NASDAQ: TTEK

Our mission is to be the world's leading consulting and engineering firm solving global challenges in water and the environment that make a positive difference in people's lives worldwide.

The following core principles form the underpinning of how we work together to serve our clients:

•Service. We put our clients first. We listen closely to better understand our clients' needs and deliver smart, cost-effective solutions that meet their needs.

•Value. We solve our clients' problems as if they were our own. We develop and implement sustainable solutions that are innovative, efficient and practical.

•Excellence. We bring superior technical capability, disciplined project management and excellence in safety and quality to all of our services.

•Opportunity. Our people are our number one asset. Opportunity means new technical challenges that provide advancement within our company and ensure a safe workplace.

We have a strong project management culture that enables us to deliver on more than 100,000 projects per year. Our client-focused project management is supported by strong fiscal management and financial tools. We use a disciplined approach

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to monitoring, managing and improving our return on investment in each of our business areas through our efforts to negotiate appropriate contract terms, manage our contract performance to minimize schedule delays and cost overruns, and promptly bill and collect accounts receivable.

We have built a broad client and contract base by proactively understanding our clients' priorities and demonstrating a long track record of successful performance that results in repeat business and limits competition. We believe that proximity to our clients is also instrumental to integrating global experience and resources with an understanding of our local clients' needs.

Throughout our history, we have supported both public and private clients, many for multiple decades of continuous contracts and repeat business. Long-term relationships provide us with institutional knowledge of our clients' programs, past projects and internal resources. Institutional knowledge is often a significant factor in winning competitive proposals and providing cost-effective solutions tailored to our clients' needs.

We are often at the leading edge of new challenges where we are delivering one-of-a-kind solutions. These might be a new water treatment technology, a unique solution to addressing coastal erosion, an AI-enabled system for remote assessment of infrastructure assets or real-time optimization of water management systems.

We combine interdisciplinary capabilities, technical resources and institutional knowledge to implement complex projects that are at the leading edge of policy and technology development for our clients around the world.

Leading with Science®

At Tetra Tech, we provide value-generating solutions by combining operational expertise, science and technology. By Leading with Science® and leveraging our collective technology including advanced data analytics, digital technologies and AI, we create transformational solutions for our clients.

Tetra Tech's proprietary technologies and solutions, referred to collectively as the Tetra Tech Delta, differentiate us in the market and provide us with a competitive advantage. We create customized solutions; from smart data collection and advanced analytics that support decision making to AI-enabled solutions for asset management. Our Tetra Tech Delta technologies are drawn from our decades of operational experience and a reservoir of technical applications that are shared throughout our company as well as scalable solutions that are sold externally as software subscriptions. Our high-end teams connect interdisciplinary experts from across our company's more than 25,000 staff worldwide. Tetra Tech mobilizes teams that include analysts, statisticians, digital engineers and industry experts who effectively implement value-generating and pragmatic solutions for our clients.

These advanced analytical solutions enable us to provide clients with real-time reporting, automated and remote data collection and dashboards for tracking and communicating results. Tetra Tech Delta is continually expanding and includes cutting-edge tools on interpretive analysis, modeling of physical systems, forecasting and scenario analysis, optimization and operations research. Our subscription solutions provide our clients with extended capabilities for AI-enabled large scale data management, spatial data interpretation, and ability to optimize land, coastal and infrastructure systems.

Leading with Science® also means fully leveraging the collective expertise provided by our global workforce of more than 25,000 associates. We actively share information, ideas and resources across our global operations through our network structure, guided subject matter teams and project team building. We use company-wide virtual events to engage Tetra Tech experts world-wide to solve client challenges and identify the best ideas for further development. We also proactively share emerging technology and new ideas through our knowledge transfer system, Tetra Tech Technology Transfer ("T4"). T4 facilitates our innovation culture through webcasts, blogs, multi-media and social media across our global operations. Our Tetra Tech Learning Hub provides a full suite of training resources including project management, leadership development, and broad technical skills. Learning Hub curriculum is provided through online training, virtual workshops and in-person events.

Reportable Segments

We manage our operations under two reportable segments. Our Government Services Group ("GSG") reportable segment primarily includes activities with U.S. government clients (federal, state and local) and all activities with development agencies worldwide. Our Commercial/International Services Group ("CIG") reportable segment primarily includes activities with U.S. commercial clients and international clients other than development agencies. These reportable segments allow us to capitalize on our growing market opportunities and enhance the development of high-end consulting and technical solutions to meet our growing client demand.

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The following table presents the percentage of our revenue by reportable segment:

Fiscal Year

Reportable Segment 2025 2024 2023

GSG 49.1% 47.8% 47.7%

CIG 52.3 53.6 53.6

Inter-segment elimination (1.4) (1.4) (1.3)

100.0% 100.0% 100.0%

For additional information regarding our reportable segments, see Note 19, "Reportable Segments" of the "Notes to Consolidated Financial Statements" included in Item 8. For more information on risks related to our business, reportable segments and geographic regions, including risks related to foreign operations, see Item 1A, “Risk Factors” of this report.

Government Services Group

GSG provides high-end consulting and engineering services primarily to U.S. government clients (federal, state and local) and international development agencies worldwide. GSG supports U.S. government civilian and defense agencies with services in water, environment, sustainable infrastructure, information technology and disaster management. GSG also provides engineering design services for U.S. based federal and municipal clients, especially in water infrastructure, flood protection and solid waste.

