10-K

QuickLinks -- Click here to rapidly navigate through this document

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 10-K

(Mark One)

/x/	Annual report pursuant to section 13 or 15(d) of the Securities Exchange Act of 1934 for the fiscal year ended September 30, 2001.
/ /	Transition report pursuant to section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from                to               .

Commission file number 0-19655

TETRA TECH, INC.
(Exact name of registrant as specified in its charter)

Delaware (State or other jurisdiction of incorporation or organization)	95-4148514 (I.R.S. Employer Identification No.)
670 N. Rosemead Blvd. Pasadena, California (Address of principal executive offices)	91107 (Zip Code)
(Registrant's telephone number, including area code)	(626) 351-4664
Securities registered pursuant to Section 12(b) of the Act:
(Title of each class) None	(Name of each exchange on which registered) None

Securities registered pursuant to Section 12(g) of the Act:

(Title of Class)
Common Stock, $.01 par value

    Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes /x/ No / /

    Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. / /

    The aggregate market value of the voting stock held by non-affiliates of the registrant on December 11, 2001 was $941,155,063.

    The number of shares of Common Stock, $.01 par value, outstanding (the only class of common stock of the registrant outstanding) was 52,381,602 on December 11, 2001.

    Portions of registrant's Annual Report to Stockholders for the fiscal year ended September 30, 2001 are incorporated by reference in Part II of this report. Portions of registrant's Proxy Statement for its 2002 Annual Meeting of Stockholders are incorporated by reference in Part III of this report.

PART I

Item 1.  Business.

    Tetra Tech, Inc. is a leading provider of specialized management consulting and technical services in three principal business areas: resource management, infrastructure and communications. As a specialized management consultant, we assist our clients in defining problems and developing innovative and cost-effective solutions. Our management consulting services are complemented by our technical services. These technical services, which implement solutions, include research and development, applied science, engineering and architectural design, construction management, and operations and maintenance. Our clients include a diverse base of public and private organizations located in the United States and internationally.

    Since our initial public offering in December 1991, we have increased the size and scope of our business and have expanded our service offerings through a series of strategic acquisitions and internal growth. As of the end of our last fiscal year, we had more than 7,400 employees worldwide, primarily located in North America in more than 300 locations. In addition, we have established a presence in Asia, South America and Europe.

Industry Overview

    Due to increased competition, changing regulatory environments and rapid technological advancement, many organizations face new and complex challenges. Increasingly, these organizations are turning to professional services firms to assist them with addressing these challenges. Since each industry presents its own unique set of challenges, organizations often seek professional service firms with industry-specific expertise to analyze their problems and develop appropriate solutions. These solutions are then implemented by firms possessing the required engineering and technical service capabilities. Each of the following three business areas faces its own unique set of problems:

    Resource Management.  The world's natural resources, including water, air and soil, are interdependent, creating a delicate balance. Factors such as agricultural and residential development, commercial construction and industrialization often upset this balance. Public concern over environmental issues, especially water quality and availability, has been a driving force behind numerous laws and regulations that are designed to prevent environmental degradation and mandate restorative measures. To comply with environmental laws and regulations, respond to public pressure and attain operating efficiencies, public and private organizations are increasing their focus on resource management. Two areas particularly affected by these trends are water management and waste management.

•

Water Management. Insufficient water supplies, concern over the cost, quality and availability of water and the need in many parts of the world to replace aging infrastructure used to capture, safeguard and distribute water are critical social and economic concerns. According to the U.S. Environmental Protection Agency (EPA), contamination of groundwater and surface water resulting from agricultural, residential, commercial and industrial development is one of the most serious environmental problems facing the United States. To alleviate these social and economic concerns, public and private organizations seek water management advice.



•

Waste Management. In the past, many waste disposal practices caused significant environmental damage. Since the 1970s, more stringent controls on municipal and industrial waste have been established by governments around the world to protect the environment. Organizations seek waste management advice to comply with complex and evolving environmental regulations, to minimize the economic impact of waste generation and disposal, and to realize significant cost savings through increased operating efficiencies.

2

    Infrastructure.  Continued population and economic growth place significant strain on an overburdened infrastructure, thereby requiring additional development. This development includes water and wastewater treatment plants, roads, pipelines, communication and power networks, and educational, recreational and correctional facilities. Additionally, as existing facilities age, they require upgrading or replacement. Further, the trend toward privatization of infrastructure is causing public and private organizations that develop and maintain these facilities to evaluate their cost structures and establish more efficient systems. These factors drive the need for development and planning services that are often provided by consulting firms.

    Communications.  Technological change and government deregulation have spurred sweeping changes in the communications industry. Local and long-distance telephone companies, cable operators and wireless service providers are penetrating each other's markets and trying to establish a foothold in new markets created by new technologies. For example, traditional cable operators are installing advanced capabilities such as digital cable, cable modem, cable telephony and other high-speed data transmission services at the same time as wireless communications providers are seeking access to the Internet. At the same time, various service providers are consolidating in order to offer their subscribers a comprehensive set of services and to maintain dominance in their markets. As these trends continue, network service providers will increasingly turn to professional service firms for advice and assistance in planning, deploying and maintaining their communications networks.

    Increased pricing competition is forcing service providers to outsource their network development activities, which we provide. In addition, organizations within each of the above business areas face unique problems but often lack the internal resources and experience necessary to identify issues and evaluate possible solutions. As a result, many of these organizations rely on advice from outside management consultants. Most consulting companies provide limited front-end problem assessment and solution design and require clients to engage other engineering and technical services companies to implement recommended solutions. A significant opportunity exists for consulting companies that not only develop, but also implement, solutions. These professional service firms are often in the best position to help clients respond to the challenges they face.

The Tetra Tech Solution

    Tetra Tech provides the specialized management consulting services that assist clients in identifying industry-specific problems and defining appropriate solutions. We also provide the technical services required to implement these solutions. We believe that we are a leader in this market and that the following factors distinguish us from our competitors:

    Understanding Client Needs.  The ability to identify client needs is essential to strategic planning and execution. Even before the proposal process begins, we assist our clients by helping them define their business objectives and strategies and identify issues that are critical to their success. We strive to develop numerous contacts at various levels within our clients' organizations to help us identify the key issues from a variety of perspectives. We believe that our long history and exposure to a broad client base increase our awareness of the issues being confronted by organizations and thereby help us identify and solve our clients' problems.

    Capitalizing on Our Extensive Technical Experience.  Since our inception in 1966, we have provided innovative consulting and engineering services, historically focusing on cost-effective solutions to water resource management and environmental problems. We have been successful in leveraging this foundation of scientific and engineering capabilities into other areas, including infrastructure and communications. Our services are provided by a wide range of professionals including: archaeologists, biologists, chemical engineers, chemists, civil engineers, computer scientists, economists, electrical engineers, environmental engineers, environmental scientists, geologists, hydrogeologists, mechanical engineers, oceanographers and toxicologists. Because of the experience that we have gained from

3

thousands of completed projects, we often are able to apply proven solutions to client problems without the time-consuming process of developing new approaches.

    Offering a Full Range of Services.  Our depth of consulting and technical skills allows us to respond to client needs at every phase of a project, including initial planning, research and development, applied science, engineering and architectural design, and construction management. Once a particular project is completed, we are able to offer our clients additional value-added services such as operations and maintenance. Our expertise across industries and our broad service offerings enable us to be a single source provider to our clients.

    Providing Broad Geographic Coverage and Local Expertise.  We believe that proximity to our clients is instrumental to understanding their needs and delivering comprehensive services. We have significantly broadened our geographic presence in recent years through strategic acquisitions and internal growth. Our historical geographic base was primarily in the western portion of the United States. However, we currently have operations in more than 40 states. We have also increased our international presence, and we now have operations in Canada, Taiwan, Japan, India, Spain, Switzerland, Poland, the Czech Republic, the Philippines, Argentina, Chile, Brazil, Germany, France and Puerto Rico.

Company Strategy

    Our objective is to become the leading provider of specialized management consulting and technical services in our chosen business areas. To achieve this objective, we plan to continue the following primary strategies that we believe have been integral to our success:

    Identify and Expand Into New Business Areas.  We use our management consulting services and certain of our technical services as an entry point to evaluate and to enter new business areas. After our consulting practice is established in a new business area, we can expand our operations by offering additional technical services. For example, based on our provision of site acquisition services to communications industry participants, we identified infrastructure services within the communications industry as an appropriate area into which we could expand our operations.

    Expand Service Offerings and Geographic Presence Through Acquisitions.  We believe that acquisition opportunities exist that will allow us to continue our growth in selected business areas, broaden our service offerings and extend our geographic presence. We intend to make acquisitions that will enable us to consolidate our position in certain key business areas, such as communications, or further strengthen our position in our more established service offerings. We believe that our reputation and public company status make us an attractive partner and provide us with an advantage in pursuing acquisitions.

    Focus on Government Projects.  We intend to continue marketing to government organizations and bidding for government projects to stay on the leading edge of policy development. This experience helps us identify market opportunities and enhances our ability to serve other public and private clients. Additionally, government contracts provide more predictable revenues than private sector contracts.

    Manage Internal Financial Controls.  We take a disciplined approach to monitoring, managing and improving our return on investment in each of our business areas through the prompt billing and collection of accounts receivables, the negotiation of favorable contract terms and the management of our contract performance to prevent cost overruns. We believe that this approach to managing our financial affairs enables us to improve our cash position and thereby fund acquisitions and internal growth.

    Leverage Existing Client Base.  Some of our clients engage us to provide limited services. We believe that we can increase our revenue by selling additional services to our existing client base. For

4

example, we may be able to secure an operations and maintenance contract after working with a client on the design and construction phases of a facility. In addition, we believe that our ability to offer a full spectrum of services will allow us to grow our business and compete more effectively for larger projects.

Services

    We provide our clients with management consulting and technical services that focus on our clients' industry-specific needs. We offer these services individually or as part of our full service approach to problem solving. We are currently performing services under contracts ranging from small site investigations to large, complex infrastructure projects. Our service offerings include:

•

Management consulting to assist clients in identifying and addressing operational and competitive problems they face within their industries;



•

Research and development to formulate solutions to complex problems and develop advanced computer simulation techniques for modeling problems, ranging from microscopic to global;



•

Applied science to assess all aspects of problems and develop practical and cost-effective solutions through the application of new technology and data interpretation;



•

Engineering and architectural design to provide services from concept development and initial planning and design through project completion;



•

Contract management to provide experienced and specialized construction managers to assist clients in minimizing the risk of cost overruns, delays and contractual conflicts; and



•

Operations and maintenance to allow clients to outsource routine functions, permitting them to streamline contractor relationships and reduce operating costs.

Business Areas

    We provide our services in the following three principal business areas: resource management, infrastructure and communications.

Resource Management

    One of our major concentrations is water resource management, where we have a leadership position in understanding the interrelationships of water quality and human activities. We support high priority government programs for water quality improvement, environmental restoration, productive reuse of defense facilities and strategic environmental resource planning. We provide comprehensive services, including management consulting, research and development, applied science, engineering and architectural design, construction management, and operations and maintenance. Our service offerings in the resource management business area are focused on the following project areas:

    Surface Water Projects:  Public concern with the quality of rivers, lakes and streams, as well as coastal and marine waters and the ensuing legislative and regulatory response, are driving demand for our services. Over the past 34 years, we have developed a specialized set of technical skills that positions us to compete effectively for surface water and watershed management projects. We provide water resource services to government clients such as the EPA, the Department of Defense (DOD) and the Department of Energy (DOE), and to a broad base of private sector clients including those in the chemical, pharmaceutical, utility, aerospace and petroleum industries. We also provide surface water services to state and local agencies, particularly in the area of watershed management.

5

    Groundwater Projects:  Groundwater is the source of drinking water for approximately 50% of the U.S. population and accounts for approximately 25% of all water consumed for residential, industrial and agricultural purposes. Our activities in the groundwater field are diverse and typically include projects such as investigating and identifying sources of chemical contamination, examining the extent of contamination, analyzing the speed and direction of contamination migration, and designing and evaluating remedial alternatives. In addition, we conduct monitoring studies to assess the effectiveness of groundwater treatment and extraction wells.

    Waste Management Projects:  We currently provide a wide range of engineering and consulting services for hazardous waste contamination and remediation projects, from initial site assessment through design and implementation phases of remedial solutions. In addition, we perform risk assessments to determine the probability of adverse health effects that may result from exposure to toxic substances. We also provide waste minimization and pollution prevention services, and evaluate the effectiveness of innovative technologies and novel solutions to environmental problems.

    Regulatory Compliance Projects:  Our regulatory compliance services include advising our clients on the full spectrum of regulatory requirements under the Resource Conservation and Recovery Act, the Clean Water Act, the Clean Air Act, the National Environmental Policy Act and other environmental laws. Although we provide services to both public and private clients, our current emphasis is on providing regulatory compliance services to the Army, Navy and Air Force.

Infrastructure

    In the infrastructure area, we focus on the development of water resource projects, institutional facilities, commercial, recreational and leisure facilities and transportation projects. These facilities are an essential part of everyday life and also sustain economic activity and the quality of life. Our engineers, architects and planners work in partnership with our clients to provide adequate infrastructure development within their financial constraints. We assist clients with infrastructure projects by providing management consulting, engineering and architectural design, construction management, and operations and maintenance. Our service offerings in the infrastructure business area are focused on the following project areas:

    Water Resource Projects:  Our technical services are applied to all aspects of water quantity and quality management ranging from stormwater management through drainage and flood control projects to major water and wastewater treatment plants. Our experience includes planning, design and construction services for drinking water projects, the design of water treatment facilities and reservoirs, and the design of distribution systems including pipelines and pump stations. Our capabilities are also applied to specialized technical challenges associated with the design and construction of fisheries and hatcheries worldwide.

    Institutional Facilities Projects:  We provide architectural engineering and construction services for projects including site planning for land development, complete architectural design, interior design, civil/structural engineering and mechanical/electrical engineering of educational, healthcare and research facilities. We have completed engineering and construction projects for a wide range of clients with specialized needs such as security systems, training and audiovisual facilities, clean rooms, laboratories, medical facilities and emergency preparedness facilities.

    Commercial, Recreational and Leisure Facilities Projects:  We specialize in the planning and design of water-related entertainment and leisure facilities from theme park attractions to large marine aquariums. Our projects also include high-rise office buildings, museums, hotels, parks, visitor centers and marinas. We have designed complex aquatic life support systems and provided structural, civil and mechanical engineering and design of interpretive exhibits for a series of large

6

aquarium projects worldwide. We have also designed integrated interior building systems for heat, light, security, and communications to improve building energy efficiency and cost effectiveness.

    Transportation Projects:  We provide architectural, engineering and construction services for transportation projects to improve public safety and mobility. Our projects include roadway improvements, commuter railway stations and expansion of airports. We have also completed numerous transportation projects including bridges, major highways, and repair, replacement and upgrading of older transportation facilities.

Communications

    In the communications area, we focus on the delivery of technical solutions necessary to build and manage communications infrastructure projects. Our capabilities support a wide range of technologies for rapid information transport including broadband and wireless communications. Our communications clients seek management consulting, applied science, engineering and architectural design, and construction management services. Our service offerings in the communications business area are focused on the following project areas:

    Network Feasibility Projects:  We apply our technical services to all aspects of assessing the feasibility of network systems development, expansion and upgrades for our clients. Our experience includes feasibility and remote site selection studies, cost-benefit modeling and market assessments. We also assist network service providers with technical requirements definition, sensitivity/risk analysis and key economic projections.

    Network Planning Projects:  We specialize in network planning, including short- and long-term network configuration and development planning. We develop outside plant designs, civil engineering and regulatory compliance assessment and support efforts. In addition, our projects have included employment analysis, staffing, logistics, planning, and materials provisioning and management.

    Network Engineering Projects:  We provide a full range of onsite and offsite premises engineering and support services for projects ranging from developing computer aided design workprints to field surveys. Our experience includes digital evaluation and terrain modeling, right-of-way permitting and site acquisition for wireless and broadband networks. Capabilities include radio frequency engineering for wireless networks and for fiber optic, coaxial cable, and hybrid coaxial fiber networks. Our engineers design each system to the specifications of the customer's transmission requirements including subscriber density, traffic demand, coverage area and cost-benefit decisions. In addition, we have performed outside and inside plant design projects for twisted pair, coaxial fiber optic and copper cable networks, and wireless networks.

    Network Development Projects:  We have performed both inside and outside plant projects for major network service providers and building owners using both broadband and wireless technologies. Our construction projects include urban and long-haul underground cable installation. We have also applied our capabilities to wireless cell site construction and aerial cable placement.

    The following table presents brief examples of specific current and recent projects in our three primary business areas:

Business Area	Representative Projects
Resource Management	•	Currently providing engineering services for Bureau of Reclamation projects throughout the southwestern U.S. Providing water quality modeling, watershed management, public consensus building, and engineering solutions for water supplies.

7

	•	Assisting the EPA Office of Wastewater Management in conducting the Clean Water Needs Survey to assess financial needs for constructing wastewater treatment plants and other clean water related infrastructure.
	•	Currently providing relicensing services for nuclear power plants to extend the operational lifespans of these facilities.
	•	Currently supporting environmental activities at Air Force installations worldwide to assist the Air Force in its environmental mission in the areas of restoration, pollution prevention, compliance, and conservation.
	•	Currently providing program management and technical support for the Comprehensive Long-term Environmental Action Navy (CLEAN) program under several ten-year contracts. Activities include installation, restoration, base realignment and closure, and underground storage tank programs.
	•	Currently serving as prime contractor for environmental operations and maintenance services at Vandenberg Air Force Base in California. Also providing operations and maintenance services for a wastewater treatment plant and a hazardous waste collection plant, and air monitoring and other services.
	•	Currently serving as prime contractor for environmental and natural resource planning at U.S. Navy facilities in four western states. Conducted air emissions modeling, noise impact studies and biological resource surveys.
Infrastructure	•	Currently implementing production process engineering efficiencies. Upgraded information management systems and implemented ISO 14000-compliant environmental management systems for several Fortune 50 industrial customers.
	•	Provided engineering design of building mechanical systems including air, power, and data distribution systems, for the world headquarters of a major corporation in Ohio.
	•	Provided complex mechanical, electrical, and other building systems for the Guggenheim Museum in Bilbao, Spain.
	•	Provided multi-modal transportation planning and design for Boston, Massachusetts' first citywide transportation plan since the 1960s.
	•	Completed the development and analysis of alternative flood control measures for the Los Angeles River.
	•	Provided design and program management for Taiwan's National Museum of Marine Biology/Aquarium. Responsible for civil, structural and mechanical engineering and for aquatic life support systems. Designed water, wastewater and parking facilities.
	•	Currently providing information technology, mechanical, electrical, plumbing and fire protection engineering for Time Warner Center, a mixed-use project in New York City, New York.
	•	Provided project management for upgrading residuals management facilities at four drinking water treatment plants in the Detroit, Michigan area that are among the largest such plants in the U.S.

8

	•	Provided design for sections of a major six-lane toll road in Southern California that included new bridges, a tunnel and numerous large regional drainage facilities.
Communications	•	Currently supporting the upgrade of a wireless data network to enhance data transmission capabilities in the western U.S. markets.
	•	Currently providing integrated voice, video, and data networks inside buildings for large corporations, colleges, and health care facilities nationwide.
	•	Currently assisting a leading provider of broadband services with deployment of a high capacity broadband fiber optic network to provide high speed Internet connections, digital cable television, and broadband telephony in several western U.S. markets.
	•	Provided turnkey network development services for broadband wireless networks in several European countries. Services included overall project management, site acquisition, radio frequency engineering, network deployment, and startup verification.
	•	Provided site acquisition, obtained entitlements, supervised construction and installation of equipment, and provided program management services for a Canadian corporation.
	•	Provided services to install over 730 miles of cable to provide telephony and expanded channel capacity to approximately 135,000 homes in the Seattle, Washington area.
	•	Provided turnkey services including site selection and optimization, architectural and engineering design, site construction, and electronics installation and optimization for cell site development in the Los Angeles, California area for a major cellular communications carrier.
	•	Providing network planning through network deployment services for approximately 1,200 sites for a wireless communications firm serving the western U.S. markets.

Clients

    We have developed a diverse client base of hundreds of clients both in the public and private sectors. During fiscal 2001, the DOD, EPA and DOE accounted for approximately 12.3%, 8.6% and 1.1%, respectively, of our net revenue. Although agencies of the Federal government are among our most significant clients, we often support multiple programs within a single Federal agency. Our private sector clients include companies in the chemical, mining, pharmaceutical, aerospace, automotive, petroleum, communications and utility industries. No private sector client accounted for more than 10% of our net revenue in fiscal 2001.

9

    The following table presents a list of representative clients in our three primary business areas:

	Representative Clients
Business Area	Federal Government	State, County and Local	Private
Resource Management	U.S. Environmental Protection Agency; U.S. Air Force; U.S. Navy; U.S. Army; U.S. Coast Guard; U.S. Forest Service; U.S. Department of Energy; U.S. Agency for International Development; Federal Energy Regulatory Commission; U.S. Postal Service	California Department of Health Services; Washington Department of Ecology; Prince Georges County, Maryland; Clarmont County, Ohio; City of San Jose, California; Salton Sea Authority	Lockheed Martin Corporation; Merck & Co.; General Electric Company; Exelon Corporation; Hewlett-Packard Corporation; Unocal Corporation
Infrastructure	U.S. Army Corps of Engineers; U.S. Bureau of Reclamation; U.S. Navy; Federal Emergency Management Agency; U.S. Department of the Interior	City of Tucson, Arizona; City of Breckenridge, Colorado; Washington Department of Transportation; City of Detroit, Michigan; City of Portland, Oregon; Texas Parks and Wildlife Department; King County, Washington; Delaware Department of Transportation; Delaware Department of Corrections; Boston Water and Sewer Commission	Boeing Corporation; E.I. DuPont de Nemours and Company; Ford Motor Company; DaimlerChrysler Corporation AG; Disney Imagineering; Lowe's Company; Marriott Corporation; AOL-Time Warner, Inc.
Communications			AT&T Wireless Services; AT&T Broadband Services; Nextel Communications, Inc.; Verizon Communications; Motorola, Inc.; Sprint Communications Company; Lucent Technologies, Inc.; Ericsson

10

Contracts

    We enter into various types of contracts with our clients, including fixed-price, fixed-rate time and materials, cost-reimbursement plus fixed fee and cost-reimbursement plus fixed and award fee contracts. In fiscal 2001, 44.6%, 33.8% and 21.6% of our net revenue was derived from fixed-price, fixed-rate time and materials, and cost-reimbursement plus fixed fee and award fee contracts, respectively. Under a fixed-price contract, the client agrees to pay a specified price for our performance of the entire contract. Fixed-price contracts carry certain inherent risks, including risks of losses from underestimating costs, delays in project completion, problems with new technologies and economic and other changes that may occur over the contract period. Consequently, the profitability of fixed-price contracts may vary substantially. The amount of the fee received for a cost-reimbursement and award fee contract partially depends upon the government's discretionary periodic assessment of our performance on that contract. Our various clients determine which type of contract we enter into for a particular engagement.

    Some contracts made with the Federal government are subject to annual approval of funding. Federal government agencies may impose spending restrictions that limit the continued funding of our existing contracts with the Federal government and may limit our ability to obtain additional contracts. These limitations, if significant, could have a material adverse effect on us. To date, spending limitations have not had a significant effect on us. All contracts made with the Federal government may be terminated by the government at any time, with or without cause.

    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 in certain cases from bidding for or performing contracts resulting from or relating to certain work we have performed for the government. In addition, services performed for a private client may create conflicts of interest that preclude or limit our ability to obtain work for another private organization. We attempt to identify actual or potential conflicts of interest and to minimize the possibility that such conflicts would 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 potential conflict of interest. However, we have not experienced disqualification during a bidding or award negotiation process by any government or private client as a result of a conflict of interest.

    Our contracts with the Federal government are subject to audit by the government, primarily by the Defense Contract Audit Agency (DCAA). The DCAA generally seeks to (1) identify and evaluate all activities which either contribute to, or have an impact on, proposed or incurred costs of government contracts; (2) evaluate the contractor's policies, procedures, controls and performance; and (3) 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 compliance by us with Cost Accounting Standards and defective-pricing clauses found within the Federal Acquisition Regulations. The DCAA also performs the 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 Cost Accounting Standards. The DCAA also audits cost-based contracts, including the close-out of those contracts.

    The DCAA also reviews all types of Federal proposals, including those of award, administration, modification and repricing. Factors considered are 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 that has a significant effect on the performance of future government contracts is also conducted during the proposal review period.

    During the course of its audit, the DCAA may disallow costs if it determines that we accounted for such costs in a manner inconsistent with Cost Accounting Standards. Under a government contract,

11

only those costs that are reasonable, allocable and allowable are recoverable. A disallowance of costs by the DCAA could have a material adverse effect on us.

    Due to the severity of the legal remedies available to the government, including the required payment of damages and/or penalties, criminal and civil sanctions, and debarment, we maintain controls to avoid the occurrence of fraud and other unlawful activity. In addition, we maintain preventative audit programs to ensure appropriate control systems and mitigate control weaknesses.

    We provide our services under contracts, purchase orders or retainer letters. Our policy provides that, where possible, all contracts will be in writing. We bill all of our clients periodically based on costs incurred, on either an hourly-fee basis or on a percentage of completion basis, as the project progresses. Generally, our contracts do not require that we provide performance bonds. A performance bond, issued by a surety company, guarantees the contractor's performance under the contract. If the contractor defaults under the contract, the surety will, in its discretion, step in to finish 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. To date, we have not incurred material damages beyond the coverage of any performance bond.

    Most of our agreements permit termination without cause by the clients upon payment of fees and expenses through the date of the termination.

Marketing

    We utilize both a centralized corporate marketing department and local marketing groups within each of our operating units. Our corporate marketing department assists management in establishing our business plan, our target markets and an overall marketing strategy. The corporate marketing department also identifies and tracks the development of large Federal programs, positions us for new business areas, selects appropriate partners, if any, for new projects and assists in the bid process for new projects. We market throughout the organizations we target, focusing primarily on senior representatives in government organizations and senior management in private companies. In addition, the corporate marketing department supports marketing activities firm-wide by coordinating corporate promotional and professional activities, including appearances at trade shows, direct mailings, telemarketing and public relations.

    Most marketing activities are performed through our local offices. We believe that these offices have a greater understanding of local issues, laws and regulations and, therefore, can better target their marketing activities. These marketing activities are coordinated by full time marketing staff located in certain of our offices. These activities include meetings with potential clients and state, county and municipal regulators, presentations to civic and professional organizations and seminars on current technical topics.

Competition

    The market for our services is highly competitive. We compete with many other firms, ranging from small local firms to large national firms that may have greater financial and marketing resources. We perform a broad spectrum of engineering and consulting services across the resource management, infrastructure and communications business areas. Services within these business areas are provided to a client base which includes Federal agencies, such as the DOD, the DOE, the Department of the Interior, the EPA and the U.S. Postal Service, state and local agencies, and the private sector. Our competition varies and is a function of the business areas in which, and client sectors for which, we perform our services. The range of competitors for any one procurement can vary from one to 100 firms, depending upon the relative value of the project, the financial terms and risks associated with the

12

work, and any restrictions placed upon competition by the client. Historically, clients have chosen among competing firms based primarily on the quality and timeliness of the firm's service. However, we believe that price has become an increasingly important competitive factor. We believe that if this trend continues it could have a material adverse effect on our operating margins and profitability.

    We believe that our principal competitors include, in alphabetical order, Black & Veatch LLP; Brown & Caldwell; Camp, Dresser & McKee Inc.; Castle Tower Corporation; CH2M Hill Companies Ltd.; Earth Tech, Inc.; IT Group, Inc.; Mastec, Inc.; Montgomery Watson Harza; o2Wireless Solutions, Inc.; Quanta Services, Inc.; Roy F. Weston, Inc.; Science Applications International Corporation; URS Corporation and Wireless Facilities, Inc.

Backlog

    At September 30, 2001, our gross revenue backlog was approximately $634.7 million, compared to $632.9 million at October 1, 2000. We include in gross revenue backlog only those contracts for which funding has been provided and work authorizations have been received. We estimate that approximately $536.5 million of the gross revenue backlog at September 30, 2001 will be recognized during fiscal 2002. No assurance can be given that all amounts included in backlog will ultimately be realized, even if evidenced by written contracts. For example, certain of our contracts with the Federal government and other clients are terminable at will. If any of these clients terminate their contracts prior to completion, we may not be able to recognize that revenue.

Environmental Legislation

    Our clients have become subject to an increasing number of frequently overlapping Federal, state and local laws concerned with the protection of the environment, as well as regulations promulgated by administrative agencies pursuant to these laws. We provide services with respect to Federal environmental laws and regulations including: the Clean Water Act; the Resource Conservation and Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA); the National Environmental Policy Act; the Safe Drinking Water Act; and other laws.

Potential Liability and Insurance

    Our business activities could expose us to potential liability under various environmental laws such as CERCLA, or under workplace health and safety regulations. In addition, we occasionally contractually assume liability under indemnification agreements. We cannot predict the magnitude of such potential liabilities.

    We currently maintain comprehensive general liability, umbrella and professional and pollution liability insurance policies. The professional and pollution liability policies are "claims made" policies. This means that only claims made during the term of the policy are covered. If we terminate our professional and pollution liability policies and do not obtain retroactive coverage, we would be uninsured for claims made after termination even if based on events or acts that occurred during the term of the policy.

    We obtain insurance coverage through a broker who is experienced in the professional liability field. The broker, together with our risk manager, periodically review the adequacy of our insurance programs. However, because there are various exclusions and retentions under our insurance policies, there can be no assurance that all potential liabilities will be covered by our insurance. Further, in the event we expand our services into new markets, there can be no assurance that we will be able to obtain the types of insurance coverages for such activities or, if insurance is obtained, the dollar amount of any liabilities incurred could exceed our insurance coverage limits.

