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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934 (Amendment No.            )

 

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LETTER TO STOCKHOLDERS
FROM OUR BOARD OF DIRECTORS

January 24, 2018

Dear Fellow Stockholder:

We thank you for your investment in Tetra Tech, and for trusting us to represent you and oversee your interests in our Company.

The Board understands that we are elected by our stockholders to oversee the Company's long-term health and overall success. We are the Company's ultimate decision-making body, except for those matters reserved to or shared with stockholders, and we play a critical role in strategic planning.

We select, oversee and evaluate a very capable management team that conducts the day-to-day business of the Company and is optimistic about the future of this business. They have taken thoughtful and decisive steps to focus the business on "Leading with Science®," and providing high-end consulting and engineering solutions that are differentiated and of long-lasting sustainable value to clients. The Company remains committed to delivering long-term value for our stockholders. Management and your Board are pleased to report a 91% increase in our total shareholder return over the last three years, and we remain optimistic about the Company's future.

One of our priorities is listening to the views of our stockholders and considering them as we make decisions in the boardroom. Through management, we engage with stockholders during an annual outreach cycle and, based on this engagement, we made significant enhancements to the Company's governance and compensation programs over the last few years.

Executive Compensation

Our stockholders continue to tell us that a fundamental principle underlying any compensation program is that it should pay for performance. We agree, and our feedback from stockholders continues to contribute to our compensation decisions. Our Compensation Committee regularly assesses the Company's compensation programs, and the enhancements are designed to further align our business and talent strategies with the long-term interests of our stockholders.

Board Refreshment and Diversity

The issue of Board refreshment has emerged as an important area of focus for stockholders. We agree that new perspectives and new ideas are critical to a forward-looking and strategic Board. At the same time, it is also important to benefit from the valuable experience and insight that longer-serving Directors bring to the boardroom.

Ensuring diverse perspectives, including a mix of skills, experience and backgrounds, is key to effectively representing the long-term interests of our stockholders. Doing so is a top priority of the Board. In the last four years, three new Directors were elected and one long-term Director retired. As a result, the average tenure for our Directors has been reduced and our Board's gender diversity is currently one third women. Further, the Board determined that the role of Presiding Director would rotate to ensure independence,

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and the term of the Presiding Director would be limited to four years. We remain committed to ensuring that your Board is composed of a highly capable and diverse group of Directors, well-equipped to oversee the success of the business and effectively represent the interests of our stockholders.

Board Risk Oversight

The Board oversees the Company's risk profile and monitors the management of risks within the Company. The Strategic Planning and Enterprise Risk Committee has been tasked with coordinating the Board's risk oversight function. This Committee oversees our enterprise risk management policies and procedures, particularly in the areas of strategic, operational and compliance risk. Each of our other three Committees also oversees specific areas of risk management.

Cybersecurity is also a critical priority for the entire Company. The Strategic Planning and Enterprise Risk Committee receives reports from the Chief Information Officer regarding the Company's information technology systems, and dedicates time in its agenda for a discussion of cybersecurity and other important risk issues.

Board Accountability

As we conduct the activities of this Board, we consider accountability to stockholders as not only a mark of good governance, but a key to the long-term success of our Company. We remain accountable through a variety of governance practices, including:

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The annual election of all Directors;



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A majority vote bylaw in uncontested Director elections;



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An independent Presiding Director who presides over executive sessions of all independent directors;



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An annual Board evaluation process;



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The right of stockholders to call a special meeting;



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An annual advisory vote on executive compensation; and



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Proactive stockholder engagement.

Communicating with the Board

Finally, we value your input and encourage you to share your thoughts or concerns with us. To facilitate communication by stockholders, please address communications to the Tetra Tech Board of Directors in care of the Corporate Secretary, Tetra Tech, Inc., 3475 E. Foothill Boulevard, Pasadena, California 91107 or by email to asktheboard@tetratech.com.

As always, thank you for the trust you have placed in us.

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January 24, 2018

Dear Tetra Tech Stockholders:

              You are cordially invited to attend the Annual Meeting of Stockholders of Tetra Tech, Inc., which will be held at the Westin Pasadena, 191 N. Los Robles Avenue, Pasadena, California 91101, on Thursday, March 8, 2018, at 10:00 a.m. Pacific Time.

              Details of the business to be conducted at the Annual Meeting are given in the Notice of Annual Meeting of Stockholders and the proxy statement.

              We use the Internet as our primary means of furnishing proxy materials to our stockholders. Consequently, most stockholders will not receive paper copies of our proxy materials. We will instead send these stockholders a notice with instructions for accessing the proxy materials and voting via the Internet. The notice also provides information on how stockholders may obtain paper copies of our proxy materials if they so choose. Internet transmission and voting are designed to be efficient, minimize cost and conserve natural resources.

              Whether or not you plan to attend the Annual Meeting, please vote as soon as possible. As an alternative to voting in person at the Annual Meeting, you may vote via the Internet, by telephone or, if you receive a paper proxy card in the mail, by mailing the completed proxy card. Voting by any of these methods will ensure your representation at the Annual Meeting.

              Thank you for your continued support of Tetra Tech. We look forward to seeing you at the Annual Meeting.