GSG provides consulting and engineering services for a broad range of water, environment and sustainable infrastructure-related needs primarily for U.S. government clients. The primary GSG markets include water resources analysis and water management, environmental monitoring, data analytics, government consulting, waste management and a broad range of civil infrastructure master planning and resilient engineering design for facilities, transportation and local development projects. GSG's services span from early data collection and monitoring, to data analysis and information management, to science and engineering applied research, to engineering design, to project management and operations and maintenance.

GSG provides our clients with sustainable solutions that optimize their water management and environmental programs to address regulatory requirements, improve operational efficiencies and manage assets. Our services advance the resiliency of infrastructure, including design of energy efficiency and resource conservation programs, development of disaster preparedness and response plans and improvement in water and land resource management practices. We provide energy management consulting, and greenhouse gas ("GHG") inventory assessment, certification, reduction and management services. GSG also provides planning, architectural and engineering services for U.S. federal, state and local government facilities. We support government agencies with related resilient infrastructure needs, asset management for military housing and educational, institutional and research facilities.

Many government organizations face complex problems due to increased demand and competition for water and natural resources, newly understood threats to human health and the environment, aging infrastructure and demand for new and more resilient infrastructure. Our integrated water management services support government agencies responsible for managing water supplies, wastewater treatment, storm water management and flood protection. We help our clients develop more resilient water supplies and more sustainable management of water resources, while addressing a wide range of local and national government requirements and policies. Fluctuations in weather patterns and extreme events, such as prolonged droughts and more frequent flooding, are increasing concerns over the reliability of water supplies, the need to protect coastal areas and flood mitigation and adaptation in metropolitan areas. We provide smart water infrastructure solutions that integrate water modeling, instrumentation and controls and real-time controls to create flexible water systems that respond to changing conditions, optimize use of existing infrastructure and provide clients with the ability to monitor and manage their water infrastructure more efficiently. We provide operational technology for secure management of water treatment and wastewater systems, including cybersecurity assessments and digital twin solutions.

We also support government agencies in the full range of disaster response and community resilience services including monitoring and environmental response, damage assessment and program management services and resilient engineering design and mitigation planning. We have a full suite of Tetra Tech Delta technology and specialized software that support our disaster response, planning and management support services. These tools and procedures address disaster management and community resilience data management needs, including information technology systems, portals, dashboards, data management, data analytics and statistical analysis.

GSG provides a wide range of consulting and engineering services for solid waste management, including landfill design and management, and recycling facility design throughout the United States; providing design, project management and maintenance services to manage solid and hazardous waste; as well as innovative renewable energy projects such as solar energy-generating landfill caps; and providing full-service solutions for gas-to-energy facilities to efficiently use landfill methane gas.

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We provide high-end advanced analytics and information technology ("IT") consulting and support to various federal clients including AI applications, machine learning, modernization of IT systems and cloud migration. We design solutions to manage and analyze data for major federal agency programs including data related to health, security, environment and water programs. We provide technical support for the Federal Aviation Administration to optimize the U.S. airspace system and support for related aviation systems integration for the U.S. and other countries' metropolitan airports. We provide specialized software products, modeling and data analytics for airspace acoustic analysis. Our aviation airspace services include data management, data processing, communications and outreach and systems development; and providing systems analysis and information management.

Commercial/International Services Group

CIG primarily provides high-end consulting and engineering services to U.S. commercial clients, and international clients inclusive of the commercial and government sectors. CIG supports commercial clients worldwide in energy, industrial, high-performance buildings and aerospace markets. CIG also provides sustainable infrastructure and related environmental, engineering and project management services to commercial and local government clients across Canada, in Asia Pacific (primarily Australia and New Zealand), Europe, the United Kingdom, and South America (primarily Brazil).

CIG provides consulting and engineering services worldwide for a broad range of water, environment and sustainable infrastructure-related needs in both developed and emerging economies. The primary markets for CIG's services include natural resources, energy and utilities, as well as sustainable infrastructure master planning and engineering design for facilities, transportation and local development projects. CIG's services span from early data collection and monitoring to data analysis and information management, to feasibility studies and assessments, to science and engineering applied research, to engineering design, to project management and operations and maintenance. CIG advances the application and development of Tetra Tech Delta technologies and integrates our high-end AI-enabled software solutions for a wide range of applications including condition assessments, digital twins, integration of satellite and drone imagery and advanced rapid scanning techniques.

CIG's environmental services include cleanup and beneficial reuse of sites contaminated with hazardous materials, toxic chemicals and oil and petroleum products, which cover all phases of the remedial planning process, starting with disaster response and initial site assessment through removal actions, remedial design and implementation oversight; and supporting both commercial and government clients in planning and implementing remedial activities at numerous sites around the world, and providing a broad range of environmental analysis and planning services.

CIG also supports commercial clients by providing design services to renovate, upgrade and modernize industrial water supplies, and address industrial water treatment and water reuse needs; and provides plant engineering, project execution and program management services for industrial water treatment projects throughout the world.

