Exhibit 99.1

NEWS RELEASE August 9, 2023

Tetra Tech Reports Record Third Quarter Results

Pasadena, California. Tetra Tech, Inc. (NASDAQ: TTEK), a leading provider of high-end consulting and engineering services, today announced results for the third quarter ended July 2, 2023.

Third Quarter Results

Tetra Tech achieved record quarterly results in key financial metrics including revenue, net revenue, EBITDA, and backlog. Revenue in the third quarter totaled $1.21 billion and revenue, net of subcontractor costs (net revenue)¹, was $988 million, up 36% and 37%, respectively, over last year. EBITDA¹ was $119 million, up 33% year-over-year. Earnings per share (“EPS”) was $1.12; adjusted EPS was $1.29, up 19% over the third quarter of fiscal 2022¹. Cash generated from operations was $133 million, up 35% over the same period last year. Backlog increased to an all-time high of $4.39 billion, up 25% year-over-year.

Quarterly Dividend

On August 7, 2023, Tetra Tech’s Board of Directors approved its 37^th consecutive quarterly dividend at an amount of $0.26 per share, a 13% increase year-over-year, payable on September 6, 2023, to stockholders of record as of August 23, 2023.

Chairman and CEO Comments

Tetra Tech Chairman and CEO, Dan Batrack, commented, “Tetra Tech delivered another quarter of record financial performance driven by our differentiated Leading with Science^® services in water, environment and sustainable infrastructure. We are seeing increasing demand from both our commercial and government clients to address the impacts of climate change including water scarcity, infrastructure vulnerability, and environmental degradation. This has resulted in a significant broad-based increase in project awards from our key clients in North America, U.K., and Australia. The combination with RPS is exceeding our expectations, including the speed of margin expansion and the identification of revenue synergies. Based on our strong performance and record high backlog, we are increasing our net revenue and earnings per share guidance for fiscal 2023.”

¹ Non-GAAP financial measures which the Company believes provide valuable perspectives on its business results. Refer to tables at the end of the release and Regulation G Information for reconciliations to the comparable GAAP metrics.

Nine-Month Results

Revenue for the nine-month period was $3.26 billion and net revenue was $2.69 billion, up 25% and 28%, respectively, over the same period in fiscal 2022. EBITDA was $328 million, up 26%. EPS was $4.10, up 23%, and adjusted EPS was $3.80, an increase of 17% over the first nine months of last year. The days sales outstanding (“DSO”) improved to a record low 58 days.

Business Outlook

The following statements are based on current expectations. These statements are forward-looking, and the actual results could differ materially. These statements do not include the potential impact of transactions that may be completed or developments that become evident after the date of this release. The Business Outlook section should be read in conjunction with the information on forward-looking statements at the end of this release. The Company is relying on the exception provided in the applicable SEC rules to exclude the reconciliation of adjusted EPS to EPS for future outlook, the most directly comparable GAAP measure, since it is not able to predict with sufficient precision acquisition, integration and intangible amortization expenses related to the RPS transaction. Similarly, the Company is not able to provide a reconciliation of net revenue to revenue since it is not able to predict with sufficient precision subcontractor costs.

For fiscal 2023, Tetra Tech is increasing adjusted EPS guidance to range from $5.22 to $5.27 and is increasing net revenue guidance to range from $3.16 billion to $3.21 billion. Tetra Tech expects adjusted EPS for the fourth quarter of fiscal 2023 to range from $1.40 to $1.45 and net revenue to range from $790 million to $840 million.

RPS is expected to contribute additional net revenue of approximately $175 million in the fourth quarter and $500 million for fiscal 2023. The impact to adjusted EPS, excluding acquisition, integration and intangible amortization expenses, is expected to be approximately $0.03 accretive for the fourth quarter and $0.01 accretive for fiscal 2023.

Webcast

Investors will have the opportunity to access a live audio-visual webcast and supplemental financial information concerning the third quarter of fiscal 2023 results through a link posted on the Company’s website at tetratech.com on August 10, 2023, at 8:00 a.m. (PT).

Reconciliation of GAAP and Non-GAAP Items 

In thousands (except EPS data)

About Tetra Tech

Tetra Tech is a leading provider of high-end consulting and engineering services for projects worldwide. With 27,000 employees working together, Tetra Tech provides clear solutions to complex problems in water, environment, sustainable infrastructure, renewable energy, and international development. We are Leading with Science^® to provide sustainable and resilient solutions for our clients. For more information about Tetra Tech, please visit tetratech.com or follow us on LinkedIn, Twitter, and Facebook.