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NOTICE OF 2018 ANNUAL MEETING OF STOCKHOLDERS

To Our Stockholders:

              You are cordially invited to attend our 2018 Annual Meeting of Stockholders to be held on Thursday, March 8, 2018, at 10:00 a.m. Pacific Time, at the Westin Pasadena, 191 N. Los Robles Avenue, Pasadena, California 91101. At the meeting, stockholders will vote on the following items of business:

1.

To elect the nine directors nominated by our Board to serve a one-year term;



2.

To approve, on an advisory basis, our executive compensation;



3.

To approve our 2018 Equity Incentive Plan;



4.

To ratify the appointment of PricewaterhouseCoopers LLP as our independent registered public accounting firm for fiscal year 2018; and



5.

To transact any other business properly brought before the meeting or any adjournment or postponement thereof.

              The record date for determining those stockholders who will be entitled to notice of, and to vote at, the Annual Meeting and any adjournments or postponements thereof is January 12, 2018. Our Board recommends that stockholders vote FOR each of the director nominees nominated by our Board, and FOR Items 2, 3 and 4. After considering these items of business at the meeting, Dan Batrack, our Chairman and Chief Executive Officer, will review our fiscal 2017 performance and answer your questions.

              Even if you cannot attend the Annual Meeting, it is important that your shares be represented and voted. You may vote as follows:

              On behalf of the Board of Directors, management and employees of Tetra Tech, thank you for your continued support.

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              This section contains summary information described in greater detail in other parts of this proxy statement and does not contain all the information you should consider before voting. Stockholders are urged to read the entire proxy statement before voting.

TETRA TECH

              Tetra Tech is a leading provider of consulting and engineering services that focuses on water, environment, infrastructure, resource management, energy and international development. We are a global company that is renowned for our expertise in providing water-related solutions for public and private clients. Engineering News-Record, the leading trade journal for our industry, has ranked Tetra Tech as the number one water services firm for 14 consecutive years, most recently in its May 2017 "Top 500 Design Firms" issue. In 2017, we were also ranked number one in water treatment/desalination, water treatment and supply, environmental management, dams and reservoirs, solid waste, and wind power. We were ranked among the 10 largest firms in numerous other services lines, including engineering/design, environmental science, chemical and soil remediation, site assessment and compliance, and hazardous waste.

              Our approach is to serve our clients by Leading with Science®, which differentiates us in the marketplace, and emphasizes innovation and investment in new and emerging technologies in growing our business. Our reputation for high-end consulting and engineering expertise, and our ability to apply our skills to develop innovative solutions for our clients, has supported our growth for over 50 years. By combining ingenuity and practical experience, we have helped to advance solutions for managing water, protecting the environment, providing energy, and engineering the infrastructure for our cities and communities. Today, we are working on projects worldwide, and currently have more than 16,000 staff, and over 400 offices.

ANNUAL MEETING INFORMATION

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ITEMS BEING VOTED ON AT ANNUAL MEETING

FISCAL 2017 PERFORMANCE HIGHLIGHTS

              Summary.    Tetra Tech's fiscal 2017 operating results reflected a significant improvement compared to fiscal 2016, which was itself a year of strong operational and financial performance, and we achieved record-highs in revenue, operating income, and diluted earnings per share (EPS). Our focus on providing clients with high-end consulting and engineering services, primarily in the water, environment and infrastructure markets, has resulted in increased margins and reduced risk in our business.

              Our fiscal 2017 revenue growth was generally consistent with our annual operating plan, and resulted from broad-based contract wins. The revenue growth was led by our U.S. federal government business, which increased 15% compared to fiscal 2016, and our U.S. state and local government business, which increased 14% compared to the prior year. We began fiscal 2018 with authorized and funded backlog that reached an all-time high in the fourth quarter of fiscal 2017.

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              Highlights of our fiscal 2017 results of operations as reported in our fiscal year 2017 Annual Report on Form 10-K are noted below:

Fiscal 2017 Highlights
($ in millions, except EPS)

              Strong Stock Price Performance.    Our strong annual total stockholder return (TSR) of 32% in fiscal 2017 (September 30, 2016 to September 29, 2017) contributed to our cumulative TSR of 91% for the fiscal 2015 through fiscal 2017 period (September 26, 2014 to September 29, 2017). We compare our TSR to the S&P 1000 and our TSR peer group (listed on p. 52 of this proxy statement), and outperformed both in fiscal 2017 and over the cumulative three-year period. Our three-year percentile vs. our TSR peer group and the S&P 1000 was 89% and 82%, respectively. TSR measures the return that we have provided our stockholders, including stock price appreciation and dividends paid (assuming reinvestment thereof).

One- and Three-Year TSR

              Disciplined Capital Allocation.    Effectively deploying capital is one of our core strategies, and we have been consistently disciplined in our execution of that strategy by returning cash to our stockholders through dividends and stock repurchases, while being a strategic and financially disciplined investor with respect to acquisitions. Over the last three years, we have returned $360 million to stockholders.