CIG provides planning, architectural and high-performance building engineering services for commercial and government facilities. We provide high-end design of resilient energy, water and GHG decarbonization solutions including civil, electrical, mechanical, structural and hydraulic engineering for buildings, campuses and surrounding developments. We provide high-end services in addressing indoor health and associated assessment, consulting and retrofits of buildings to address indoor air quality and safety. We also provide engineering services for a wide range of clients with specialized needs, such as data centers, advanced manufacturing, security systems, training and audiovisual facilities, clean rooms, laboratories, medical facilities and disaster preparedness facilities.

CIG's international services, especially in Canada, Europe, the United Kingdom, and Asia Pacific, include high-end analytical, engineering, architecture, geotechnical, project management and advisory services for infrastructure projects, including early project planning, rail and roadway monitoring and asset management services, collection of condition data, optimization of upgrades and long-term planning for expansion; planning and design services for airport facilities, bridges and ports and harbors; and designing resilient solutions to modernize infrastructure.

CIG provides infrastructure design services in extreme and remote areas by using specialized techniques that are adapted to local resources, while minimizing environmental impacts, and considering potential climate change impacts. These include providing consulting, geotechnical and design services to owners of transportation, natural resources, energy and community infrastructure in areas of permafrost or extreme climate regions.

CIG's energy services include support for electric power utilities and independent power producers worldwide, ranging from macro-level planning and management advisory services to project-specific environmental, engineering, project management and operational services, and advising on energy security and the design and implementation of smart grids, both domestically and internationally, including increasing utility automation, information and operational technologies and critical infrastructure security. For utilities and governmental regulatory agencies, our services include policy and regulatory development, utility management, performance improvement and asset management and evaluation. For developers and owners of renewable energy resources such as solar grid and off-grid, on-shore and off-shore wind, biogas and biomass, tidal, hydropower, conventional power generation facilities, micro-grid and battery or alternative storage facilities, as well as

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transmission and distribution assets, our services include environmental, electrical, mechanical and civil engineering, procurement, and regulatory support for all project phases.

CIG supports industrial clients globally. Our services include environmental permitting support, siting studies, strategic planning and analyses; design of site civil works; water management; biological and cultural assessments, and site investigations; and hazardous waste site remediation.

CIG also provides environmental remediation and reconstruction services to evaluate and restore lands to beneficial use, remediating, and restoring contaminated facilities in the U.S. and around the world; managing large, complex sediment remediation programs that help restore rivers and coastal waters to beneficial use; and supporting utilities in the U.S. in implementing restoration and environmental management programs.

Project Examples

Project examples are provided on our company website located at tetratech.com, including expert interviews, in-depth articles and project profiles that demonstrate our services across water, environment and sustainable infrastructure.

Clients

We provide services to a diverse base of U.S. federal government, U.S. state and local government, U.S. commercial and international clients. The following table presents the percentage of our revenue by client sector:

Fiscal Year

Client Sector 2025 2024 2023

U.S. federal government (1)
31.6% 32.2% 30.7%

U.S. state and local government 14.5 11.8 13.4

U.S. commercial 16.5 17.5 19.2

International (2)
37.4 38.5 36.7

100.0% 100.0% 100.0%

(1) Includes revenue generated under U.S. federal government contracts performed outside the United States.

(2) Includes revenue generated from non-U.S. clients, primarily in Australia, Canada and the United Kingdom.

U.S. federal government agencies are significant clients. The United States Agency for International Development ("USAID") accounted for 10.6%, 13.0% and 12.2% of our revenue in fiscal 2025, 2024 and 2023, respectively. The Department of Defense ("DoD") accounted for 11.6%, 8.5% and 8.9% of our revenue in fiscal 2025, 2024 and 2023, respectively. We typically support multiple programs within a single U.S. federal government agency, both domestically and internationally. We also assist U.S. state and local government clients in various jurisdictions across the United States. Our international clients are primarily focused in Australia, Canada, Europe and the United Kingdom, and consist of a relatively equal sized mix of government and commercial clients. Our U.S. commercial clients include companies in the chemical, energy, technology, retail, aerospace and automotive industries. No single client, except for the U.S. federal government clients, accounted for more than 10% of our revenue in fiscal 2025.

Contracts

Our services are performed under three principal types of contracts with our clients: fixed-price, time-and-materials and cost-plus. The following table presents the percentage of our revenue by contract type:

Fiscal Year

Contract Type 2025 2024 2023

Fixed-price 43.5% 38.8% 36.3%

Time-and-materials 42.6 45.0 48.0

Cost-plus 13.9 16.2 15.7

100.0% 100.0% 100.0%

Under a fixed-price contract, clients agree to pay a specified price for our performance of the entire contract or a specified portion of the contract. Some fixed-price contracts can include date-certain and/or performance obligations. Fixed-price contracts carry certain inherent risks, including risks of losses from underestimating costs, delays in project completion, problems with new technologies, price increases for materials and economic and other changes that may occur over the contract period. Consequently, the profitability of fixed-price contracts may vary substantially. Under time-and-materials contracts, we are paid for labor at negotiated hourly billing rates and paid for other expenses. Profitability on these contracts is driven by billable headcount and cost control. Many of our time-and-materials contracts are subject to maximum contract values and,

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accordingly, revenue related to these contracts is recognized as if these contracts were fixed-price contracts. Under our cost-plus contracts, some of which are subject to a contract ceiling amount, we are reimbursed for allowable costs and fees, which may be fixed or performance-based. If our costs exceed the contract ceiling or are not allowable, we may not be able to obtain full reimbursement. Further, the amount of the fee received for a cost-plus award fee contract partially depends upon the client's discretionary periodic assessment of our performance on that contract.