13

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

Employees

    At September 30, 2001, we had approximately 7,400 total employees or approximately 6,820 full-time equivalent employees. Our professional staff includes archaeologists, biologists, chemical engineers, chemists, civil engineers, computer scientists, economists, electrical engineers, environmental engineers, environmental scientists, geologists, hydrogeologists, mechanical engineers, oceanographers, toxicologists and project managers. Our ability to retain and expand our staff of qualified professionals will be an important factor in determining our future growth and success. We currently have 208 employees represented by seven labor organizations. Management considers its relations with our employees to be good.

    In addition, we supplement our consultants on certain engagements with independent contractors. We believe that the practice of retaining independent contractors on a per engagement basis provides us with significant flexibility in adjusting professional personnel levels in response to changes in demand for our services.

14

RISK FACTORS

Some of the information in this Annual Report on Form 10-K contains forward-looking statements that involve substantial risks and uncertainties. You can identify these statements by forward-looking words such as "may," "will," "expect," "anticipate," "believe," "estimate" and "continue" or similar words. You should read statements that contain these words carefully because they: (1) discuss our future expectations; (2) contain projections of our future operating results or of our future financial condition; or (3) state other "forward-looking" information. We believe it is important to communicate our expectations to our investors. There may be events in the future, however, that we are not accurately able to predict or over which we have no control. The risk factors listed in this section, as well as any cautionary language in this Annual Report on Form 10-K, provide examples of risks, uncertainties and events that may cause our actual results to differ materially from the expectations we describe in our forward-looking statements. You should be aware that the occurrence of any of the events described in these risk factors and elsewhere in this Annual Report on Form 10-K could have a material adverse effect on our business, financial condition and results of operations and that upon the occurrence of any of these events, the trading price of our common stock could decline.

There are risks associated with our acquisition strategy that could adversely impact our business and operating results

    A significant part of our growth strategy is to acquire other companies that complement our lines of business or that broaden our geographic presence. During fiscal 2001, we purchased 11 companies in ten separate transactions. We expect to continue to acquire companies as an element of our growth strategy. Acquisitions involve certain risks that could cause our actual growth or operating results to differ from our expectations or the expectations of securities analysts. For example:

•

We may not be able to identify suitable acquisition candidates or to acquire additional companies on favorable terms;



•

We compete with others to acquire companies. Competition may increase and may result in decreased availability of or increased price for suitable acquisition candidates;



•

We may not be able to obtain the necessary financing, on favorable terms or at all, to finance any of our potential acquisitions;



•

We may ultimately fail to consummate an acquisition even if we announce that we plan to acquire a company;



•

We may not be able to retain key employees of an acquired company which could negatively impact these companies' future performance;



•

We may fail to successfully integrate or manage these acquired companies due to differences in business backgrounds or corporate cultures;



•

These acquired companies may not perform as we expect;



•

We may find it difficult to provide a consistent quality of service across our geographically diverse operations; and



•

If we fail to successfully integrate any acquired company, our reputation could be damaged. This could make it more difficult to market our services or to acquire additional companies in the future.

In addition, our acquisition strategy may divert management's attention away from our primary service offerings, result in the loss of key clients or personnel and expose us to unanticipated liabilities.

    Finally, acquired companies that derive a significant portion of their revenues from the Federal government and that do not follow the same cost accounting policies and billing procedures as we do

15

may be subject to larger cost disallowances for greater periods than we typically encounter. If we fail to determine the existence of unallowable costs and establish appropriate reserves in advance of an acquisition, we may be exposed to material unanticipated liabilities, which could have a material adverse effect on our business.

Our quarterly operating results may fluctuate significantly, which could have a negative effect on the price of our common stock

    Our quarterly revenues, expenses and operating results may fluctuate significantly because of a number of factors, including:

•

The seasonality of the spending cycle of our public sector clients and the spending patterns of our private sector clients;



•

Employee hiring and utilization rates;



•

The number and significance of client engagements commenced and completed during a quarter;



•

Credit worthiness and solvency of clients;



•

The ability of our clients to terminate engagements without penalties;



•

Delays incurred in connection with an engagement;



•

The size and scope of engagements;



•

The timing of expenses incurred for corporate initiatives;



•

The timing and size of the return on investment capital; and



•

General economic or political conditions.

    Variations in any of these factors could cause significant fluctuations in our operating results from quarter to quarter and could result in net losses.

The value of our common stock could continue to be volatile

    The trading price of our common stock has fluctuated widely. In addition, in recent years the stock market has experienced extreme price and volume fluctuations. The overall market and the price of our common stock may continue to fluctuate greatly. The trading price of our common stock may be significantly affected by various factors, including:

•

Quarter to quarter variations in our operating results;



•

Changes in environmental legislation;



•

Changes in investors' and analysts' perception of the business risks and conditions of our business;



•

Investors' and analysts' assessment of third party reports or conclusions;



•

Broader market fluctuations; and



•

General economic or political conditions.

If we are not able to successfully manage our growth strategy, our business and results of operations may be adversely affected

    We are growing rapidly. Our growth presents numerous managerial, administrative, operational and other challenges. Our ability to manage the growth of our operations will require us to continue to improve our operational, financial and human resource management information systems and our other

16

internal systems and controls. In addition, our growth will increase our need to attract, develop, motivate and retain both our management and professional employees. The inability of our management to manage our growth effectively or the inability of our employees to achieve anticipated performance or utilization levels could have a material adverse effect on our business.

The loss of key personnel or our inability to attract and retain qualified personnel could significantly disrupt our business

    We depend upon the efforts and skills of our executive officers, senior managers and consultants. With limited exceptions, we do not have employment agreements with any of these individuals. The loss of the services of any of these key personnel could adversely affect our business. Although we have obtained non-compete agreements from certain principals and stockholders of companies we have acquired, we generally do not have non-compete or employment agreements with key employees who were not once equity holders of these companies. We do not maintain key-man life insurance policies on any of our executive officers or senior managers.

    Our future growth and success depends on our ability to attract and retain qualified scientists and engineers. The market for these professionals is competitive and we may not be able to attract and retain such professionals.

Changes in existing laws and regulations could reduce the demand for our services

    A significant amount of our resource management business is generated either directly or indirectly as a result of existing Federal and state governmental laws, regulations and programs. Any changes in these laws or regulations that reduce funding or affect the sponsorship of these programs could reduce the demand for our services and could have a material adverse effect on our business.

Our revenue from agencies of the Federal government is concentrated, and a reduction in spending by these agencies could adversely affect our business and operating results

    Agencies of the Federal government are among our most significant clients. During fiscal 2001, approximately 24.5% of our net revenue was derived from Federal agencies, of which 12.3% was derived from the Department of Defense (DOD), 8.6% from the Environmental Protection Agency (EPA), 1.1% from the Department of Energy (DOE) and 2.5% from various other Federal agencies. Some contracts with Federal government agencies require annual funding approval and may be terminated at their discretion. A reduction in spending by Federal government agencies could limit the continued funding of our existing contracts with them and could limit our ability to obtain additional contracts. These limitations, if significant, could have a material adverse effect on our business.

Our revenue from commercial clients is significant, and the credit risks associated with certain of these clients could adversely affect our operating results

    During fiscal 2001, approximately 54.2% of our net revenue was derived from commercial clients. We rely upon the financial stability and credit worthiness of these clients. To the extent the credit quality of these clients deteriorates or these clients seek bankruptcy protection, our ability to collect our receivables, and ultimately our operating results, may be adversely affected.

    On July 2, 2001, our client, Metricom, Inc. ("Metricom"), filed for protection under Chapter 11 of the U.S. Bankruptcy Code. At the time of filing, we had outstanding accounts receivable with Metricom in the aggregate amount of $38.3 million. In the third quarter of fiscal 2001, we took a charge in that amount to provide a reserve for Metricom.

17

Our contracts with governmental agencies are subject to audit, which could result in the disallowance of certain costs

    Contracts with the Federal government and other governmental agencies are subject to audit. Most of these audits are conducted by the Defense Contract Audit Agency (DCAA), which reviews our overhead rates, operating systems and cost proposals. The DCAA may disallow costs if it determines that we accounted for these costs incorrectly or in a manner inconsistent with Cost Accounting Standards. A disallowance of costs by the DCAA, or other governmental auditors, could have a material adverse effect on our business.

Our business and operating results could be adversely affected by losses under fixed-price contracts or termination of contracts at the client's discretion

    We contract with Federal and state governments as well as with the commercial sector. These contracts are often subject to termination at the discretion of the client with or without cause. Additionally, we enter into various types of contracts with our clients, including fixed-price contracts. During fiscal 2001, approximately 44.6% of our net revenue was derived from fixed-price contracts. Fixed-price contracts protect clients and expose us to a number of risks. These risks include underestimation of costs, problems with new technologies, unforeseen costs or difficulties, delays beyond our control and economic and other changes that may occur during the contract period. Losses under fixed-price contracts or termination of contracts at the discretion of the client could have a material adverse effect on our business.

Our inability to find qualified subcontractors could adversely affect the quality of our service and our ability to perform under certain contracts

    Under some of our contracts, we depend on the efforts and skills of subcontractors for the performance of certain tasks. Reliance on subcontractors varies from project to project. During fiscal 2001, subcontractor costs comprised 25.0% of our gross revenue. The absence of qualified subcontractors with whom we have a satisfactory relationship could adversely affect the quality of our service and our ability to perform under some of our contracts.

Our industry is highly competitive and we may be unable to compete effectively

    We provide specialized management consulting and technical services to a broad range of public and private sector clients. The market for our services is highly competitive and we compete with many other firms. These firms range from small regional firms to large national firms which have greater financial and marketing resources than ours.

    We focus primarily on the resource management, infrastructure and communications business areas. We provide services to our clients which include Federal, state and local agencies, and organizations in the private sector.

    We compete for projects and engagements with a number of competitors which can vary from one to 100 firms. Historically, clients have chosen among competing firms based on the quality and timeliness of the firm's service. We believe, however, that price has become an increasingly important factor.

    We believe that our principal competitors include, in alphabetical order, Black & Veatch LLP; Brown & Caldwell; Camp, Dresser & McKee Inc.; Castle Tower Corporation; CH2M Hill Companies Ltd.; Earth Tech, Inc.; IT Group, Inc.; Mastec, Inc.; Montgomery Watson Harza; o2 Wireless Solutions, Inc.; Quanta Services, Inc.; Roy F. Weston, Inc.; Science Applications International Corporation; URS Corporation and Wireless Facilities, Inc.

18

Our services expose us to significant risks of liability and our insurance policies may not provide adequate coverage

    Our services involve significant risks of professional and other liabilities which may substantially exceed the fees we derive from our services. Our business activities could expose us to potential liability under various environmental laws such as the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). In addition, we sometimes contractually assume liability under indemnification agreements. We cannot predict the magnitude of such potential liabilities.

    We currently maintain comprehensive general liability, umbrella professional and pollution liability insurance policies. We believe that our insurance policies are adequate for our business operations. The professional and pollution liability policies are "claims made" policies. Only claims made during the term of the policy are covered. Should we terminate our professional and pollution liability policies and fail to obtain retroactive coverage, we would be uninsured for claims made after termination even if the claims were based on events or acts that occurred during the term of the policy. Additionally, our insurance policies may not protect us against potential liability due to various exclusions and retentions. In addition, if we expand into new markets, there can be no assurance that we will be able to obtain insurance coverage for the new activities or, if insurance is obtained, the dollar amount of any liabilities incurred could exceed our insurance coverage limits. Partially or completely uninsured claims, if successful and of significant magnitude, could have a material adverse affect on our business.

We may be precluded from providing certain services due to conflict of interest issues

    Many of our clients are concerned about potential or actual conflicts of interest in retaining management consultants. 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, among other things, may prevent us from bidding for or performing contracts resulting from or relating to certain work we have performed for the government. In addition, services performed for a private client may create a conflict of interest that precludes or limits our ability to obtain work from other public or private organizations. We have, on occasion, declined to bid on projects because of these conflicts of interest issues.

Our international operations expose us to risks such as foreign currency fluctuations

    During fiscal 2001, approximately 3.2% of our net revenue was derived from the international marketplace. Some contracts with our international clients are denominated in foreign currencies. As such, these contracts contain inherent risks including foreign currency exchange risk and the risk associated with expatriating funds from foreign countries. If our international revenue increases, our exposure to foreign currency fluctuations may also increase. We periodically enter into forward exchange contracts to address foreign currency fluctuations.

Item 2.  Properties.

    Our corporate headquarters facilities are located in Pasadena, California. These facilities contain approximately 47,600 square feet of office space. In addition, we lease office space in approximately 310 locations in the United States. In total, our facilities contain approximately 1.8 million square feet of office space and are subject to leases which expire beyond the year 2002. We also rent additional office space on a month-to-month basis.

    We believe that our existing facilities are adequate to meet current requirements and that suitable additional or substitute space will be available as needed to accommodate any expansion of operations and for additional offices.

19

Item 3.  Legal Proceedings.

    We are subject to certain claims and lawsuits typically filed against the engineering and consulting professions, primarily alleging professional errors or omissions. We carry professional liability insurance, subject to certain deductibles and policy limits against such claims. Management is of the opinion that the resolution of these claims will not have a material adverse effect on our financial position or results of operations. See "Item 1. Business—Potential Liability and Insurance."

Item 4.  Submissions of Matters to a Vote of Security Holders.

    In June 2001, we distributed a Consent Solicitation Statement to our stockholders of record on May 25, 2001 in connection with the solicitation of stockholder consents by our board of directors, in lieu of a meeting of stockholders, with respect to the approval of our 2001 Stock Plan. In August 2001, we were advised by our transfer agent, U.S. Stock Transfer Corporation, that 13,048,779 shares of common stock had been voted to approve the plan, 18,778,485 shares had been voted against the plan and 126,383 shares had abstained. As a result, the plan was not approved and terminated by its terms.

20

PART II

    The information required by Items 5 through 8 of this report is set forth on pages 19 through 42 of our Annual Report to Stockholders for the fiscal year ended September 30, 2001. Such information is incorporated in this report and made a part hereof by reference. Item 9 is not applicable.

PART III

    The information required by Items 10 through 13 of this report is set forth in the sections entitled "Security Ownership of Certain Beneficial Owners and Management," "Election of Directors," and "Executive Compensation" in our Proxy Statement for our 2002 Annual Meeting of Stockholders. Such information is incorporated in this report and made a part hereof by reference.

PART IV

Item 14.  Exhibits, Financial Statement Schedules and Reports on Form 8-K.

(a)	1. and 2.	Financial Statements and Financial Statement Schedules.
		The Financial Statements filed as part of this report are listed in the accompanying index at page 25.
	3.	Exhibits.
	3.1	Restated Certificate of Incorporation of the Company (incorporated herein by reference to Exhibit 3.1 to the Company's Annual Report on Form 10-K for the fiscal year ended October 1, 1995).
	3.2	Bylaws of the Company as amended to date (incorporated herein by reference to Exhibit 3.2 to the Company's Registration Statement on Form S-1, No. 33-43723).
	3.3	Certificate of Amendment of Certificate of Incorporation of the Company (incorporated herein by reference to Exhibit 3.4 to the Company's Annual Report on Form 10-K for the fiscal year ended October 4, 1998).
	3.4	Certificate of Amendment of Certificate of Incorporation of the Company (incorporated herein by reference to Exhibit 3.4 to the Company's Quarterly Report on Form 10-Q as amended for the fiscal quarter ended April 1, 2001).
	10.1	Credit Agreement dated as of March 17, 2000 among the Company and the financial institutions named therein (incorporated herein by reference to Exhibit 10.1 to the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended April 2, 2000).
	10.2	First Amendment dated as of April 9, 2001 to the Credit Agreement dated as of March 17, 2000 among the Company and the financial institutions named therein (incorporated herein by reference to Exhibit 10.2 to the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended July 1, 2001).
	10.3	Second Amendment dated as of August 13, 2001 to the Credit Agreement dated as of March 17, 2000 among the Company and the financial institutions named therein.
	10.4	Note Purchase Agreement dated as of May 15, 2001 among the Company and the purchasers named therein (incorporated herein by reference to Exhibit 10.3 to the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended July 1, 2001).
	10.5	First Amendment dated as of September 30, 2001 to the Note Purchase Agreement dated as of May 15, 2001 among the Company and the purchasers named therein.

21

10.6	1989 Stock Option Plan dated as of February 1, 1989 (incorporated herein by reference to Exhibit 10.13 to the Company's Registration Statement on Form S-1, No. 33-43723).
10.7	Form of Incentive Stock Option Agreement executed by the Company and certain individuals in connection with the Company's 1989 Stock Option Plan (incorporated herein by reference to Exhibit 10.14 to the Company's Registration Statement on Form S-1, No. 33-43723).
10.8	Executive Medical Reimbursement Plan (incorporated herein by reference to Exhibit 10.16 to the Company's Registration Statement on Form S-1, No. 33-43723).
10.9	1992 Incentive Stock Plan (incorporated herein by reference to Exhibit 10.18 to the Company's Annual Report on Form 10-K for the fiscal year ended October 3, 1993).
10.10	Form of Incentive Stock Option Agreement used by the Company in connection with the Company's 1992 Incentive Stock Plan (incorporated herein by reference to Exhibit 10.19 to the Company's Annual Report on Form 10-K for the fiscal year ended October 3, 1993).
10.11	1992 Stock Option Plan for Nonemployee Directors (incorporated herein by reference to Exhibit 10.20 to the Company's Annual Report on Form 10-K for the fiscal year ended October 3, 1993).
10.12	Form of Nonqualified Stock Option Agreement used by the Company in connection with the Company's 1992 Stock Option Plan for Nonemployee Directors (incorporated herein by reference to Exhibit 10.21 to the Company's Annual Report on Form 10-K for the fiscal year ended October 3, 1993).
10.13	1994 Employee Stock Purchase Plan (incorporated herein by reference to Exhibit 10.22 to the Company's Annual Report on Form 10-K for the fiscal year ended October 2, 1994).
10.14	Form of Stock Purchase Agreement used by the Company in connection with the Company's 1994 Employee Stock Purchase Plan (incorporated herein by reference to Exhibit 10.23 to the Company's Annual Report on Form 10-K for the fiscal year ended October 2, 1994).
10.15	2002 Stock Option Plan.
10.16	Form of Incentive Option Agreement used by the Company in connection with the 2002 Stock Option Plan.
10.17	Registration Rights Agreement dated as of March 31, 2000 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.22 to the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended July 2, 2000).
10.18	Registration Rights Agreement dated as of May 3, 2000 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.23 to the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended July 2, 2000).
10.19	Registration Rights Agreement dated as of May 17, 2000 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.24 to the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended July 2, 2000).

22

10.20	Registration Rights Agreement dated as of May 24, 2000 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.25 to the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended July 2, 2000).
10.21	Registration Rights Agreement dated as of December 21, 2000 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.26 to the Company's Annual Report on Form 10-K for the fiscal year ended October 1, 2000).
10.22	Registration Rights Agreement dated as of March 2, 2001 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.27 to the Company's Quarterly Report on Form 10-Q as amended for fiscal quarter ended April 1, 2001).
10.23	Registration Rights Agreement dated as of March 30, 2001 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.28 to the Company's Quarterly Report on Form 10-Q as amended for fiscal quarter ended April 1, 2001).
10.24	Registration Rights Agreement dated as of May 21, 2001 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.31 to the Company's Quarterly Report on Form 10-Q for fiscal quarter ended July 1, 2001).
10.25	Registration Rights Agreement dated as of May 25, 2001 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.32 to the Company's Quarterly Report on Form 10-Q for fiscal quarter ended July 1, 2001).
10.26	Registration Rights Agreement dated as of June 1, 2001 among the Company and the parties listed on Schedule A attached thereto (incorporated herein by reference to Exhibit 10.33 to the Company's Quarterly Report on Form 10-Q for fiscal quarter ended July 1, 2001).
10.27	Registration Rights Agreement dated as of September 26, 2001 among the Company and the parties listed on Schedule A attached thereto.
10.28	Registration Rights Agreement dated as of September 26, 2001 among the Company and the parties listed on Schedule A attached thereto.
13.	Annual Report to Stockholders for the fiscal year ended September 30, 2001, portions of which are incorporated by reference in this report as set forth in Part II hereof. With the exception of these portions, such Annual Report is not deemed filed as part of this report.
21.	Subsidiaries of the Company.
23.	Independent Auditors' Consent.

(b)

Reports on Form 8-K

    On July 6, 2001, we filed with the Securities and Exchange Commission a Current Report on Form 8-K. The items reported in the Form 8-K were Item 5 (Other Events) and Item 7 (Financial Statements and Exhibits), which related to the press release dated July 2, 2001, titled "Tetra Tech Updates Guidance for Third Quarter Based on Charge for Metricom Work." The date of the Form 8-K was July 2, 2001.

    On July 19, 2001, we filed with the Securities and Exchange Commission a Current Report on Form 8-K. The items reported in the Form 8-K were Item 5 (Other Events) and Item 7 (Financial Statements and Exhibits), which related to the press release dated July 18, 2001, titled "Tetra Tech Reports Third Quarter 2001 Results." The date of the Form 8-K was July 18, 2001.

23

SIGNATURES

    Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	TETRA TECH, INC.
Date: December 28, 2001	By:	/s/ LI-SAN HWANG Li-San Hwang, Chairman of the Board of Directors and Chief Executive Officer

    Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Signature	Title	Date
/s/ LI-SAN HWANG Li-San Hwang	Chairman of the Board of Directors and Chief Executive Officer (Principal Executive Officer)	December 28, 2001
/s/ JAMES M. JASKA James M. Jaska	President, Chief Financial Officer and Treasurer (Principal Financial and Accounting Officer)	December 28, 2001
/s/ DANIEL A. WHALEN Daniel A. Whalen	Director	December 27, 2001
/s/ J. CHRISTOPHER LEWIS J. Christopher Lewis	Director	December 27, 2001
/s/ PATRICK C. HADEN Patrick C. Haden	Director	December 27, 2001
/s/ JAMES J. SHELTON James J. Shelton	Director	December 27, 2001

24

INDEX TO FINANCIAL STATEMENTS

    The consolidated financial statements, together with the Notes thereto and report thereon of Deloitte & Touche LLP dated November 14, 2001, appearing on pages 28 through 43 of the accompanying 2001 Annual Report to Stockholders, are incorporated by reference in this Annual Report on Form 10-K. With the exception of the aforementioned information and Part II information set forth on pages 19 through 27, the 2001 Annual Report to Stockholders is not to be deemed filed as part of this report.

Financial Statements Schedules

	Page No.
Independent Auditors' Report	26
Financial Statement Schedule
Schedule II—Valuation and Qualifying Accounts and Reserves	27

25

INDEPENDENT AUDITORS' REPORT

Tetra Tech, Inc.:

    We have audited the consolidated financial statements of Tetra Tech, Inc. and its subsidiaries as of September 30, 2001 and October 1, 2000, and for each of the three years in the period ended September 30, 2001, and have issued our report thereon dated November 14, 2001; such financial statements and report are included in your 2001 Annual Report to Stockholders and are incorporated herein by reference. Our audits also included the financial statement schedule of Tetra Tech, Inc. and its subsidiaries, listed in Item 14. This financial statement schedule is the responsibility of the Company's management. Our responsibility is to express an opinion based on our audits. In our opinion, such financial statement schedule, when considered in relation to the basic consolidated financial statements taken as a whole, presents fairly in all material respects the information set forth therein.

/s/ DELOITTE & TOUCHE LLP

Los Angeles, California
November 14, 2001

26

TETRA TECH, INC.

SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

For the Fiscal Years Ended
October 3, 1999, October 1, 2000 and September 30, 2001

	Balance at Beginning of Period		Additions through Acquisitions		Charges to Costs and Earnings			Deductions, Net of Recoveries			Balance at End of Period
Fiscal year ended October 3, 1999
Allowance for uncollectible accounts receivable	$	12,685,000	$	747,000	$	(667,000	)	$	(4,236,000	)	$	8,529,000
Fiscal year ended October 1, 2000
Allowance for uncollectible accounts receivable	$	8,529,000	$	391,000	$	3,056,000		$	(4,903,000	)	$	7,073,000
Fiscal year ended September 30, 2001
Allowance for uncollectible accounts receivable	$	7,073,000	$	1,442,000	$	44,025,000		$	(6,643,000	)	$	45,897,000

27

QuickLinks

PART I

Item 1. Business.

RISK FACTORS

Item 2. Properties.
Item 3. Legal Proceedings.
Item 4. Submissions of Matters to a Vote of Security Holders.

PART II
PART III
PART IV

Item 14. Exhibits, Financial Statement Schedules and Reports on Form 8-K.

SIGNATURES
INDEX TO FINANCIAL STATEMENTS
INDEPENDENT AUDITORS' REPORT
TETRA TECH, INC. SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS AND RESERVES For the Fiscal Years Ended October 3, 1999, October 1, 2000 and September 30, 2001

EX-10.3

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.3

SECOND AMENDMENT

    THIS SECOND AMENDMENT (this "Amendment") dated as of August 13, 2001 is to the Credit Agreement (the "Credit Agreement") dated as of March 17, 2000 among TETRA TECH, INC. (the "Company"), various financial institutions and BANK OF AMERICA, N.A., as administrative agent (the "Agent"). Unless otherwise defined herein, terms defined in the Credit Agreement are used herein as defined therein.

    WHEREAS, the parties hereto have entered into the Credit Agreement which provides for the Banks to make Loans to, and to issue Letters of Credit for the account of, the Company from time to time; and

    WHEREAS, the parties hereto desire to amend the Credit Agreement as set forth below;

    NOW THEREFORE, in consideration of the premises and for other good and valuable consideration (the receipt and sufficiency of which are hereby acknowledged), the parties hereto agree as follows:

    SECTION 1 AMENDMENTS. Effective on (and subject to the occurrence of) the Amendment Effective Date (as defined below), the Credit Agreement shall be amended as follows:

    Section 1.1 Definitions. Section 1 of the Credit Agreement is amended by inserting the following definition in the appropriate alphabetical order:

    "Adjusted Leverage Ratio means, for any Computation Period, the Leverage Ratio for such Computation Period, provided that for purposes of computing the Adjusted Leverage Ratio, EBITDA shall be adjusted by (x) adding back the special charge (but not more than $38,300,000) taken by the Company in the third Fiscal Quarter of Fiscal Year 2001 in connection with the bankruptcy of Metricom, Inc., to the extent taken in such Computation Period; and (y) deducting any recovery received on the obligations which gave rise to the special charge referred to in clause (x), to the extent received during such Computation Period."

    Section 1.2 Leverage Covenant. Section 10.6.3 of the Credit Agreement is amended by inserting the word "Adjusted" before the words "Leverage Ratio" therein.

    Section 1.3 Addition of Covenant. Section 10 of the Credit Agreement is amended by adding the following:

    "10.23 Note Purchase Agreement Covenants. Comply with the terms set forth in Sections 10.1 (Indebtedness; Priority Debt), 10.2 (Fixed Charge Coverage) and 10.3 (Adjusted Consolidated Net Worth) of the Note Purchase Agreement dated as of May 15, 2001 executed in connection with the Private Placement Debt, as such Note Purchase Agreement is in effect on the date hereof (without giving effect to any amendment thereto or waiver thereof unless consented to by the Required Banks)."

    Section 1.4 Events of Default. Clause (a) of Section 12.1.5 of the Credit Agreement is amended by adding the following at the end thereof (after the reference to "10.21" and before the semi-colon): "and 10.23".

    SECTION 2 REPRESENTATIONS AND WARRANTIES. The Company represents and warrants to the Agent and the Banks that (a) each warranty set forth in Section 9 of the Credit Agreement is true and correct as if made on the date hereof, (b) the execution and delivery by the Company of this Amendment and the performance by the Company of its obligations under the Credit Agreement as amended hereby (as so amended, the "Amended Credit Agreement") (i) are within the corporate powers of the Company, (ii) have been duly authorized by all necessary corporate action, (iii) have received all

1

necessary governmental approval and (iv) do not and will not contravene or conflict with any provision of law or of the charter or by-laws of the Company or any Subsidiary or of any indenture, loan agreement or other material contract, or any judgment, order or decree, which is binding upon the Company or any Subsidiary, and (c) this Amendment and the Amended Credit Agreement are the legal, valid and binding obligations of the Company, enforceable against the Company in accordance with their terms, except as enforceability may be limited by bankruptcy, insolvency or other similar laws of general application affecting the enforcement of creditor's rights or by general principles of equity.

    SECTION 3 EFFECTIVENESS. The amendments set forth in Section 1 shall become effective, as of the day and year first above written, on such date (the "Amendment Effective Date") that the Agent shall have received each of the following: (a) counterparts of this Amendment executed by the Company and the Required Banks; (b) a Confirmation in the form of Exhibit A hereto signed by the Company and each Subsidiary; (c) for the account of each Bank that has executed and delivered a counterpart hereof to the agent (via facsimile or otherwise) by 1:00 PM (Chicago Time) on August 13, 2001, an amendment fee in an amount equal to 0.10% of such Bank's commitment; and (d) such other documents as the Agent or any Bank may reasonably request.

    SECTION 4 MISCELLANEOUS.

    Section 4.1 Continuing Effectiveness, etc. As herein amended, the Credit Agreement shall remain in full force and effect and is hereby ratified and confirmed in all respects.

    Section 4.2 Counterparts. This Amendment may be executed in any number of counterparts and by the different parties on separate counterparts, and each such counterpart shall be deemed to be an original but all such counterparts shall together constitute one and the same Second Amendment.

    Section 4.3 Governing Law. This Amendment shall be a contract made under and governed by the laws of the State of Illinois applicable to contracts made and to be performed entirely within such State.

    Section 4.4 Successors and Assigns. This Amendment shall be binding upon the Company and the Agent and their respective successors and assigns, and shall inure to the benefit of the Company and the Agent and the successors and assigns of the Agent.

    Section 4.5 Expenses. The Company agrees to pay the reasonable costs and expenses of the Agent (including attorneys' fees) in connection with the preparation, execution and delivery of this Amendment.