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Return of Cash to Stockholders

CORPORATE GOVERNANCE HIGHLIGHTS

              Our corporate governance policies and practices reflect our values, and allow our Board to effectively oversee our company in the interest of creating long-term value. The key elements of our program and the related benefits to our stockholders are set forth below:

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2018 DIRECTOR NOMINEES

              Our Board has overseen the continuing transformation of our company, including our strategic decision to focus on our high-end consulting and engineering business. Further, the Board has overseen the continuation of our capital allocation plan, which included share repurchases of $100 million and cash dividends of $22 million in fiscal 2017. Our Board members have demonstrated their commitment to diligently and effectively executing their fiduciary duties on behalf of our stockholders, and we recommend that each of the following currently serving directors be re-elected at the Annual Meeting.

AC = Audit Committee         CC = Compensation Committee         GC = Nominating and Corporate Governance Committee
SC = Strategic Planning and Enterprise Risk Committee         M = Member         C = Chair         PD = Presiding Director

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EXECUTIVE COMPENSATION HIGHLIGHTS

              Our Board's Compensation Committee designs our executive compensation program to motivate our executives to execute our business strategies and deliver long-term stockholder value. We pay for performance, with compensation dependent on our achieving financial and business performance objectives that advance the interests of our stockholders.

              We value our stockholders' opinions about our governance and compensation practices, and we actively solicit input through our stockholder outreach program. In advance of the 2018 Annual Meeting, we engaged in telephonic, email and/or in-person discussions with stockholders representing more than 50% of our outstanding shares.

              The TDC paid to our executives is comprised of the following three components:

Fiscal 2017 Elements of Annual and Long-Term Compensation

              We structure the TDC of our Named Executive Officers (NEOs) so that it results in payments that approximate the market median, giving consideration to various factors, including: responsibilities, individual performance, tenure, retention, company performance, succession planning and competitive market levels. The majority of this compensation is tied to financial, operational or stock price performance and is therefore "at risk", meaning that if we fail to achieve our financial objectives and create stockholder value, our executives may ultimately not realize some or all of the performance-based

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components of compensation and result in payments below the market median. In fiscal 2017, 82% of our CEO's target TDC, and an average of 64% of our other NEOs' target TDC, was at-risk (all compensation components other than base salary). Further, 67% of our CEO's target TDC, and an average of 54% of our other NEOs' target TDC, was performance-based (AIP award, options and PSUs).

Fiscal 2017 Target Total Direct Compensation Mix*

*

See the Compensation Discussion and Analysis section of this proxy statement for a description of the manner in which these amounts are determined.

Pay for Performance

              Our Compensation Committee designed the executive compensation program to reflect its philosophy that a majority of compensation should be tied to our success in meeting predetermined performance objectives, the achievement of which should positively influence our stock price. The objective is to motivate the executives to achieve these annual and long-term financial goals in order to deliver a consistent and sustainable return to our stockholders. As indicated below, for the period from fiscal 2014 to 2017, our CEO reported compensation increased 20% and, on average, our other NEOs reported compensation increased 27%, compared to the 91% increase in our TSR performance over the same period. See the Compensation Discussion and Analysis and the Summary Compensation Table in this proxy statement for additional information.

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Change in Reported Compensation Compared to Three-Year Cumulative TSR
Fiscal 2014 to Fiscal 2017

Compensation Best Practices

              As summarized below and described in further detail in the Compensation Discussion and Analysis section of this proxy statement, our executive compensation program is aligned with our goals and strategies and reflects best practices.

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APPROVAL OF THE 2018 EQUITY INCENTIVE PLAN

              We last sought shareholder approval of a new equity incentive plan in 2015. We are seeking approval and adoption of the Tetra Tech, Inc. 2018 Equity Incentive Plan (2018 Plan), which provides for the grant of stock options (including non-qualified and incentive stock options, SARs, restricted stock, restricted stock units (RSUs), stock bonus awards, dividend equivalents and performance compensation awards (including, but not limited to, performance stock units (PSUs)). The purpose of the 2018 Plan is to promote the interests of the company and our stockholders by enabling us to offer our employees, directors, consultants and advisors an opportunity to acquire an equity interest in the company so as to better attract, retain, and reward our service providers and, accordingly, to strengthen the mutuality of interests between participants in the 2018 Plan and our stockholders by providing such participants with a proprietary interest in pursuing our long-term growth and financial success. Our Board unanimously determined that the 2018 Plan is in the best interests of our company and its stockholders.

RATIFICATION OF APPOINTMENT OF PWC

              Our Board's Audit Committee has appointed PricewaterhouseCoopers LLP (PwC) as our independent registered public accounting firm for the 2018 fiscal year, and our Board is seeking stockholder ratification of the appointment. PwC is knowledgeable about our operations and accounting practices, and is well qualified to act as our independent registered public accounting firm. The Audit Committee considered the qualifications, performance and independence of PwC, the quality of its discussions with PwC, and the fees charged by PwC for the level and quality of services provided during fiscal 2017, and has determined that the reappointment of PwC is in the best interest of our company and its stockholders.

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PROXY STATEMENT FOR TETRA TECH, INC.
2018 ANNUAL MEETING OF STOCKHOLDERS

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              Our mission is to be the premier worldwide consulting and engineering firm, focusing on water, environment, infrastructure, resource management, energy and international development services. We are renowned for our expertise in providing water-related solutions for public and private clients. We typically begin at the earliest stage of a project by identifying technical solutions and developing execution plans tailored to our clients' needs and resources. Our solutions may span the entire life cycle of consulting and engineering projects.