Some contracts with the U.S. federal government are subject to annual funding approval. U.S. federal government agencies may impose spending restrictions that limit the continued funding of our existing contracts and may limit our ability to obtain additional contracts. These limitations, if significant, could have a material adverse effect on us. All contracts with the U.S. federal government may be terminated by the government at any time, with or without cause.

U.S. federal government agencies have formal policies against continuing or awarding contracts that would create actual or potential conflicts of interest with other activities of a contractor. These policies may prevent us from bidding for or performing government contracts resulting from or related to certain work we have performed. In addition, services performed for a commercial or government sector client may create conflicts of interest that preclude or limit our ability to obtain work for a private organization. We attempt to identify actual or potential conflicts of interest and to minimize the possibility that such conflicts could affect our work under current contracts or our ability to compete for future contracts. We have, on occasion, declined to bid on a project because of an existing or potential conflict of interest.

Some of our operating units have contracts with the U.S. federal government that are subject to audit by the government, primarily the Defense Contract Audit Agency ("DCAA"). The DCAA generally seeks to (i) identify and evaluate all activities that contribute to, or have an impact on, proposed or incurred costs of government contracts; (ii) evaluate a contractor's policies, procedures, controls and performance; and (iii) prevent or avoid wasteful, careless and inefficient production or service. To accomplish this, the DCAA examines our internal control systems, management policies and financial capability; evaluates the accuracy, reliability and reasonableness of our cost representations and records; and assesses our compliance with Cost Accounting Standards ("CAS") and defective-pricing clauses found within the Federal Acquisition Regulation ("FAR"). The DCAA also performs an annual review of our overhead rates and assists in the establishment of our final rates. This review focuses on the allowability of cost items and the applicability of CAS. The DCAA also audits cost-based contracts, including the close-out of those contracts.

The DCAA reviews all types of U.S. federal government proposals, including those of award, administration, modification and re-pricing. The DCAA considers our cost accounting system, estimating methods and procedures and specific proposal requirements. Operational audits are also performed by the DCAA. A review of our operations at every major organizational level is conducted during the proposal review period. During the course of its audit, the U.S. federal government may disallow certain costs if it determines that we accounted for such costs in a manner inconsistent with CAS. Under a government contract, only those costs that are reasonable, allocable and allowable are recoverable. A disallowance of costs by the U.S. federal government could have a material adverse effect on our financial results.

In accordance with our corporate policies, we maintain controls to minimize any occurrence of fraud or other unlawful activities that could result in severe legal remedies, including the payment of damages and/or penalties, criminal and civil sanctions and debarment. In addition, we maintain preventative audit programs and mitigation measures to ensure that appropriate control systems are in place.

We provide services under contracts, purchase orders or retainer letters. Our policy requires that all contracts must be in writing. We bill our clients in accordance with the contract terms and periodically based on costs incurred, on either an hourly-fee basis or on a percentage-of-completion basis, as the project progresses. Most of our agreements permit our clients to terminate the agreements without cause upon payment of fees and expenses through the date of the termination. Generally, our contracts do not require that we provide performance bonds. If required, a performance bond, issued by a surety company, guarantees a contractor's performance under the contract. If the contractor defaults under the contract, the surety will, at its discretion, complete the job or pay the client the amount of the bond. If the contractor does not have a performance bond and defaults in the performance of a contract, the contractor is responsible for all damages resulting from the breach of contract. These damages include the cost of completion, together with possible consequential damages such as lost profits.

Growth Strategy

Our management team establishes Tetra Tech's overall business strategy. Our strategic plan defines and guides our investment in marketing and business development to leverage our differentiators and target priority programs and growth markets. We maintain centralized business development resources to develop our corporate branding and marketing materials, support proposal preparation and planning, conduct market research and manage promotional and professional activities, including appearances at trade shows, advertising and public relations.

We have established company-wide growth initiatives that reinforce internal coordination, track the development of new programs, identify and coordinate collective resources for major bids and bring together high-end interdisciplinary teams

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that provide innovative solutions for major pursuits. Our growth initiatives provide a forum for cross-sector collaboration, access to technical solutions and the development of interdisciplinary solutions. We continuously identify new markets that are consistent with our strategic plan and service offerings, and we leverage our full-service capabilities and internal coordination structure to develop and implement strategies to research, anticipate and position us for future procurements and emerging programs. Our Tetra Tech Delta program facilitates access and exchange of technology solutions and AI-enabled software solutions across our company, through the use of internal training, communities of practice, and facilitated virtual networking events.

Business development activities are implemented by our technical and professional management staff throughout Tetra Tech with the support of company-wide resources and expertise. Our project managers and technical staff have the best understanding of our clients' needs and the effect of client-specific issues, local laws and regulations and procurement procedures. Our professional staff members hold frequent meetings with existing and potential clients; give presentations to civic and professional organizations and present seminars on research and technical applications. Effective development of business is facilitated by each staff member's access to all of our service offerings including our Tetra Tech Delta technology resources and software. Our strong internal networking programs help our professional staff members to pursue new opportunities and build multi-disciplinary teams for both existing and new clients. These networks also facilitate our ability to provide services throughout the project life cycle from the early studies to operations and maintenance. Networking is further supported by our enterprise-wide knowledge management systems which include skills search tools, business development tracking and collaboration tools.

