Tetra Tech Wins $35 million Sediment Remediation Contract

Tetra Tech, Inc. (NASDAQ: TTEK) announced today that the District of Columbia (D.C.) Department of the Environment has awarded the Company a $35 million general environmental services contract that includes technical support services related to the assessment and remediation of contaminated sediments in the tidal portion of the Anacostia River, a heavily urbanized river flowing through the Nation’s Capital. Restoration activities will be implemented at sites throughout the watershed as part of large-scale efforts initiated by the D.C. government to revitalize the river and the surrounding communities.

Under the Cleaner Anacostia River initiative, Tetra Tech will further define areas of sediment contamination in the Anacostia River. Tetra Tech scientists will sample surface water, river sediment, groundwater seepage, and fish for a wide variety of chemicals to provide the first comprehensive assessment of the nature and extent of pollution in the river. Tetra Tech will then develop and evaluate potential remedial actions to reduce risks to human health and the environment.

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.