CONTACTS:

Jim Wu, Investor Relations
Charlie MacPherson, Media & Public Relations
(626) 470-2844

Forward-Looking Statements

This release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. The use of words such as "anticipate," "expect," "could," "may," "intend," "plan" and "believe," among others, generally identify forward-looking statements. These forward-looking statements are based on currently available operating, financial, economic and other information, and are subject to a number of risks and uncertainties. Readers are cautioned that these forward-looking statements are only predictions and may differ materially from actual future events or results. A variety of factors, many of which are beyond our control, could cause actual future results or events to differ materially from those projected in the forward-looking statements in this release, including but not limited to: continuing worldwide political and economic uncertainties; the U.S. Administration’s potential changes to fiscal policies; the cyclicality in demand for our overall services; the fluctuation in demand for oil and gas, and mining services; risks related to international operations; concentration of revenues from U.S. government agencies and potential funding disruptions by these agencies; dependence on winning or renewing U.S. government contracts; the delay or unavailability of public funding on U.S. government contracts; the U.S. government’s right to modify, delay, curtail or terminate contracts at its convenience; compliance with government procurement laws and regulations; the impact of global pandemics like COVID-19; credit risks associated with certain clients in certain geographic areas or industries; acquisition strategy and integration risks; goodwill or other intangible asset impairment; the failure to comply with worldwide anti-bribery laws; the failure to comply with domestic and international export laws; the failure to properly manage projects; the loss of key personnel or the inability to attract and retain qualified personnel; the ability of our employees to obtain government granted eligibility; the use of estimates and assumptions in the preparation of financial statements; the ability to maintain adequate workforce utilization; the use of the percentage-of-completion method of accounting; the inability to accurately estimate and control contract costs; the failure to adequately recover on our claims for additional contract costs; the failure to win or renew contracts with private and public sector clients; growth strategy management; backlog cancellation and adjustments; risks relating to cyber security breaches; the failure of partners to perform on joint projects; the failure of subcontractors to satisfy their obligations; requirements to pay liquidated damages based on contract performance; the adoption of new legal requirements; changes in resource management, environmental or infrastructure industry laws, regulations or programs; changes in bank and capital markets and the access to capital; credit agreement covenants; industry competition; liability related to legal proceedings, investigations, and disputes; the availability of third-party insurance coverage; the ability to obtain adequate bonding; employee, agent, or partner misconduct; employee risks related to international travel; safety programs; conflict of interest issues; liabilities relating to reports and opinions; liabilities relating to environmental laws and regulations; force majeure events; protection of intellectual property rights; stock price volatility; the ability to impede a business combination based on Delaware law and charter documents; and other risks and uncertainties as may be described in Tetra Tech’s periodic filings with the Securities and Exchange Commission, including those described in the “Risk Factors” section of Tetra Tech’s Annual Report on Form 10-K for the fiscal year ended October 2, 2022. Readers should not place undue reliance on forward-looking statements since such information speaks only as of the date of this release. Tetra Tech does not intend to update forward-looking statements and expressly disclaims any obligation to do so.

Non-GAAP Financial Measures

To supplement the financial results presented in accordance with generally accepted accounting principles in the United States (“GAAP”), we present certain non-GAAP financial measures within the meaning of Regulation G under the Securities Exchange Act of 1934, as amended. We provide these non-GAAP financial measures because we believe they provide a valuable perspective on our financial results. However, non-GAAP measures have limitations as analytical tools and should not be considered in isolation and are not in accordance with, or a substitute for, GAAP measures. In addition, other companies may define non-GAAP measures differently which limits the ability of investors to compare non-GAAP measures of Tetra Tech to those used by our peer companies. A reconciliation of these non-GAAP financial measures to the most directly comparable GAAP financial measures is included in this release.

Tetra Tech, Inc.

Regulation G Information

July 2, 2023

Reconciliation of Revenue to Revenue, Net of Subcontractor Costs ("Net Revenue")

(in millions)

Reconciliation of Net Income Attributable to Tetra Tech to EBITDA

(in thousands)

¹ Includes write-off of deferred debt origination fees of $2.7M in Q1-23 and $1.1M in Q2-23