To support our growth plans, we actively attract, recruit, engage and retain key hires. Our combination of high-end science, technology resources and consulting culture coupled with practical applications provides challenging and rewarding opportunities for our workforce, thereby enhancing our ability to recruit and retain top quality talent. Our internal networking programs, leadership training, entrepreneurial environment, focus on Leading with Science® and global project portfolio help to attract and retain highly qualified individuals.

Our strategic growth plans are augmented by our selective investment in acquisitions aligned with our business. Acquisitions advance our strategy by adding new technologies, broadening our service offerings, adding contract capacity and expanding our geographic presence. Our long-established experience in identifying and integrating acquisitions strengthens our ability to integrate and rapidly leverage the resources of the acquired companies post-acquisition.

Sustainability Program

Sustainability is an integral part of our global business, rooted in our internal culture and extending throughout our projects around the world. For more than 50 years, we have leveraged cutting-edge expertise and the latest technology to deliver more sustainable solutions to clients and continually improve the way we do business.

Through our Sustainability Program, we continue to enhance the sustainability of our daily practices, reduce our GHG emissions, and provide an exceptional working environment for our employees across our global operations. As a signatory of the United Nations ("UN") Global Compact on human rights, labor, environment and anti-corruption, we embrace the UN Global Compact's Ten Principles.

We actively engage with our stakeholders, internally and externally, to encourage input on the materiality of various sustainability issues to Tetra Tech and have incorporated input into our double materiality analysis and sustainability program. Our annual sustainability reporting and key metrics are aligned with the priorities we have set on ethics, professional development, and health & safety. We have supplier programs that integrate and emphasize sustainability in the procurement of goods and services and subcontracting for our projects. We have reported annually on GHG emissions for more than a decade, significantly reducing our emissions from program inception. In 2021, we expanded our reporting and set new goals for scope 1, 2, and 3 emissions.

Our Sustainability Program is led by our Chief Sustainability Officer, who has been appointed by our Board of Directors and is supported by corporate and operations representatives through our Sustainability Council. We continuously review sustainability-related policies and practices, integrate input from stakeholders, and assess the results of our efforts in order to make future improvements. Tetra Tech's Board of Directors reviews and approves the Sustainability Program and evaluates our progress as outlined in Tetra Tech's annual Sustainability Report.

Acquisitions and Divestitures

Acquisitions. We continuously evaluate the marketplace for acquisition opportunities to further our strategic growth plans. Due to our reputation, size, financial resources, geographic presence and range of services, we have numerous opportunities to acquire privately and publicly held companies or selected portions of such companies. We evaluate an acquisition opportunity based on its ability to strengthen our leadership in the markets we serve, the technologies and solutions they provide and the additional new geographies and clients they bring. Also, during our evaluation, we examine an acquisition's ability to drive organic growth, its accretive effect on long-term earnings and its ability to generate return on

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investment. Generally, we proceed with an acquisition if we believe that it will strategically expand our service offerings, improve our long-term financial performance and increase shareholder returns.

We view acquisitions as a key component in the execution of our growth strategy, and we intend to use cash, debt or equity, as we deem appropriate, to fund acquisitions. We may acquire other businesses that we believe are synergistic and will ultimately increase our revenue and net income, strengthen our ability to achieve our strategic goals, provide critical mass with existing clients and further expand our lines of service. We typically pay a purchase price that results in the recognition of goodwill, generally representing the intangible value of a successful business with an assembled workforce specialized in our areas of interest. Acquisitions are inherently risky, and no assurance can be given that our previous or future acquisitions will be successful or will not have a material adverse effect on our financial position, results of operations or cash flows. All acquisitions require the approval of our Board of Directors.

In the second quarter of fiscal 2025, we acquired Carron + Walsh ("CAW"), based in the Republic of Ireland. CAW delivers project and cost management solutions for large-scale commercial, life science, residential and infrastructure programs across Europe. In the third quarter of fiscal 2025, we acquired SAGE Group Holdings ("SAGE"), an Australian consulting firm that provides innovative technology and high-quality automation services that optimize operational efficiency and drive digital transformation for commercial and government clients across the municipal water, energy, transportation, defense and manufacturing sectors. Both CAW and SAGE are included in our CIG segment.

In fiscal 2024, we acquired LS Technologies ("LST"), an innovative U.S. federal enterprise technology services and management consulting firm based in Fairfax, Virginia. LST provides high-end consulting and engineering services including advanced data analytics, cybersecurity and digital transformation solutions to U.S. government clients. In fiscal 2024, we also acquired Convergence Controls & Engineering ("CCE"), an industry leader in process automation and systems integration solutions. CCE’s expertise includes customized digital controls and software solutions, advanced data analytics, cloud data integration and cybersecurity applications. Both LST and CCE are included in our GSG segment.

In fiscal 2023, we completed the acquisition of RPS Group plc ("RPS"), a publicly traded company on the London Stock Exchange in an all-cash transaction totaling $784 million. We funded the RPS acquisition with debt, net of $109 million in proceeds from a foreign exchange forward contract that we entered into at the same time we made the formal offer to acquire RPS on September 23, 2022. RPS operates in the United Kingdom, Europe, Asia Pacific and North America, delivering high-end solutions, especially in energy transformation, water and program management for government and commercial clients. Substantially all of RPS is included in our CIG segment. In fiscal 2023, we also acquired Amyx, Inc. (“Amyx”), an enterprise technology services, cybersecurity and management consulting firm based in Reston, Virginia. Amyx provides application modernization, cybersecurity, systems engineering, financial management and program management support on over 30 U.S. federal government programs. Amyx is included in our GSG segment.

