U.S. Department of Energy Awards Tetra Tech Joint Venture $400 Million Contract

Tetra Tech, Inc. (NASDAQ: TTEK) announced today that its joint venture with Sealaska Technical Services was selected to provide design-build services to the U.S. Department of Energy’s National Nuclear Security Administration (NNSA). Under the Design, Integration, Construction, Communication, and Engineering (DICCE) contract, the joint venture will share in the $400-million contract ceiling over seven years.

The DICCE contract is administered by the NNSA Office of Nuclear Smuggling Detection and Deterrence (NSDD), which strengthens the capabilities and commitment of U.S. partner countries to deter, detect, and interdict illicit trafficking of nuclear and other radioactive materials within the interiors of partner countries, across international borders, and through the global maritime shipping system.

The joint venture team will provide design-build services to support the installation and deployment of fixed and mobile radiation detection systems and associated infrastructure at border checkpoints, airports, seaports, internal country locations, and maritime borders outside of the United States.

“Tetra Tech has provided engineering design and installation services to the NSDD office since 2002,” said Dan Batrack, Tetra Tech’s Chairman and CEO. “We look forward to working with our joint venture partner to continue supporting the NNSA in this important program.”

About the National Nuclear Security Administration (www.nnsa.energy.gov)

About Tetra Tech

Tetra Tech is a leading provider of consulting and engineering services. For 50 years, the Company has supported commercial and government clients focused on water, environment, infrastructure, resource management, energy, and international development. With 16,000 staff worldwide, Tetra Tech provides clear solutions to complex problems. For more information about Tetra Tech, please visit tetratech.com, follow us on Twitter (@TetraTech), or like us on Facebook.

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.

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Tetra Tech, Inc.Jim Wu, Investor RelationsCharlie MacPherson, Media & Public Relations626-470-2844