AS FILED WITH THEAs filed with the Securities and Exchange Commission on October 21, 1999
Registration No. 333-
- ------------------------------------------------------------------------------
- ------------------------------------------------------------------------------

SECURITIES AND EXCHANGE COMMISSION
ON JANUARY 8, 1999

REGISTRATION NO. 333-70053

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

SECURITIES AND EXCHANGE COMMISSION
WASHINGTON,Washington, D.C. 20549
--------------------------

AMENDMENT NO. 1

TO----------------------

FORM S-3
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933
------------------------------------------------
TETRA TECH, INC.
(Exact name of registrant as specified in its charter)

DELAWARE 95-4148514
(State or other jurisdiction of (IRS Employer
of Identification
incorporation or organization) Identification No.)

670 NORTH ROSEMEAD BOULEVARD
PASADENA, CALIFORNIA 91107
(626) 351-4664
(Address, including zip code, and telephone number, including
area code, of registrant'sregistrants' principal executive offices)
------------------------------------------------
LI-SAN HWANG
PRESIDENT AND CHIEF EXECUTIVE OFFICER
TETRA TECH, INC.
670 NORTH ROSEMEAD BOULEVARD
PASADENA, CALIFORNIA 91107
(626) 351-4664
(Name, address, including zip code, and telephone number,
including area code, of agent for service)
--------------------------

COPIES TO:----------------------
Copies to:
JANIS B. SALIN
ALAN K. AUSTIN
Riordan & McKinzie Wilson Sonsini Goodrich & Rosati
300 South Grand Avenue
650 Page Mill Road
29th Floor Palo Alto, California 94304
Los Angeles, California 90071
------------------------------------------------

APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: AS SOON ASAs soon
as PRACTICABLE AFTER THIS REGISTRATION STATEMENT BECOMES EFFECTIVE.after this Registration Statement becomes effective.

If the only securities being registered on this Form are being offered
pursuant to dividend or interest reinvestment plans, please check the
following box. / /__

If any of the securities being registered on this Form are to be offered
on a delayed or continuous basis pursuant to Rule 415 under the Securities Act
of 1933, other than securities offered only in connection with dividend or
interest reinvestment plans, check the following box. / /X
---

If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following
box and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. / /__

If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /__

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. / /

--------------------------__

CALCULATION OF REGISTRATION FEE
=====================================================================================================
TITLE OF EACH CLASS OF AMOUNT PROPOSED MAXIMUM PROPOSED MAXIMUM AMOUNT OF
SECURITIES TO BE TO BE OFFERING PRICE AGGREGATE REGISTRATION
REGISTERED REGISTERED PER UNIT(1) OFFERING PRICE(1) FEE(1)
- -----------------------------------------------------------------------------------------------------

Common Stock, $.01 par value... 144,482 shares $14 31/32 $2,162,715 $602
=====================================================================================================

(1) Estimated solely for the purpose of calculating the registration fee
pursuant to Rule 457.

THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT
SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS
REGISTRATION STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH
SECTION 8(A)8(a) OF THE SECURITIES ACT OF 1933 OR UNTIL THIS REGISTRATION
STATEMENT SHALL BECOME EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING
PURSUANT TO SAID SECTION 8(A)8(a), MAY DETERMINE.
- --------------------------------------------------------------------------------------------------------------------------------------------------------------
- --------------------------------------------------------------------------------------------------------------------------------------------------------------

THE INFORMATION IN THISThe information in this prospectus is not complete and may be changed.
These securities may not be sold until the registration statement filed with
the Securities and Exchange Commission is effective. This prospectus is not
an offer to sell securities, and we are not soliciting offers to buy these
securities, in any state where the offer or sale is not permitted.

PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY
NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER
TO SELL SECURITIES, AND WE ARE NOT SOLICITING OFFERS TO BUY THESE SECURITIES, IN
ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.
SUBJECT TO COMPLETION
DATED JANUARY 8,OCTOBER 21, 1999

[LOGO]

3,175,000TETRA TECH, INC.