              Our reputation for high-end consulting and engineering expertise and our ability to apply our skills to develop innovative solutions for our clients has supported our growth over 50 years. By combining ingenuity and practical experience, we have helped to advance solutions for managing water, protecting the environment, providing energy, and engineering the infrastructure for our cities and communities.

CORPORATE GOVERNANCE

              Under the oversight of our Board of Directors, we have designed our corporate governance program to ensure continued compliance with applicable laws and regulations, the rules of the Securities and Exchange Commission (SEC) and the listing standards of the Nasdaq Stock Market (Nasdaq), and to reflect best practices as informed by the recommendations of our outside advisors, the voting guidelines of our stockholders, the policies of proxy advisory firms, and the policies of other public companies.

              We are committed to operating with honesty and integrity, and maintaining the highest level of ethical conduct. We encourage stockholders to visit the Corporate Governance section of our website, which includes the following corporate governance documents:

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Code of Business Conduct;



•

Finance Code of Professional Conduct, which applies to our CEO and all members of our finance department, including our chief financial officer and principal accounting officer;



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Corporate Governance Policies;



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Charters for our Board's Audit Committee, Compensation Committee, NCG Committee, and Strategic Planning and Enterprise Risk Committee; and



•

Stock Ownership Guidelines.

              You can access these documents by going to our website at www.tetratech.com/en/corporate-governance, but should note that information on our website is not and should not be considered part of, nor is it incorporated by reference into, this proxy statement. You can also receive copies of these documents, without charge, by written request mailed to our Corporate Secretary at Tetra Tech, Inc., 3475 E. Foothill Boulevard, Pasadena, California 91107.

              We maintain a hotline that is available to all employees for the anonymous submission of employee complaints. All complaints go directly to our General Counsel, and all complaints relating to accounting, internal controls or auditing matters also go directly to the Chairman of our Audit Committee. We also maintain an internal audit control function that provides critical oversight over the key areas of our business and financial processes and controls, and reports directly to the Audit Committee. Our Board

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has also adopted a written related person transactions policy. Under the policy, the Audit Committee (or other committee designated by the NCG Committee) reviews transactions between us and "related persons."

              Our company conducts its business on the bases of the quality of its services and the integrity of its association with its clients and others. Our Code of Conduct demonstrates our commitment to ascribe to the highest standards of ethical conduct in the pursuit of our business, and applies to all of our directors, officers and employees. It has been translated into five languages, and our employees are trained on it and affirm their commitment to comply with it when they first join our company and periodically thereafter.

SUSTAINABILITY

              Tetra Tech supports clients in more than 100 countries around the world, helping them to solve complex problems and achieve solutions that are technically, socially and economically sustainable. Our high-end consulting and engineering services focus on using innovative technologies and creative solutions to minimize environmental impacts. Our greatest contribution toward sustainability is through the projects we perform every day for our clients. Sustainability is embedded in our projects – from recycling freshwater supplies to recycling water products, reducing energy consumption, and reducing greenhouse gas emissions in developing countries.

              Our Sustainability Program focuses on supporting our mission to be a premier provider of consulting and engineering services focused on water, natural resources, environment, infrastructure, energy, and international development. We seek to achieve this mission by adopting a sustainability goal of "embracing sustainability in our business and operations while supporting the company in delivering excellent services to our clients, maintaining superior financial performance, and emphasizing safety in the execution of services."

              Our Sustainability Program allows us to further expand our commitment to sustainability by encouraging, coordinating and reporting on actions to minimize our collective impacts on the environment. The Program has three primary pillars: Projects – the solutions we provide for our clients; Procurement – our procurement and subcontracting approaches; and Processes – the internal policies and processes that promote sustainable practices, reduce costs and minimize environmental impacts. In addition, our program is based on the Global Reporting Initiative (GRI) Sustainability Report Framework, the internationally predominant sustainability reporting protocol for corporate sustainability plans. The GRI includes three fundamental impact areas: environmental, economic, and social sustainability.

              Our Sustainability Program is led by our Chief Sustainability Officer, who has been appointed by executive management and is supported by other key corporate and operations representatives via our Sustainability Council. We have established specific metrics for the company and six corporate service departments. In addition to measuring our performance against these established metrics, we compile best practices from our operations and corporate service groups by means of a quarterly sustainability survey. This survey is used to identify sustainable practices that can be introduced across the company. We compile best practices from our operations and corporate service groups by means of a sustainability survey. This survey is used to identify sustainable practices that can be transferred enterprise-wide and used to assess participation in our Sustainability Program.

              Our executive management team reviews and approves the Sustainability Program and evaluates our progress in achieving the goals and objectives outlined in our plan. Additional information on our Sustainability Program and our annual sustainability report that documents our progress may be found on our website at http://www.tetratech.com/en/sustainability.

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CORPORATE SOCIAL RESPONSIBILITY

              Our company seeks clear, sustainable solutions that improve the quality of life. We take this responsibility seriously because our work often places us at the center of our clients' environmental, safety and sustainability challenges. These challenges often involve the opinions of public, industry and government stakeholders who seek our advice on complex issues. We have helped thousands of towns, cities, industries and governments find sustainable solutions to complex issues concerning resource management and infrastructure.

