Exhibit 99.1

NEWS RELEASE November 15, 2023

Tetra Tech Reports Record Fourth Quarter and Fiscal 2023 Results

Pasadena, California. Tetra Tech, Inc. (NASDAQ: TTEK), a leading provider of high-end consulting and engineering services, today announced results for the fourth quarter and fiscal year ended October 1, 2023.

Fourth Quarter Results

Tetra Tech achieved record quarterly results in key financial metrics including revenue, net revenue, operating income, EBITDA, adjusted EPS and backlog. Revenue in the fourth quarter totaled $1.26 billion and revenue, net of subcontractor costs (net revenue)1, was $1.06 billion, up 40% and 44%, respectively, over last year. Adjusted EBITDA1 was $153 million, up 51% year-over-year. GAAP EPS was $1.00. Adjusted EPS was $1.78, up 41% year-over year, which excluded the final RPS integration costs, including office consolidations and non-recurring tax charges. Cash generated from operations was $122 million, up 103% over the same period last year. Backlog increased to an all-time high of $4.79 billion, up $1.05 billion and 28% year-over-year.

Quarterly Dividend

On November 13, 2023, Tetra Tech’s Board of Directors approved the Company’s 38th consecutive quarterly dividend at an amount of $0.26 per share, a 13% increase year-over-year, payable on December 13, 2023, to stockholders of record as of November 30, 2023.

Fiscal Year Results

Tetra Tech also achieved record annual results with all-time highs for revenue, net revenue, operating income, adjusted EBITDA, earnings and cash flow. Revenue for fiscal 2023 was $4.52 billion and net revenue was $3.75 billion, up 29% and 32%, respectively, over fiscal 2022. Adjusted EBITDA was $481 million, up 33% compared to last year. GAAP EPS was $5.10; adjusted EPS was $5.58, an increase of 24% over last fiscal year. The days sales outstanding (DSO) improved to a record low 54 days, contributing to an all-time high cash provided by operations of $368 million.

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.

Chairman and CEO Comments

Tetra Tech Chairman and CEO, Dan Batrack, commented, “As we completed fiscal year 2023, our differentiated Leading with Science® approach to the water, environment and sustainable infrastructure markets generated the highest financial results of any quarter and year in our history. In addition to our all-time high results in revenue, earnings and backlog, we accomplished significant strategic milestones this year, including closing the largest transaction in our history, enhancing our capital structure, and expanding our Tetra Tech Delta Technologies to include a subscription software practice.

Our clients are continuing to increase funding for water and environmental programs, including climate change mitigation and adaptation to address water security, coastal flooding, energy transition and biodiversity protection. With our market leadership in these key areas, we booked nearly $2 billion in new orders in the fourth quarter and increased our backlog by more than $1 billion over last year. Building on this momentum, we expect double-digit revenue growth in fiscal 2024 and further margin expansion.”

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.

Tetra Tech expects EPS for the first quarter of fiscal 2024 to range from $1.30 to $1.38 and net revenue to range from $950 million to $1.00 billion. For fiscal 2024, Tetra Tech expects EPS to range from $5.70 to $6.00, and net revenue to range from $4.05 billion to $4.25 billion.2 The first quarter and fiscal 2024 EPS guidance ranges are on a GAAP basis inclusive of all intangible amortization expenses. On a comparable basis, fiscal 2023 EPS was $5.10. The midpoint of the fiscal 2024 net revenue and EPS guidance represents a 11% and 15% year-over-year increase, respectively.

Webcast

Investors will have the opportunity to access a live audio-visual webcast and supplemental financial information concerning the fourth quarter of fiscal 2023 results through a link posted on the Company’s website at tetratech.com on November 16, 2023, at 8:00 a.m. (PT).

2 Reconciliation of the net revenue guidance to the most directly comparable GAAP measure is not available without unreasonable efforts because the Company cannot predict the magnitude and timing of all the components required to provide such reconciliation with sufficient precision.

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

Consolidated Balance Sheets

(unaudited - in thousands, except par value)

Tetra Tech, Inc

Consolidated Statements of Income

(unaudited - in thousands, except per share data)

Tetra Tech, Inc.

Consolidated Statements of Cash Flows

(in thousands)

Tetra Tech, Inc.

Regulation G Information

October 1, 2023

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

(in millions)

Reconciliation of Net Income Attributable to Tetra Tech to Adjusted EBITDA

(in thousands)

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

2 Includes lease impairment charge of $16.4M in Q4-23