    Delivered at Chicago, Illinois, as of the day and year first above written.

TETRA TECH, INC.
By:	/s/ JAMES M. JASKA
Title:	Chief Financial Officer
BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT
By:	/s/ KRISTINE D HYDE
Title:	Vice President

2

BANK OF AMERICA, N.A., AS SWING LINE BANK, ISSUING BANK AND AS A BANK
By:	/s/ JENNIFER L. GERDES
Title:	Vice President
WELLS FARGO BANK, N.A., AS DOCUMENTATION AGENT AND AS A BANK
By:	/s/ RANDALL J. REPP
Title:	Vice President
HARRIS TRUST AND SAVINGS BANK, AS SYNDICATION AGENT AND AS A BANK
By:	/s/ ISABELLA BATTISTA
Title:	Vice President
THE FUJI BANK, LIMITED
By:	/s/ STEVEN T. BRENNAN
Title:	Senior Vice President
PACIFIC CENTURY BANK, N.A.
By:
Title:

3

EXHIBIT A

CONFIRMATION

Dated as of August 13, 2001

    Each of the undersigned hereby acknowledges and agrees to the foregoing Second Amendment and the Amended Credit Agreement and hereby confirms the continuing validity and enforceability of the Guaranty and the Security Agreement after giving effect thereto.

HSI GEOTRANS, INC.
By:	/s/ JAMES M. JASKA
Title:	Assistant Treasurer
SCM CONSULTANTS, INC.
By:	/s/ JAMES M. JASKA
Title:	Assistant Treasurer
TETRA TECH EM, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
WHALEN & COMPANY, INC.
By:	/s/ JAMES M. JASKA
Title:	Chief Financial Officer
TETRA TECH NUS, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer

4

MFG, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
COLLINS-PINA CONSULTING ENGINEERS, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
DEA CONSTRUCTION COMPANY, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
BAHA COMMUNICATIONS, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
UTILITIES & C.C., INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer

5

ASL CONSULTING ENGINEERS, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
ASL CONSULTING ENGINEERS ARIZONA, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
ASL CONSULTANTS, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
COSENTINI ASSOCIATES, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
EVERGREEN UTILITY CONTRACTORS, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
KCM, INC.
By:	/s/ JAMES M. JASKA
Title:	Assistant Treasurer

6

LC OF ILLINOIS, INC.
By:	/s/ JAMES M. JASKA
Title:	Treasurer
MCNAMEE, PORTER & SEELEY, INC.
By:	/s/ JAMES M. JASKA
Title:	Assistant Treasurer
MCNAMEE INDUSTRIAL SERVICES, INC.
By:	/s/ JAMES M. JASKA
Title:	Assistant Treasurer
PDR ENGINEERS, INC.
By:	/s/ JAMES M. JASKA
Title:	Chief Financial Officer

7

QuickLinks

Exhibit 10.3
SECOND AMENDMENT
EXHIBIT A CONFIRMATION Dated as of August 13, 2001

EX-10.5

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.5

EXECUTION COPY

TETRA TECH, INC.

FIRST AMENDMENT TO
NOTE PURCHASE AGREEMENT

$110,000,000
Senior Secured Notes

$92,000,000
7.28% Senior Secured Notes,
Series A, due May 30, 2011

$18,000,000
7.08% Senior Secured Notes,
Series B, due May 30, 2008

Dated as of September 30, 2001

To the Holders of the Senior Notes
of Tetra Tech, Inc. Named in
the Attached Schedule I

Ladies and Gentlemen:

    Reference is made to the Note Purchase Agreement dated as of May 15, 2001 (the "Note Agreement") between Tetra Tech, Inc., a Delaware corporation (the "Company"), and you pursuant to which the Company issued $92,000,000 aggregate principal amount of its 7.28% Senior Secured Notes, Series A, due May 30, 2011 (the "Series A Notes") and $18,000,000 aggregate principal amount of its 7.08% Senior Secured Notes, Series B, due May 30, 2008 (the "Series B Notes" and, together with the Series A Notes, the "Notes"). You are referred to herein individually as a "Holder" and collectively as the "Holders". Capitalized terms used and not otherwise defined herein shall have the meanings ascribed to them in the Note Agreement, as amended hereby.

    The Company has requested that the Note Agreement be amended to exclude a special charge related to the bankruptcy of Metricom, Inc. from Adjusted EBITDA for purposes of the Indebtedness covenant. You have agreed to such amendment on the terms and conditions set forth herein.

    In consideration of the premises and for good and valuable consideration, the receipt and sufficiency of which are acknowledged, the Company and the Holders agree as follows:

1.  AMENDMENT OF NOTE AGREEMENT

    1.1. Section 10.1(a). Section 10.1(a) of the Note Agreement is amended to read in its entirety as follows:

    "(a) the ratio of Consolidated Indebtedness (as of any date) to Adjusted EBITDA (for the Company's then most recently completed four fiscal quarters) to be greater that 2.75 to 1.00; provided, however, that for purposes of this Section 10.1(a), Adjusted EBITDA shall be adjusted by (x) adding back the special charge (but not more than $38,300,000) taken by the Company in the fiscal quarter ended July 1, 2001 in connection with the bankruptcy of Metricom, Inc. to the extent taken during the Company's then most recently completed four fiscal quarters and (y) deducting any recovery received on the obligations that gave rise to the special charge referred

S–1

to in clause (x) to the extent received during the Company's then most recently completed four fiscal quarters; or"

2.  REAFFIRMATION; REPRESENTATIONS AND WARRANTIES`

    2.1. Reaffirmation of Note Agreement. The Company reaffirms its agreement to comply with each of the covenants, agreements and other provisions of the Note Agreement and the Notes, including the amendment of such provisions effected by this First Amendment.

    2.2. Note Agreement. The Company represents and warrants that the representations and warranties contained in the Note Agreement are true and correct as of the date hereof, except (a) to the extent that any of such representations and warranties specifically relate to an earlier date, (b) for such changes, facts, transactions and occurrences that have arisen since May 22, 2001 in the ordinary course of business, (c) for such other matters as have been previously disclosed in writing by the Company (including in its financial statements and notes thereto) to the Holders and (d) for other changes that could not reasonably be expected to have a Material Adverse Effect.

    2.3. No Default or Event of Default. After giving effect to the transactions contemplated hereby, there will exist no Default or Event of Default.

    2.4. Authorization. The execution, delivery and performance by the Company of this First Amendment have been duly authorized by all necessary corporate action and, except as provided herein, do not require any registration with, consent or approval of, notice to or action by, any Person (including any Governmental Authority) in order to be effective and enforceable. The Note Agreement and this First Amendment each constitute the legal, valid and binding obligations of the Company, enforceable in accordance with their respective terms, except as such enforceability may be limited by (i) applicable bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium or other similar laws affecting the enforcement of creditors' rights generally and (ii) general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law).

3.  EFFECTIVE DATE

    This First Amendment shall become effective as of the date set forth above upon the satisfaction of the following conditions:

    3.1. Consent of Holders to First Amendment. Execution by the Holders of at least a majority of the aggregate principal amount of the Notes outstanding and receipt by the Holders of a counterpart of this First Amendment duly executed by the Company.

    3.2. Amendment Fee. Each Holder shall have received payment of an amendment fee equal to 0.1% of the principal amount of the outstanding Notes held by such Holder.

    3.3. Expenses. The Company shall have paid all fees and expenses of special counsel to the Holders.

4.  MISCELLANEOUS

    4.1. Ratification. Except as amended hereby, the Note Agreement, including the representations and warranties contained therein, shall remain in full force and effect and is ratified, approved and confirmed in all respects as of the date hereof.

    4.2. Reference to and Effect on the Note Agreement. Upon the final effectiveness of this First Amendment, each reference in the Note Agreement and in other documents describing or referencing the Note Agreement to the "Agreement," "Note Agreement," "hereunder," "hereof," "herein," or

S–2

words of like import referring to the Note Agreement, shall mean and be a reference to the Note Agreement, as amended hereby.

    4.3. Binding Effect. This First Amendment shall be binding upon and inure to the benefit of the respective successors and assigns of the parties hereto.

    4.4. Governing Law. This First Amendment shall be governed by and construed in accordance with Illinois law.

    4.5. Counterparts. This First Amendment may be executed in any number of counterparts, each executed counterpart constituting an original, but altogether only one instrument.

IN WITNESS WHEREOF, the Company and the Holders have caused this First Amendment to be executed and delivered by their respective officer or officers thereunto duly authorized.

TETRA TECH, INC.
By:	/s/ JAMES M. JASKA
Name:	James M. Jaska
Title:	Chief Financial Officer

S–3

HOLDERS:

The foregoing is agreed
to as of the date thereof.

MASSMUTUAL ASIA LIMITED
By:	David L. Babson & Company Inc. as Investment Adviser
By:	/s/ MARK A. AHMED
Name:	Mark A. Ahmed
Title:	Managing Director
MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
By:	David L. Babson & Company Inc. as Investment Adviser
By:	/s/ MARK A. AHMED
Name:	Mark A. Ahmed
Title:	Managing Director
C.M. LIFE INSURANCE COMPANY
By:	David L. Babson & Company Inc. as Investment Adviser
By:	/s/ MARK A. AHMED
Name:	Mark A. Ahmed
Title:	Managing Director
CONNECTICUT GENERAL LIFE INSURANCE COMPANY
By:	CIGNA Investments, Inc. (authorized agent)
By:	/s/ STEPHEN H. WILSON
Name:	Stephen H. Wilson
Title:	Managing Director

S–4

LIFE INSURANCE COMPANY OF NORTH AMERICA
By:	CIGNA Investments, Inc. (authorized agent)
By:	/s/ STEPHEN H. WILSON
Name:	Stephen H. Wilson
Title:	Managing Director
UNITED OF OMAHA LIFE INSURANCE COMPANY
By:	/s/ EDWIN H. GARRISON JR.
Name:	Edwin H. Garrison Jr.
Title:	First Vice President
MUTUAL OF OMAHA INSURANCE COMPANY
By:	/s/ EDWIN H. GARRISON JR.
Name:	Edwin H. Garrison Jr.
Title:	First Vice President
HARTFORD LIFE INSURANCE COMPANY
By:	Hartford Investment Services, Inc., its Agent and Attorney-in-Fact
By:	/s/ KURT H. NYMAN
Name:	Kurt H. Nyman
Title:	Vice President
NATIONWIDE LIFE INSURANCE COMPANY
By:	/s/ MARK W. POEPPELMAN
Name:	Mark W. Poeppelman
Title:	Associate Vice President

S–5

NATIONWIDE LIFE AND ANNUITY INSURANCE COMPANY
By:	/s/ MARK W. POEPPELMAN
Name:	Mark W. Poeppelman
Title:	Associate Vice President
PROVIDENT MUTUAL LIFE INSURANCE COMPANY
By:	/s/ JAMES D. KESTNER
Name:	James D. Kestner
Title:	Vice President
SECURITY FINANCIAL LIFE INSURANCE CO.
By:	/s/ KEVIN W. HAMMOND
Name:	Kevin W. Hammond
Title:	Chief Investment Officer
THE CANADA LIFE ASSURANCE COMPANY
By:	/s/ PAUL ENGLISH
Name:	Paul English
Title:	Associate Treasurer
CANADA LIFE ASSURANCE COMPANY OF NEW YORK
By:	/s/ PAUL ENGLISH
Name:	Paul English
Title:	Associate Treasurer

S–6

LUTHERAN BROTHERHOOD
By:	/s/ KERI L. REICH
Name:	Keri L. Reich
Title:	Portfolio Manager
MODERN WOODMEN OF AMERICA
By:	/s/ NICK S. COIN
Name:	Nick S. Coin
Title:	Manager, Securities Division

S–7

SCHEDULE I

Series A Holders	Principal Amount
Massachusetts Mutual Life Insurance Company	$	21,500,000
C.M. Life Insurance Company		3,000,000
MassMutual Asia Limited		500,000
Connecticut General Life Insurance Company		17,000,000
Life Insurance Company of North America		3,000,000
United of Omaha Life Insurance Company		12,000,000
Mutual of Omaha Insurance Company		3,000,000
Hartford Life Insurance Company		15,000,000
Nationwide Life Insurance Company		7,000,000
Nationwide Life and Annuity Insurance Company		3,000,000
Provident Mutual Life Insurance Company		5,000,000
Security Financial Life Insurance Co.		2,000,000

Series B Holders	Principal Amount
The Canada Life Assurance Company	$	8,700,000
Canada Life Insurance Company of New York		300,000
Lutheran Brotherhood		6,000,000
Modern Woodmen of America		3,000,000

S–8

QuickLinks

Exhibit 10.5 EXECUTION COPY
TETRA TECH, INC. FIRST AMENDMENT TO NOTE PURCHASE AGREEMENT $110,000,000 Senior Secured Notes $92,000,000 7.28% Senior Secured Notes, Series A, due May 30, 2011 $18,000,000 7.08% Senior Secured Notes, Series B, due May 30, 2008
Dated as of September 30, 2001
SCHEDULE I

EX-10.15

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.15

Tetra Tech, Inc.

2002 Stock Option Plan

1. Purpose.

    The purpose of the Tetra Tech, Inc. 2002 Stock Option Plan ("Plan") is to promote the interests of Tetra Tech, Inc. ("Company") and its stockholders by enabling the Company to offer Participants an opportunity to acquire an equity interest in the Company so as to better attract, retain, and reward its employees, directors (excluding nonemployee directors) and other persons providing services to the Company and, accordingly, to strengthen the mutuality of interests between Participants and the Company's stockholders by providing Participants with a proprietary interest in pursuing the Company's long-term growth and financial success.

2. Definitions.

    For purposes of this Plan, the following terms shall have the meanings set forth below.

    (a) "Board" means the Board of Directors of Tetra Tech, Inc.

    (b) "Code" means the Internal Revenue Code of 1986, and the applicable regulations thereunder. Reference to any specific section of the Code shall be deemed to be a reference to any successor provision.

    (c) "Committee" means the committee appointed by the Board, if any, to administer this Plan as permitted by Section 5 below or, if no such committee is appointed, the Board.

    (d) "Common Stock" means the common stock of the Company or any security issued in substitution, exchange, or in lieu thereof.

    (e) "Company" means Tetra Tech, Inc., a Delaware corporation, or any successor corporation. Except where the context indicates otherwise, the term "Company" shall include its Subsidiaries.

    (f)  "Disabled" means permanent and total disability, as defined in Code Section 22(e)(3).

    (g) "Exchange Act" means the Securities Exchange Act of 1934.

    (h) "Fair Market Value" of Common Stock for any day shall be determined in accordance with the following rules.

     (i) If the Common Stock is admitted to trading or listed on a national securities exchange, the last reported sale price on that day regular way, or if no such reported sale takes place on that day, the average of the last reported bid and ask prices on that day regular way, in either case on the principal national securities exchange on which the Common Stock is admitted to trading or listed.

    (ii) If not listed or admitted to trading on any national securities exchange, the last sale price regular way on that day reported on the Nasdaq National Market ("Nasdaq National Market") of the Nasdaq Stock Market ("NSM") or, if no such reported sale takes place on that day, the average of the closing bid and ask prices regular way on that day.

    (iii) If not traded or listed on a national securities exchange or included in the Nasdaq National Market, the last reported sale price on that day regular way, or if no such reported sale takes place on that day, the average of the closing bid and ask prices regular way on that day reported by the NSM, or any comparable system on that day.

    (iv) If the Common Stock is not included in (i), (ii) or (iii) above, the last reported sale price on that day regular way, or if no such reported sale takes place on that day, the closing

bid and ask prices regular way on that day as furnished by any member of the National Association of Securities Dealers, Inc. ("NASD") selected from time to time by the Company for that purpose.

If the national securities exchange, Nasdaq National Market, NSM or NASD as applicable, are closed on such date, the "Fair Market Value" shall be determined as of the last preceding day on which the Common Stock was traded or for which bid and ask prices are available. In the case of an Incentive Stock Option, "Fair Market Value" shall be determined without reference to any restriction other than one that, by its terms, will never lapse.

    (i)  "Incentive Stock Option" means an option to purchase Common Stock that is an incentive stock option within the meaning of Code Section 422.

    (j)  "Insider" means a person who is subject to Section 16 of the Exchange Act.

    (k) "Non-Qualified Stock Option" means any option to purchase Common Stock that is not an Incentive Stock Option.

    (l)  "Option" means an Incentive Stock Option or a Non-Qualified Stock Option.

    (m) "Participant" means a person who was been granted an Option under the Plan.

    (n) "Plan" means this Tetra Tech, Inc. 2002 Stock Option Plan, as it may be amended from time to time.

    (o) "Severance" means, with respect to a Participant, the termination of the Participant's provision of services to the Company as an employee or independent contractor, whether by reason of death, disability, or any other reason. For purposes of determining the exercisability of an Incentive Stock Option, a Participant who is on a leave of absence that exceeds ninety (90) days will be considered to have incurred a Severance on the ninety-first (91st) day of the leave of absence, unless the Participant's rights to reemployment are guaranteed by statute or contract. However, a Participant will not be considered to have incurred a Severance because of a transfer of employment between the Company and a Subsidiary (or vice versa).

    (p) "Subsidiary" means any corporation or entity in which Tetra Tech, Inc., directly or indirectly, controls fifty percent (50%) or more of the total voting power of all classes of its stock having voting power, as determined in accordance with the rules of Code Section 424(f).

    (q) "Ten Percent Shareholder" means any person who owns (after taking into account the constructive ownership rules of Code Section 424(d)) more than ten percent (10%) of the stock of the Tetra Tech, Inc. or of any of its Subsidiaries.

3. Eligibility.

    All employees (including employee directors) and other persons providing bona fide services to the Company or any Subsidiary are eligible to receive Options under this Plan. However, Incentive Stock Options may only be granted to employees of the Company or of a Subsidiary.

4. Substitute Options.

    In the event the Company acquires another entity, the Committee may authorize the issuance of Options ("Substitute Options") to employees and other persons in substitution of stock options previously granted to them in connection with their performance of services for such acquired entity upon such terms and conditions as the Committee shall determine but which shall not be contrary to applicable law, taking into account the limitations of Code Section 424(a) in the case of any Substitute Option that is intended to be an Incentive Stock Option.

2

5. Administration.

    (a) This Plan shall be administered by a Committee consisting of two or more members of the Board appointed by the Board. The Board may remove members from, or add members to, the Committee at any time. To the extent possible and advisable, the Committee shall be composed of individuals who satisfy Rule 16b-3 under the Exchange Act and Code Section 162(m). Notwithstanding anything herein to the contrary, any action which may be taken by the Committee may also be taken by the Board.

    (b) The Committee may conduct its meetings in person or by telephone. A majority of the members of the Committee shall constitute a quorum, and any action shall constitute the action of the Committee if it is authorized by:

     (i) A majority of the members present at any meeting conducted in accordance with the Company's bylaws; or

    (ii) The unanimous consent of all of the members in writing without a meeting.

    (c) The Committee is authorized to interpret this Plan and to adopt rules and procedures relating to the administration of this Plan. All actions of the Committee in connection with the interpretation and administration of this Plan shall be binding upon all parties.

    (d) Subject to the limitations set forth below, the Committee is expressly authorized to make such modifications to this Plan and the Options granted hereunder as are necessary to effectuate the intent of this Plan as a result of any changes in the tax, accounting, or securities laws treatment of Participants, the Company and the Plan.

    (e) The Committee may delegate its responsibilities to others under such conditions and limitations as it may prescribe, except that the Committee may not delegate its authority with regard to the granting of Options to Insiders if that would cause such grants to fail to satisfy Rule 16b-3 under the Exchange Act or Code Section 162(m).

6. Effective Date.

    This Plan shall be effective on December 19, 2001, provided it is approved by the holders of a majority of the Common Stock, at the Company's 2002 Annual Meeting. If the Plan is not approved by the stockholders at that meeting, the Plan and all Options issued under the Plan will terminate. The approval by the stockholders must relate to:

    (a) The class of individuals who are entitled to receive Incentive Stock Options; and

    (b) The maximum number of shares of Common Stock that may be issued under the Plan, except as adjusted pursuant to Section 13 of this Plan.

    If either of those items is changed, the approval of the stockholders must again be obtained.

7. Termination of Plan.

    This Plan shall terminate on December 18, 2011, except with respect to Options then outstanding. However, the Board may elect to terminate the Plan on a prior date. The termination of this Plan shall not adversely affect the rights of any Participant with respect to any Option outstanding as of the time of such termination.

8. Shares Subject to this Plan.

    (a) The maximum number of shares of Common Stock which may be issued pursuant to this Plan shall be Four Million (4,000,000). Upon the expiration or termination of an outstanding

3

Option which shall not have been exercised in full, the shares of Common Stock remaining unissued under the Option shall again become available for use under the Plan.

    (b) The maximum number of shares of Common Stock that may be issuable pursuant to Options granted during any calendar year to any Participant is two hundred thousand (200,000) shares. For purposes of determining the maximum number of shares that may be issued to a single Participant, shares subject to a terminated Option shall be considered outstanding.

    (c) In the event a Participant pays part or all of the exercise price of an Option by surrendering shares of Common Stock that the Participant previously acquired, only the number of shares issuable to the Participant in excess of those surrendered shall be taken into account for purposes of determining the maximum number of shares that may be issued under the Plan, both as to that Participant and in the aggregate (to all Participants).

9. Form of Options.

    (a) Options shall be granted under this Plan on such terms and in such form as the Committee may approve, which shall not be inconsistent with the provisions of this Plan, but which need not be the same for each such grant. Options may be either Nonqualified Stock Options or Incentive Stock Options.

    (b) The terms and conditions of each Option shall include, in addition to such other terms and conditions as may be established by the Committee, (i) the per share exercise price of such Option in accordance with subparagraph (c) below, (ii) the termination date of such Option, and (iii) the effect on such Option of the Participant's Severance. Subject to all other provisions of this Plan, each Option shall become exercisable (i) as to one-fourth (¹/4) of the full number of shares subject thereto one year after the date of grant and (ii) as to the balance in thirty-six (36) equal cumulative monthly installments following such first anniversary date, or in such other installments and at such other intervals as the Board or the Committee may in any specific case otherwise determine in granting such Option. Any Option shall be exercisable following the date of the Participant's Severance only to the extent (if at all) such Option was exercisable on the date of Severance.

    (c) The exercise price per share of Common Stock purchasable under an Option shall be set forth in the Option, which in all cases shall be at least equal to the Fair Market Value of the Common Stock on the date of the grant. The exercise price of an Incentive Stock Option granted to a Ten Percent Shareholder shall be no less than one hundred ten percent (110%) of the Fair Market Value of the Common Stock on the date of the grant.

    (d) Any Option which is intended, as evidenced by its designation, as an Incentive Stock Option shall be made subject to such terms and conditions as may be required for such Option to qualify as an Incentive Stock Option. Incentive Stock Options granted under this Plan shall also include a requirement that the Participant receiving such Incentive Stock Option must notify the Company if he or she disposes of Common Stock acquired pursuant to the exercise thereof prior to the expiration of the holding periods prescribed in Section 422(a)(1) of the Code.

    (e) If an Option is intended to be exempt from the million dollar ($1,000,000) compensation deduction limitation of Code Section 162(m), in addition to the exercise price requirement of subparagraph (c), the grant must be made by a committee composed exclusively of two (2) or more "outside directors" as that term is defined under Code Section 162(m).

10. Modification of Options.

    (a) The Committee may modify any existing Option as it deems appropriate. Such authority shall include, without limitation, the right to accelerate the right to exercise any Option, extend or

4

renew any Option, and modify any restrictions with respect to any Option. However, in no event will the exercise price of any outstanding Option be reduced or repriced (as determined under applicable accounting standards), including any repricing effected by issuing replacement stock options for outstanding stock options that have an exercise price greater than the Fair Market Value of the Common Stock, without first obtaining stockholder approval.

    (b) No modification may be made to any Option that would adversely affect the rights of the Participant holding the Option without the Participant's consent. Further, no such modification may be made within taking into consideration any consequences under Code Section 162(m).

    (c) In the event the Committee amends the terms of an Option so that it no longer qualifies as an Incentive Stock Option, the limitations imposed upon the Option under the Code and the Plan by virtue of it (formerly) qualifying as an Incentive Stock Option shall no longer apply, to the extent specified in the amendment.

    (d) Whether a modification of an existing Incentive Stock Option will be treated as the issuance of a new Incentive Stock Option will be determined in accordance with the rules of Code Section 424(h). Whether a modification of an existing Option granted to an Insider will be treated as a new grant for purposes of Section 16 of the Exchange Act will be determined in accordance with Rule 16b-3 under the Exchange Act.

11. Termination of Options.

    Except to the extent the terms of an Option require its prior termination, each Option shall terminate on the earliest of the following dates:

    (a) The date which is ten (10) years from the date on which the Option is granted or five (5) years in the case of an Incentive Stock Option granted to a Ten Percent Shareholder.

    (b) The date which is one (1) year from the date of the Severance of the Participant to whom the Option was granted, if the Participant was Disabled at the time of Severance.

    (c) The date which is one (1) year from the date of the Severance of the Participant to whom the Option was granted, if the Participant's death occurs:

     (i) While the Participant is employed by the Company; or

    (ii) Within three (3) months following the Participant's Severance.

    (d) In the case of any Severance other than one described in subparagraphs (b) or (c) above, the date that is three (3) months from the date of the Participant's Severance.

12. Non-transferability of Options.

    No Option under this Plan shall be assignable or transferable except by will or the laws of descent and distribution.

13. Adjustments

    (a) In the event of any change in the capitalization of the Company affecting its Common Stock (e.g., a stock split, reverse stock split, stock dividend, recapitalization, combination, or reclassification), the Committee shall authorize such adjustments as it may deem appropriate with respect to:

     (i) The maximum number of shares of Common Stock that may be issued under this Plan;

    (ii) The number of shares of Common Stock covered by each outstanding Option;

5

    (iii) The exercise price per share in respect of each outstanding Option; and

    (iv) The maximum number of shares that may be issued to a single individual.

    (b) The Committee may also make such adjustments in the event of a spin-off or other distribution of Company assets to stockholders, other than normal cash dividends.

14. Change in Control.

    In connection with any merger or consolidation of the Company with or into another entity in which the Company is not the surviving corporation or as a result of which the Common Stock ceases or will cease to be publicly traded, the Committee may, but shall not be required to, authorize the termination of all outstanding Options upon the consummation of such merger or consolidation. However, as a condition to such termination, all restrictions on the exercisability of such Options (i.e., vesting provisions) shall be eliminated and the holders thereof shall be given at least twenty (20) days prior to such termination to exercise their Options without regard to any such restrictions.

15. Amendment and Termination.

    (a) The Board may at any time amend or terminate this Plan. However, no modification may be made to the Plan that would impair the rights of the Participant holding an Option without the Participant's consent.

    (b) Without the approval of the holders of a majority of the Common Stock, the Board may not amend the provisions of this Plan for the purpose of:

     (i) Modifying the class of individuals entitled to receive Options;

    (ii) Increasing the maximum number of shares of Common Stock that may be issued under the Plan, except as provided in Section 13 of this Plan; or

    (iii) Materially increasing the benefits which accrue to Participants under this Plan.

16. Withholding.

    (a) The Company shall have the right to take such actions as may be necessary to satisfy its tax withholding obligations relating to the operation of this Plan.

    (b) If Common Stock that was surrendered by the Participant is used to satisfy the Company's tax withholding obligations, the stock shall be valued based on its Fair Market Value when the tax withholding is required to be made. The maximum number of shares that may be withheld is the minimum number of shares necessary to satisfy the applicable tax withholding rules.

17. Additional Rights.

    (a) Neither the adoption of this Plan nor the granting (or exercise) of any Option shall:

     (i) Affect or restrict in any way the power of the Company to undertake any corporate action otherwise permitted under applicable law;

    (ii) Confer upon any Participant the right to continue performing services for the Company; or

    (iii) Interfere in any way with the right of the Company to terminate the services of any Participant at any time, with or without cause, subject to such other contractual obligations as may exist.

6

    (b) No Participant shall have any rights as a stockholder with respect to any shares covered by an Option granted to the Participant until the date a certificate for such shares has been issued to the Participant following the exercise of the Option.

18. Securities Law Restrictions.

    (a) No shares of Common Stock shall be issued under this Plan unless the Committee shall be satisfied that the issuance will be in compliance with applicable federal and state securities laws, as well as the requirements of any stock exchange or quotation system upon which the Common Stock is listed or quoted.

    (b) The Committee may require certain investment (or other) representations and undertakings by the Participant (or other person exercising an Option by reason of the death of the Participant) in order to comply with applicable law.

    (c) Certificates for shares of Common Stock delivered under this Plan may be subject to such restrictions as the Committee may deem advisable. The Committee may cause a legend to be placed on the certificates to refer to these restrictions.

19. Indemnification.

    (a) To the maximum extent permitted by law, the Company shall indemnify each member of the Board, as well as any other employee of the Company with duties under this Plan, against expenses (including any amount paid in settlement) reasonably incurred by the individual in connection with any claims against him or her by reason of the performance of the individual's duties under this Plan, unless the losses are due to the individual's gross negligence or lack of good faith.

    (b) The Company will have the right to select counsel and to control the prosecution or defense of the suit.

    (c) In the event that more than one person who is entitled to indemnification is subject to the same claim, all such persons shall be represented by a single counsel, unless such counsel advises the Company in writing that he or she cannot represent all such persons under applicable rules of professional responsibility.

    (d) The Company will not be required to indemnify any person for any amount incurred through any settlement unless the Company consents in writing to the settlement.

20. Governing Law. This Plan and all actions taken thereunder shall be governed by and construed in accordance with the laws of the State of Delaware.

7

QuickLinks

Exhibit 10.15
Tetra Tech, Inc. 2002 Stock Option Plan

EX-10.16

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.16

Tetra Tech, Inc.
2002 Stock Option Plan

Incentive Stock Option Agreement

This Incentive Stock Option Agreement is dated as of ____________, ______ by and between Tetra Tech, Inc., a Delaware corporation ("Company") and ____________ ("Optionee") pursuant to the Company's 2002 Stock Option Plan ("Plan"). Capitalized terms that are used but not defined in this document shall have the meaning set forth in the Plan.