              To provide solutions to these challenges, we believe in maintaining our technical objectivity. We have earned our reputation for technical objectivity over more than five decades. We have designed progressive, green buildings in New York City, helped the U.S. Department of Defense with pollution prevention and clean-up, and helped many Fortune 500 companies balance environmental needs with business goals. We are helping Vancouver achieve its goal of becoming the greenest city in the world. Tetra Tech companies hold memberships with the U.S. Green Building Council and the Chicago Climate Exchange.

              We also encourage our professionals to participate in outreach programs to help improve the communities in which they live and work. Tetra Tech associates and offices around the globe participate in many financial, in-kind, volunteer, and pro bono activities each year. In 2016, we advanced our commitment to Leading with Science® by launching our Science, Technology, Engineering, and Mathematics (STEM) Program to help shape the next generation of innovators and problem solvers. As a sponsor of the nonprofit humanitarian organization Engineers Without Borders USA and Engineers Without Borders Canada, we are committed to helping communities in developing countries meet their basic human needs through lasting, scalable projects and technologies.

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OVERVIEW

              Our Board of Directors is responsible for overseeing, counseling and directing management in serving the long-term interests of our company and stockholders, with the goal of building long-term stockholder value and ensuring the strength of our company for our clients, employees and other stakeholders. In this capacity, the Board's primary responsibilities include establishing an effective corporate governance program, with a Board and Committee structure that ensures independent oversight; overseeing our business, strategies and risks; maintaining the integrity of our financial statements; evaluating the performance of our senior executives and determining their compensation; undertaking succession planning for our CEO and other senior executives; and reviewing our annual operating plan and significant strategic and operational objectives and actions.

BOARD COMPOSITION

              Our bylaws provide that our Board consist of between five and ten directors, with the exact number fixed from time to time by Board resolution. The Board has fixed the number at nine. We believe a limited number of directors helps maintain personal and group accountability. Our Board is independent in composition and outlook, other than our CEO. All of our current directors have been nominated for election by the Board of Directors upon recommendation by the NCG Committee and have decided to stand for election.

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BOARD MEETINGS AND ATTENDANCE

              During fiscal 2017, our Board of Directors held eight meetings. During this period, all of the incumbent directors attended or participated in 100% of the aggregate of the total number of meetings of the Board and the total number of meetings held by all committees of the Board on which each such director served, during the period for which each such director served. Our directors are strongly encouraged to attend the annual meeting of stockholders, and all of our directors then in office attended last year's annual meeting.

CORPORATE GOVERNANCE POLICIES

              Our Corporate Governance Policies, as updated in July 2017, provide the corporate governance framework for our company and reflect the beliefs of our Board with respect to the matters described below. They are reviewed at least annually and amended from time to time to reflect changes in regulatory requirements, evolving market practices, and recommendations from our stockholders and advisors.

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DIRECTOR INDEPENDENCE

              Upon recommendation of the NCG Committee, our Board of Directors has determined that each member of the Board of Directors other than Mr. Batrack is independent under the criteria established by Nasdaq for director independence. Mr. Batrack is not independent because he is an employee.

              In connection with the assessment of Mr. Thompson's independence, we reviewed the facts and circumstances of his role as an independent director of Coeur Mining, Inc. and Pioneer Natural Resources Company, two of our clients, and Alaska Air Group, Inc., one of our vendors. We concluded that Mr. Thompson is an independent director because his role at each of these companies is limited to that of an independent director, each of the companies is a large public company, and the amount of business done with each of the companies is immaterial to us (less than 1% of our fiscal 2017 net revenue) and each such company.

              All members of each of our Audit, Compensation, NCG, and Strategic Planning and Enterprise Risk committees are independent directors. In addition, the members of the Audit Committee meet the additional independence criteria required for audit committee membership under applicable Nasdaq listing standards, and each has been determined by our Board to be an "audit committee financial expert" under SEC rules.

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              There were no payments by third parties to any of our directors or director nominees in connection with their candidacy for, and/or service on, our Board of Directors.

BOARD LEADERSHIP STRUCTURE

              We currently have a combined Chairman/CEO role, as well as an independent Presiding Director. We believe that the combined Chairman/CEO role is appropriate because it allows for one individual to lead our company with a cohesive vision, the ability to execute that vision, and the understanding of the significant enterprise risks that need to be mitigated or overcome to achieve that vision. It also fosters clear accountability, effective decision-making and alignment on corporate strategy. Combined leadership at the top also provides the necessary flexibility for us to rapidly address the changing needs of our business.

              Balancing our combined Chairman/CEO is our Presiding Director, elected by and from the independent directors, who has critical duties in the boardroom to ensure effective and independent oversight of Board decision-making. In November 2015, the Board determined that the role of Presiding Director would rotate to ensure independence, and the term would be four years. At a meeting in January 2016, the independent directors elected Mr. Smith to serve as Presiding Director for a four-year term ending in January 2020.

              Our Governance Policies describe the Presiding Director's duties, which delineate clear responsibilities to ensure independent stewardship of our Board, as summarized below.

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              Supplementing the Presiding Director are our Committee Chairs and members, all of whom are independent. With the Compensation Committee conducting a rigorous annual evaluation of the CEO's performance that is discussed by all independent directors during executive sessions, we believe our Board leadership structure provides independent oversight of our company.