Divestitures. We regularly review and evaluate our existing operations to determine whether our business model should change through the divestiture of certain businesses. Accordingly, from time to time, we may divest or wind-down certain non-core businesses and reallocate our resources to businesses that better align with our long-term strategic direction. In fiscal 2025, we divested a subsidiary in South America and a line of business in Australia, both of which were immaterial. We did not divest any businesses in fiscal 2023 and 2024.

For detailed information regarding acquisitions, see Note 5, "Acquisitions and Divestitures" of the "Notes to Consolidated Financial Statements" included in Item 8.

Competition

The market for our services is generally competitive. We often compete with many other firms ranging from small regional firms to large international firms.

We perform a broad spectrum of consulting, engineering and technical services across the water, environment and sustainable infrastructure markets. Our competition varies and is a function of the business areas in which, and the client sectors for which, we perform our services. The number of competitors for any procurement can vary widely, depending upon technical qualifications, the relative value of the project, geographic location, the financial terms and risks associated with the work and any restrictions placed upon competition by the client. Historically, clients have chosen among competing firms by weighing the quality, innovation and timeliness of the firm's service versus its cost to determine which firm offers the best value.

Our competitors vary depending on end markets and clients, and often we may only compete with a portion of a firm. We believe that our principal competitors include the following firms, in alphabetical order: AECOM; Arcadis NV; AtkinsRéalis; Black & Veatch Corporation; Booz Allen Hamilton; Brown & Caldwell; CDM Smith Inc.; Exponent, Inc.; GHD; ICF International, Inc.; Jacobs Solutions, Inc.; Leidos, Inc.; SAIC; Stantec Inc.; TRC Companies, Inc.; Weston Solutions, Inc.; and WSP Global Inc.

Backlog

We include in our backlog only those contracts for which funding has been provided and work authorization has been received. We estimate that approximately 70% of our backlog at the end of fiscal 2025 will be recognized as revenue in fiscal

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2026, as work is being performed. However, we cannot guarantee that the revenue projected in our backlog will be realized or, if realized, will result in profits. In addition, project cancellations or scope adjustments may occur with respect to contracts reflected in our backlog. For example, certain of our contracts with the U.S. federal government and other clients are terminable at the discretion of the client, with or without cause. These types of backlog reductions could adversely affect our revenue and margins. Accordingly, our backlog as of any particular date is an uncertain indicator of our future earnings.

Our backlog at fiscal 2025 year-end was $4.1 billion. GSG and CIG reported $1.98 billion and $2.22 billion of backlog, respectively, at fiscal 2025 year-end.

Regulations

We engage in various service activities that are subject to government oversight, including environmental laws and regulations, general government procurement laws and regulations and other regulations and requirements imposed by the specific government agencies with which we conduct business.

Environmental. A significant portion of our business involves the planning, design and program management of pollution control facilities, as well as the assessment and management of remediation activities at hazardous waste sites, U.S. Superfund sites and military bases. In addition, we contract with U.S. federal government entities to destroy hazardous materials. These activities require us to manage, handle, remove, treat, transport and dispose of toxic or hazardous substances.

Some environmental laws, such as the U.S. Superfund law and similar state, provincial and local statutes, can impose liability for the entire cost of clean-up for contaminated facilities or sites upon present and former owners and operators, as well as generators, transporters and persons arranging for the treatment or disposal of such substances. In addition, while we strive to handle hazardous and toxic substances with care and in accordance with safe methods, the possibility of accidents, leaks, spills and events of force majeure always exist. Humans exposed to these materials, including workers or subcontractors engaged in the transportation and disposal of hazardous materials and persons in affected areas, may be injured or become ill. This could result in lawsuits that expose us to liability and substantial damage awards. Liabilities for contamination or human exposure to hazardous or toxic materials, or a failure to comply with applicable regulations, could result in substantial costs, including clean-up costs, fines, civil or criminal sanctions, third party claims for property damage or personal injury or the cessation of remediation activities.

Certain of our business operations are covered by U.S. Public Law 85-804, which provides for government indemnification against claims and damages arising out of unusually hazardous activities performed at the request of the government. Due to changes in public policies and law, however, government indemnification may not be available in the case of any future claims or liabilities relating to other hazardous activities that we perform.

Government Procurement. The services we provide to the U.S. federal government are subject to the FAR and other rules and regulations applicable to government contracts. These rules and regulations:

•require certification and disclosure of all cost and pricing data in connection with the contract negotiations under certain contract types;

•impose accounting rules that define allowable and unallowable costs and otherwise govern our right to reimbursement under certain cost-based government contracts; and

•restrict the use and dissemination of information classified for national security purposes and the exportation of certain products and technical data.

In addition, services provided to the DoD and U.S. federal civil agencies are monitored by the Defense Contract Management Agency and audited by the DCAA. Our government clients can also terminate any of their contracts, and many of our government contracts are subject to renewal or extension annually. Further, the services we provide to state and local government clients are subject to various government rules and regulations.