    Pursuant to authorization by the Committee of the Plan ("Committee") appointed by the Board of Directors of the Company, the parties agree as follows:

1. Grant of Option.

    (a) The Company hereby grants to the Optionee the right ("Option") to purchase all or any portion of ______ shares ("Shares") of the common stock of the Company ("Common Stock") at a purchase price of $______ per share ("Option Price").

    (b) It is intended that this Option will qualify for treatment as an incentive stock option under Internal Revenue Code ("Code") Section 422.

2. Term of Option.

    Except as provided in the Section of the Plan entitled "Change in Control," this Option shall terminate upon the earliest of the following events:

    (a) Ten (10) years from the date of this Option;

    (b) In the case of the termination of the Optionee's employment with the Company ("Severance"), the following rules shall apply in determining the date on which the Option shall terminate.

     (i) If the Optionee dies while employed by the Company or during the three (3) month period immediately subsequent to Optionee's Severance, the Option shall terminate one (1) year from the date of the Severance.

    (ii) If the Optionee was disabled (within the meaning of Section 22(e)(3) of the Code) at the time of Optionee's Severance, the Option shall terminate one (1) year following the Severance.

    (iii) In all other cases, the Option shall terminate three (3) months following the Severance.

    (c) If a Participant is transferred between the Company and a subsidiary thereof, or vice versa, or between subsidiaries, Severance shall not be deemed to have occurred.

3. Exercisability.

    (a) The Shares subject to this Option shall become exercisable ("vest") as follows, provided the Optionee is employed by the Company at the time of vesting:

     (i) As to one-fourth (¹/4) of the Shares on the first anniversary of the date hereof; and

    (ii) As to the balance of the Shares, in thirty-six (36) equal cumulative monthly installments following such first anniversary date.

    (b) These installments shall be cumulative, so that this Option may be exercised as to any or all of the Shares covered by an installment at any time or times after the installment becomes vested and until this Option terminates.

    (c) The Participant's Severance (whether by reason of death or otherwise) shall not accelerate the number of shares with respect to which an Option may be exercised.

4. Method of Exercising.

    This Option may be exercised by the Optionee upon delivery of the following documents to the Company at its principal executive offices:

    (a) Written notice specifying the number of full Shares to be purchased;

    (b) Payment of the full purchase price therefor in cash, by check, or in such other form of lawful consideration as the Committee may approve from time to time;

    (c) Such agreements or undertakings that are required by the Committee pursuant to the Plan; and

    (d) Payment of any taxes (including withholding taxes) which may be required by the Committee.

5. Assignments.

    (a) This Option shall be exercisable only by the Optionee during the Optionee's lifetime.

    (b) The rights of the Optionee under this Option may not be assigned or transferred except by will or by the laws of descent and distribution.

6. No Rights as a Stockholder.

    The Optionee shall have no rights as a stockholder of any Shares covered by this Option until the date a certificate for such Shares has been issued to him or her following the exercise of the Option.

7. Interpretation of Option.

    (a) This Option is made under the provisions of the Plan and shall be interpreted in a manner consistent with it.

    (b) Any provision in this Option inconsistent with the Plan shall be superseded and governed by the Plan, including Section 13 of the Plan relating to adjustments with respect to Options in the case of certain corporate events. A copy of the Plan is available to the Optionee at the Company's principal executive offices upon request and without charge.

8. Legends on Certificates.

    The Optionee acknowledges that the certificates representing the Shares issued upon exercise of this Option may bear such legends and be subject to such restrictions on transfer as the Company may deem necessary to comply with all applicable state and federal securities laws and regulations.

9. Amendments.

    This Option may be amended at any time with the consent of the Company and the Optionee.

2

IN WITNESS WHEREOF, the Company and the Optionee have executed this Option as of the date first written above.

OPTIONEE	TETRA TECH, INC.
	By:
Name:	Name:
	Title:

3

QuickLinks

Exhibit 10.16
Tetra Tech, Inc. 2002 Stock Option Plan Incentive Stock Option Agreement

EX-10.27

QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 10.27

REGISTRATION RIGHTS AGREEMENT

    This Registration Rights Agreement (the "Agreement") is entered into as of September 26, 2001 by and between Tetra Tech, Inc., a Delaware corporation ("Tetra Tech"), and Shepherd Miller, Inc., a Colorado corporation (the "Holder").

R E C I T A L S

    A.  Tetra Tech, the Holder, MFG Inc., a Delaware corporation and wholly-owned subsidiary of Tetra Tech ("Acquisition"), are parties to the Asset Purchase Agreement of even date (the "Asset Purchase Agreement"), pursuant to which Acquisition will purchase substantially all of the assets of the Holder.

    B.  Pursuant to the Asset Purchase Agreement, the Holder will receive 42,404 shares of the common stock, $.01 par value, of Tetra Tech ("Tetra Tech Common Stock"); and

    C.  This Agreement is the Registration Rights Agreement referred to in Section 7.2 of the Asset Purchase Agreement and, pursuant thereto, must be entered into by the parties in connection with the consummation of the transactions contemplated by the Asset Purchase Agreement.

A G R E E M E N T

    NOW, THEREFORE, in consideration of the mutual covenants and agreements contained herein, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

    1.  Certain Definitions.  As used in this Agreement, the following terms shall have the following respective meanings:

    "Exchange Act" shall mean the Securities Exchange Act of 1934, as amended from time to time.

    "Form S-3" shall mean such form under the Securities Act as in effect on the date hereof or any successor registration form under the Securities Act subsequently adopted by the SEC which permits inclusion or incorporation of substantial information by reference to other documents filed by Tetra Tech with the SEC.

    "Prospectus" shall mean the prospectus included in any Registration Statement, as amended or supplemented by any prospectus supplement, with respect to the terms of the offering of any portion of the Registrable Securities covered by the Registration Statement and by all other amendments and supplements to the prospectus, including post-effective amendments and all material incorporated by reference in such Prospectus.

    "Register", "registered" and "registration" shall mean and refer to a registration effected by preparing and filing a Registration Statement and taking all other actions that are necessary or appropriate in connection therewith, and the declaration or ordering of effectiveness of such Registration Statement by the SEC.

    "Registration Expenses" shall have the meaning set forth in Section 4.

    "Registrable Securities" shall mean the shares of Tetra Tech Common Stock (i) issued pursuant to the Asset Purchase Agreement, and (ii) issued as a dividend or other distribution with respect to or in exchange for or in replacement of the shares referenced in (i) above; provided, however, that Registrable Securities shall not include any shares of Tetra Tech Common Stock that have previously been registered and sold to the public or have been sold pursuant to Rule 144 (or similar successor Rule) after the date of this Agreement.

    "Registration Statement" shall mean any registration statement of Tetra Tech in compliance with the Securities Act that covers Registrable Securities pursuant to the provisions of this Agreement, including, without limitation, the Prospectus, all amendments and supplements to such Registration

Statement, including all post-effective amendments, all exhibits and all material incorporated by reference in such Registration Statement.

    "Rule 144" shall mean Rule 144 promulgated under the Securities Act or any similar successor rule, as the same shall be in effect from time to time.

    "Rule 144A" shall mean Rule 144A promulgated under the Securities Act or any similar successor rule, as the same shall be in effect from time to time.

    "Rule 415" shall mean Rule 415 promulgated under the Securities Act, or any similar successor rule, as the same shall be in effect from time to time.

    "Securities Act" shall mean the Securities Act of 1933, as amended from time to time.

    "SEC" shall mean the Securities and Exchange Commission.

    "Underwritten offering" shall mean a registration in which securities of Tetra Tech are sold to an underwriter or through an underwriter as agent for reoffering to the public.

    2.  Registration for the Holder.

    (a) Tetra Tech shall file a Registration Statement on Form S-3 providing for the registered sale by the Holder, pursuant to Rule 415, and/or any similar rule that may be adopted by the SEC, of the Registrable Securities from time to time during the effectiveness of the registration. Subject to subparagraph (c) below, Tetra Tech shall file such Registration Statement on or before October 1, 2001, and shall keep such Registration Statement continuously effective for a period ending on the date on which the Holder is eligible to sell Registrable Securities under Rule 144 (or similar successor rule) without any volume limitation. Tetra Tech represents and warrants that it is currently eligible to file a Registration Statement on Form S-3. However, if, at the time Tetra Tech is required to file a Registration Statement pursuant to this Section 2(a), Tetra Tech is not eligible to file a Registration Statement on Form S-3 to register resales by stockholders, Tetra Tech shall initially file a Registration Statement on Form S-1 and shall comply with the provisions of the immediately preceding sentence. Upon becoming eligible to use the Registration Statement on Form S-3 to register resales by stockholders (whether pursuant to a ruling or waiver from the SEC or otherwise), Tetra Tech shall promptly file a Registration Statement on Form S-3 or convert the existing Registration Statement to Form S-3 relating to the offer and sale of Registrable Securities by the Holder from time to time. Thereafter, Tetra Tech shall use commercially reasonable efforts to cause such new or amended Registration Statement to be declared effective by the SEC as promptly as practicable.

    (b) The Holder shall not have the right to register securities under this Agreement unless the Holder provides and/or confirms in writing prior to or after the filing of the Registration Statement such information (including, without limitation, information as to the number of Registrable Securities that the Holder has sold pursuant to any such Registration Statement from time to time) as Tetra Tech reasonably requests in connection with such Registration Statement.

    (c) Notwithstanding the foregoing, for a period not to exceed 90 days, Tetra Tech shall not be obligated to prepare and file the Registration Statement required hereunder if Tetra Tech, in its good faith judgment, reasonably believes that the filing of such Registration Statement would require the disclosure of material non-public information regarding Tetra Tech and, accordingly, that the filing thereof, at the time requested, or the offering of Tetra Tech Common Stock pursuant thereto, would materially and adversely affect (i) a pending or scheduled public offering or private placement of securities of Tetra Tech, (ii) an acquisition, merger, consolidation or similar transaction by or of Tetra Tech, (iii) preexisting and continuing negotiations, discussions or pending proposals with respect to any of the foregoing transactions, or (iv) the financial condition of Tetra

2

Tech in view of the disclosure of any pending or threatened litigation, claim, assessment or governmental investigation which might be required thereby.

    In the event that Tetra Tech, in good faith, reasonably believes that such conditions are continuing after such 90-day period, it may, with the consent of the Holder, which consent shall not be unreasonably withheld, extend such 90-day period for an additional 30 days. Any further delay shall require the consent of the Holder.

    In the event of any delay in the filing of the Registration Statement pursuant to this subparagraph (c), Tetra Tech will effect such filing as soon as practicable.

    3.  Registration Procedures.  In connection with Tetra Tech's registration obligations pursuant to Section 2 hereof, Tetra Tech will use commercially reasonable efforts to effect such registration to permit the sale of the Registrable Securities covered thereby in accordance with the Holder's intended method or methods of disposition thereof (which shall include, without limitation, cash sales in market or other transactions), and pursuant thereto Tetra Tech will:

    (a) prepare and file with the SEC a Registration Statement with respect to such Registrable Securities and use its commercially reasonable efforts to cause such Registration Statement to become effective as soon as practicable; provided that, before filing any Registration Statement or Prospectus or any amendments or supplements thereto, Tetra Tech will furnish to the Holder and its counsel, copies of all such documents proposed to be filed at least ten days prior thereto, and Tetra Tech will not file any such Registration Statement or amendment thereto or any Prospectus or any supplement thereto to which the Holder shall reasonably object within such ten day period; provided, further, that Tetra Tech will not name or otherwise provide any information with respect to the Holder in any Registration Statement or Prospectus without the express written consent of the Holder, unless required to do so by the Securities Act and the rules and regulations thereunder;

    (b) prepare and file with the SEC such amendments, post-effective amendments and supplements to the Registration Statement and the Prospectus as may be necessary to comply with the provisions of the Securities Act and the rules and regulations thereunder with respect to the disposition of all securities covered by such Registration Statement, including but not limited to such amendments, post-effective amendments and supplements as may be necessary to list as selling stockholders under the Registration Statement and Prospectus each shareholder of the Holder who receives a distribution from the Holder of Registrable Securities;

    (c) notify the Holder (i) when the Prospectus or any Prospectus supplement or post-effective amendment has been filed, and, with respect to the Registration Statement or any post-effective amendment, when the same has become effective, (ii) of any request by the SEC for amendments or supplements to the Registration Statement or the Prospectus or for additional information, (iii) of the issuance by the SEC of any stop order suspending the effectiveness of the Registration Statement or the initiation of any proceedings for that purpose, (iv) of the receipt by Tetra Tech of any notification with respect to the suspension of the qualification of the Registrable Securities for sale in any jurisdiction or the initiation or threatening of any proceeding for such purpose and (v) of the happening of any event which makes any statement made in the Registration Statement, the Prospectus or any document incorporated therein by reference untrue or which requires the making of any changes in the Registration Statement, the Prospectus or any document incorporated therein by reference in order to make the statements therein not misleading in light of the circumstances then existing;

    (d) make every commercially reasonable effort to obtain the withdrawal of any order suspending the effectiveness of the Registration Statement at the earliest possible moment;

3

    (e) deliver to the Holder, without charge, such reasonable number of conformed copies of the Registration Statement (and any post-effective amendment thereto) and such number of copies of the Prospectus (including each preliminary prospectus) and any amendment or supplement thereto (and any documents incorporated by reference therein) as the Holder may reasonably request. Tetra Tech consents to the use of the Prospectus or any amendment or supplement thereto by the Holder in connection with the offer and sale of the Registrable Securities covered by the Prospectus or any amendment or supplement thereto;

    (f)  prior to any offering of Registrable Securities covered by a Registration Statement, register or qualify or cooperate with the Holder in connection with the registration or qualification of such Registrable Securities for offer and sale under the securities or blue sky laws of such jurisdictions as the Holder reasonably requests, and use commercially reasonable efforts to keep each such registration or qualification effective, including through new filings, or amendments or renewals, during the period such Registration Statement is required to be kept effective pursuant to the terms of this Agreement; and do any and all other acts or things necessary or advisable to enable the disposition in all such jurisdictions reasonably requested by the Holder of the Registrable Securities covered by such Registration Statement, provided that under no circumstances shall Tetra Tech be required in connection therewith or as a condition thereof to qualify to do business or to file a general consent to service of process in any such states or jurisdictions;

    (g) cooperate with the Holder to facilitate the timely preparation and delivery of certificates representing Registrable Securities to be sold, free of any and all restrictive legends, such certificates to be in such denominations and registered in such names as the Holder may request;

    (h) upon the occurrence of any event contemplated by Section 3(c)(v) above, prepare a supplement or post-effective amendment to the Registration Statement or the Prospectus or any document incorporated therein by reference or file any other required document so that, as thereafter delivered to the purchasers of the Registrable Securities, the Prospectus will not contain an untrue statement of a material fact or omit to state any material fact necessary to make the statements therein, in light of the circumstances under which they were made, not misleading;

    (i)  make generally available to the holders of Tetra Tech's outstanding securities earnings statements satisfying the provisions of Section 11(a) of the Securities Act, no later than 60 days after the end of any 12 month period (or 90 days, if such period is a fiscal year) beginning with the first month of Tetra Tech's first fiscal quarter commencing after the effective date of the Registration Statement, which statements shall cover said 12 month period;

    (j)  provide and cause to be maintained a transfer agent and registrar for all Registrable Securities covered by each Registration Statement from and after a date not later than the effective date of such Registration Statement;

    (k) use its reasonable best efforts to cause all Registrable Securities covered by each Registration Statement to be listed, subject to notice of issuance, prior to the date of the first sale of such Registrable Securities pursuant to such Registration Statement, on each securities exchange on which the Tetra Tech Common Stock is then listed, and admitted to trading on the Nasdaq Stock Market, if the Tetra Tech Common Stock is then admitted to trading on the Nasdaq Stock Market;

    (l)  enter into such agreements (including underwriting agreements in customary form containing, among other things, reasonable and customary indemnities) and take such other actions as the Holder shall reasonably request in order to expedite or facilitate the disposition of such Registrable Securities; and

4

    (m) cooperate with the Holder and the managing underwriter or underwriters in their marketing efforts with respect to the sale of the Registrable Securities, including participation by Tetra Tech management in "road show" presentations.

    The Holder agrees that, upon receipt of any notice from Tetra Tech of the happening of any event of the kind described in Section 3(c)(v) hereof, the Holder will forthwith discontinue disposition of Registrable Securities under the Prospectus related to the applicable Registration Statement until the Holder's receipt of the copies of the supplemented or amended Prospectus contemplated by Section 3(h) hereof, or until it is advised in writing by Tetra Tech that the use of the Prospectus may be resumed.

    It shall be a condition precedent to the obligations of Tetra Tech to take any action pursuant to this Section 3 with respect to the Registrable Securities of the Holder that the Holder shall furnish to Tetra Tech upon request such information regarding itself and the Registrable Securities held by it as shall be required by the Securities Act to effect the registration of the Holder's Registrable Securities.

    4.  Registration Expenses.  All expenses incident to any registration to be effected hereunder and incident to Tetra Tech's performance of or compliance with this Agreement, including without limitation all registration and filing fees, fees and expenses of compliance with securities or blue sky laws, printing expenses, messenger and delivery expenses, National Association of Securities Dealers, Inc., stock exchange and qualification fees, fees and disbursements of Tetra Tech's counsel and of independent certified public accountants of Tetra Tech (including the expenses of any special audit required by or incident to such performance), the fees and disbursements of one counsel and one accountant representing the Holder in such offering, expenses of the underwriters that are customarily requested in similar circumstances by such underwriters (excluding discounts, commissions or fees of underwriters, selling brokers, dealer managers or similar securities industry professionals relating to the distribution of the Registrable Securities, which will be borne by the Holder), all such expenses being herein called "Registration Expenses," will be borne by Tetra Tech. Tetra Tech will also pay its internal expenses, the expense of any annual audit and the fees and expenses of any person retained by Tetra Tech.

    5.  Indemnification.

    (a)  Indemnification by Tetra Tech.  Tetra Tech agrees to indemnify and hold harmless the Holder, its officers, directors, partners, agents, representatives, attorneys and employees and each person who controls the Holder (within the meaning of Section 15 of the Securities Act) from and against any and all losses, claims, damages and liabilities (including any investigation, legal or other expenses reasonably incurred in connection with, and any amount paid in settlement of, any action, suit or proceeding or any claim asserted) (collectively, "Damages") to which the Holder may become subject under the Securities Act, the Exchange Act or other federal or state securities law or regulation, at common law or otherwise, insofar as such Damages arise out of or are based upon (i) any untrue statement or alleged untrue statement of a material fact contained in any Registration Statement, Prospectus or preliminary prospectus or any amendment or supplement thereto, (ii) the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading or (iii) any violation or alleged violation by Tetra Tech of the Securities Act, the Exchange Act or any state securities or blue sky laws in connection with the Registration Statement, Prospectus or preliminary prospectus or any amendment or supplement thereto, provided that Tetra Tech will not be liable to the Holder to the extent that such Damages arise from or are based upon any untrue statement or omission (x) based upon written information furnished to Tetra Tech by the Holder expressly for the inclusion in such Registration Statement, (y) made in any preliminary prospectus if the Holder failed to deliver a copy of the Prospectus with or prior to the delivery of written confirmation of the sale by the Holder to the party asserting the claim underlying such Damages and such Prospectus would have corrected such

5

untrue statement or omission and (z) made in any Prospectus if such untrue statement or omission was corrected in an amendment or supplement to such Prospectus which was delivered to the Holder prior to the Holder's sale and the Holder failed to deliver such amendment or supplement prior to or concurrently with the sale of Registrable Securities to the party asserting the claim underlying such Damages.

    (b)  Indemnification by Holder of Registrable Securities.  The Holder agrees to indemnify and hold harmless Tetra Tech, its directors and each officer who signed such Registration Statement and each person who controls Tetra Tech (within the meaning of Section 15 of the Securities Act), under the same circumstances as the foregoing indemnity from Tetra Tech to the Holder but only if and to the extent that such losses, claims, damages, liabilities or actions arise out of or are based upon any untrue statement of a material fact or omission of a material fact that was made in the Prospectus, the Registration Statement, or any amendment or supplement thereto, in reliance upon and in conformity with information relating to the Holder furnished in writing to Tetra Tech by the Holder expressly for use therein, provided that in no event shall the aggregate liability of the Holder exceed the amount of the net proceeds received by the Holder upon the sale of the Registrable Securities giving rise to such indemnification obligation. Tetra Tech and the Holder shall be entitled to receive indemnities from underwriters, selling brokers, dealer managers and similar securities industry professionals participating in the distribution, to the same extent as customarily furnished by such persons in similar circumstances.

    (c)  Conduct of Indemnification Proceedings.  Any person entitled to indemnification hereunder will (i) give prompt notice to the indemnifying party of any claim with respect to which it seeks indemnification and (ii) permit such indemnifying party to assume the defense of such claim with counsel reasonably satisfactory to the indemnified party; provided, however, that any person entitled to indemnification hereunder shall have the right to employ separate counsel and to participate in the defense of such claim, but the fees and expenses of such counsel shall be at the expense of such person and not of the indemnifying party unless (A) the indemnifying party has agreed to pay such fees or expenses, (B) the indemnifying party shall have failed to assume the defense of such claim and employ counsel reasonably satisfactory to such person or (C) in the reasonable judgment of such person and the indemnifying party, based upon advice of their respective counsel, a conflict of interest may exist between such person and the indemnifying party with respect to such claims (in which case, if the person notifies the indemnifying party in writing that such person elects to employ separate counsel at the expense of the indemnifying party, the indemnifying party shall not have the right to assume the defense of such claim on behalf of such person). If such defense is not assumed by the indemnifying party, the indemnifying party will not be subject to any liability for any settlement made without its consent (but such consent will not be unreasonably withheld). No indemnified party will be required to consent to entry of any judgment or enter into any settlement which does not include as an unconditional term thereof the giving by all claimants or plaintiffs to such indemnified party of a release from all liability in respect to such claim or litigation. Any indemnifying party who is not entitled to, or elects not to, assume the defense of a claim will not be obligated to pay the fees and expenses of more than one counsel for all parties indemnified by such indemnifying party with respect to such claim. As used in this Section 5(c), the terms "indemnifying party", "indemnified party" and other terms of similar import are intended to include only Tetra Tech (and its officers, directors and control persons as set forth above) on the one hand, and the Holder (and its officers, directors, partners, employees, attorneys and control persons as set forth above) on the other hand, as applicable.

    (d)  Contribution.  If for any reason the foregoing indemnity is unavailable under applicable law, then the indemnifying party shall contribute to the amount paid or payable by the indemnified party as a result of such losses, claims, damages, liabilities or expenses in such proportion as is appropriate to reflect the relative fault of the indemnifying party and the indemnified party in

6

connection with the statements or omissions which resulted in such losses, claims, damages, liabilities or expenses, as well as any other relevant equitable considerations. The relative fault of such indemnifying party and indemnified party shall be determined by reference to, among other things, whether the untrue statement or alleged untrue statement of a material fact or omission or alleged omission to state a material fact relates to information supplied by such indemnifying party or by such indemnified party, and the parties' relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The parties acknowledge and agree that it would not be just and equitable if contribution pursuant to this Section 5(d) were determined by pro rata allocation or by any other method of allocation which does not take into account the equitable considerations referred to in this Section 5(d). Notwithstanding the foregoing, the Holder shall not be required to contribute any amount in excess of the amount the Holder would have been required to pay to an indemnified party if the indemnity under Section 5(b) hereof was available. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation joint.

    (e)  Timing of Payments.  An indemnifying party shall make payments of all amounts required to be made pursuant to the foregoing provisions of this Section 5 to or for the account of the indemnified party from time to time promptly upon receipt of bills or invoices relating thereto or when otherwise due or payable.

    (f)  Survival.  The indemnity and contribution agreements contained in this Section 5 shall remain in full force and effect, regardless of any investigation made by or on behalf of Tetra Tech, the Holder, its officers, directors, partners, attorneys, agents or any person, if any, who controls Tetra Tech or the Holder as aforesaid, and shall survive the transfer of such Registrable Securities by the Holder.

    6.  Preparation; Reasonable Investigation.  In connection with the preparation and filing of a Registration Statement pursuant to the terms of this Agreement:

    (a) Tetra Tech shall, with respect to a Registration Statement filed pursuant to Section 2, give the Holder, its underwriters, if any, and their respective counsel and accountants the opportunity to participate in the preparation of such Registration Statement (other than reports and proxy statements incorporated therein by reference and properly filed with the SEC) and each Prospectus included therein or filed with the SEC, and each amendment thereof or supplement thereto; and

    (b) Tetra Tech shall give the Holder, its underwriters, if any, and their respective counsel and accountants such reasonable access to its books and records and such opportunities to discuss the business of Tetra Tech with its officers and the independent public accountants who have certified its financial statements as shall be necessary, in the opinion of the Holder or such underwriters, to conduct a reasonable investigation within the meaning of Section 11(b)(3) of the Securities Act.

    7.  Rule 144.  Tetra Tech covenants that it will use commercially reasonable efforts to file, on a timely basis, the reports required to be filed by it under the Securities Act and the Exchange Act and the rules and regulations adopted by the SEC thereunder, and it will take such further action as the Holder may reasonably request (including, without limitation, compliance with the current public information requirements of Rule 144(c) and Rule 144A), all to the extent required from time to time to enable the Holder to sell Registrable Securities without registration under the Securities Act within the limitation of the conditions provided by Rule 144, Rule 144A or any similar rule or regulation hereafter adopted by the SEC. Upon the request of the Holder, Tetra Tech will promptly deliver to the Holder a written statement verifying that it has complied with such information and requirements.

7

    8.  Specific Performance.  The Holder, in addition to being entitled to exercise all rights provided herein or granted by law, including recovery of damages, will be entitled to specific performance of its rights under this Agreement. Tetra Tech agrees that monetary damages would not be adequate compensation for any loss incurred by reason of a breach by it of the provisions of this Agreement and hereby agrees to waive the defense in any action for specific performance that a remedy at law would be adequate.

    9.  Notices.  All notices and other communications required or permitted hereunder shall be in writing and shall be mailed by United States first-class mail, postage prepaid, sent by facsimile or delivered personally by hand or nationally recognized courier addressed (a) if to the Holder, at such address for the Holder set forth in the Asset Purchase Agreement, or at such other address as the Holder or permitted assignee shall have furnished to Tetra Tech in writing, or (b) if to Tetra Tech, at such address for Tetra Tech set forth in the Asset Purchase Agreement. All such notices and other written communications shall be effective on the date of mailing, facsimile transfer or delivery.

    10.  Successors and Assigns: Assignment of Rights.  The rights and benefits of the Holder hereunder may not be assigned to a transferee or assignee without the consent of Tetra Tech, which consent shall not be unreasonably withheld. Notwithstanding the foregoing, this Agreement shall be freely assignable by Holder in connection with a sale or transfer of the Common Stock in which Tetra Tech may legend the replacement certificates under Section 7 of the Investment Letter (as defined in the Asset Purchase Agreement), including but not limited to transfers in connection with distributions of Registrable Securities to the shareholders of the Holder on or after the date hereof.

    11.  Severability.  In the event that any one or more of the provisions contained herein, or the application thereof in any circumstance, is held invalid, illegal or unenforceable, the validity, legality and enforceability of any such provision in every other respect and of the remaining provisions contained herein shall not be affected or impaired thereby.

    12.  Entire Agreement; Amendment; Waiver.  This Agreement, the Asset Purchase Agreement and the other agreements contemplated thereby constitute the full and entire understanding and agreement among the parties with regard to the subjects hereof and thereof. Without limiting the foregoing, the rights of the Holder to registration pursuant to the terms of this Agreement shall be subject to the limitations on resale contained in the Investment Letter (as defined in the Asset Purchase Agreement). Neither this Agreement nor any term hereof may be amended, waived, discharged or terminated, except by a written instrument signed by Tetra Tech and the Holder and any such amendment, waiver, discharge or termination shall be binding upon all the parties hereto, but in no event shall the obligation of any party hereto be materially increased, except upon the written consent of such party.

    13.  Counterparts.  This Agreement may be executed in any number of counterparts, each of which shall be original, and all of which together shall constitute one instrument.

    14.  Governing Law.  This Agreement shall be governed by, and construed in accordance with, the laws of the State of Delaware without giving effect to principles of conflicts of laws thereof.

    15.  No Third Party Beneficiaries.  The covenants and agreements set forth herein are for the sole and exclusive benefit of the parties hereto and their respective successors and assigns and such covenants and agreements shall not be construed as conferring, and are not intended to confer, any rights or benefits upon any other persons.

8

    IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the day and year first above written.

TETRA TECH, INC.
By:	/s/ LI-SAN HWANG Li-San Hwang President and Chief Executive Officer
SHEPHERD MILLER, INC.
By:	/s/ THOMAS A. SHEPHERD

9

QuickLinks

EXHIBIT 10.27
REGISTRATION RIGHTS AGREEMENT
R E C I T A L S
A G R E E M E N T

EX-10.28

QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 10.28

REGISTRATION RIGHTS AGREEMENT

    This Registration Rights Agreement (the "Agreement") is entered into as of September 26, 2001 by and between Tetra Tech, Inc., a Delaware corporation ("Tetra Tech"), and Elizabeth L. Anderson, an individual (the "Holder").

R E C I T A L S

    A.  Tetra Tech and the Holder are parties to the Agreement and Plan of Reorganization of even date (the "Reorganization Agreement"), pursuant to which Science International, Inc., a Delaware corporation ("SII"), will merge with and into SII Acquisition Corporation, a Delaware corporation and wholly-owned subsidiary of Tetra Tech.