144,482 SHARES OF COMMON STOCK

----------------

The stockholders of Tetra Tech, Inc. islisted herein are offering 1,000,000and
selling 144,482 shares of its Common Stock andof Tetra Tech, Inc. under this
prospectus.

----------------

INVESTING IN TETRA TECH, INC. COMMON STOCK INVOLVES RISKS.
SEE "RISK FACTORS" BEGINNING ON PAGE 2.

----------------

All of the Selling Stockholders are selling an additional 2,175,000 shares.stockholders obtained their shares of Common Stock on
June 18, 1999 in connection with Tetra Tech, Inc.'s acquisition of Utilities
& C.C., Inc. Some or all of the selling stockholders expect to sell their
shares.

The selling stockholders may offer their shares of Common Stock through
public or private transactions, on or off the Nasdaq National Market, at
prevailing market prices, or at privately negotiated prices.

----------------

Tetra Tech, Inc. Common Stock is traded on the Nasdaq National Market
under the symbol "WATR." The last reported saleOn October 20, 1999, the closing price of the
Common Stock on the Nasdaq National Market on December 29, 1998 was $26.50$15 3/4 per share.

------------------------

INVESTING IN OUR COMMON STOCK INVOLVES RISKS.
SEE "RISK FACTORS" BEGINNING ON PAGE 7.

------------------------

PER SHARE TOTAL
----------- -------------

Public Offering Price.................................................................. $ $
Underwriting Discounts and Commissions................................................. $ $
Proceeds to Tetra Tech, Inc. .......................................................... $ $
Proceeds to the Selling Stockholders................................................... $ $
----------------

THE SECURITIES AND EXCHANGE COMMISSION AND STATE SECURITIES REGULATORS
HAVE NOT APPROVED OR DISAPPROVED THESE SECURITIES, OR DETERMINED IF THIS
PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

Tetra Tech, Inc. and the Selling Stockholders have granted the
underwriters a 30-day option to purchase up to an additional 476,250 shares of
Common Stock to cover over-allotments. BancBoston Robertson Stephens Inc.
expects to deliver the shares of Common Stock to purchasers on ,
1999.

------------------------

BANCBOSTON ROBERTSON STEPHENS

NATIONSBANC MONTGOMERY SECURITIES LLC

CLEARY GULL & REILAND INC.

FIRST ANALYSIS SECURITIES CORPORATION----------------

THE DATE OF THIS PROSPECTUS IS JANUARY ,OCTOBER ___, 1999

YOU SHOULD RELY ONLY ON THE INFORMATION CONTAINED OR INCORPORATED BY
REFERENCE IN THIS PROSPECTUS. WE HAVE NOT AUTHORIZED ANYONE TO PROVIDE YOU WITH
INFORMATION DIFFERENT FROM THAT CONTAINED IN THIS PROSPECTUS. WE ARE OFFERING TO
SELL, AND SEEKING OFFERS TO BUY, SHARES OF COMMON STOCK ONLY IN JURISDICTIONS
WHERE OFFERS AND SALES ARE PERMITTED. THE INFORMATION CONTAINED IN THIS
PROSPECTUS IS ACCURATE ONLY AS OF THE DATE OF THIS PROSPECTUS, REGARDLESS OF THE
TIME OF DELIVERY OF THIS PROSPECTUS OR OF ANY SALE OF THE COMMON STOCK. IN THIS
PROSPECTUS, "TETRA TECH" THE "COMPANY," "WE," "US" AND "OUR" REFER TO TETRA
TECH, INC. AND ITS SUBSIDIARIES.

------------------------

TABLE OF CONTENTS

PAGE

Summary.............................. 3

Risk Factors......................... 7

Use of Proceeds...................... 13

Price Range of Common Stock.......... 14

Dividend Policy...................... 14

Capitalization....................... 15

Selected Consolidated Financial
Data............................... 16

Management's Discussion and Analysis
of Financial Condition and Results
of Operations...................... 17