Seasonality

We experience seasonal trends in our business. Our revenue and operating income are typically lower in the first half of our fiscal year, primarily due to the Thanksgiving (in the U.S. and Canada), Christmas and New Year's holidays. Many of our clients' employees, as well as our own employees, take vacations during these holiday periods. Further, seasonal inclement weather conditions occasionally cause some of our offices to close temporarily or may hamper our project field work in the northern hemisphere's temperate and arctic regions. These occurrences result in fewer billable hours worked on projects and, correspondingly, less revenue recognized.

Climate Risk Assessment

We assess the impact of climate risk and opportunity on our operations and business periodically, with the oversight of our Board of Directors. Climate risk is a consideration in business continuity planning and security in regions that may

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experience climate-related disruptions due to extreme weather, fires or flooding. Climate-related impacts may also create increased demand for our services for response and longer-term recovery needs. In some cases, we may be working in regions that also experience socio-political impacts and security disruptions due to the impacts of extreme weather or prolonged drought conditions. As a professional services company, our workforce is highly mobile, able to work remotely, and can in most cases quickly adapt to changes in local conditions. We have business continuity planning and processes in place to address any acute impact to locally affected operations can rapidly move to remote and flexible working arrangements while restoring or relocating affected operations. We maintain a strong information technology infrastructure to facilitate remote working and provide virtual access to systems. Our enterprise and project data is accessible through cloud-based systems, reducing the risk of localized disruptions of data access and computer systems. Our offices are typically leased, so we are not at significant risk of physical building assets being impacted. Selecting project activities can be impacted by climate related events; however, these are addressed through our extensive project risk management process. Climate-related disruptions do, in many cases, result in increased opportunity for project work for Tetra Tech. We provide post-disaster response services and may have additional demand for our expertise if there is an increase in the frequency of climate-related events. We can mobilize rapidly to deploy additional staff and resources to affected areas. Furthermore, our business includes providing a wide range of water, environment and sustainable infrastructure services, many of which are increasingly in demand to address the longer-term impacts associated with drought, water scarcity, heat, flooding and fire risk.

Risk Management and Insurance

Our business activities could expose us to potential risk and liability under various laws and under workplace health and safety regulations. In addition, we occasionally assume liability by contract under indemnification agreements. We cannot predict the magnitude of such potential liabilities. Our Office of Risk Management reviews and oversees the risk profile of our operations, and reports to our Board of Directors.

We maintain a comprehensive general liability insurance policy with an umbrella policy that covers losses beyond the general liability limits. We also maintain professional errors and omissions liability, contractor's pollution liability, and cyber liability insurance policies. We believe that these policies provide adequate coverage for our business. When we perform higher-risk work, we obtain, if available, the necessary types of insurance coverage for such activities, as is typically required by our clients.

We obtain insurance coverage through a broker that is experienced in our industry. The broker and our risk manager regularly review the adequacy of our insurance coverage. Because there are various exclusions and retentions under our policies, or an insurance carrier may become insolvent, there can be no assurance that all potential liabilities will be covered by our insurance policies or paid by our carrier.

We evaluate the risk associated with insurance claims. If we determine that a loss is probable and reasonably estimable, we establish an appropriate reserve. A reserve is not established if we determine that a claim has no merit or is not probable or reasonably estimable. Our historic levels of insurance coverage and reserves have been adequate. However, partially or completely uninsured claims, if successful and of significant magnitude, could have a material adverse effect on our business.

Human Capital Management

Employees. At fiscal 2025 year-end, we had more than 25,000 staff worldwide. A large percentage of our employees have technical and professional backgrounds and undergraduate and/or advanced degrees, including the employees of recently acquired companies. Our professional staff includes, but is not limited to, analysts, archaeologists, architects, biologists, chemical engineers, chemists, civil engineers, data scientists, computer scientists, digital engineers, economists, electrical engineers, environmental engineers, environmental scientists, geologists, hydrogeologists, mechanical engineers, software engineers, statisticians, oceanographers, project managers and toxicologists. We consider the current relationships with our employees to be favorable. We are not aware of any employment circumstances that are likely to disrupt work at any of our facilities. See Part I, Item 1A, "Risk Factors" for a discussion of the risks related to the loss of key personnel or our inability to attract and retain qualified personnel.

Health and Safety. Tetra Tech is committed to providing and maintaining a healthy and safe work environment for our associates. We provide training to all associates to support the safe execution of their work to improve their understanding of behaviors that can be perceived as discriminatory, exclusionary and/or harassing, and provide safe avenues for associates to report such behaviors.

Ethics and Compliance. Tetra Tech maintains an unwavering commitment to integrity, ethical practices, and conducting business in full compliance with the law. Our Code of Business Ethics and Conduct outlines the general ethical principles that help us make the right decisions when conducting business worldwide. To support our employees, we provide a variety of resources and training and offer multiple avenues to raise questions or concerns - to help ensure long-term success for our employees, company, clients, and shareholders.

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Equal Employment Opportunity. Tetra Tech ensures that our practices and processes attract a diverse range of candidates and that candidates are recruited, hired, assigned, developed and promoted based on merit and their alignment with our values.

Enhancing learning and development opportunities. To support our employees in reaching their full potential, Tetra Tech offers a wide range of internal and external learning and development opportunities. Education assistance is offered to financially support associates who seek to expand their knowledge and skill base.

