $20 Million U.S. EPA Research Contract

Tetra Tech, Inc. (NASDAQ: TTEK) announced today it has been awarded a five-year, $20 million multiple-award contract by the U.S. Environmental Protection Agency (EPA) National Homeland Security Research Center (NHSRC). Through this contract Tetra Tech will support testing, evaluation, and reporting to address chemical, biological, radiological and other contaminating agents.

Tetra Tech will provide technical support services to develop tools and technologies used to quickly detect and mitigate contaminants that may enter drinking water supplies, wastewater systems, and urban areas. These tools may include methodologies to monitor water quality, technologies to treat wastewater generated during decontamination, and techniques to sample and analyze for the presence of various contaminants.

“Tetra Tech has supported EPA’s mission since the 1970s to protect human health and the environment, and we are pleased to broaden our services to the NHSRC with the award of this contract,” said Dan Batrack, Tetra Tech Chairman and CEO.

About Tetra Tech (www.tetratech.com)

Tetra Tech is a leading provider of consulting, engineering, program management, and construction management services. The Company supports commercial and government clients focused on water, environment, infrastructure, resource management, and energy. With 13,000 staff worldwide, Tetra Tech provides clear solutions to complex problems.

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.

Tetra Tech, Inc.Jim Wu, Investor RelationsCharlie MacPherson, Media & Public Relations(626) 470-2844