BOARD COMMITTEES

              Each of our Board committees has a written charter that describes its purposes, membership, meeting structure, authority and responsibilities. These charters, which may be found in the Corporate Governance section of our website at www.tetratech.com/en/corporate-governance, are reviewed by the respective committee on an annual basis, with any recommended changes adopted upon approval by our Board. Updated charters are promptly posted on our website.

              We have four standing committees consisting solely of independent directors, each with a different independent director serving as chairperson of the committee. Our Board committees are: the Audit Committee, the Compensation Committee, the NCG Committee, and the Strategic Planning and Enterprise Risk Committee. We hold our Board committee meetings sequentially (i.e., committee meetings do not overlap with one another). As a result of holding sequential meetings, each of our Board members is given the opportunity to attend each committee meeting. We believe this practice is highly beneficial to our Board as a whole and the company in general because each of our Board members is aware of the detailed work conducted by each Board committee. This practice also affords each of our Board members the opportunity to provide input to the committee members before any conclusions are reached.

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              The primary responsibilities, membership and meeting information for our four standing committees are summarized below.

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EXECUTIVE SESSIONS

              Our Board believes it is important to have executive sessions without our CEO being present, which are scheduled after every regular meeting of the Board. Our independent directors have robust and candid discussions at these executive sessions during which they can critically evaluate the performance of our company, CEO and management.

              In addition, executive sessions of the Audit Committee are scheduled following each regular meeting of the Audit Committee (with our independent auditors, with the head of our Management Audit Department, and with executive management, if deemed necessary), and an executive session of the Compensation Committee is scheduled following the Compensation Committee meeting each November at which executive compensation determinations are made.

RISK OVERSIGHT

Enterprise Risk Management (ERM) and Strategic Risks

              We believe that risk is inherent in the pursuit of long-term growth opportunities. Our management is responsible for day-to-day risk management activities. The Board of Directors, acting directly and through its committees, is responsible for the oversight of our risk management. With this oversight, we have implemented an ERM program with practices and policies designed to help manage the risks to which we are exposed in our business and to align risk-taking appropriately with our efforts to increase stockholder value.

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              The Strategic Planning and Enterprise Risk Committee is responsible for the oversight of the ERM. Our Corporate Risk Management Officer reports the status of the ERM to this committee on a semi-annual basis. The reports address our risk management effectiveness, those projects that may significantly impact our financial condition, and any new risk issues and mitigation measures that have been implemented.

              As part of the overall risk oversight framework, other committees of the Board also oversee certain categories of risk associated with their respective areas of responsibility to better coordinate with management and serve the long-term interests of our stockholders. Our Board receives reports from the committees regarding topics discussed at the committee meetings, which include the areas of risk overseen primarily by the committees.

              In addition, the Board participates in regular discussions among the directors and with our senior management with respect to several core subjects in which risk oversight is an inherent element, including strategy, operations, finance, mergers and acquisitions, and legal matters. The Board believes that the leadership structure described above under "Board Leadership Structure" facilitates the Board's oversight of risk management because it allows the Board, with leadership from the Presiding Director and working through its committees, to participate actively in the oversight of management's actions.

OVERSIGHT OF RISK

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Risks Associated with Compensation Policies and Practices

              As described in the Compensation Discussion and Analysis section of this proxy statement, we maintain best practices in compensation and corporate governance that collectively encourage ongoing risk assessment and mitigation. The Compensation Committee periodically reviews our executive compensation program to ensure that it does not provide incentives that encourage our employees to take excessive risks in managing their respective businesses or functional areas. Our compensation program includes the following safeguards:

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the program balances executive retention with rewarding stockholder value creation;



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the majority of executive compensation is variable, with a mix that is consistent with market practices and primarily equity-based to promote long-term performance and sustainable growth;



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the incentive mix is balanced, with short- and long-term performance metrics that do not overlap, cover different time periods and are balanced among annual financial objectives and long-term economic and stockholder value creation;



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our AIP and LTIs appropriately balance profitable growth in the near term with sustainable long-term financial success, use multiple performance metrics, measure performance at multiple levels (corporate, business group and individual), and provide realized compensation based primarily on our performance;



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the Compensation Committee may exercise downward discretion to adjust the objective, formulaic AIP awards, based on individual performance;



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AIP awards are not guaranteed, with below threshold performance yielding zero payout, and payments subject to an overall cap of 200% of an executive's target AIP award;



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our incentive metrics and performance goals have multiple approval levels and oversight, including approval by members of the Compensation Committee;



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our PSU awards are performance-based, use multiple performance metrics, are subject to maximum payout opportunities to encourage appropriate performance focus and limit potential risk-taking, and cliff vest at the end of three years;



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our change of control plans are reasonable and appropriate, with change of control benefits provided on a double-trigger basis, and these benefits do not provide excessive incentive to seek a transaction and are not grossed up for excise taxes;



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our clawback policy and stock ownership guidelines are consistent with market practices; and



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our stock ownership guidelines, annual stock awards and vesting provisions create sustained and consistent ownership stakes.

              Based on these and other factors, as well as the advice of its independent compensation consultant, the Compensation Committee has concluded that our compensation policies and practices strike an appropriate compensation-risk balance, do not encourage excessive risk-taking and do not as a whole create risks that are reasonably likely to have a material adverse effect on our company.