    B.  Pursuant to the Reorganization Agreement, the Holder will receive 110,007 shares of the common stock, $.01 par value, of Tetra Tech ("Tetra Tech Common Stock"); and

    C.  This Agreement is the Registration Rights Agreement referred to in Section 6.2 of the Reorganization Agreement and, pursuant thereto, must be entered into by the parties in connection with the consummation of the transactions contemplated by the Reorganization Agreement.

A G R E E M E N T

    NOW, THEREFORE, in consideration of the mutual covenants and agreements contained herein, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

    1.  Certain Definitions.  As used in this Agreement, the following terms shall have the following respective meanings:

    "Exchange Act" shall mean the Securities Exchange Act of 1934, as amended from time to time.

    "Form S-3" shall mean such form under the Securities Act as in effect on the date hereof or any successor registration form under the Securities Act subsequently adopted by the SEC which permits inclusion or incorporation of substantial information by reference to other documents filed by Tetra Tech with the SEC.

    "Prospectus" shall mean the prospectus included in any Registration Statement, as amended or supplemented by any prospectus supplement, with respect to the terms of the offering of any portion of the Registrable Securities covered by the Registration Statement and by all other amendments and supplements to the prospectus, including post-effective amendments and all material incorporated by reference in such Prospectus.

    "Register", "registered" and "registration" shall mean and refer to a registration effected by preparing and filing a Registration Statement and taking all other actions that are necessary or appropriate in connection therewith, and the declaration or ordering of effectiveness of such Registration Statement by the SEC.

    "Registration Expenses" shall have the meaning set forth in Section 4.

    "Registrable Securities" shall mean the shares of Tetra Tech Common Stock (i) issued pursuant to the Reorganization Agreement (including, if applicable, shares of Tetra Tech Common Stock issued under Article 8 thereof), and (ii) issued as a dividend or other distribution with respect to or in exchange for or in replacement of the shares referenced in (i) above; provided, however, that Registrable Securities shall not include any shares of Tetra Tech Common Stock that have previously been registered and sold to the public or have been sold pursuant to Rule 144 (or similar successor Rule) after the date of this Agreement.

    "Registration Statement" shall mean any registration statement of Tetra Tech in compliance with the Securities Act that covers Registrable Securities pursuant to the provisions of this Agreement,

including, without limitation, the Prospectus, all amendments and supplements to such Registration Statement, including all post-effective amendments, all exhibits and all material incorporated by reference in such Registration Statement.

    "Rule 144" shall mean Rule 144 promulgated under the Securities Act or any similar successor rule, as the same shall be in effect from time to time.

    "Rule 144A" shall mean Rule 144A promulgated under the Securities Act or any similar successor rule, as the same shall be in effect from time to time.

    "Rule 415" shall mean Rule 415 promulgated under the Securities Act, or any similar successor rule, as the same shall be in effect from time to time.

    "Securities Act" shall mean the Securities Act of 1933, as amended from time to time.

    "SEC" shall mean the Securities and Exchange Commission.

    "Underwritten offering" shall mean a registration in which securities of Tetra Tech are sold to an underwriter or through an underwriter as agent for reoffering to the public.

    2.  Registration for the Holder.

    (a) Tetra Tech shall file a Registration Statement on Form S-3 providing for the registered sale by the Holder, pursuant to Rule 415, and/or any similar rule that may be adopted by the SEC, of the Registrable Securities from time to time during the effectiveness of the registration. Tetra Tech shall file such Registration Statement on or before September 27, 2001, and shall keep such Registration Statement continuously effective for a period ending on the date on which the Holder is eligible to sell Registrable Securities under Rule 144 (or similar successor rule) without any volume limitation. Tetra Tech represents and warrants that it is currently eligible to file a Registration Statement on Form S-3. Tetra Tech further represents and warrants that upon the effective date of the Registration Statement the Holder shall have the right to transfer the Registrable Securities in the absence of any event described in Section 3(c)(v) below.

    (b) The Holder shall not have the right to register securities under this Agreement unless the Holder provides and/or confirms in writing prior to or after the filing of the Registration Statement such information (including, without limitation, information as to the number of Registrable Securities that the Holder has sold pursuant to any such Registration Statement from time to time) as Tetra Tech reasonably requests in connection with such Registration Statement.

    3.  Registration Procedures.  In connection with Tetra Tech's registration obligations pursuant to Section 2 hereof, Tetra Tech will use commercially reasonable efforts to effect such registration to permit the sale of the Registrable Securities covered thereby in accordance with the Holder's intended method or methods of disposition thereof (which shall include, without limitation, cash sales in market or other transactions), and pursuant thereto Tetra Tech will:

    (a) prepare and file with the SEC a Registration Statement with respect to such Registrable Securities and use its commercially reasonable efforts to cause such Registration Statement to become effective as soon as practicable; provided that, before filing any Registration Statement or Prospectus or any amendments or supplements thereto, Tetra Tech will furnish to the Holder and its counsel, copies of all such documents proposed to be filed at least two days prior thereto, and Tetra Tech will not file any such Registration Statement or amendment thereto or any Prospectus or any supplement thereto to which the Holder shall reasonably object within such two day period; provided, further, that Tetra Tech will not name or otherwise provide any information with respect to the Holder in any Registration Statement or Prospectus without the express written consent of the Holder, unless required to do so by the Securities Act and the rules and regulations thereunder;

2

    (b) prepare and file with the SEC such amendments, post-effective amendments and supplements to the Registration Statement and the Prospectus as may be necessary to comply with the provisions of the Securities Act and the rules and regulations thereunder with respect to the disposition of all securities covered by such Registration Statement;

    (c) notify the Holder (i) when the Prospectus or any Prospectus supplement or post-effective amendment has been filed, and, with respect to the Registration Statement or any post-effective amendment, when the same has become effective, (ii) of any request by the SEC for amendments or supplements to the Registration Statement or the Prospectus or for additional information, (iii) of the issuance by the SEC of any stop order suspending the effectiveness of the Registration Statement or the initiation of any proceedings for that purpose, (iv) of the receipt by Tetra Tech of any notification with respect to the suspension of the qualification of the Registrable Securities for sale in any jurisdiction or the initiation or threatening of any proceeding for such purpose and (v) of the happening of any event which makes any statement made in the Registration Statement, the Prospectus or any document incorporated therein by reference untrue or which requires the making of any changes in the Registration Statement, the Prospectus or any document incorporated therein by reference in order to make the statements therein not misleading in light of the circumstances then existing;

    (d) make every commercially reasonable effort to obtain the withdrawal of any order suspending the effectiveness of the Registration Statement at the earliest possible moment;

    (e) deliver to the Holder, without charge, such reasonable number of conformed copies of the Registration Statement (and any post-effective amendment thereto) and such number of copies of the Prospectus (including each preliminary prospectus) and any amendment or supplement thereto (and any documents incorporated by reference therein) as the Holder may reasonably request. Tetra Tech consents to the use of the Prospectus or any amendment or supplement thereto by the Holder in connection with the offer and sale of the Registrable Securities covered by the Prospectus or any amendment or supplement thereto;

    (f)  prior to any offering of Registrable Securities covered by a Registration Statement, register or qualify or cooperate with the Holder in connection with the registration or qualification of such Registrable Securities for offer and sale under the securities or blue sky laws of such jurisdictions as the Holder reasonably requests, and use commercially reasonable efforts to keep each such registration or qualification effective, including through new filings, or amendments or renewals, during the period such Registration Statement is required to be kept effective pursuant to the terms of this Agreement; and do any and all other acts or things necessary or advisable to enable the disposition in all such jurisdictions reasonably requested by the Holder of the Registrable Securities covered by such Registration Statement, provided that under no circumstances shall Tetra Tech be required in connection therewith or as a condition thereof to qualify to do business or to file a general consent to service of process in any such states or jurisdictions;

    (g) cooperate with the Holder to facilitate the timely preparation and delivery of certificates representing Registrable Securities to be sold, free of any and all restrictive legends, such certificates to be in such denominations and registered in such names as the Holder may request;

    (h) upon the occurrence of any event contemplated by Section 3(c)(v) above, prepare a supplement or post-effective amendment to the Registration Statement or the Prospectus or any document incorporated therein by reference or file any other required document so that, as thereafter delivered to the purchasers of the Registrable Securities, the Prospectus will not contain an untrue statement of a material fact or omit to state any material fact necessary to make the statements therein, in light of the circumstances under which they were made, not misleading;

3

    (i)  make generally available to the holders of Tetra Tech's outstanding securities earnings statements satisfying the provisions of Section 11(a) of the Securities Act, no later than 60 days after the end of any 12 month period (or 90 days, if such period is a fiscal year) beginning with the first month of Tetra Tech's first fiscal quarter commencing after the effective date of the Registration Statement, which statements shall cover said 12 month period;

    (j)  provide and cause to be maintained a transfer agent and registrar for all Registrable Securities covered by each Registration Statement from and after a date not later than the effective date of such Registration Statement;

    (k) use its reasonable best efforts to cause all Registrable Securities covered by each Registration Statement to be listed, subject to notice of issuance, prior to the date of the first sale of such Registrable Securities pursuant to such Registration Statement, on each securities exchange on which the Tetra Tech Common Stock is then listed, and admitted to trading on the Nasdaq Stock Market, if the Tetra Tech Common Stock is then admitted to trading on the Nasdaq Stock Market;

    (l)  enter into such agreements (including underwriting agreements in customary form containing, among other things, reasonable and customary indemnities) and take such other actions as the Holder shall reasonably request in order to expedite or facilitate the disposition of such Registrable Securities; and

    (m) cooperate with the Holder and the managing underwriter or underwriters in their marketing efforts with respect to the sale of the Registrable Securities, including participation by Tetra Tech management in "road show" presentations.

    The Holder agrees that, upon receipt of any notice from Tetra Tech of the happening of any event of the kind described in Section 3(c)(v) hereof, the Holder will forthwith discontinue disposition of Registrable Securities under the Prospectus related to the applicable Registration Statement until the Holder's receipt of the copies of the supplemented or amended Prospectus contemplated by Section 3(h) hereof, or until it is advised in writing by Tetra Tech that the use of the Prospectus may be resumed.

    It shall be a condition precedent to the obligations of Tetra Tech to take any action pursuant to this Section 3 with respect to the Registrable Securities of the Holder that the Holder shall furnish to Tetra Tech upon request such information regarding itself and the Registrable Securities held by it as shall be required by the Securities Act to effect the registration of the Holder's Registrable Securities.

    4.  Registration Expenses.  All expenses incident to any registration to be effected hereunder and incident to Tetra Tech's performance of or compliance with this Agreement, including without limitation all registration and filing fees, fees and expenses of compliance with securities or blue sky laws, printing expenses, messenger and delivery expenses, National Association of Securities Dealers, Inc., stock exchange and qualification fees, fees and disbursements of Tetra Tech's counsel and of independent certified public accountants of Tetra Tech (including the expenses of any special audit required by or incident to such performance), the fees and disbursements of one counsel and one accountant representing the Holder in such offering, expenses of the underwriters that are customarily requested in similar circumstances by such underwriters (excluding discounts, commissions or fees of underwriters, selling brokers, dealer managers or similar securities industry professionals relating to the distribution of the Registrable Securities, which will be borne by the Holder), all such expenses being herein called "Registration Expenses," will be borne by Tetra Tech. Tetra Tech will also pay its internal expenses, the expense of any annual audit and the fees and expenses of any person retained by Tetra Tech.

4

    5.  Indemnification.

    (a)  Indemnification by Tetra Tech.  Tetra Tech agrees to indemnify and hold harmless the Holder, its officers, directors, partners, agents, representatives, attorneys and employees and each person who controls the Holder (within the meaning of Section 15 of the Securities Act) from and against any and all losses, claims, damages and liabilities (including any investigation, legal or other expenses reasonably incurred in connection with, and any amount paid in settlement of, any action, suit or proceeding or any claim asserted) (collectively, "Damages") to which the Holder may become subject under the Securities Act, the Exchange Act or other federal or state securities law or regulation, at common law or otherwise, insofar as such Damages arise out of or are based upon (i) any untrue statement or alleged untrue statement of a material fact contained in any Registration Statement, Prospectus or preliminary prospectus or any amendment or supplement thereto, (ii) the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading or (iii) any violation or alleged violation by Tetra Tech of the Securities Act, the Exchange Act or any state securities or blue sky laws in connection with the Registration Statement, Prospectus or preliminary prospectus or any amendment or supplement thereto, provided that Tetra Tech will not be liable to the Holder to the extent that such Damages arise from or are based upon any untrue statement or omission (x) based upon written information furnished to Tetra Tech by the Holder expressly for the inclusion in such Registration Statement, (y) made in any preliminary prospectus if the Holder failed to deliver a copy of the Prospectus with or prior to the delivery of written confirmation of the sale by the Holder to the party asserting the claim underlying such Damages and such Prospectus would have corrected such untrue statement or omission and (z) made in any Prospectus if such untrue statement or omission was corrected in an amendment or supplement to such Prospectus which was delivered to the Holder prior to the Holder's sale and the Holder failed to deliver such amendment or supplement prior to or concurrently with the sale of Registrable Securities to the party asserting the claim underlying such Damages.

    (b)  Indemnification by Holder of Registrable Securities.  The Holder agrees to indemnify and hold harmless Tetra Tech, its directors and each officer who signed such Registration Statement and each person who controls Tetra Tech (within the meaning of Section 15 of the Securities Act), under the same circumstances as the foregoing indemnity from Tetra Tech to the Holder but only if and to the extent that such losses, claims, damages, liabilities or actions arise out of or are based upon any untrue statement of a material fact or omission of a material fact that was made in the Prospectus, the Registration Statement, or any amendment or supplement thereto, in reliance upon and in conformity with information relating to the Holder furnished in writing to Tetra Tech by the Holder expressly for use therein, provided that in no event shall the aggregate liability of the Holder exceed the amount of the net proceeds received by the Holder upon the sale of the Registrable Securities giving rise to such indemnification obligation. Tetra Tech and the Holder shall be entitled to receive indemnities from underwriters, selling brokers, dealer managers and similar securities industry professionals participating in the distribution, to the same extent as customarily furnished by such persons in similar circumstances.

    (c)  Conduct of Indemnification Proceedings.  Any person entitled to indemnification hereunder will (i) give prompt notice to the indemnifying party of any claim with respect to which it seeks indemnification and (ii) permit such indemnifying party to assume the defense of such claim with counsel reasonably satisfactory to the indemnified party; provided, however, that any person entitled to indemnification hereunder shall have the right to employ separate counsel and to participate in the defense of such claim, but the fees and expenses of such counsel shall be at the expense of such person and not of the indemnifying party unless (A) the indemnifying party has agreed to pay such fees or expenses, (B) the indemnifying party shall have failed to assume the

5

defense of such claim and employ counsel reasonably satisfactory to such person or (C) in the reasonable judgment of such person and the indemnifying party, based upon advice of their respective counsel, a conflict of interest may exist between such person and the indemnifying party with respect to such claims (in which case, if the person notifies the indemnifying party in writing that such person elects to employ separate counsel at the expense of the indemnifying party, the indemnifying party shall not have the right to assume the defense of such claim on behalf of such person). If such defense is not assumed by the indemnifying party, the indemnifying party will not be subject to any liability for any settlement made without its consent (but such consent will not be unreasonably withheld). No indemnified party will be required to consent to entry of any judgment or enter into any settlement which does not include as an unconditional term thereof the giving by all claimants or plaintiffs to such indemnified party of a release from all liability in respect to such claim or litigation. Any indemnifying party who is not entitled to, or elects not to, assume the defense of a claim will not be obligated to pay the fees and expenses of more than one counsel for all parties indemnified by such indemnifying party with respect to such claim. As used in this Section 5(c), the terms "indemnifying party", "indemnified party" and other terms of similar import are intended to include only Tetra Tech (and its officers, directors and control persons as set forth above) on the one hand, and the Holder (and its officers, directors, partners, employees, attorneys and control persons as set forth above) on the other hand, as applicable.

    (d)  Contribution.  If for any reason the foregoing indemnity is unavailable under applicable law, then the indemnifying party shall contribute to the amount paid or payable by the indemnified party as a result of such losses, claims, damages, liabilities or expenses in such proportion as is appropriate to reflect the relative fault of the indemnifying party and the indemnified party in connection with the statements or omissions which resulted in such losses, claims, damages, liabilities or expenses, as well as any other relevant equitable considerations. The relative fault of such indemnifying party and indemnified party shall be determined by reference to, among other things, whether the untrue statement or alleged untrue statement of a material fact or omission or alleged omission to state a material fact relates to information supplied by such indemnifying party or by such indemnified party, and the parties' relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The parties acknowledge and agree that it would not be just and equitable if contribution pursuant to this Section 5(d) were determined by pro rata allocation or by any other method of allocation which does not take into account the equitable considerations referred to in this Section 5(d). Notwithstanding the foregoing, the Holder shall not be required to contribute any amount in excess of the amount the Holder would have been required to pay to an indemnified party if the indemnity under Section 5(b) hereof was available. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation joint.

    (e)  Timing of Payments.  An indemnifying party shall make payments of all amounts required to be made pursuant to the foregoing provisions of this Section 5 to or for the account of the indemnified party from time to time promptly upon receipt of bills or invoices relating thereto or when otherwise due or payable.

    (f)  Survival.  The indemnity and contribution agreements contained in this Section 5 shall remain in full force and effect, regardless of any investigation made by or on behalf of Tetra Tech, the Holder, its officers, directors, partners, attorneys, agents or any person, if any, who controls Tetra Tech or the Holder as aforesaid, and shall survive the transfer of such Registrable Securities by the Holder.

6

    6.  Preparation; Reasonable Investigation.  In connection with the preparation and filing of a Registration Statement pursuant to the terms of this Agreement:

    (a) Tetra Tech shall, with respect to a Registration Statement filed pursuant to Section 2, give the Holder, its underwriters, if any, and their respective counsel and accountants the opportunity to participate in the preparation of such Registration Statement as provided in Section 3(a) hereof (other than reports and proxy statements incorporated therein by reference and properly filed with the SEC) and each Prospectus included therein or filed with the SEC, and each amendment thereof or supplement thereto; and

    (b) Tetra Tech shall give the Holder, its underwriters, if any, and their respective counsel and accountants such reasonable access to its books and records and such opportunities to discuss the business of Tetra Tech with its officers and the independent public accountants who have certified its financial statements as shall be necessary, in the opinion of the Holder or such underwriters, to conduct a reasonable investigation within the meaning of Section 11(b)(3) of the Securities Act.

    7.  Rule 144.  Tetra Tech covenants that it will use commercially reasonable efforts to file, on a timely basis, the reports required to be filed by it under the Securities Act and the Exchange Act and the rules and regulations adopted by the SEC thereunder, and it will take such further action as the Holder may reasonably request (including, without limitation, compliance with the current public information requirements of Rule 144(c) and Rule 144A), all to the extent required from time to time to enable the Holder to sell Registrable Securities without registration under the Securities Act within the limitation of the conditions provided by Rule 144, Rule 144A or any similar rule or regulation hereafter adopted by the SEC. Upon the request of the Holder, Tetra Tech will promptly deliver to the Holder a written statement verifying that it has complied with such information and requirements.

    8.  Specific Performance.  The Holder, in addition to being entitled to exercise all rights provided herein or granted by law, including recovery of damages, will be entitled to specific performance of its rights under this Agreement. Tetra Tech agrees that monetary damages would not be adequate compensation for any loss incurred by reason of a breach by it of the provisions of this Agreement and hereby agrees to waive the defense in any action for specific performance that a remedy at law would be adequate.

    9.  Notices.  All notices and other communications required or permitted hereunder shall be in writing and shall be mailed by United States first-class mail, postage prepaid, sent by facsimile or delivered personally by hand or nationally recognized courier addressed (a) if to the Holder, at such address for the Holder set forth in the Reorganization Agreement, or at such other address as the Holder or permitted assignee shall have furnished to Tetra Tech in writing, or (b) if to Tetra Tech, at such address for Tetra Tech set forth in the Reorganization Agreement. All such notices and other written communications shall be effective on the date of mailing, facsimile transfer or delivery.

    10.  Successors and Assigns: Assignment of Rights.  The rights and benefits of the Holder hereunder may not be assigned to a transferee or assignee without the consent of Tetra Tech, which consent shall not be unreasonably withheld, except this Agreement shall be freely assignable by Holder in connection with a sale or transfer of the Common Stock in which Tetra Tech may legend the replacement certificates under Section 8 of the Investment Letter (as defined in the Reorganization Agreement).

    11.  Severability.  In the event that any one or more of the provisions contained herein, or the application thereof in any circumstance, is held invalid, illegal or unenforceable, the validity, legality and enforceability of any such provision in every other respect and of the remaining provisions contained herein shall not be affected or impaired thereby.

    12.  Entire Agreement; Amendment; Waiver.  This Agreement, the Reorganization Agreement and the other agreements contemplated thereby constitute the full and entire understanding and agreement

7

among the parties with regard to the subjects hereof and thereof. Without limiting the foregoing, the rights of the Holder to registration pursuant to the terms of this Agreement shall be subject to the limitations on resale contained in the Investment Letter (as defined in the Reorganization Agreement). Neither this Agreement nor any term hereof may be amended, waived, discharged or terminated, except by a written instrument signed by Tetra Tech and the Holder and any such amendment, waiver, discharge or termination shall be binding upon all the parties hereto, but in no event shall the obligation of any party hereto be materially increased, except upon the written consent of such party.

    13.  Counterparts.  This Agreement may be executed in any number of counterparts, each of which shall be original, and all of which together shall constitute one instrument.

    14.  Governing Law.  This Agreement shall be governed by, and construed in accordance with, the laws of the State of Delaware without giving effect to principles of conflicts of laws thereof.

    15.  No Third Party Beneficiaries.  The covenants and agreements set forth herein are for the sole and exclusive benefit of the parties hereto and their respective successors and assigns and such covenants and agreements shall not be construed as conferring, and are not intended to confer, any rights or benefits upon any other persons.

    IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the day and year first above written.

TETRA TECH, INC.
By:	/s/ LI-SAN HWANG Li-San Hwang President and Chief Executive Officer
/s/ ELIZABETH L. ANDERSON Elizabeth L. Anderson

8

QuickLinks

EXHIBIT 10.28
REGISTRATION RIGHTS AGREEMENT
R E C I T A L S
A G R E E M E N T

EX-13

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 13

FINANCIAL HIGHLIGHTS

		Fiscal Year Ended
		Sept. 30, 2001(3)		Oct. 1, 2000(4)			Oct. 3, 1999(5)		Oct. 4, 1998			Sept. 28, 1997
		(in thousands, except per share data)
Gross revenue		$	973,944	$	794,578		$	566,490	$	382,934		$	246,767
Net revenue			730,064		598,121			432,080		297,597			190,791
Income from operations			49,242		74,245			55,424		39,813			24,599
Net income			30,825		40,442			29,115		20,586			14,256
Basic earnings per share(1)			0.61		0.83			0.63		0.47			0.39
Diluted earnings per share(1)			0.57		0.78			0.59		0.45			0.37
Weighted average common shares outstanding:(1)
	Basic		50,939		48,754			46,449		43,703			36,518
	Diluted		54,166		52,003			49,438		45,610			38,525
Net cash flow from operating activities(2)			44,274		(12,188	)		30,258		(6,620	)		1,144
Working capital			192,991		154,341			86,313		77,049			42,539
Total assets			607,221		526,038			380,478		266,610			159,513
Long-term obligations, excluding current  portion			111,779		85,532			37,289		33,546			—
Stockholders' equity			372,146		297,907			234,432		167,781			107,641

(1)

Reflects the effect, on a retroactive basis, of the 5-for-4 stock split, effected in the form of a 25% stock dividend, in December 2001.

(2)

Net cash flow from operating activities was reduced by $5.2 million, $10.7 million, $9.3 million, $10.3 million and $15.6 million for the fiscal years ended September 30, 2001, October 1, 2000, October 3, 1999, October 4, 1998 and September 28, 1997, respectively, as a result of our assignment of accounts receivable to the former owners of certain acquired companies.

(3)

Income from operations was negatively impacted by a charge in the amount of $38.3 million, or $23.4 million on an after-tax basis, to provide a reserve for an account debtor. In addition, income tax expense was favorably impacted by tax credits for prior years of $7.0 million.

(4)

Revenue and income from operations were favorably impacted by reserve reversals in the amount of $2.0 million, or $1.16 million on an after-tax basis. In addition, income tax expense was favorably impacted by tax credits for prior years of $1.46 million.

(5)

Revenue and income from operations were favorably impacted by reserve reversals in the amount of $1.75 million, or $0.98 million on an after-tax basis.

SELECTED CONSOLIDATED FINANCIAL DATA

		Fiscal Year Ended
		Sept. 30, 2001(2)		Oct. 1, 2000(3)		Oct. 3, 1999(4)		Oct. 4, 1998(5)		Sept. 28, 1997(6)
		(in thousands, except per share data)
Statements of Income Data
Gross revenue		$	973,944	$	794,578	$	566,490	$	382,934	$	246,767
Subcontractor costs			243,880		196,457		134,410		85,337		55,976
Net revenue			730,064		598,121		432,080		297,597		190,791
Cost of net revenue			559,474		452,872		327,336		223,871		141,019
Gross profit			170,590		145,249		104,744		73,726		49,772
Selling, general and administrative expenses			121,348		71,004		49,320		33,913		25,173
Income from operations			49,242		74,245		55,424		39,813		24,599
Net interest expense			8,543		7,026		3,135		1,910		20
Income before minority interest and income tax expense			40,699		67,219		52,289		37,903		24,579
Minority interest			—		—		—		1,397		—
Income before income tax expense			40,699		67,219		52,289		36,506		24,579
Income tax expense			9,874		26,777		23,174		15,920		10,323
Net income		$	30,825	$	40,442	$	29,115	$	20,586	$	14,256
Basic earnings per share(1)		$	0.61	$	0.83	$	0.63	$	0.47	$	0.39
Diluted earnings per share(1)		$	0.57	$	0.78	$	0.59	$	0.45	$	0.37
Weighted average common shares outstanding:(1)
	Basic		50,939		48,754		46,449		43,703		36,518
	Diluted		54,166		52,003		49,438		45,610		38,525

	Sept. 30, 2001		Oct. 1, 2000		Oct. 3, 1999		Oct. 4, 1998		Sept. 28, 1997
	(in thousands)
Balance Sheet Data
Working capital	$	192,991	$	154,341	$	86,313	$	77,049	$	42,539
Total assets		607,221		526,038		380,478		266,610		159,513
Long-term obligations, excluding current portion		111,779		85,532		37,289		33,546		—
Stockholders' equity		372,146		297,907		234,432		167,781		107,641

(1)

Reflects the effect, on a retroactive basis, of the 5-for-4 stock split, effected in the form of a 25% stock dividend, in December 2001.

(2)

Income from operations was negatively impacted by a charge in the amount of $38.3 million, or $23.4 million on an after-tax basis, to provide a reserve for an account debtor. Additionally, income tax expense was favorably impacted by tax credits for prior years of $7.0 million. Further, we have included the results of operations and financial positions of Rocky Mountain Consultants, Inc. (acquired December 21, 2000), Wahco Construction, Inc. (acquired March 2, 2001), Williams, Hatfield & Stoner, Inc. (acquired March 30, 2001), Vertex Engineering Services, Inc. (acquired May 21, 2001), Maxim Technologies, Inc. (acquired May 25, 2001), Commonwealth Technology, Inc. (acquired June 1, 2001), The Design Exchange Architects, Inc. (acquired June 27, 2001), Western Utility Contractors, Inc.

2

and Western Utility Cable, Inc. (collectively acquired June 29, 2001), Shepherd Miller, Inc. (acquired September 26, 2001) and Sciences International, Inc. (acquired September 26, 2001) from the effective acquisition dates.

(3)

Included in our revenue and income from operations is $2.0 million, or $1.16 million on an after-tax basis, relating to certain reserve reversals. Additionally, income tax expense was favorably impacted by tax credits for prior years of $1.46 million. Further, we have included the results of operations and financial positions of LC of Illinois, Inc. and HFC Technologies, Inc. (collectively acquired October 25, 1999), Edward A. Sears Associates (acquired March 30, 2000), eXpert Wireless Solutions, Inc. (acquired April 3, 2000), 1261248 Ontario, Inc., which does business as Engineered Communications (acquired May 3, 2000), FHC, Inc. (acquired May 17, 2000), Rizzo Associates, Inc. (acquired May 24, 2000), Drake Contractors, Inc. (acquired June 16, 2000) and Wm. Bethlehem Trenching Ltd. (acquired July 5, 2000) from the effective acquisition dates.

(4)

Included in our revenue and income from operations is $1.75 million, or $0.98 million on an after-tax basis, relating to certain reserve reversals. Further, we have included the results of operations and financial positions of MFG, Inc. (formerly McCulley, Frick & Gilman, Inc., acquired February 26, 1999), Collins/Piña Consulting Engineers, Inc. (acquired May 7, 1999), D.E.A. Construction Company (acquired May 19, 1999), BAHA Communications, Inc. (acquired May 21, 1999), Utilities & C.C., Inc. (acquired June 18, 1999), ASL Consultants, Inc. (acquired June 25, 1999), Cosentini Associates, Inc. (formerly partnership interests and certain companies affiliated with Cosentini Associates LLP, acquired June 30, 1999), PDR Engineers, Inc. (acquired September 3, 1999) and Evergreen Utility Contractors, Inc., Continental Utility Contractors, Inc. and Gig Harbor Construction, Inc. (collectively acquired October 2, 1999) from the effective acquisition dates.

(5)

We have included the results of operations and financial positions of Tetra Tech NUS, Inc. (acquired December 31, 1997), Whalen/Sentrex LLC (formed March 2, 1998), C.D.C. Engineering, Inc. (acquired March 26, 1998 and subsequently merged into Tetra Tech, Inc. on July 29, 1999), McNamee, Porter & Seeley, Inc. (acquired July 8, 1998) and the Sentrex Group of Companies (acquired September 22, 1998) from the effective acquisition dates.