PAGE

Business............................. 26

Management........................... 38

Principal and Selling Stockholders... 43

Underwriting......................... 45

Where You Can Find More Information.. 47

Legal Matters........................ 47

Experts.............................. 48

Index to Consolidated Financial
Statements......................... F-1

------------------------

SUMMARY

THIS SUMMARY IS QUALIFIED BY THE MORE DETAILED INFORMATION APPEARING IN
OTHER SECTIONS OF THIS PROSPECTUS. THE OTHER INFORMATION IS IMPORTANT. WE URGE
YOU TO READ THE ENTIRE PROSPECTUS CAREFULLY BEFORE YOU DECIDE WHETHER TO INVEST
IN SHARES OF OUR COMMON STOCK. UNLESS OTHERWISE INDICATED, ALL INFORMATION IN
THIS PROSPECTUS REFLECTS OUR 5-FOR-4 STOCK SPLIT, EFFECTED IN THE FORM OF A 25%
STOCK DIVIDEND IN SEPTEMBER 1998, AND ASSUMES THAT THE UNDERWRITERS WILL NOT
EXERCISE THEIR OVER-ALLOTMENT.

OUR COMPANY

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.

From fiscal 1991 through fiscal 1998, we generated a net revenue
compounded annual growth rate of approximately 34.2% and achieved a net income
compounded annual growth rate of approximately 36.4%. Our net revenue was $297.6
million for the fiscal year ended October 4, 1998, and our backlog on that date
was approximately $405.0 million.

INDUSTRY OVERVIEW

Due to increased competition, changing regulatory environments and rapid
technological advancement in the resource management, infrastructure and
communications business areas, many organizations in these areas face new and
complex challenges. Increasingly, these organizations seek professional services
firms like Tetra Tech to assist them with addressing these challenges. The
business areas that we serve and the challenges they face are as follows:

RESOURCE MANAGEMENT. 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 and searching for ways to improve their business.

INFRASTRUCTURE. Continued population and economic growth places
significant strain on an overburdened infrastructure, thereby requiring
additional development. Additionally, as existing facilities age, they require
upgrading and replacement. Infrastructure development related to water and
wastewater treatment plants, roads, pipelines, communication and power networks,
and educational, recreational and correctional facilities often requires
extensive planning. In addition, cost structure and project efficiencies are
becoming more important to both public and private organizations.

in order to offer their subscribers a comprehensive set of services and to
maintain dominance in their markets. We believe that as the communications
industry undergoes consolidation and expansion, the need for consulting and
technical services will increase.

OUR SOLUTION

Our specialized management consulting services help clients identify
problems and develop appropriate solutions while our broad range of technical
services enable us to implement the various solutions. We believe that our 32
years of experience, involvement in thousands of projects, vast technical
experience and diverse geographic presence throughout the United States and
internationally help us understand and meet the needs of our clients regardless
of their size or location.

OUR STRATEGY

Our objective is to become the leading provider of 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 new business areas through our management consulting services
and expand vertically into additional business areas as we broaden our
industry expertise;

- Expand our service offerings and geographic presence through
acquisitions;

- Focus on government projects to stay on the leading edge of policy
development;

- Manage our internal financial controls to improve our cash position and
maximize our return on investment; and

- Leverage our existing client base by offering our clients additional
services.

OUR ADDRESS

Our principal executive offices are located at 670 North Rosemead
Boulevard, Pasadena, California 91107, and our telephone number is (626)
351-4664. Our website is located at www.tetratech.com. Information
contained in our website is not a part of this prospectus.

THE OFFERING

Common Stock offered byUSE OF PROCEEDS

The selling stockholders are offering all of the Company............................. 1,000,000 shares
Common Stock offered by the Selling Stockholders................ 2,175,000 shares
Common Stock to be outstanding after the Offering............... 29,666,131 shares(1)
Use of proceeds................................................. For the partial repayment of outstanding
indebtedness, possible acquisitions of
businesses and general corporate purposes.
Nasdaq National Market Symbol................................... WATR

- ---------

(1) This information is based on 28,666,131 shares outstanding at December
18, 1998. It excludes 2,441,754 shares of common stock issuable upon the
exercise of stock options outstanding at December 18, 1998 at a weighted
average exercise price of $11.71 per share. It also excludes 107,404
shares reserved for issuance under our stock option plans.