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SUCCESSION PLANNING

              Our Board is involved in the identification and cultivation of our future leaders. We maintain an annual performance review process and leadership development program for our key employees. Management develops leadership at lower levels of our organization by identifying core talent, cultivating the skills and capabilities that will allow identified individuals to become our future leaders, assessing their development, and identifying gaps and developmental needs in skills and experience. At its meetings, the Board has the opportunity to meet with leaders of our company, including business group leaders and leaders in finance, law, information technology, risk management and human resources. In addition, Board members have freedom of access to key employees.

              The NCG Committee conducts executive succession planning annually, including progress in current job position and career development in terms of strategy, leadership and execution. During this review, the CEO and the independent directors discuss future candidates for senior leadership positions, succession timing for those positions, and development plans for the highest-potential candidates. This process ensures continuity of leadership over the long term, and it forms the basis on which we make ongoing leadership assignments.

BOARD AND COMMITTEE EVALUATIONS

              The NCG Committee oversees and conducts an annual evaluation of our Board and Board committees. For the Board, the comprehensive self-assessment covers areas such as effectiveness, composition, culture, resources and meetings. Each of the 35 topics within these areas is scored from 1 (Needs Improvement) to 5 (Role Model), with 3 being Acceptable. The Board then discusses each topic that has received a score from any director of 3 or less.

              The directors also comment on the Board's most significant contribution to the company during the last 12 months, the most important issues the Board should address in the next 12 months, and the areas in which the company could improve its Board management practices. These comments result in action items that are placed on the agenda and addressed in subsequent Board meetings.

              For each of the Committees, the self-assessment covers areas such as Committee composition, effectiveness, structure, information and resources, and meetings. As with the Board self-assessment, each of the topics within these areas is scored from 1 to 5. The members of the Committee also comment on the Committee's greatest contribution to the company during the last 12 months and the most important issues the Committee should address in the next 12 months. The Chair of each Committee then leads a discussion among the Committee members of each topic that has received a score from any Committee member of 3 or less, and of the general comments. The responses result in action items that are placed on the agenda and addressed in subsequent Committee meetings.

              Many of the improvements in our corporate governance practices, and Board and Committee processes, have resulted from the annual evaluation process. Our Board views the annual evaluation process as an integral part of its commitment to cultivating excellence and best practices in its performance.

ACTIVE STOCKHOLDER ENGAGEMENT AND COMMUNICATIONS POLICY

Governance Engagement

              We value our stockholders' opinions about our governance policies and practices, and we actively solicit input through our stockholder engagement program. In advance of the 2018 Annual

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Meeting, we proactively contacted our largest institutional stockholders, representing a majority of our then-outstanding shares, to solicit their views on our corporate governance and executive compensation programs. We welcome feedback on our corporate governance program that this active and ongoing engagement with stockholders provides.

Contacting the Board

              Stockholders may contact our Board, Chairman, Presiding Director, any Committee or Committee Chair, or any other individual director concerning business-related matters by writing to: Board of Directors (or a particular subgroup or individual director), c/o Corporate Secretary, Tetra Tech, Inc., 3475 E. Foothill Boulevard, Pasadena, California 91107; or via email to asktheboard@tetratech.com.

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              Our bylaws provide for a Board of between five and ten directors, with the exact number fixed from time to time by a resolution of our Board. The Board has fixed the number at nine, and there are currently nine directors on our Board. All of the incumbent directors are nominated for election at the Annual Meeting for a one-year term. Each of the nine nominees has consented to being named in this proxy statement and to continue serving if elected.

MAJORITY VOTING STANDARD

              Our bylaws provide for the majority voting of directors in uncontested elections like this one. Consequently, in order to be elected, a nominee must receive more votes "for" than "against" and the number of votes "for" must be at least a majority of the required quorum. Should any of the nominees fail to receive the vote required to be elected in accordance with our bylaws, that director must promptly tender his or her resignation to the Board of Directors. In that event, the NCG Committee will make a recommendation to the Board as to whether to accept or reject the tendered resignation, or whether other action should be taken. The Board will then act on the tendered resignation, taking into account the NCG Committee's recommendation, and publicly disclose its decision regarding the tendered resignation and the rationale behind the decision within ninety (90) days from the date of the certification of the election results.

              In voting for the election of directors, each share has one vote for each position to be filled and there is no cumulative voting.

RECOMMENDATION OF BOARD OF DIRECTORS

              Our Board of Directors recommends that you vote FOR each of the director nominees.    The persons named as proxies will vote for the election of each of the nine nominees unless you specify otherwise. If any director nominee were to become unavailable prior to the Annual Meeting, your proxy would be voted for a substitute nominee designated by our Board or we would reduce the size of the Board.

SELECTION OF DIRECTOR NOMINEES

              Director nominees are generally recommended by the NCG Committee for nomination by our Board and subsequent election by our stockholders. Director nominees may also be recommended by the NCG Committee for appointment to our Board, with election by stockholders to follow at the next Annual Meeting. Our Board believes that the backgrounds and qualifications of our directors, considered as a group, provide a mix of complementary experience, knowledge and abilities that allows our directors to effectively fulfill their oversight responsibilities.