(6)

We have included the results of operations and financial positions of IWA Engineers (acquired December 11, 1996 and subsequently merged into Tetra Tech,  Inc. on July 29, 1999), FLO Engineering, Inc. (acquired December 20, 1996 and subsequently merged into Tetra Tech, Inc. on July 29, 1999), SCM Consultants, Inc. (acquired March 19, 1997), Whalen & Company, Inc. and Whalen Service Corps Inc. (collectively acquired June 11, 1997) and CommSite Development Corporation (acquired July 11, 1997 and subsequently merged into Whalen & Company, Inc. on January 4, 1999) from the effective acquisition dates.

3

MANAGEMENT'S DISCUSSION AND ANALYSIS
OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Except for the historical information contained below, the matters discussed in this section are forward-looking statements that involve a number of risks and uncertainties. Our actual liquidity needs, capital resources and operating results may differ materially from the discussion set forth below in these forward-looking statements. For additional information, refer to the Notes to Consolidated Financial Statements.

Overview

    Tetra Tech, Inc. is a leading provider of specialized management consulting and technical services in three principal business areas: resource management, infrastructure and communications. As a specialized management consultant, we assist our clients in defining problems and developing innovative and cost-effective solutions. Our management consulting services are complemented by our technical services. These technical services, which implement solutions, include research and development, applied science, engineering and architectural design, construction management, and operations and maintenance. Our clients include a diverse base of public and private organizations located in the United States and internationally.

    Since our initial public offering in December 1991, we increased the size and scope of our business and have expanded our service offerings through a series of strategic acquisitions and internal growth. From fiscal 1991 through fiscal 2001, we generated a net revenue compounded annual growth rate of approximately 34.4% and achieved a net income compounded annual growth rate of approximately 29.4%, or 35.0% excluding charges and credits, as discussed in the following results of operations.

    We derive our revenue from fees from professional services. Our services are billed under various types of contracts with our clients, including:

•

fixed-price;

•

fixed-rate time and materials;

•

cost-reimbursement plus fixed fee; and

•

cost-reimbursement plus fixed and award fee.

    In the course of providing our services, we routinely subcontract services. These subcontractor costs are passed through to our clients and, in accordance with industry practice, are included in our gross revenue. Because subcontractor services can change significantly from project to project, we believe net revenue, which is gross revenue less the cost of subcontractor services, is a more appropriate measure of our performance.

    Our cost of net revenue includes professional compensation and certain direct and indirect overhead costs such as rents, utilities and travel. Professional compensation represents the majority of these costs. Our selling, general and administrative (SG&A) expenses are comprised primarily of our corporate headquarters' costs related to the executive offices, corporate accounting, information technology, marketing, and bid and proposal costs. These costs are generally unrelated to specific client projects. Included in our fiscal 2001 SG&A expense is a charge to provide a reserve for an account debtor as discussed in the following results of operations. We also include amortization of certain intangible assets resulting from acquisitions in SG&A expenses.

4

    We provide services to a diverse base of Federal, state and local government agencies, and private and international clients. The following table presents, for the periods indicated, the approximate percentage of our net revenue attributable to these client sectors:

	Percentage of Net Revenue
Client	Fiscal 2001		Fiscal 2000		Fiscal 1999
Federal government	24.5	%	29.1	%	39.1	%
State and local governments	18.1		16.3		16.3
Private	54.2		51.4		41.3
International	3.2		3.2		3.3
Total	100.0	%	100.0	%	100.0	%

    We manage our business in three operating segments: Resource Management, Infrastructure and Communications. The following table presents, for the periods indicated, the approximate percentage of net revenue attributable to the operating segments:

	Percentage of Net Revenue
Operating Segment	Fiscal 2001		Fiscal 2000		Fiscal 1999
Resource Management	40.0	%	41.3	%	53.6	%
Infrastructure	34.0		31.8		25.9
Communications	25.3		25.6		20.5
Other revenue	0.7		1.3		0.0
Total	100.0	%	100.0	%	100.0	%

    Our revenue and operating results fluctuate from quarter to quarter as a result of a number of factors, such as:

•

The seasonality of the spending cycle of our public sector clients and the spending patterns of our private sector clients;

•

Employee hiring and utilization rates;

•

The number and significance of client engagements commenced and completed during a quarter;

•

Creditworthiness and solvency of clients;

•

Delays incurred in connection with an engagement;

•

The ability of clients to terminate engagements without penalties;

•

The size and scope of engagements;

•

The timing of expenses incurred for corporate initiatives;

•

The timing and size of the return on investment capital; and

•

General economic or political conditions.

Variations in any of these factors can cause significant variations in operating results from quarter to quarter and could result in losses.

Recent Acquisitions

    As a part of our growth strategy, we expect to pursue complementary acquisitions to expand our geographical reach and the breadth and depth of our service offerings. During fiscal 2001, we purchased 11 companies in the following ten transactions:

    Rocky Mountain Consultants, Inc.—In December 2000, we acquired Rocky Mountain Consultants, Inc. (RMC). The purchase was valued at approximately $15.2 million. RMC, a Colorado-

5

based engineering services firm, provides water-related engineering and facility development services to state and local governments and private clients primarily in the western and midwestern regions of the United States.

    Wahco Construction, Inc.—In March 2001, we acquired Wahco Construction, Inc. (WCI). The purchase was valued at approximately $0.8 million. WCI, a Washington-based field services firm, provides network and field services to utility and communications companies primarily in the northwestern region of the United States.

    Williams, Hatfield & Stoner, Inc.—In March 2001, we acquired Williams, Hatfield & Stoner, Inc. (WHS). The purchase was valued at approximately $9.1 million. WHS, a Florida-based engineering services firm, provides civil engineering, planning and environmental services to state and local governments and private clients primarily in the southeastern region of the United States.

    Vertex Engineering Services, Inc.—In May 2001, we acquired Vertex Engineering Services, Inc. (VES). The purchase was valued at approximately $10.4 million. VES, a Massachusetts-based engineering services firm, provides environmental, engineering and consulting services with full general construction capabilities and specializes in surety and insurance construction management throughout the United States.

    Maxim Technologies, Inc.—In May 2001, we acquired Maxim Technologies, Inc. (MTI). The purchase was valued at approximately $14.0 million. MTI, a Texas-based professional consulting firm, provides engineering and environmental services to a variety of clients throughout the United States.

    Commonwealth Technology, Inc.—In June 2001, we acquired certain assets of Commonwealth Technology, Inc. (CTI). The purchase was valued at approximately $3.6 million. CTI, a Kentucky-based environmental and infrastructure engineering and consulting firm, provides civil, environmental and industrial engineering services to state and local governments and private clients primarily in the southeastern region of the United States.

    The Design Exchange Architects, Inc.—In June 2001, we acquired The Design Exchange Architects, Inc. (DXA). The purchase was valued at approximately $1.3 million. DXA, a Delaware-based architectural firm, provides architectural, planning and interior design services to private clients throughout the eastern region of the United States.

    Western Utility Contractors, Inc.—In June 2001, we acquired Western Utility Contractors, Inc. and Western Utility Cable, Inc. (collectively, WUC). The purchase was valued at approximately $15.6 million. WUC, an Illinois-based engineering, design and construction firm, provides walkout, design and construction of coaxial and fiber-optic related infrastructure to private clients primarily in the midwestern region of the United States.

    Shepherd Miller, Inc.—In September 2001, we acquired, through our wholly-owned subsidiary, MFG, Inc., certain assets of Shepherd Miller, Inc. (SMI). The purchase was valued at approximately $2.5 million. SMI, a Colorado-based environmental and engineering consulting firm, provides solutions to mining environmental and operational problems throughout the United States.

    Sciences International, Inc.—In September 2001, we acquired Sciences International, Inc. (SII). The purchase was valued at approximately $5.1 million. SII, a Virginia-based consulting firm, provides health and environmental risk assessment services to private industries, governments and law firms throughout the United States.

Results of Operations

    Our results of operations for fiscal years 2001, 2000 and 1999 reflected certain charges and credits infrequently encountered in our normal recurring operations. Fiscal 2001 results included a charge to provide a reserve for an account debtor that filed for Chapter 11 protection under the U.S. Bankruptcy

6

Code. The amount of this charge, on a pre-tax basis, was $38.3 million and was included in SG&A expense. Based upon our current effective tax rate of 39%, this charge had an adverse impact on our net income of $23.4 million. Additionally, fiscal 2001 results included the favorable impact of $7.0 million in income tax credits relating to prior years. Fiscal 2000 and 1999 results included the favorable impact of certain pre-acquisition reserve reversals in the amounts of $2.0 million and $1.75 million, respectively. These amounts were included in revenue and had a net income effect of $1.2 million and $1.0 million, respectively, in fiscal 2000 and 1999. Fiscal 2000 results were also favorably impacted by income tax credits relating to prior years of $1.5 million. Unless otherwise noted, for comparability purposes, the following discussion of our results of operations excludes these items. The actual results, including these items, are reflected in the Consolidated Financial Statements and the notes thereto.

    The following table sets forth, for the periods indicated, certain operating information as a percentage of net revenue:

	Percentage of Net Revenue
	Fiscal Year Ended
	Sept. 30, 2001		Oct. 1, 2000		Oct. 3, 1999
Net revenue	100.0	%	100.0	%	100.0	%
Cost of net revenue	76.6		76.0		76.1
Gross profit	23.4		24.0		23.9
Selling, general and administrative expenses	11.4		11.9		11.4
Income from operations	12.0		12.1		12.5
Net interest expense	1.2		1.2		0.8
Income before income tax expense	10.8		10.9		11.7
Income tax expense	4.4		4.6		5.2
Net income	6.4	%	6.3	%	6.5	%

Fiscal 2001 Compared to Fiscal 2000

    Net Revenue.  Net revenue increased $133.9 million, or 22.5%, to $730.1 million in fiscal 2001 from $596.1 million in fiscal 2000. As previously noted, the fiscal 2000 results exclude for comparability purposes the favorable reserve reversal of $2.0 million. Including this revenue, net revenue increased $131.9 million, or 22.1%. All three business segments and all four client sectors continued to show net revenue increases in actual dollars. Our Resource Management business area recognized growth in its net revenue of 19.4%. This growth was primarily attributable to growth in our water and waste management business coupled with the fiscal 2001 acquisitions. Our Infrastructure business area recognized net revenue growth of 30.3% due to the expansion of our infrastructure services throughout the United States, as well as our fiscal 2001 acquisitions. Although the net revenue growth in our Communications business area has declined from growth levels we experienced in the past, we still achieved a 20.4% net revenue growth in this area. Net revenue provided by our Federal government clients increased by 3.9%, while net revenue from our state and local government, commercial and international clients increased 35.8%, 28.8% and 20.4%, respectively. We segregate from our total revenue, revenue derived from companies acquired during the current fiscal year as well as revenue recognized from acquired companies during the first 12 months following their respective effective dates of acquisition. Revenue recognized from acquired companies during such first 12 months is referred to as acquisitive revenue. Organic revenue is measured as total revenue less any acquisitive revenue. Net revenue provided by companies acquired during fiscal 2001 totaled $51.8 million. Excluding this net revenue, we realized 13.8% growth in our net revenue from fiscal 2000 to fiscal

7

2001. Acquisitive net revenue for fiscal 2001 totaled $84.2 million. Excluding this net revenue, we realized organic growth in our net revenue of 8.4%.

    Gross revenue increased $181.4 million, or 22.9%, to $973.9 million from $792.6 million in fiscal 2000. As a percentage of gross revenue, subcontractor costs were 25.0% in fiscal 2001 as compared to 24.8% in fiscal 2000. Including the fiscal 2000 favorable reserve reversal of $2.0 million, gross revenue increased $179.4 million, or 22.6%.

    Cost of Net Revenue.  Cost of net revenue increased $106.6 million, or 23.5%, to $559.5 million in fiscal 2001 from $452.9 million in fiscal 2000. As a percentage of net revenue, cost of net revenue increased slightly to 76.6% in fiscal 2001 from 76.0% in fiscal 2000. Professional compensation, the largest component of our cost of net revenue, rose as the number of employees, measured as full-time equivalents, increased by 700, or 11.4%, to 6,820 in fiscal 2001 from 6,120 in fiscal 2000. Excluding the 938 employees provided from acquired companies, we had a reduction in our number of full-time equivalent employees. Gross profit increased $27.3 million, or 19.1%, to $170.6 million in fiscal 2001 from $143.2 million in fiscal 2000. As a percentage of net revenue, gross profit decreased to 23.4% in fiscal 2001 from 24.0% in fiscal 2000.

    Selling, General and Administrative Expenses.  SG&A expenses, exclusive of amortization expense, increased $9.3 million, or 14.4%, to $73.9 million in fiscal 2001 from $64.5 million in fiscal 2000. As a percentage of net revenue, SG&A expenses decreased to 10.1% in fiscal 2001 from 10.8% in fiscal 2000. Including the $38.3 million charge that was taken in the third quarter of fiscal 2001 to provide for a reserve for an account debtor, our SG&A expenses increased $47.6 million, or 73.8%, to $112.2 million in fiscal 2001 from $64.5 million in fiscal 2000. Our SG&A expenses vary as a result of corporate initiatives such as business development and upgrade of the corporate business systems, as well as other discretionary spending. Fiscal 2000 reflected higher proportional costs in these areas. Our SG&A expenses will continue to vary due to the timing and magnitude of discretionary expenditures. The amortization expense related to acquisitions increased $2.7 million, or 42.2%, to $9.2 million in fiscal 2001 from $6.5 million in fiscal 2000.

    Net Interest Expense.  Net interest expense increased $1.5 million, or 21.6%, to $8.5 million in fiscal 2001 from $7.0 million in fiscal 2000. This increase was primarily attributable to higher borrowings on our credit facility and our private placement of fixed-rate senior secured notes to fund working capital and investing needs of acquisitions, offset by decreases in interest rates. In fiscal 2001, borrowings on our credit facility and senior secured notes averaged $130.9 million at a weighted average interest rate of 7.1% compared to $95.4 million at a weighted average interest rate of 7.4% on our credit facility in fiscal 2000. In addition, interest income increased $0.8 million or 231.3%, to $1.1 million in fiscal 2001 from $0.3 million in fiscal 2000. This increase was primarily attributable to higher cash and cash equivalent balances and interest related to anticipated tax refunds.

    Income Tax Expense.  Income tax expense increased $4.4 million, or 16.2%, to $31.8 million in fiscal 2001 from $27.4 million in fiscal 2000. This increase was due to higher income before income tax expense. Beginning in fiscal 2000, we performed an extensive review of our effective tax rate and tax position. During the fourth quarter of fiscal 2000, based upon estimates of credits, primarily research and experimentation credits as provided under the Internal Revenue Code, we realized a reduction in our then current effective tax rate from 44.3% to 42.0%. These credits were also available for prior years. During fiscal 2001, we further refined our estimates and determined that our current effective tax rate is approximately 39.0%. Accordingly, we amended our fiscal 2000 Federal income tax return to reflect these credits and are currently amending tax returns for fiscal years 1997, 1998 and 1999. Including the current and prior year credits, as well as the effective income tax effect of the fiscal 2000 reserve reversals and the income tax effect of the charge taken in fiscal 2001, our income tax expense decreased $16.9 million, or 63.1%, to $9.9 million in fiscal 2001 from $26.8 million in fiscal 2000.

8

Fiscal 2000 Compared to Fiscal 1999

    Net Revenue.  Net revenue increased $165.8 million, or 38.5%, to $596.1 million in fiscal 2000 from $430.3 million in fiscal 1999. All three business segments and all four client sectors continued to show net revenue increases in actual dollars. These increases were primarily attributable to the expansion of our infrastructure services throughout the United States, the continued expansion of new lines of service in our communications business and companies we acquired in fiscal 2000. As a percentage of net revenue, an increase was realized in the private sector. We segregate from our total revenue, revenue derived from companies acquired during the current fiscal year as well as revenue recognized from acquired companies during the first 12 months following their respective effective dates of acquisition. Revenue recognized from acquired companies during such first 12 months is referred to as acquisitive revenue. Organic revenue is measured as total revenue less any acquisitive revenue. Net revenue provided by companies acquired during fiscal 2000 totaled $32.7 million. Excluding this net revenue, we realized 30.9% growth in our net revenue from fiscal 1999 to fiscal 2000. Acquisitive net revenue for fiscal 2000 totaled $114.2 million. Excluding this net revenue, we realized organic growth in our net revenue of 12.0%.

    Gross revenue increased $227.8 million, or 40.3%, to $792.6 million in fiscal 2000 from $564.7 million in fiscal 1999. In fiscal 2000, subcontractor costs comprised 24.8% of gross revenue compared to 23.8% for fiscal 1999.

    Cost of Net Revenue.  Cost of net revenue increased $125.5 million, or 38.4%, to $452.9 million in fiscal 2000 from $327.3 million in fiscal 1999. As a percentage of net revenue, cost of net revenue decreased from 76.1% in fiscal 1999 to 76.0% in fiscal 2000. Professional compensation, the largest component of our cost of net revenue, rose as the number of our employees increased by 677, or 12.4%, to 6,120 in fiscal 2000 from 5,443 in fiscal 1999. However, excluding the 681 employees provided from acquired companies, the number of our employees remained flat. Gross profit increased $40.3 million, or 39.1%, to $143.2 million in fiscal 2000 from $103.0 million in fiscal 1999. As a percentage of net revenue, gross profit increased from 23.9% in fiscal 1999 to 24.0% in fiscal 2000.

    Selling, General and Administrative Expenses.  SG&A expenses, exclusive of amortization expense, increased $20.0 million, or 45.1%, to $64.5 million in fiscal 2000 from $44.5 million in fiscal 1999. This increase was primarily attributable to expenses associated with the automation of our corporate business systems and processes, business development activities and higher administrative costs associated with acquired companies. As a percentage of net revenue, SG&A expenses, exclusive of amortization expense, increased to 10.8% in fiscal 2000 from 10.3% in fiscal 1999. The amortization expense related to acquisitions increased $1.7 million, or 33.5%, to $6.5 million in fiscal 2000 from $4.8 million in fiscal 1999.

    Net Interest Expense.  Net interest expense increased $3.9 million, or 124.1%, from $3.1 million in fiscal 1999 to $7.0 million in fiscal 2000. This increase was primarily attributable to increased borrowings on our credit facility in order to fund working capital and investing needs of acquisitions, as well as increases in interest rates. In fiscal 2000, borrowings on our credit facility averaged $95.4 million at a weighted average interest rate of 7.4% compared to $44.6 million at a weighted average interest rate of 6.6% in fiscal 1999.

    Income Tax Expense.  Including the favorable impact of tax credits of $1.5 million in fiscal 2000 and the tax effect of the reversal of certain pre-acquisition reserves, income tax expense increased $3.6 million, or 15.6%, to $26.8 million in fiscal 2000 from $23.2 million in fiscal 1999. This increase was due to higher income before income taxes and a change in our effective tax rate. During fiscal 2000, we performed an extensive review of our current tax position and certain tax strategies which could reduce our effective tax rate. As a result of this review, we determined that we were entitled to certain tax credits for fiscal 2000 as well as certain prior years. These credits were primarily responsible for the reduction in our effective tax rate to 39.8% in fiscal 2000 from 44.3% in fiscal 1999.

9

Unaudited Quarterly Operating Results

    The following tables set forth certain unaudited quarterly operating results for each of our last three fiscal years ended September 30, 2001, October 1, 2000 and October 3, 1999. This data is also expressed as a percentage of net revenue for the respective quarters. The information has been derived from unaudited consolidated financial statements that, in our opinion, reflect all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of such quarterly information. The operating results for any quarter are not necessarily indicative of the results to be expected for any future period.

	Fiscal 2001 Quarter Ended									Fiscal 2000 Quarter Ended								Fiscal 1999 Quarter Ended
	Dec. 31, 2000		Apr. 1, 2001		Jul. 1, 2001			Sep. 30, 2001		Jan. 2, 2000		Apr. 2, 2000		Jul. 2, 2000		Oct. 1, 2000		Jan. 3, 1999		Apr. 4, 1999		Jul. 4, 1999		Oct. 3, 1999
	(in thousands)
Net revenue	$	167,138	$	179,658	$	191,548		$	191,720	$	129,171	$	138,846	$	156,468	$	173,636	$	89,245	$	96,955	$	120,739	$	125,141
Cost of net revenue		128,405		138,254		147,022			145,793		100,417		109,562		116,266		126,627		70,187		74,402		88,189		94,558
Gross profit		38,733		41,404		44,526			45,927		28,754		29,284		40,202		47,009		19,058		22,553		32,550		30,583
Selling, general and administrative expenses		20,583		21,043		60,046			19,676		14,021		13,304		20,529		23,150		8,871		10,684		16,951		12,814
Income (loss) from operations		18,150		20,361		(15,520	)		26,251		14,733		15,980		19,673		23,859		10,187		11,869		15,599		17,769
Net interest expense		1,994		2,200		2,278			2,071		1,228		1,473		1,958		2,367		699		532		550		1,354
Income (loss) before income tax expense		16,156		18,161		(17,798	)		24,180		13,505		14,507		17,715		21,492		9,488		11,337		15,049		16,415
Income tax expense		6,786		7,627		(13,969	)		9,430		5,942		6,383		7,795		6,657		4,061		4,875		6,546		7,692
Net income (loss)	$	9,370	$	10,534	$	(3,829	)	$	14,750	$	7,563	$	8,124	$	9,920	$	14,835	$	5,427	$	6,462	$	8,503	$	8,723

	Fiscal 2001 Quarter Ended								Fiscal 2000 Quarter Ended								Fiscal 1999 Quarter Ended
	Dec. 31, 2000		Apr. 1, 2001		Jul. 1, 2001		Sep. 30, 2001		Jan. 2, 2000		Apr. 2, 2000		Jul. 2, 2000		Oct. 1, 2000		Jan. 3, 1999		Apr. 4, 1999		Jul. 4, 1999		Oct. 3, 1999
Net revenue	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%	100.0	%
Cost of net revenue	76.8		77.0		76.8		76.0		77.7		78.9		74.3		72.9		78.6		76.7		73.0		75.6
Gross profit	23.2		23.0		23.2		24.0		22.3		21.1		25.7		27.1		21.4		23.3		27.0		24.4
Selling, general and administrative expenses	12.3		11.7		31.3		10.3		10.9		9.6		13.1		13.4		10.0		11.1		14.1		10.2
Income (loss) from operations	10.9		11.3		(8.1	)	13.7		11.4		11.5		12.6		13.7		11.4		12.2		12.9		14.2
Net interest expense	1.2		1.2		1.2		1.1		0.9		1.1		1.3		1.3		0.8		0.5		0.4		1.1
Income (loss) before income tax expense	9.7		10.1		(9.3	)	12.6		10.5		10.4		11.3		12.4		10.6		11.7		12.5		13.1
Income tax expense	4.1		4.2		(7.3	)	4.9		4.6		4.5		5.0		3.9		4.5		5.0		5.5		6.1
Net income (loss)	5.6	%	5.9	%	(2.0	)%	7.7	%	5.9	%	5.9	%	6.3	%	8.5	%	6.1	%	6.7	%	7.0	%	7.0	%

Liquidity and Capital Resources

    As of September 30, 2001, our working capital was $193.0 million, an increase of $38.7 million from $154.3 million on October 1, 2000, of which cash and cash equivalents totaled $16.2 million at September 30, 2001. In fiscal 2001, $44.3 million was provided by operating activities and $51.2 million was used in investing activities, of which $40.2 million was related to business acquisitions. In fiscal 2000, $12.2 million was used in operating activities and $42.3 million was used in investing activities, of which $27.5 million was related to business acquisitions.

    In both fiscal years 2001 and 2000, cash provided by/used in operating activities was affected by the structure of certain transactions. One of our acquisition structures is to assign accounts receivable to the former owners of the company at the time of the transaction in lieu of cash consideration. This structure allows us to reduce our cash used in investing activities. However, cash must be invested in future periods to finance the working capital needs of the acquired company. In fiscal 2001, in the WHS acquisition, accounts receivable in the aggregate amount of $3.8 million were assigned to the former owners. Collections on previously assigned receivables totaled $5.2 million. If we had not assigned these receivables at the time of acquisition, cash provided by operating activities in fiscal 2001 could have been $49.5 million. In fiscal 2000, in the eXpert Wireless Solutions, Inc. and Drake

10

Contractors, Inc. acquisitions, accounts receivable in the aggregate amount of $3.9 million were assigned to the former owners. Collections on assigned receivables totaled $10.7 million. If we had not assigned these receivables at the time of acquisition, cash used in operating activities in fiscal 2000 could have been $1.5 million. In fiscal 1999, in the BAHA Communications, Inc. and Cosentini Associates, Inc. acquisitions, accounts receivable in the aggregate amount of $19.4 million were assigned to the former owners. Collections on these receivables during fiscal 1999 totaled $9.3 million. If we had not assigned these receivables at the time of acquisition, cash provided by operating activities in fiscal 1999 could have been $39.6 million.

    Our capital expenditures during fiscal years 2001 and 2000 were approximately $11.0 million and $14.7 million, respectively. Capital expenditures were primarily for the replacement of field equipment, the enhancement of computer equipment and office expansion.

    We have a credit agreement with various financial institutions (the "Credit Agreement") which provides us with a revolving credit facility (the "Facility") of $140.0 million. The Facility matures on March 17, 2005 or earlier at our discretion upon payment in full of loans and other obligations. Throughout fiscal 2001, maximum borrowings under the Facility were $134.5 million. At September 30, 2001, borrowings and standby letters of credit on this facility totaled $14.0 million and $1.7 million, respectively. On May 22, 2001, to provide additional debt capacity to fund working capital needs and acquisitions, we issued two series of senior secured notes in the aggregate amount of $110.0 million in a private placement. Series A, totaling $92.0 million with an interest rate of 7.28%, matures on May 30, 2011. Series B, totaling $18.0 million with an interest rate of 7.08%, matures on May 30, 2008. At September 30, 2001, the outstanding principal balance on the senior secured notes was $110.0 million.

    We expect that internally generated funds, our existing cash balances and availability under the Credit Agreement will be sufficient to meet our capital requirements through the end of fiscal 2002. However, should we pursue an acquisition or acquisitions in which the potential cash consideration exceeds the then current availability of cash, we may pursue additional financing.

    In conjunction with our investment strategy, we continuously evaluate the marketplace for strategic acquisition opportunities. Once an opportunity is identified, we examine the effect an acquisition may have on the business environment, as well as on our results of operations. We proceed with an acquisition if we determine that the acquisition is anticipated to have an accretive effect on future operations or could expand our service offerings. As successful integration and implementation are essential to achieve favorable results, no assurances can be given that all acquisitions will provide accretive results. Our strategy is to position ourselves to address existing and emerging markets. We view acquisitions as a key component of our growth strategy, and we intend to use both cash and our securities, as we deem appropriate, to fund such acquisitions.

    We believe our operations have not been and, in the foreseeable future, are not expected to be materially adversely affected by inflation or changing prices. However, current general economic conditions may impact our client base and as such, may impact their creditworthiness and our ability to collect cash to meet our operating needs.

Recently Issued Financial Standards

    In July 2001, the Financial Accounting Standards Board (FASB) issued Statement of Financial Accounting Standard (SFAS) No. 141, Business Combinations, which supercedes Accounting Principles Board (APB) Opinion No. 16, Business Combinations. SFAS No. 141 eliminates the pooling-of-interest method of accounting for business combinations for combinations initiated after July 1, 2001. This statement also changes the criteria to recognize intangible assets apart from goodwill. The provisions of this statement are effective for any business combination accounted for by the purchase method that is completed after June 30, 2001.

    In July 2001, the FASB issued SFAS No. 142, Goodwill and Other Intangible Assets, which supercedes APB Opinion No. 17, Intangible Assets. Under SFAS No. 142, goodwill and other indefinite-

11

lived intangible assets are no longer amortized but are reviewed, at a minimum, annually for impairment. Separable intangible assets that have finite lives will continue to be amortized over their useful lives. For the year ended September 30, 2001, goodwill amortization expense was $9.2 million. The amortization provisions of this statement are effective for goodwill and intangible assets acquired after June 30, 2001. The remaining provisions of this statement are effective for fiscal years beginning after December 15, 2001, although early adoption is permitted. The adoption of this statement will result in the Company's discontinuation of amortization of its goodwill; however, the Company will be required to test its goodwill for impairment under SFAS No. 142 in the first six months of fiscal 2003. We are currently analyzing the impact of this statement and will adopt this statement in fiscal 2003.

    In October 2001, the FASB issued SFAS No. 144, Accounting for the Impairment or Disposal of Long-Lived Assets, which supercedes SFAS No. 121, Accounting for the Impairment of Long-Lived Assets and for Long-Lived Assets To Be Disposed Of.  SFAS No. 144 addresses financial accounting and reporting requirements for the impairment or disposal of long-lived assets. This statement also expands the scope of a discontinued operation to include a component of an entity, and eliminates the current exemption to consolidation when control over a subsidiary is likely to be temporary. The provisions of this statement are effective for fiscal years beginning after December 15, 2001 and interim periods within those fiscal years, although early adoption is permitted. We are currently analyzing the impact of this statement and will adopt this statement in fiscal 2003.