SUMMARY CONSOLIDATED FINANCIAL DATA
(IN THOUSANDS, EXCEPT PER SHARE DATA)

FISCAL YEAR ENDED
-----------------------------------------------------------

OCT. 2, OCT. 1, SEPT. 29, SEPT. 28, OCT. 4,
1994(2) 1995(3) 1996(4) 1997(5) 1998(6)
--------- ----------- ----------- ----------- ---------
STATEMENTS OF INCOME DATA:
Revenue:
Gross revenue............................................... $ 96,472 $ 120,034 $ 220,099 $ 246,767 $ 382,934
Subcontractor costs......................................... 28,653 32,160 59,062 55,976 85,337
--------- ----------- ----------- ----------- ---------
Net revenue................................................... 67,819 87,874 161,037 190,791 297,597
Cost of net revenue........................................... 51,069 65,484 122,084 141,019 223,871
--------- ----------- ----------- ----------- ---------
Gross profit.................................................. 16,750 22,390 38,953 49,772 73,726
Selling, general and administrative expenses.................. 7,589 10,634 21,218 25,173 33,913
--------- ----------- ----------- ----------- ---------
Income from operations........................................ 9,161 11,756 17,735 24,599 39,813
Net interest income (expense)................................. 354 833 (776) (20) (1,910)
--------- ----------- ----------- ----------- ---------
Income before minority interest and income tax expense........ 9,515 12,589 16,959 24,579 37,903
Minority interest............................................. -- -- -- -- 1,397
--------- ----------- ----------- ----------- ---------
Income before income tax expense.............................. 9,515 12,589 16,959 24,579 36,506
Income tax expense............................................ 3,806 5,036 6,854 10,323 15,920
--------- ----------- ----------- ----------- ---------
Net income.................................................... $ 5,709 $ 7,553 $ 10,105 $ 14,256 $ 20,586
--------- ----------- ----------- ----------- ---------
--------- ----------- ----------- ----------- ---------
Basic earnings per share(1)................................... $ 0.28 $ 0.37 $ 0.46 $ 0.61 $ 0.74
--------- ----------- ----------- ----------- ---------
--------- ----------- ----------- ----------- ---------
Diluted earnings per share(1)................................. $ 0.27 $ 0.36 $ 0.45 $ 0.58 $ 0.71
--------- ----------- ----------- ----------- ---------
--------- ----------- ----------- ----------- ---------
Weighted average common shares outstanding:(1)
Basic(1).................................................... 20,464 20,585 21,851 23,371 27,970
--------- ----------- ----------- ----------- ---------
--------- ----------- ----------- ----------- ---------
Diluted(1).................................................. 20,811 21,146 22,581 24,656 29,191
--------- ----------- ----------- ----------- ---------
--------- ----------- ----------- ----------- ---------

OCTOBER 4, 1998
-------------------------
ACTUAL AS ADJUSTED(7)
--------- --------------

BALANCE SHEET DATA:
Working capital......................................................................... $ 77,049 $ 77,049
Total assets............................................................................ 266,610 266,610
Long-term obligations, excluding current portion........................................ 33,546 8,920
Stockholders' equity.................................................................... 167,781 192,407

- ---------

(1) Reflects the effect, on a retroactive basis, of a 5-for-4 stock split,
effected in the form of a 25% stock dividend, in September 1998.

(2)Common Stock
covered by this prospectus. We have included the results of operations and financial positions of
Simons, Li & Associates, Inc. (acquired October 4, 1993) and
Hydro-Search, Inc. (acquired June 3, 1994)will not receive any proceeds from the dates set forth in
the related purchase agreements.

(3) We have included the resultssales
of operations and financial position of
Tetra Tech EM Inc., formerly known as PRC Environmental Management, Inc.
(acquired September 15, 1995), from the date set forth in the related
purchase agreement.

(4) We have included the results of operations and financial position of
KCM, Inc. (acquired November 7, 1995) from the date set forth in the
related purchase agreement.

(5) We have included the results of operations and financial positions of
IWA Engineers (acquired December 11, 1996), FLO Engineering, Inc.
(acquired December 20, 1996), SCM Consultants, Inc. (acquired March 19,
1997), Whalen & Company, Inc. (acquired June 11, 1997) and CommSite
Development Corporation (acquired July 11, 1997) from the dates set forth
in the related purchase agreements.