Professional Development. Tetra Tech provides access for all employees to training, technical exchange and collaboration, and skill development resources through its customized Learning Management System, providing professional development opportunities throughout our employees' careers. Technology skills development includes access to a series of live webcasts and recorded technology transfer sessions. Company-wide networking events provide interactive skills development activities. Employees are also provided with access to training in leadership development, project management skills, and interpersonal skills development. Various personal development and wellness programs are sponsored by our Human Resources team. Our Corporate Information Technology team provides access to software training and skills development modules to all employees. Tetra Tech also supports our employees in discipline specific training, certifications, and accreditation programs across the Company. Programs such as specific health and safety programs, hazardous waste investigation, environmental certifications, and professional certifications are encouraged as per client, project and professional development needs.

Executive Officers of the Registrant

The following table shows the name, age and position of each of our executive officers as of November 20, 2025:

Name Age Position

Dan L. Batrack

67 Chairman and Chief Executive Officer

Mr. Batrack joined our predecessor in 1980 and was named Chairman in January 2008. He has served as our Chief Executive Officer and a director since November 2005, and as our President from October 2008 to September 2019. Mr. Batrack has served in numerous capacities over the last 40 years, including arctic research scientist, deep water oceanographic hydrographer, coastal hydrodynamic modeler, environmental data analyst, project and program manager, President of the Engineering Division, and in 2004 he was appointed Chief Operating Officer. He has managed complex programs for many small and Fortune 500 clients, both in the United States and internationally. Mr. Batrack holds a B.A. degree in Business Administration from the University of Washington.

Roger R. Argus 64 President

Mr. Argus was appointed President in October 2025. He served as Executive Vice President, Corporate Development from November 2024 to October 2025, and President, Commercial/International Services Group from October 2023 to October 2025. Prior to this, Mr. Argus served as Senior Vice President and President, Government Services Group from October 2018 to October 2024, and President, U.S. Government Division from October 2017 to November 2024. He is a chemical engineer with 40 years of experience, including over 30 years with us in operational leadership, program and project management and quality assurance for projects encompassing a broad spectrum of environmental, engineering, information technology and disaster management services. Mr. Argus holds a B.S. in Chemical Engineering from California State University, Long Beach.

Steven M. Burdick

61 Executive Vice President, Chief Financial Officer

Mr. Burdick has served as our Executive Vice President, Chief Financial Officer since April 2011. He served as our Senior Vice President, Corporate Controller and Chief Accounting Officer from January 2004 to March 2011. Mr. Burdick joined us in April 2003 as Vice President, Management Audit. Previously, Mr. Burdick served in senior financial and executive positions with Aura Systems, Inc., TRW Ventures, and Ernst & Young LLP. Mr. Burdick holds a B.S. degree in Business Administration from Santa Clara University and is a Certified Public Accountant.

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Name Age Position

Preston Hopson 49 Executive Vice President, Chief Legal and Human Capital Officer and Secretary

Mr. Hopson was appointed Executive Vice President, Chief Legal and Human Capital Officer in November 2024, having served as Senior Vice President, General Counsel and Secretary to the Board of Directors since January 2018. He also serves as the Chief Ethics and Compliance Officer. Previously, Mr. Hopson served as Vice President, Assistant General Counsel and Assistant Corporate Secretary at AECOM. Prior to this, he was a corporate and securities lawyer at O’Melveny & Myers LLP and also worked at the U.S. Court of Appeals. Mr. Hopson holds B.A. and J.D. degrees from Yale University.

Leslie Shoemaker

68 Executive Vice President, Chief Innovation and Sustainability Officer

Dr. Shoemaker currently serves as Executive Vice President, Chief Innovation and Sustainability Officer focused on the advancement of Tetra Tech Delta technologies, development and deployment of our subscription software offerings, and company-wide technology innovation programs. Dr. Shoemaker joined us in 1991, and has served in various management capacities, including Tetra Tech President, Chief Strategist, business group president, and water resources project manager. Her technical expertise is in development models and data analytics that leverage emerging technologies to optimize the management of large-scale complex watersheds. Since the inception of our sustainability program in 2010, she has served as Chief Sustainability Officer leading the formation and evolution of the program. Dr. Shoemaker holds a B.A. in Mathematics from Hamilton College, a Master of Engineering from Cornell University and a Ph.D. in Agricultural Engineering from the University of Maryland. She was inducted into the United States' National Academy of Engineers in 2022.

Brian N. Carter 58 Senior Vice President, Corporate Controller and Chief Accounting Officer

Mr. Carter joined us as Vice President, Corporate Controller and Chief Accounting Officer in June 2011 and was appointed Senior Vice President in October 2012. Previously, Mr. Carter served in finance and auditing positions in private industry and with Ernst & Young LLP. Mr. Carter holds a B.S. in Business Administration from Miami University and is a Certified Public Accountant.

Available Information

Our internet website address is www.tetratech.com. We made available, free electronic copies of our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and all amendments to those reports through the “Investor Relations” portion of our website, under the heading “SEC Filings” filed under “Financial Information.” These reports are available on our website as soon as reasonably practicable after we electronically file them with the Securities and Exchange Commission ("SEC"). These reports, and any amendments to them, are also available at the Internet website of the SEC, https://www.sec.gov. Also available on our website are our Corporate Governance Policies, Board Committees, Corporate Code of Conduct and Finance Code of Professional Conduct.