Market Risks

    We do not currently utilize any material derivative financial instruments which expose us to significant market risk. We are exposed to cash flow risk due to interest rate fluctuations with respect to our long-term obligations. At our option, we borrow on our Facility (a) at a base rate (the greater of the federal funds rate plus 0.50% or the bank's reference rate) or (b) at a eurodollar rate plus a margin which ranges from 0.75% to 1.25%. Borrowings at the base rate have no designated term and may be repaid without penalty any time prior to the Facility's maturity date. Borrowings at a eurodollar rate have a term no less than 30 days and no greater than 90 days. Typically, at the end of such term, such borrowings may be rolled over at our discretion into either a borrowing at the base rate or a borrowing at a eurodollar rate with similar terms, not to exceed the maturity date of the Facility. The Facility matures on March 17, 2005 or earlier at our discretion upon payment in full of loans and other obligations. Accordingly, we classify total outstanding debt between current liabilities and long-term obligations based on anticipated payments within and beyond one year's period of time. We presently anticipate repaying $14.3 million of our long-term obligations in fiscal 2002. Assuming we pay our long-term obligations in the amount of $14.3 million ratably throughout the year, and our average interest rate on our long-term obligations increases or decreases by one percentage point, our interest expense could increase or decrease by $0.1 million. However there can be no assurance that we will, or will be able to, repay our debt in the prescribed manner or obtain alternate financing. We could incur additional debt under our Facility or our operating results could be worse than we expect. In addition, we have outstanding senior secured notes which bear interest at a fixed rate. The Series A Notes bear interest at 7.28% and are payable at $13.1 million per year commencing fiscal 2005 through fiscal 2011. The Series B Notes bear interest at 7.08% and are payable at $3.6 million per year commencing fiscal 2004 through fiscal 2008. If interest rates increased by 1%, the fair value of the senior secured notes could decrease by $5.1 million. If interest rates decreased by 1%, the fair value could increase by $5.5 million. We presently have no material contracts under which the currency is not denominated in U.S. dollars. Accordingly, foreign exchange rate fluctuations will not have a material impact on our financial statements.

12

INDEPENDENT AUDITORS' REPORT

Tetra Tech, Inc.:

    We have audited the accompanying consolidated balance sheets of Tetra Tech, Inc. and its subsidiaries as of September 30, 2001 and October 1, 2000, and the related consolidated statements of income, stockholders' equity, and cash flows for each of the three years in the period ended September 30, 2001. These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on these financial statements based on our audits.

    We conducted our audits in accordance with auditing standards generally accepted in the United States of America. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements. An audit also includes assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

    In our opinion, such consolidated financial statements present fairly, in all material respects, the financial position of Tetra Tech, Inc. and its subsidiaries as of September 30, 2001 and October 1, 2000, and the results of their operations and their cash flows for each of the three years in the period ended September 30, 2001, in conformity with accounting principles generally accepted in the United States of America.

/s/ DELOITTE & TOUCHE LLP

Los Angeles, California
November 14, 2001

13

TETRA TECH, INC.

CONSOLIDATED BALANCE SHEETS

			Sept. 30, 2001			Oct. 1, 2000
ASSETS
Current Assets:
	Cash and cash equivalents		$	16,240,000		$	7,557,000
	Accounts receivable—net			152,761,000			153,527,000
	Unbilled receivables—net			120,925,000			117,870,000
	Contract retentions			5,103,000			4,232,000
	Prepaid expenses and other current assets			13,927,000			11,203,000
	Income taxes receivable			3,608,000			—
	Deferred income taxes			3,723,000			2,551,000
		Total Current Assets		316,287,000			296,940,000
Property and Equipment:
	Equipment, furniture and fixtures			69,077,000			59,361,000
	Leasehold improvements			6,715,000			4,182,000
		Total		75,792,000			63,543,000
	Accumulated depreciation and amortization			(35,856,000	)		(28,331,000	)
Property and Equipment—Net				39,936,000			35,212,000
Intangible Assets—Net				245,019,000			190,452,000
Other Assets				5,979,000			3,434,000
Total Assets			$	607,221,000		$	526,038,000
LIABILITIES AND STOCKHOLDERS' EQUITY
Current Liabilities:
	Accounts payable		$	53,977,000		$	50,304,000
	Accrued compensation			29,738,000			25,705,000
	Billings in excess of costs on uncompleted contracts			10,354,000			15,947,000
	Other current liabilities			14,899,000			17,523,000
	Income taxes payable			—			7,120,000
	Current portion of long-term obligations			14,328,000			26,000,000
		Total Current Liabilities		123,296,000			142,599,000
Long-term Obligations				111,779,000			85,532,000
Commitments and Contingencies (Notes 8 and 10)
Stockholders' Equity:
	Preferred stock—authorized, 2,000,000 shares of $.01 par value; issued and outstanding 0 shares at September 30, 2001 and October 1, 2000			—			—
	Exchangeable stock of a subsidiary			13,239,000			13,887,000
	Common stock—authorized, 85,000,000 shares of $.01 par value; issued and outstanding 52,247,777 and 49,788,292 shares at September 30, 2001 and October 1, 2000, respectively			522,000			498,000
	Additional paid-in capital			195,126,000			150,291,000
	Accumulated other comprehensive loss			(1,641,000	)		(844,000	)
	Retained earnings			164,900,000			134,075,000
Total Stockholders' Equity				372,146,000			297,907,000
Total Liabilities and Stockholders' Equity			$	607,221,000		$	526,038,000

See accompanying Notes to Consolidated Financial Statements.

14

TETRA TECH, INC.

CONSOLIDATED STATEMENTS OF INCOME

		Fiscal Year Ended
		Sept. 30, 2001		Oct. 1, 2000		Oct. 3, 1999
Revenue:
	Gross revenue	$	973,944,000	$	794,578,000	$	566,490,000
	Subcontractor costs		243,880,000		196,457,000		134,410,000
Net Revenue			730,064,000		598,121,000		432,080,000
Cost of Net Revenue			559,474,000		452,872,000		327,336,000
Gross Profit			170,590,000		145,249,000		104,744,000
Selling, General and Administrative Expenses			121,348,000		71,004,000		49,320,000
Income From Operations			49,242,000		74,245,000		55,424,000
Interest Expense			9,633,000		7,355,000		3,561,000
Interest Income			1,090,000		329,000		426,000
Income Before Income Tax Expense			40,699,000		67,219,000		52,289,000
Income Tax Expense			9,874,000		26,777,000		23,174,000
Net Income		$	30,825,000	$	40,442,000	$	29,115,000
Basic Earnings Per Share		$	0.61	$	0.83	$	0.63
Diluted Earnings Per Share		$	0.57	$	0.78	$	0.59
Weighted Average Common Shares Outstanding:
	Basic		50,939,000		48,754,000		46,449,000
	Diluted		54,166,000		52,003,000		49,438,000

See accompanying Notes to Consolidated Financial Statements.

15

TETRA TECH, INC.

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY

FISCAL YEARS ENDED SEPTEMBER 30, 2001, OCTOBER 1, 2000 AND OCTOBER 3, 1999

			Exchangeable Stock					Common Stock									Accumulated Other Comprehensive Loss
												Additional Paid-In Capital			Retained Earnings
			Shares		Amount			Shares		Amount										Total
BALANCE, OCTOBER 4, 1998,			920,354		$	15,411,000		35,788,250		$	357,000	$	87,495,000		$	64,518,000	$	—		$	167,781,000
	as previously reported Five-for-four common stock split							8,947,063			90,000		(90,000	)							—
BALANCE, OCTOBER 4, 1998			920,354			15,411,000		44,735,313			447,000		87,405,000			64,518,000		—			167,781,000
	Comprehensive income:
		Net income														29,115,000					29,115,000
		Foreign currency translation adjustment																(802,000	)		(802,000	)
	Comprehensive income																				28,313,000
	Shares issued in secondary offering							1,562,500			16,000		22,155,000								22,171,000
	Shares issued in acquisitions							983,814			10,000		11,561,000								11,571,000
	Stock options exercised							362,465			4,000		1,919,000								1,923,000
	Shares issued in Employee Stock Purchase Plan							195,451			2,000		2,220,000								2,222,000
	Exchangeable shares of a subsidiary exchanged for common shares		(129,712	)		(2,172,000	)	202,675			2,000		2,170,000								—
	Tax benefit for disqualifying dispositions of stock options												473,000								473,000
	Payment for fractional shares							(191	)				(22,000	)							(22,000	)
BALANCE, OCTOBER 3, 1999			790,642			13,239,000		48,042,027			481,000		127,881,000			93,633,000		(802,000	)		234,432,000
	Comprehensive income:
		Net income														40,442,000					40,442,000
		Foreign currency translation adjustment																(42,000	)		(42,000	)
	Comprehensive income																				40,400,000
	Shares issued in acquisitions		33,606			648,000		732,244			7,000		11,379,000								12,034,000
	Stock options exercised							806,382			8,000		5,692,000								5,700,000
	Shares issued in Employee Stock Purchase Plan							207,639			2,000		2,843,000								2,845,000
	Tax benefit for disqualifying dispositions of stock options												2,496,000								2,496,000
BALANCE, OCTOBER 1, 2000			824,248			13,887,000		49,788,292			498,000		150,291,000			134,075,000		(844,000	)		297,907,000
	Comprehensive income:
		Net income														30,825,000					30,825,000
		Foreign currency translation adjustment																(797,000	)		(797,000	)
	Comprehensive income																				30,028,000
	Shares issued in acquisitions							1,578,575			16,000		33,043,000								33,059,000
	Stock options exercised							667,918			6,000		5,153,000								5,159,000
	Shares issued in Employee Stock Purchase Plan							170,985			2,000		3,068,000								3,070,000
	Exchangeable shares of a subsidiary exchanged for common shares		(33,606	)		(648,000	)	42,007			—		648,000								—
	Tax benefit for disqualifying dispositions of stock options												2,923,000								2,923,000
BALANCE, SEPTEMBER 30, 2001			790,642		$	13,239,000		52,247,777		$	522,000	$	195,126,000		$	164,900,000	$	(1,641,000	)	$	372,146,000

See accompanying Notes to Consolidated Financial Statements.

16

TETRA TECH, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

				Fiscal Year Ended
				Sept. 30, 2001			Oct. 1, 2000			Oct. 3, 1999
Cash Flows From Operating Activities:
	Net income			$	30,825,000		$	40,442,000		$	29,115,000
	Adjustments to reconcile net income to net cash provided by (used in) operating activities:
		Depreciation and amortization			21,362,000			13,709,000			12,708,000
		Deferred income taxes			(1,172,000	)		723,000			(211,000	)
		Provision for losses on receivables			44,025,000			3,056,000			(667,000	)
	Changes in operating assets and liabilities, net of effects of acquisitions:
		Accounts receivable			(24,865,000	)		(57,177,000	)		(465,000	)
		Unbilled receivables			6,571,000			(32,489,000	)		(13,645,000	)
		Contract retentions			(771,000	)		1,050,000			(82,000	)
		Prepaid expenses and other assets			(3,974,000	)		(4,337,000	)		998,000
		Accounts payable			(6,400,000	)		12,746,000			(8,306,000	)
		Accrued compensation			472,000			3,053,000			(935,000	)
		Billings in excess of costs on uncompleted contracts			(6,401,000	)		10,075,000			5,178,000
		Other current liabilities			(4,801,000	)		(2,185,000	)		3,973,000
		Income taxes receivable/payable			(10,597,000	)		(854,000	)		2,597,000
			Net Cash Provided By (Used In) Operating Activities		44,274,000			(12,188,000	)		30,258,000
Cash Flows From Investing Activities:
	Capital expenditures				(11,017,000	)		(14,745,000	)		(7,040,000	)
	Payments for business acquisitions, net of cash acquired				(40,165,000	)		(27,515,000	)		(50,655,000	)
			Net Cash Used In Investing Activities		(51,182,000	)		(42,260,000	)		(57,695,000	)
Cash Flows From Financing Activities:
	Payments on long-term obligations				(195,636,000	)		(67,763,000	)		(67,605,000	)
	Proceeds from issuance of long-term obligations				204,000,000			112,000,000			72,841,000
	Proceeds from issuance of common stock				8,229,000			8,545,000			26,576,000
	Payment of deferred financing fees				(890,000	)		—			—
			Net Cash Provided By Financing Activities		15,703,000			52,782,000			31,812,000
Effect of Exchange Rate Changes on Cash					(112,000	)		1,034,000			(1,075,000	)
Net Increase (Decrease) in Cash and Cash Equivalents					8,683,000			(632,000	)		3,300,000
Cash and Cash Equivalents at Beginning of Year					7,557,000			8,189,000			4,889,000
Cash and Cash Equivalents at End of Year				$	16,240,000		$	7,557,000		$	8,189,000
Supplemental Cash Flow Information:
	Cash paid during the year for:
		Interest		$	7,184,000		$	6,734,000		$	3,524,000
		Income taxes, net of refunds received		$	19,107,000		$	27,844,000		$	20,067,000
(continued)

17

				Fiscal Year Ended
				Sept. 30, 2001			Oct. 1, 2000			Oct. 3, 1999
Supplemental Non-Cash Investing and Financing Activities:
	In fiscal 2001, the Company purchased all of the capital stock of Rocky Mountain Consultants, Inc., Wahco Construction, Inc., Williams, Hatfield & Stoner, Inc., Vertex Engineering Services, Inc., Maxim Technologies, Inc., The Design Exchange Architects, Inc., Western Utility Contractors, Inc., Western Utility Cable, Inc. and Sciences International, Inc. The Company also purchased certain assets of Commonwealth Technology, Inc. and Shepherd Miller, Inc. In conjunction with these acquisitions, liabilities were assumed as follows:
		Fair value of assets acquired		$	104,877,000
		Cash paid			(44,779,000	)
		Issuance of common stock			(32,968,000	)
		Purchase price receivable			653,000
		Other acquisition costs			(607,000	)
			Liabilities assumed	$	27,176,000
	In fiscal 2000, the Company purchased all of the capital stock of LC of Illinois, Inc., HFC Technologies, Inc., eXpert Wireless Solutions, Inc., 1261248 Ontario, Inc., FHC, Inc., Rizzo Associates, Inc., Drake Contractors, Inc. and Wm. Bethlehem Trenching Ltd. The Company also purchased certain assets of Edward A. Sears Associates. In conjunction with these acquisitions, liabilities were assumed as follows:
		Fair value of assets acquired					$	59,653,000
		Cash paid						(29,466,000	)
		Issuance of common stock and exchangeable stock						(11,903,000	)
		Purchase price payable						(1,500,000	)
		Other acquisition costs						(730,000	)
			Liabilities assumed				$	16,054,000
	In fiscal 1999, the Company purchased all of the capital stock of McCulley, Frick & Gilman, Inc., Collins/Piña Consulting Engineers, Inc., D.E.A. Construction Company, BAHA Communications, Inc., Utilities & C.C., Inc., ASL Consultants, Inc., Cosentini Associates, Evergreen Utility Contractors, Inc., Continental Utility Contractors, Inc., Gig Harbor Construction, Inc. and PDR Engineers, Inc. In conjunction with these acquisitions, liabilities were assumed as follows:
		Fair value of assets acquired								$	110,616,000
		Cash paid									(52,275,000	)
		Issuance of common stock									(11,571,000	)
		Purchase price payable									(282,000	)
		Other acquisition costs									(965,000	)
			Liabilities assumed							$	45,523,000
(concluded)

See accompanying Notes to Consolidated Financial Statements.

18

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
FISCAL YEARS ENDED SEPTEMBER 30, 2001,
OCTOBER 1, 2000 AND OCTOBER 3, 1999

1.  SIGNIFICANT ACCOUNTING POLICIES

    Business—Tetra Tech, Inc. (the "Company") provides specialized management consulting and technical services in three principal business areas: resource management, infrastructure and communications. The Company's management consulting services are complemented by its technical services. These technical services, which implement solutions, include research and development, applied science, engineering and architectural design, construction management, and operations and maintenance.

    Principles of Consolidation—The consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries and its majority-owned subsidiary Tetra Tech Canada Ltd. All significant intercompany balances and transactions have been eliminated in consolidation.

    Fiscal Year—The Company reports results of operations based on 52- or 53-week periods ending near September 30. Fiscal years 2001, 2000 and 1999 each contained 52 weeks.

    Contract Revenue and Costs—In the course of providing its services, the Company routinely subcontracts for services. These costs are passed through to clients and, in accordance with industry practice, are included in the Company's gross revenue. Because subcontractor services can change significantly from project to project, changes in gross revenue may not be indicative of business trends. Accordingly, the Company also reports net revenue, which is gross revenue less the cost of subcontractor services. Contract revenue and contract costs on both cost-type and fixed-price-type contracts are recorded using the percentage-of-completion (cost-to-cost) method. Under this method, contract revenue on long-term contracts is recognized in the ratio that contract costs incurred bear to total estimated costs. Costs and income on long-term contracts are subject to revision throughout the lives of the contracts and any required adjustments are made in the period in which the revisions become known. Losses on contracts are recorded in full as they are identified.

    Selling, general and administrative costs are expensed in the period incurred.

    Net revenue under Federal government contracts and subcontracts accounted for approximately 24.5%, 29.1% and 39.1% of net revenue for the fiscal years ended September 30, 2001, October 1, 2000, and October 3, 1999, respectively.

    Cash and Cash Equivalents—Cash equivalents include all investments with initial maturities of 90 days or less.

    Property and Equipment—Property and equipment are recorded at cost and are depreciated over their estimated useful lives using the straight-line method. Expenditures for maintenance and repairs are expensed as incurred.

    Generally, estimated useful lives range from three to ten years for equipment, furniture and fixtures. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the remaining terms of the leases.

    Long-Lived Assets—The Company's policy regarding long-lived assets is to evaluate the recoverability of its assets when the facts and circumstances suggest that the assets may be impaired. This assessment is performed based on the estimated undiscounted cash flows compared with the carrying value of the assets. If the future cash flows (undiscounted and without interest charges) are

19

less than the carrying value, a writedown would be recorded to reduce the related asset to its estimated fair value.

    Intangible assets as of September 30, 2001 and October 1, 2000 consist principally of goodwill resulting from business acquisitions which is being amortized over periods ranging from 15 to 30 years. The accumulated amortization of intangible assets as of September 30, 2001 and October 1, 2000 was $27.0 million and $17.8 million, respectively.

    Income Taxes—The Company files a consolidated Federal income tax return and combined California franchise tax reports, as well as other returns which are required in the states in which the Company does business, which include the Company and its subsidiaries. Income taxes are recognized for (a) the amount of taxes payable or refundable for the current period, and (b) deferred income tax assets and liabilities for the future tax consequences of events that have been recognized in the Company's financial statements or income tax returns. The effects of income taxes are measured based on enacted tax laws and rates.

    Earnings Per Share—Basic Earnings Per Share (EPS) excludes dilution and is computed by dividing the income available to common stockholders by the weighted average number of common shares outstanding for the period. Diluted EPS is computed by dividing income available to common stockholders by the weighted average number of common shares outstanding and dilutive potential common shares. The Company includes as potential common shares the weighted average number of shares of exchangeable stock of a subsidiary and the weighted average dilutive effects of outstanding stock options. The exchangeable stock of a subsidiary is non-voting and is exchangeable on a one to one basis, as adjusted for stock splits and stock dividends subsequent to the original issuance, for the Company's common stock. Basic and diluted EPS reflect, on a retroative basis, a 5-for-4 stock split effected in the form of a 25% stock dividend wherein one additional share of stock was issued on December 17, 2001 for each four shares outstanding as of the record date of November 28, 2001.

    Fair Value of Financial Instruments—The carrying amounts of cash and cash equivalents, accounts receivable, unbilled receivables and accounts payable approximate fair value because of the short maturities of these instruments. The carrying amount of the revolving credit facility approximates fair value because the interest rates are based upon variable reference rates. The carrying amount of the senior secured notes approximates fair value because the notes bear interest at rates which approximate current market rates.

    Concentration of Credit Risk—Financial instruments which subject the Company to credit risk consist primarily of cash and cash equivalents, accounts receivable and unbilled receivables. The Company places its temporary cash investments with high credit quality financial institutions and, by policy, limits the amount of investment exposure to any one financial institution. As of September 30, 2001, approximately 10.5% of accounts receivable was due from various agencies of the Federal government. The remaining accounts receivable are generally diversified due to the large number of organizations comprising the Company's client base and their geographic dispersion. The Company performs ongoing credit evaluations of its clients and maintains an allowance for potential credit losses.

    Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

20

    Accounting Pronouncements—In July 2001, the Financial Accounting Standards Board (FASB) issued SFAS No. 141, Business Combinations, which supercedes Accounting Principles Board (APB) Opinion No. 16, Business Combinations. SFAS No. 141 eliminates the pooling-of-interest method of accounting for business combinations for combinations initiated after July 1, 2001. The statement also changes the criteria to recognize intangible assets apart from goodwill. The provisions of this statement are effective for any business combination accounted for by the purchase method that is completed after June 30, 2001.

    In July 2001, the FASB issued SFAS No. 142, Goodwill and Other Intangible Assets, which supercedes APB Opinion No. 17, Intangible Assets. Under SFAS No. 142, goodwill and other indefinite-lived intangible assets are no longer amortized but are reviewed, at a minimum, annually for impairment. Separable intangible assets that have finite lives will continue to be amortized over their useful lives. For the year ended September 30, 2001, goodwill amortization expense was $9.2 million. The amortization provisions of this statement are effective for goodwill and intangible assets acquired after June 30, 2001. The remaining provisions of this statement are effective for fiscal years beginning after December 15, 2001, although early adoption is permitted. The adoption of this statement will result in the Company's discontinuation of amortization of its goodwill; however, the Company will be required to test its goodwill for impairment under SFAS No. 142 in the first six months of fiscal 2003. The Company is currently analyzing the impact of this statement and has determined it will adopt this statement in fiscal 2003.

    In October 2001, the FASB issued SFAS No. 144, Accounting for the Impairment or Disposal of Long-Lived Assets, which supercedes SFAS No. 121, Accounting for the Impairment of Long-Lived Assets and for Long-Lived Assets To Be Disposed Of. SFAS No. 144 addresses financial accounting and reporting requirements for the impairment or disposal of long-lived assets. This statement also expands the scope of a discontinued operation to include a component of an entity, and eliminates the current exemption to consolidation when control over a subsidiary is likely to be temporary. The provisions of this statement are effective for fiscal years beginning after December 15, 2001 and interim periods within those fiscal years, although early adoption is permitted. The Company is currently analyzing the impact of this statement and will adopt this statement in fiscal 2003.

2.  MERGERS AND ACQUISITIONS

    On February 26, 1999, the Company acquired 100% of the capital stock of McCulley, Frick & Gilman, Inc. (MFG), a provider of professional environmental science and consulting services to private-sector clients. The purchase was valued at approximately $8.1 million, as adjusted, consisting of cash and 296,766 shares of Company common stock, of which 7,403 shares were issued in October 1999 pursuant to the purchase price adjustment clause in the related purchase agreement.

    On May 7, 1999, the Company acquired 100% of the capital stock of Collins/Piña Consulting Engineers, Inc. (CPC), a provider of consulting engineering and related services primarily in Arizona. The purchase was valued at approximately $2.7 million, as adjusted, consisting of cash and 6,172 shares of Company common stock.

    On May 19, 1999, the Company acquired 100% of the capital stock of D.E.A. Construction Company (DCC), a provider of engineering and network infrastructure services for cable television and fiber optic telephone networks including design and construction and maintenance capabilities of communications and information transport systems. The purchase was valued at approximately $15.5 million, as adjusted, consisting of cash.

21

    On May 21, 1999, the Company acquired 100% of the capital stock of BAHA Communications, Inc. (BCI), a supplier of infrastructure installation and maintenance services to the wireless personal communications industry. The purchase was valued at approximately $2.6 million, consisting of 220,210 shares of Company common stock. Simultaneously with the acquisition, BCI assigned to its former owners accounts receivable having a net value of $1.0 million.

    On June 18, 1999, the Company acquired 100% of the capital stock of Utilities & C.C., Inc. (UCC), a supplier of infrastructure installation and maintenance services to the wireless personal communications industry. The purchase was valued at approximately $2.2 million, as adjusted, consisting of 180,602 shares of Company common stock, of which 8,190 shares were issued in October 1999, pursuant to the purchase price adjustment clause in the related purchase agreement.

    On June 25, 1999, the Company acquired 100% of the capital stock of ASL Consultants, Inc. (ASL), a provider of water and wastewater treatment, transportation, and other engineering services. The purchase was valued at approximately $10.1 million, consisting of cash.

    On June 30, 1999, the Company acquired 100% of the capital stock of L.M.W. Associates, Inc., Cosentini Associates, Inc. and Cobin, Inc., and 100% of the limited liability partnership interests of Cosentini Associates IL LLP, Cosentini Associates MA LLP, Cosentini Associates DC LLP and Cosentini Associates FL LLP (collectively, CAA). The purchase was valued at approximately $5.3 million, consisting of cash. Simultaneously with the acquisition, CAA assigned to its former owners accounts receivable having a gross value of $18.4 million.

    On September 3, 1999, the Company acquired 100% of the capital stock of PDR Engineers, Inc. (PDR), a provider of engineering consulting services to Federal, state and local government and private-sector clients. The purchase was valued at approximately $6.6 million, consisting of cash and 295,656 shares of Company common stock.

    On October 2, 1999, the Company acquired 100% of the capital stock of Evergreen Utility Contractors, Inc., Continental Utility Contractors, Inc. and Gig Harbor Construction, Inc. (collectively, EUC), a provider of engineering and network services for cable TV and fiber optic networks in the pacific northwest region of the United States. The purchase was valued at approximately $11.8 million, consisting of cash.

    On October 25, 1999, the Company acquired 100% of the capital stock of LC of Illinois, Inc. and HFC Technologies, Inc. (collectively, LCI), providers of engineering and network infrastructure services for cable television and fiber optic telephone networks including design, construction and maintenance capabilities for communications and information transport systems. The purchase was valued at approximately $1.6 million and consisted of cash.

    On March 30, 2000, Tetra Tech Engineers, P.C. acquired certain assets of Edward A. Sears Associates (ESA), a provider of engineering services to hospitals in New York. Concurrent with this transaction, the Company's subsidiary, Cosentini Associates, Inc., acquired certain non-licensed assets of ESA from Tetra Tech Engineers, P.C. The purchase was valued at approximately $0.4 million and consisted of cash.

    On April 3, 2000, the Company acquired 100% of the capital stock of eXpert Wireless Solutions, Inc. (EWS), a provider of radio-frequency engineering and consulting services to the wireless communications industry. The purchase was valued at approximately $18.8 million and consisted of cash (of which $500,000 was dependent on operational performance) and 509,846 shares of Company common stock. Simultaneously with the acquisition, EWS distributed to its former shareholders accounts receivable valued at approximately $1.8 million.

22

    On May 3, 2000, the Company, through its majority-owned subsidiary, Tetra Tech Canada Ltd. (TTC), acquired 100% of the capital stock of 1261248 Ontario, Inc., which does business as Engineered Communications (ENG), a provider of engineering and network services for the wired communications industry in Ontario, Canada. The purchase was valued at approximately $1.5 million and consisted of cash and 33,606 shares of exchangeable stock of TTC.

    On May 17, 2000, the Company acquired 100% of the capital stock of FHC, Inc. (FHC), a provider of engineering consulting services primarily to the state and local governments in Oklahoma. The purchase was valued at approximately $5.2 million and consisted of cash and 70,417 shares of Company common stock.

    On May 24, 2000, the Company acquired 100% of the capital stock of Rizzo Associates, Inc. (RAI), a provider of engineering consulting services to state and local governments and commercial clients in the upper northeast region of the United States. This purchase was valued at approximately $10.3 million and consisted of cash and 140,545 shares of Company common stock.

    On June 16, 2000, the Company acquired 100% of the capital stock of Drake Contractors, Inc. (DCI), a provider of infrastructure installation and maintenance services primarily in Colorado. The purchase was valued at approximately $5.5 million and consisted of cash (of which $1.0 million was contingent on operational performance). Simultaneously with the acquisition, DCI distributed to its former shareholders accounts receivable valued at approximately $2.1 million.

    On July 5, 2000, the Company, through TTC, acquired 100% of the capital stock of Wm. Bethlehem Trenching Ltd. (BTL), a provider of infrastructure installation and maintenance services primarily in Ontario, Canada. The purchase was valued at approximately $0.3 million and consisted of cash.

    On December 21, 2000, the Company acquired 100% of the capital stock of Rocky Mountain Consultants, Inc. (RMC), a provider of water-related engineering and facility development services to state and local governments and private clients primarily in the western and midwestern regions of the United States. The purchase was valued at approximately $15.2 million and consisted of cash and 370,833 shares of Company common stock.

    On March 2, 2001, the Company acquired 100% of the capital stock of Wahco Construction, Inc. (WCI), a provider of network and field services to the utility and communications industries primarily in the northwestern region of the United States. The purchase was valued at approximately $0.8 million and consisted of cash and 64,977 shares of Company common stock and is subject to a purchase price and purchase allocation adjustment based upon the final determination of WCI's net asset value as of March 2, 2001.

    On March 30, 2001, the Company acquired 100% of the capital stock of Williams, Hatfield & Stoner, Inc. (WHS), a provider of civil engineering, planning and environmental services primarily in the southeastern region of the United States. The purchase was valued at approximately $9.1 million and consisted of cash and 159,433 shares of Company common stock and is subject to a purchase price and purchase allocation adjustment based upon the final determination of WHS's net asset value as of March 30, 2001. Simultaneously with the acquisition, WHS distributed to its former shareholders accounts receivable valued at approximately $3.8 million.

    On May 21, 2001, the Company acquired 100% of the capital stock of Vertex Engineering Services, Inc. (VES), a provider of environmental engineering, consulting and surety and insurance construction management services throughout the United States. The purchase was valued at approximately $10.4 million and consisted of cash and 374,417 shares of Company common stock and is

23

subject to a purchase price and purchase allocation adjustment based upon the final determination of VES's net asset value as of May 21, 2001.

    On May 25, 2001, the Company acquired 100% of the capital stock of Maxim Technologies, Inc. (MTI), a provider of environmental and engineering consulting services throughout the United States. The purchase was valued at approximately $14.0 million and consisted of cash and 296,995 shares of Company common stock and is subject to a purchase price and purchase allocation adjustment based upon the final determination of MTI's net asset value as of May 25, 2001.

    On June 1, 2001, the Company acquired certain assets of Commonwealth Technology, Inc. (CTI), a provider of environmental and infrastructure engineering and consulting services primarily in the southeastern region of the United States. The purchase was valued at approximately $3.6 million and consisted of cash and 108,137 shares of Company common stock and is subject to a purchase price and purchase allocation adjustment based upon the final determination of CTI's net asset value as of June 1, 2001.