              In considering whether to recommend a candidate as a director nominee, the NCG Committee applies the criteria described in our Governance Policies, including independence, integrity, unwavering personal and professional ethics, sound business judgment, integrity, and the ability and willingness to commit sufficient time to the Board. In evaluating the suitability of individual Board members, the NCG Committee takes into account many factors, including a general understanding of business development and strategy, risk management, finance, financial reporting, and other disciplines relevant to the success of a publicly-traded company in the then-current business environment; understanding of our business and the issues affecting that business; relevant education and professional background; personal

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accomplishment; and diversity. The NCG Committee does not assign specific weights to the criteria, and no particular criterion is necessarily applicable to all nominees.

              In recommending candidates for election to the Board of Directors, the NCG Committee considers nominees recommended by directors, officers and others, using the same criteria to evaluate all candidates. The Committee reviews each candidate's qualifications, including whether a candidate possesses any of the specific qualities and skills desirable in certain members of the Board of Directors. Evaluations of candidates generally involve a review of background materials, internal discussions and interviews with selected candidates as appropriate. Upon selection of a qualified candidate, the NCG Committee recommends the candidate for consideration by the full Board. The Committee may engage consultants or third-party search firms to assist in identifying and evaluating potential nominees.

STOCKHOLDER SUBMISSION OF DIRECTOR NOMINEES

              Stockholders may recommend director candidates by submitting the candidate's name, together with his or her biographical information, professional experience and written consent to nomination, to NCG Committee Chair, c/o Corporate Secretary, Tetra Tech, Inc., 3475 E. Foothill Boulevard, Pasadena, California 91107. To be considered at the 2019 Annual Meeting, stockholder nominations must comply with the requirements described in the Meeting and Voting Information section of this proxy statement under "Submission of Stockholder Items for 2019 Annual Meeting." The NCG Committee considers stockholder nominees on the same basis as it considers all other nominees.

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DIRECTOR QUALIFICATIONS

              The qualifications that are particularly desirable for our directors to possess to provide oversight and stewardship of our company include the following:

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              The graph below shows the qualifications of our director nominees:

BOARD REFRESHMENT

              Our Governance Policies reflect our belief that directors should not be subject to term limits. While term limits could facilitate fresh ideas and viewpoints being consistently brought to the Board, we believe they are counter-balanced by the disadvantage of causing the loss of a director who over a period of time has developed insight into our strategies, operations and risks, and continues to provide valuable contributions to Board deliberations. We believe that our decision not to establish term limits is consistent with the prevailing practice among companies in the S&P 1000. We recognize that certain governance stakeholders have suggested that longer-serving directors may have decreased independence and objectivity; however, we believe that an arbitrary decision to remove knowledgeable directors and the consistent oversight they bring weighs against strict restrictions on director tenure. Ultimately, it is our Board's responsibility to establish board refreshment policies, using its discretion in the best interest of our company and stockholders.

              We have adopted the policies shown below to facilitate refreshment of our Board and ensure that it continues to appropriately challenge our management.

POLICIES SUPPORTING BOARD REFRESHMENT

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              The graph below shows the tenure of our director nominees:

DIRECTOR DIVERSITY

              As provided in our Governance Policies, we are committed to considering candidates for the Board regardless of gender, ethnicity and national origin. While diversity is a consideration, nominees are not chosen or excluded solely or primarily based on such basis. Rather, the NCG Committee focuses on skills, expertise and background to complement the existing Board in light of the diverse and global nature of our businesses and operations. The two independent directors appointed to our Board in 2013, and the independent director appointed in 2016, are women.

2018 DIRECTOR NOMINEES

              The following pages provide information on each nominee for election at the Annual Meeting, including his or her age, board leadership roles held, and business experience during at least the past five years. We also indicate the name of any other public company for which each nominee currently serves as a director. For these purposes, "public company" means one that is required to file reports with the SEC.

              Presented below is information regarding each nominee's experience and qualifications that led our Board to the conclusion that he or she should serve as a director. We believe that each of these nominees has integrity and adheres to our high ethical standards. In addition, each nominee has demonstrated the ability to exercise sound judgment, as well as a commitment to serving the long-term interests of our stockholders.

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Chairman Emeritus

              Dr. Li-San Hwang has served as our Chairman Emeritus since March 2006. As Chairman Emeritus, Dr. Hwang is invited to attend Board and Board committee meetings, but he does not have voting rights. Chairman Emeritus is an unpaid position; however, we reimburse Dr. Hwang for his attendance-related expenses. Dr. Hwang joined our predecessor in 1967 and led our acquisition of the Water Management Group of Tetra Tech, Inc. from Honeywell Inc. in March 1988. He served as our Chief Executive Officer from our formation until November 2005. Dr. Hwang has served as an advisor to numerous government and professional society committees and has published extensively in the field of hydrodynamics. He is a graduate of the National Taiwan University, Michigan State University and the California Institute of Technology, holding B.S., M.S. and Ph.D. degrees, respectively, in Civil Engineering, specializing in water resources.

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DIRECTOR COMPENSATION

              The NCG Committee works with the independent compensation consultant to target non-employee director compensation at the median of our peer companies to support the recruitment and retention of our non-employee directors. The majority of this compensation is delivered in equity to align director interests with those of our stockholders.

Fiscal 2017 Cash Compensation

              During fiscal 2017, our non-employee director cash compensation program consisted of the following:

ANNUAL NON-EMPLOYEE DIRECTOR CASH COMPENSATION