    On June 27, 2001, the Company acquired 100% of the capital stock of The Design Exchange Architects, Inc. (DXA), a provider of architectural, planning and interior design services primarily in the eastern region of the United States. The purchase was valued at approximately $1.3 million and consisted of cash and is subject to a purchase price and purchase allocation adjustment based upon the final determination of DXA's net asset value as of June 27, 2001.

    On June 29, 2001, the Company acquired 100% of the capital stock of Western Utility Contractors, Inc. and Western Utility Cable, Inc. (collectively, WUC), providers of engineering, design and construction services primarily in the midwestern region of the United States. The purchase was valued at approximately $15.6 million and consisted of cash and is subject to a purchase price and purchase allocation adjustment based upon the final determination of WUC's net asset value as of June 29, 2001.

    On September 26, 2001, the Company acquired, through its wholly-owned subsidiary, MFG, Inc., certain assets of Shepherd Miller, Inc. (SMI), a provider of environmental and engineering consulting services to the mining industry throughout the United States. The purchase was valued at approximately $2.5 million and consisted of cash and 53,005 shares of Company common stock and is subject to a purchase price and purchase allocation adjustment based upon the final determination of SMI's net asset value as of September 26, 2001.

    On September 26, 2001, the Company acquired Sciences International, Inc. (SII), a provider of health and environmental risk assessment services to private industries, governments and law firms throughout the United States. The purchase was valued at approximately $5.1 million and consisted of cash and 137,508 shares of Company common stock and is subject to a purchase price and purchase allocation adjustment based upon the final determination of SII's net asset value as of September 26, 2001.

    All of the acquisitions above were accounted for as purchases and, accordingly, the purchase prices of the businesses acquired were allocated to the assets and liabilities acquired based upon their fair values. The excess of the purchase cost of the acquisitions over the fair value of the net assets acquired was recorded as goodwill and is included in Intangible Assets—Net in the accompanying consolidated balance sheets. The results of operations of each of the companies acquired have been included in the Company's financial statements from the effective acquisition dates.

24

    The effect of unaudited pro forma operating results of the LCI, ESA, ENG, DCI, BTL, WCI, WHS, MTI, DXA, SMI and SII acquisitions, had they been acquired on October 4, 1999, is not material.

    The following table presents summarized unaudited pro forma operating results assuming that the Company had acquired EWS, FHC, RAI, RMC, VES, CTI and WUC on October 4, 1999:

		Fiscal Year Ended
		Sept. 30, 2001		Oct. 1, 2000
Gross revenue		$	1,001,512,000	$	885,318,000
Income before income tax expense			42,918,000		76,913,000
Net income			31,331,000		42,799,000
Basic earnings per share		$	0.61	$	0.86
Diluted earnings per share			0.57		0.80
Weighted average common shares outstanding:
	Basic		51,282,000		49,985,000
	Diluted		54,509,000		53,234,000

3.  ACCOUNTS RECEIVABLE

    Accounts receivable consisted of the following at September 30, 2001 and October 1, 2000:

		Sept. 30, 2001			Oct. 1, 2000
Billed accounts receivable		$	197,859,000		$	158,992,000
Unbilled accounts receivable:
	Billable amounts not invoiced, amounts billable at stipulated stages of completion of contract work, and unbilled amounts pending negotiation or receipt of contract modifications		121,724,000			119,478,000
	Costs and fee retention billable upon audit of total contract costs		5,103,000			4,232,000
Total unbilled accounts receivable			126,827,000			123,710,000
Billings in excess of costs on uncompleted contracts			(10,354,000	)		(15,947,000	)
Allowance for uncollectible accounts:
	Allowance for doubtful accounts		(45,098,000	)		(5,465,000	)
	Allowance for disallowed costs		(799,000	)		(1,608,000	)
Total allowance for uncollectible accounts			(45,897,000	)		(7,073,000	)
Total		$	268,435,000		$	259,682,000

    The accounts receivable valuation allowance includes amounts to provide for doubtful accounts and for the potential disallowance of billed and unbilled costs. Included in the allowance for doubtful accounts at September 30, 2001 is a $38.3 million reserve for an account debtor that filed for Chapter 11 protection under the U.S. Bankruptcy Code. This amount is included in selling, general and administrative expense in the accompanying consolidated statement of income for the year ended September 30, 2001. The allowance for disallowed costs relate primarily to contracts with the Federal government. These contracts are subject to audit by the government, primarily the Defense Contract Audit Agency (DCAA), which reviews the Company's overhead rates, operating systems and cost proposals. During the course of its audits, the DCAA may disallow costs if it determines that the Company improperly accounted for such costs in a manner inconsistent with Cost Accounting

25

Standards. Historically, the Company has not had any material cost disallowances by the DCAA as a result of audit, except for disallowances of acquired receivables as further described. There can be no assurance that DCAA audits will not result in material cost disallowances in the future.

    On September 15, 1995, the Company acquired Tetra Tech EM Inc. (EMI) which contracts with the Federal government. At the time of acquisition, audits had not been performed for years beyond 1986 and reserves for disallowances relating to those unaudited years were adjusted to reflect the estimated ultimate disallowances relating to those receivables. As of October 3, 1999, audits and negotiations relating to the EMI contracts for years 1987 through 1995 were complete, and cost disallowances as a result of these audits totaled approximately $4.4 million. Beyond the $4.4 million in cost disallowances, there remained uncollected receivables of $2.1 million. Although it was determined that the Company was entitled to payments, collectibility of such amounts was not assured as each Federal government agency must obtain separate funding approval. The reserves established for these receivables exceeded the disallowances and the uncollected amounts by $1.75 million. Accordingly, this amount was taken into income in fiscal 1999. During fiscal 2000, the Company collected $2.0 million and reversed previously established reserves related to these receivables. As of October 1, 2000, substantially all of these outstanding receivables had been collected and all reserves relating to these receivables had been reversed.

    Allowances to provide for doubtful accounts have been determined through reviews of specific amounts determined to be uncollectible, plus a general allowance for other amounts for which some potential loss is determined to be probable based on current events and circumstances. Given the above, management believes that the resolution of these matters will not have a material adverse effect on the Company's financial position or results of operations.

4.  INCOME TAXES

    Income tax expense for the fiscal years ended September 30, 2001, October 1, 2000 and October 3, 1999 consisted of the following:

		Fiscal Year Ended
		Sept. 30, 2001			Oct. 1, 2000		Oct. 3, 1999
Current:
	Federal	$	6,963,000		$	20,845,000	$	18,763,000
	State		4,083,000			5,224,000		4,661,000
Deferred			(1,172,000	)		708,000		(250,000	)
Total income tax expense		$	9,874,000		$	26,777,000	$	23,174,000

    Temporary differences comprising the net deferred income tax asset shown on the consolidated balance sheets were as follows:

	Sept. 30, 2001			Oct. 1, 2000
Allowance for doubtful accounts	$	2,925,000		$	3,041,000
Accrued vacation		3,632,000			1,871,000
Depreciation		(3,489,000	)		(2,317,000	)
Prepaid expense		(1,540,000	)		(514,000	)
State taxes		1,176,000			1,337,000
Other		1,041,000			127,000
Cash to accrual		(22,000	)		(994,000	)
Net deferred income tax asset	$	3,723,000		$	2,551,000

26

    Total income tax expense was different than the amount computed by applying the Federal statutory rate as follows:

	Fiscal Year Ended
	Sept. 30, 2001					Oct. 1, 2000					Oct. 3, 1999
	Amount			%		Amount			%		Amount		%
Tax at Federal statutory rate	$	14,245,000		35.0	%	$	23,527,000		35.0	%	$	18,301,000	35.0	%
Tax credits		(9,428,000	)	(23.2	)%		(2,800,000	)	(4.2	)%		—	—
Goodwill		3,159,000		7.8	%		2,053,000		3.1	%		1,434,000	2.7	%
State taxes, net of Federal benefit		2,116,000		5.2	%		3,495,000		5.2	%		2,719,000	5.2	%
Other		(218,000	)	(0.5	)%		502,000		0.7	%		720,000	1.4	%
Total income tax expense	$	9,874,000		24.3	%	$	26,777,000		39.8	%	$	23,174,000	44.3	%

5.  LONG-TERM OBLIGATIONS

    The Company has a credit agreement with various financial institutions (the "Credit Agreement") to support its working capital and acquisition needs. The Credit Agreement, as amended, provides a revolving credit facility of $140.0 million and matures on March 17, 2005 or earlier at the discretion of the Company upon payment in full of loans and other obligations.

    Interest on borrowings under the Credit Agreement is payable at the Company's option (a) at a base rate (the greater of the federal funds rate plus 0.50% or the bank's reference rate) as defined in the Credit Agreement or (b) at a eurodollar rate plus a margin which ranges from 0.75% to 1.25%. The weighted average interest rate on outstanding borrowings under the Credit Agreement at September 30, 2001 was 4.51%.

    Borrowings under the Credit Agreement are secured by the Company's accounts receivable and the stock of certain of the Company's subsidiaries.

    On May 22, 2001, the Company issued two series of senior secured notes (the "Senior Secured Notes") in the aggregate amount of $110.0 million. Series A, totaling $92.0 million, carries an interest rate of 7.28%. Series B, totaling $18.0 million, carries an interest rate of 7.08%. Interest on both Series A and Series B is payable semi-annually, commencing November 2001. Commencing May 30, 2005, principal payments of $13.1 million and are payable on the Series A Notes each May 30 to and including May 30, 2011. Commencing May 30, 2004, principal payments of $3.6 million are payable on the Series B Notes each May 30 to and including May 30, 2008.

    The Credit Agreement and Senior Secured Notes contain various covenants including, but not limited to, restrictions related to tangible net worth, net income, additional indebtedness, asset sales, mergers and acquisitions, creation of liens, and dividends on capital stock (other than stock dividends).

    As of September 30, 2001, outstanding borrowings under the Credit Agreement totaled $14.0 million and standby letters of credit totaled $1.7 million. Outstanding borrowings on the Senior Secured Notes totaled $110.0 million at September 30, 2001.

    At September 30, 2001, approximately $2.1 million of additional debt existed from acquired companies. This debt is primarily related to pre-acquisition borrowings to facilitate equipment purchases. The Company intends to repay these amounts prior to the end of their term and terminate all such agreements.

6.  STOCKHOLDERS' EQUITY

    On November 12, 2001, the Board of Directors approved a five-for-four split of the Company's common stock, which was effected on December 17, 2001, in the form of a 25% stock dividend, to the

27

stockholders of record on November 28, 2001. All agreements concerning stock options and other commitments payable in shares of the Company's common stock are affected by the five-for-four split. All references to number of shares (except shares authorized), stock options, share prices and per share information in the consolidated financial statements have been adjusted to reflect the stock split on a retroactive basis.

    In February 1999, the Company, along with certain selling stockholders, offered a total of 4,960,937 shares of its common stock through a public offering. The Company offered 1,562,500 shares and received approximately $22.2 million in net proceeds which were used for the partial repayment of outstanding indebtedness under the Company's revolving credit facility.

    In connection with the ENG acquisition and the fiscal 1998 acquisition of the Sentrex Group of Companies, the Company issued an aggregate of 953,960 shares of exchangeable stock of its subsidiary, Tetra Tech Canada Ltd. (the "Exchangeable Shares"), a corporation existing under the laws of the Province of Ontario, Canada. The Exchangeable Shares are non-voting but carry exchange rights under which a holder of Exchangeable Shares is entitled, at any time after five months from the date of issue of the Exchangeable Shares, to require the Company to redeem all or any part of the Exchangeable Shares for an amount per share equal to (a) the current market price of a share of the Company's common stock, which shall be satisfied in full by the Company's delivery to such holder of one share of its common stock for each Exchangeable Share presented and surrendered, plus (b) a dividend amount or dividend shares, if any. The Exchangeable Shares cannot be put back to the Company for cash.

    Pursuant to the Company's 1989 Stock Option Plan, key employees could be granted options to purchase an aggregate of 1,490,112 shares of the Company's common stock at prices ranging from 85% to 100% of the market value on the date of grant. The 1989 Stock Option Plan has been terminated, and all options granted to date by the Company have been at 100% of the market value as approved by the Board of Directors at the date of grant. These options become exercisable beginning one year from date of grant, become fully vested in four years and terminate ten years from the date of grant.

    The Company has a 1992 Incentive Stock Plan under which key employees may be granted options to purchase an aggregate of 7,202,147 shares of the Company's common stock at prices not less than 100% of the market value on the date of grant. From such date of grant, these options become exercisable after one year, are fully vested no later than five years after grant and terminate no later than ten years after grant.

    Pursuant to the Company's 1992 Stock Option Plan for Nonemployee Directors, non-employee directors may be granted options to purchase an aggregate of 178,808 shares of the Company's common stock at prices not less than 100% of the market value on the date of grant. These options vest and become exercisable when, and only if, the optionee continues to serve as a director until the Annual Meeting following the year in which the options were granted.

    The Company also has an Employee Stock Purchase Plan (the "Purchase Plan") which provides for the granting of Purchase Rights to purchase common stock to regular full and part-time employees or officers of the Company and its subsidiaries. Under the Purchase Plan, shares of common stock will be issued upon exercise of the Purchase Rights. Under the Purchase Plan, an aggregate of 1,373,290 shares may be issued pursuant to the exercise of Purchase Rights. The maximum amount that an employee can contribute during a Purchase Right Period is $4,000, and the minimum contribution per payroll period is $25.

    Under the Purchase Plan, the exercise price of a Purchase Right will be the lesser of 100% of the fair market value of such shares on the first day of the Purchase Right Period or 85% of the fair

28

market value on the last day of the Purchase Right Period. For this purpose, the fair market value of the stock is its closing price as reported on the Nasdaq Stock Market on the day in question.

    During the three years in the period ended September 30, 2001, option activity was as follows:

		Number of Options		Weighted Average Exercise Price
Balance, October 4, 1998		3,700,734		$	7.15
	Granted	1,124,105			13.21
	Exercised	(362,465	)		5.30
	Cancelled	(236,733	)		8.82
Balance, October 3, 1999		4,225,641			9.02
	Granted	887,153			10.30
	Exercised	(806,383	)		7.07
	Cancelled	(133,530	)		12.02
Balance, October 1, 2000		4,172,881			9.57
	Granted	1,195,960			21.50
	Exercised	(667,918	)		7.72
	Cancelled	(266,892	)		15.62
Outstanding at September 30, 2001		4,434,031		$	12.70
Exercisable at September 30, 2001		2,178,656		$	8.76

    The following table summarizes information concerning currently outstanding and exercisable options:

		Options Outstanding				Options Exercisable
Range of Exercise Prices		Number Outstanding	Weighted Average Remaining Contractual Life (Yrs.)	Weighted Average Exercise Price		Number Exercisable	Weighted Average Exercise Price
$	2.05 - $3.06	80,663	0.87	$	2.77	80,663	$	2.77
$	3.42 - $5.05	392,348	2.48		4.09	392,348		4.09
$	5.68 - $8.35	732,048	4.82		7.50	732,048		7.50
$	8.73 - $12.80	1,313,503	7.00		9.88	615,008		10.33
$	13.20 - $19.60	972,033	7.71		15.51	358,308		15.07
$	19.81 - $28.00	943,436	9.09		22.21	281		21.03
$	2.05 - $28.00	4,434,031	6.73	$	12.70	2,178,656	$	8.76

    The Company applies APB Opinion No. 25, Accounting for Stock Issued to Employees, and related interpretations in accounting for its stock option plans because the Company continues to apply the intrinsic value method. Accordingly, no compensation expense has been recognized for its stock-based compensation plans. Pro forma net income and earnings per share had the Company accounted for

29

stock options issued to employees in accordance with the fair value method of SFAS No. 123, Accounting for Stock-Based Compensation, are as follows:

	Fiscal Year Ended
	Sept. 30, 2001		Oct. 1, 2000		Oct. 3, 1999
Net income—as reported	$	30,825,000	$	40,442,000	$	29,115,000
Net income—pro forma		27,316,000		36,324,000		27,004,000
Basic earnings per share—as reported	$	0.61	$	0.83	$	0.63
Diluted earnings per share—as reported		0.57		0.78		0.59
Basic earnings per share—pro forma		0.54		0.75		0.58
Diluted earnings per share—pro forma		0.50		0.70		0.55

    The fair value of the Company's stock options used to compute pro forma net income and pro forma earnings per share disclosures is the estimated value using the Black-Scholes option-pricing model. The weighted average fair values per share of options granted in fiscal 2001, 2000 and 1999 are $8.77, $4.38 and $5.27, respectively. The following assumptions were used in completing the model:

	Fiscal Year Ended
	Sept. 30, 2001		Oct. 1, 2000		Oct. 3, 1999
Dividend yield	0.0	%	0.0	%	0.0	%
Expected volatility	48.6	%	46.5	%	42.2	%
Risk-free rate of return, annual	3.4	%	7.7	%	6.4	%
Expected life	3.85 yrs.		3.51 yrs.		3.26 yrs.

7.  EARNINGS PER SHARE

    The following table sets forth the computation of basic and diluted earnings per share:

			Fiscal Year Ended
			Sept. 30, 2001		Oct. 1, 2000		Oct. 3, 1999
Numerator—
	Net income		$	30,825,000	$	40,442,000	$	29,115,000
Denominator for basic earnings per share— Weighted average shares				50,939,000		48,754,000		46,449,000
Denominator for diluted earnings per share— Denominator for basic earnings per share				50,939,000		48,754,000		46,449,000
	Potential common shares
		Stock options		1,971,000		2,001,000		1,650,000
		Exchangeable stock of a subsidiary		1,256,000		1,248,000		1,339,000
	Potential common shares			3,227,000		3,249,000		2,989,000
Denominator for diluted earnings per share				54,166,000		52,003,000		49,438,000
Basic earnings per share			$	0.61	$	0.83	$	0.63
Diluted earnings per share			$	0.57	$	0.78	$	0.59

30

8.  LEASES

    The Company leases office and field equipment, vehicles, land and buildings under various operating leases. Rent expense under all operating leases was approximately $38.0 million, $28.3 million and $20.6 million for the fiscal years ended September 30, 2001, October 1, 2000 and October 3, 1999, respectively. Amounts payable under noncancelable operating lease commitments are as follows during the fiscal years ending in:

2002	$	26,939,000
2003		22,023,000
2004		18,076,000
2005		12,060,000
2006		9,098,000
Thereafter		23,752,000
Total	$	111,948,000

9.  RETIREMENT PLANS

    The Company and its subsidiaries have established defined contribution plans and 401(k) plans. Generally, employees are eligible to participate in the defined contribution plans upon completion of one year of service and in the 401(k) plans upon commencement of employment. For the fiscal years ended September 30, 2001, October 1, 2000 and October 3, 1999, employer contributions relating to the plans were approximately $10.0 million, $7.2 million and $6.4 million, respectively.

10.  CONTINGENCIES

    The Company is subject to certain claims and lawsuits typically filed against the engineering and consulting professions, primarily alleging professional errors or omissions. The Company carries professional liability insurance, subject to certain deductibles and policy limits against such claims. Management is of the opinion that the resolution of these claims will not have a material adverse effect on the Company's financial position and results of operations.

11.  OPERATING SEGMENTS

    The Company's management has organized its operations into three operating segments: Resource Management, Infrastructure and Communications. The Resource Management operating segment provides specialized environmental engineering and consulting services primarily relating to water quality and water availability to both public and private organizations. The Infrastructure operating segment provides engineering services to provide additional development, as well as upgrading and replacement of existing infrastructure to both public and private organizations. The Communications operating segment provides a comprehensive set of services including network planning, engineering, site acquisition, construction and construction management, and operations and maintenance services to telecommunications companies, wireless service providers and cable operators. Management has established these operating segments based upon the services provided, the different marketing strategies, and the specialized needs of the clients. The Company accounts for inter-segment sales and transfers as if the sales and transfers were to third parties; that is, by applying a negotiated fee onto the cost of the services performed. Management evaluates the performance of these operating segments based upon their respective income from operations before the effect of any acquisition-related amortization and any fee from inter-segment sales and transfers.

31

    The following tables set forth (in thousands) summarized financial information on the Company's reportable segments:

    Reportable Segments:

		Resource Management		Infrastructure		Communications			Total
Fiscal year ended September 30, 2001
	Gross Revenue	$	425,296	$	304,236	$	278,237		$	1,007,769
	Net Revenue		292,299		247,944		184,698			724,941
	Income (Loss) from Operations		35,034		32,202		(9,082	)		58,154
	Depreciation Expense		2,357		4,850		4,450			11,657
	Segment Assets		231,162		90,451		48,583			370,196

		Resource Management		Infrastructure		Communications		Total
Fiscal year ended October 1, 2000
	Gross Revenue	$	374,875	$	236,922	$	207,936	$	819,733
	Net Revenue		246,851		190,269		153,360		590,480
	Income from Operations		32,901		20,866		28,020		81,787
	Depreciation Expense		1,670		2,514		2,806		6,990
	Segment Assets		175,571		75,043		86,702		337,316

		Resource Management		Infrastructure		Communications		Total
Fiscal year ended October 3, 1999
	Gross Revenue	$	340,955	$	135,589	$	102,378	$	578,922
	Net Revenue		231,518		111,776		88,765		432,059
	Income from Operations		30,147		15,703		14,905		60,755
	Depreciation Expense		1,446		4,430		1,565		7,441
	Segment Assets		154,375		48,633		44,444		247,452

32

    Reconciliations:

			Fiscal Year Ended
			Sept. 30, 2001			Oct. 1, 2000			Oct. 3, 1999
Gross Revenue
	Gross revenue from reportable segments		$	1,007,769		$	819,733		$	578,922
	Elimination of inter-segment revenue			(38,948	)		(32,796	)		(15,850	)
	Other revenue			5,123			7,641			3,418
		Total consolidated gross revenue	$	973,944		$	794,578		$	566,490
Net Revenue
	Net revenue from reportable segments		$	724,941		$	590,480		$	432,059
	Other revenue			5,123			7,641			21
		Total consolidated net revenue	$	730,064		$	598,121		$	432,080
Income from Operations
	Income from operations of reportable segments		$	58,154		$	81,787		$	60,755
	Other income (expense)			280			(1,079	)		(490	)
	Amortization of intangibles			(9,192	)		(6,463	)		(4,841	)
		Total consolidated income from operations	$	49,242		$	74,245		$	55,424
Total Assets
	Total assets from reportable segments		$	370,196		$	337,316		$	247,452
	Goodwill not allocated to segments			245,019			190,452			160,686
	Elimination of inter-segment assets			(7,994	)		(1,730	)		(27,660	)
		Total consolidated total assets	$	607,221		$	526,038		$	380,478

Geographic Information:

	Fiscal Year Ended
	Sept. 30, 2001				Oct. 1, 2000				Oct. 3, 1999
	Net Revenue(a)		Long-Lived Assets(b)		Net Revenue(a)		Long-Lived Assets(b)		Net Revenue(a)		Long-Lived Assets(b)
United States	$	706,862	$	288,220	$	579,593	$	226,731	$	417,983	$	183,850
Foreign countries		23,202		2,714		18,528		2,367		14,097		1,558

(a)

Net revenue is attributed to countries based on the location of work performed.

(b)

Long-lived assets include non-current assets of the Company.

Major Clients

    The Company's net revenue attributable to the U.S. government clients was approximately $179.0 million, $174.2 million and $169.3 million for fiscal years ended September 30, 2001, October 1, 2000 and October 3, 1999, respectively. Both the Resource Management and Infrastructure operating segments report revenue from the U.S. government.

33

12.  QUARTERLY FINANCIAL INFORMATION—UNAUDITED

    In the opinion of management, the following unaudited quarterly data for the fiscal years ended September 30, 2001 and October 1, 2000 reflect all adjustments necessary for a fair statement of the results of operations. All such adjustments are of a normal recurring nature. (In thousands, except per share data)

Fiscal Year 2001		First Quarter		Second Quarter		Third Quarter			Fourth Quarter
Gross revenue		$	229,330	$	234,315	$	250,124		$	260,175
Net revenue			167,138		179,658		191,548			191,720
Gross profit			38,733		41,404		44,526			45,927
Income (loss) from operations			18,150		20,361		(15,520	)		26,251
Net income (loss)			9,370		10,534		(3,829	)		14,750
Basic earnings (loss) per share		$	0.19	$	0.21	$	(0.07	)	$	0.28
Diluted earnings (loss) per share			0.17		0.20		(0.07	)		0.27
Weighted average common shares outstanding:
	Basic		50,017		50,453		51,233			52,048
	Diluted		53,855		53,505		51,233			54,866

Fiscal Year 2000		First Quarter		Second Quarter		Third Quarter		Fourth Quarter
Gross revenue		$	170,241	$	177,581	$	203,795	$	242,961
Net revenue			129,171		138,846		156,468		173,636
Gross profit			28,754		29,284		40,202		47,009
Income from operations			14,733		15,980		19,673		23,859
Net income			7,563		8,124		9,920		14,835
Basic earnings per share		$	0.16	$	0.17	$	0.20	$	0.30
Diluted earnings per share			0.15		0.16		0.19		0.28
Weighted average common shares outstanding:
	Basic		48,066		48,187		49,109		49,651
	Diluted		50,522		51,425		52,630		53,237

34

SECURITIES INFORMATION

    Tetra Tech's common stock is traded on the Nasdaq National Market under the symbol TTEK. There were 2,213 stockholders of record as of December 11, 2001. Tetra Tech has not paid any cash dividends since its inception and does not intend to pay any cash dividends on its common stock in the foreseeable future. The high and low sales prices for the common stock for the last two fiscal years, as reported by the National Association of Securities Dealers, Inc., are set forth in the following tables. The prices have been adjusted to reflect, on a retroactive basis, the five-for-four stock split, effected in the form of a 25% stock dividend, in December 2001.

Fiscal Year 2001	High		Low
First Quarter	$	30.05	$	19.80
Second Quarter		25.50		13.60
Third Quarter		25.06		14.40
Fourth Quarter		21.72		15.92

Fiscal Year 2000	High		Low
First Quarter	$	14.10	$	8.40
Second Quarter		22.60		10.70
Third Quarter		21.20		12.75
Fourth Quarter		25.15		16.90

35

QuickLinks

Exhibit 13
FINANCIAL HIGHLIGHTS
SELECTED CONSOLIDATED FINANCIAL DATA
MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
INDEPENDENT AUDITORS' REPORT
TETRA TECH, INC. CONSOLIDATED BALANCE SHEETS
TETRA TECH, INC. CONSOLIDATED STATEMENTS OF INCOME
TETRA TECH, INC. CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY FISCAL YEARS ENDED SEPTEMBER 30, 2001, OCTOBER 1, 2000 AND OCTOBER 3, 1999
TETRA TECH, INC. CONSOLIDATED STATEMENTS OF CASH FLOWS
TETRA TECH, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS FISCAL YEARS ENDED SEPTEMBER 30, 2001, OCTOBER 1, 2000 AND OCTOBER 3, 1999
SECURITIES INFORMATION

EX-21

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 21

SUBSIDIARIES OF TETRA TECH, INC.

GeoTrans, Inc., a Virginia corporation
Tetra Tech EM Inc., a Delaware corporation
KCM, Inc., a Washington corporation
Tetra Tech Technical Services, Inc., a Delaware corporation
SCM Consultants, Inc., a Washington corporation
Whalen & Company, Inc., a Delaware corporation
Whalen Service Corps Inc., a Delaware corporation
Tetra Tech NUS, Inc., a Delaware corporation
McNamee, Porter & Seeley, Inc., a Michigan corporation
Tetra Tech Canada Ltd., a Province of Ontario, Canada corporation (dba Sentrex Communications Company)
IWA Services, Inc., a California corporation
MFG, Inc., a Delaware corporation
D.E.A. Construction Company, a Colorado corporation
BAHA Communications, Inc., a Nevada corporation
Utilities & C. C., Inc., a California corporation
Cosentini Associates, Inc., a New York corporation
PDR Engineers, Inc., a Delaware corporation
Continental Utility Contractors, Inc., a Washington corporation
Evergreen Utility Contractors, Inc., a Washington corporation
Gig Harbor Construction, Inc., a Washington corporation
LC of Illinois, Inc., an Illinois corporation
HFC Technologies, Inc., a Colorado corporation
eXpert Wireless Solutions, Inc., a Delaware corporation
FHC, Inc., an Oklahoma corporation
Rizzo Associates, Inc., a Massachusetts corporation
Drake Contractors, Inc., a Colorado corporation
Rocky Mountain Consultants, Inc., a Delaware corporation
Williams, Hatfield & Stoner, Inc., a Florida corporation
Vertex Engineering Services, Inc., a Massachusetts corporation
Maxim Technologies, Inc., a Delaware corporation
Commonwealth Technology, Inc., a Delaware corporation
The Design Exchange Architects, Inc., a Delaware corporation
Western Utility Contractors, Inc., a Illinois corporation
Western Utility Cable, Inc., a Illinois corporation
Sciences International, Inc., a Delaware corporation
Tetra Tech Executive Services, Inc., a California corporation
Tetra Tech Consulting & Remediation, Inc., a Delaware corporation

All of such subsidiaries, other than Tetra Tech Canada Ltd., are wholly-owned by Tetra Tech, Inc.

QuickLinks

Exhibit 21
SUBSIDIARIES OF TETRA TECH, INC.

EX-23

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 23

INDEPENDENT AUDITORS' CONSENT

    We consent to the incorporation by reference in Registration Statement Nos. 033-46240, 033-47533, 033-80606, 033-94706, 333-11757 and 333-53036 of Tetra Tech, Inc. on Form S-8 and 333-95083, 333-43942, 333-48848, 333-53034, 333-61066, 333-61828, 333-63584, 333-67628 and 333-70352 of Tetra Tech, Inc. on Form S-3 of our reports dated November 14, 2001, appearing in, and incorporated by reference in, this Annual Report on Form 10-K for the year ended September 30, 2001.

/s/ DELOITTE & TOUCHE LLP

Los Angeles, California
December 28, 2001

QuickLinks

Exhibit 23