(6) We have included the results of operations and financial positions of
Tetra Tech NUS, Inc. (acquired December 31, 1997), CDC Engineering, Inc.
(acquired March 26, 1998), McNamee, Porter & Seeley, Inc. (acquired July
8, 1998), Whalen/Sentrex LLC (formed March 2, 1998) and the Sentrex Group
of Companies (acquired September 22, 1998) from the dates set forth in
the related purchase agreements.

(7) We have adjusted these figures to give effect to our sale of 1,000,000
shares of common stock at an assumed public offering price of $26.50,
after deducting the estimated underwriting discounts and commissions and
estimated offering expenses and other fees.

6
shares.

RISK FACTORS

AN INVESTMENT IN THE SHARES OF OUR COMMON STOCK OFFERED BY THIS PROSPECTUS
INVOLVES A HIGH DEGREE OF RISK. YOU SHOULD CAREFULLY REVIEW THE FOLLOWING
RISK FACTORS AS WELL AS THE OTHER INFORMATION SET FORTH IN THIS PROSPECTUS
BEFORE MAKING AN INVESTMENT.

SOME OF THE INFORMATION IN THIS PROSPECTUS OR INCORPORATED BY REFERENCE
IN THIS PROSPECTUS 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
PROSPECTUS, 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. BEFORE YOU INVEST IN OUR COMMON
STOCK, YOU SHOULD BE AWARE THAT THE OCCURRENCE OF ANY OF THE EVENTS DESCRIBED
IN THESE RISK FACTORS AND ELSEWHERE IN THIS PROSPECTUS COULD HAVE A MATERIAL
ADVERSE EFFECT ON OUR BUSINESS, FINANCIAL CONDITION AND OPERATING RESULTS AND
THAT UPON THE OCCURRENCE OF ANY OF THESE EVENTS, THE TRADING PRICE OF OUR
COMMON STOCK COULD DECLINE AND YOU COULD LOSE ALL OR PART OF YOUR INVESTMENT.

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 1998, we purchased ten companies in five separate
transactions. During the nine months ended July 4, 1999, we purchased seven
companies. 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 security 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. We believe that this
competition will increase and may result in decreased availability 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 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.

7
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 may be subject to larger
cost disallowances for greater periods than we are.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.

FLUCTUATIONS IN 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,
notably the Federal government;

- Employee hiring and utilization rates;

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

- Delays incurred in connection with an engagement;

- The ability of our 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 and 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.

POTENTIAL VOLATILITYTHE VALUE OF OUR COMMON STOCK PRICECOULD CONTINUE TO BE VOLATILE

The trading price of our common stockCommon 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 stockCommon Stock
may continue to fluctuate greatly. The trading price of our common stockCommon 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;

- Broader market fluctuations; and

- General economic or political conditions.

MANAGEMENTIF WE ARE NOT ABLE TO SUCCESSFULLY MANAGE OUR GROWTH STRATEGY, OUR BUSINESS
AND RESULTS OF GROWTHOPERATIONS 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 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 8
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.

RELIANCE ONTHE LOSS OF KEY PERSONNEL OR OUR INABILITY TO ATTRACT AND RETAIN QUALIFIED
PROFESSIONALSPERSONNEL 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 the principalcertain principals and stockholders of each of the
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.

DEPENDENCE UPONCHANGES 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.

CONCENTRATION4

OUR REVENUES FROM AGENCIES OF REVENUESTHE FEDERAL GOVERNMENT ARE 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 1998 and the nine months ended July 4, 1999,
approximately 46.8% and 39.6%, respectively, of our net revenue was derived
from three federalFederal agencies as follows: 26.2% and 22.2%, respectively, of our
net revenue was derived from the Department of Defense (DOD), 17.1% and
12.5%, respectively, from the Environmental Protection Agency (EPA), and 3.5%
and 2.9%, respectively, from the Department of Energy (DOE). Some of our
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.

Additionally the failure of clients to pay significant amounts due us
for our services could adversely affect our business. For example, we
recently
received notification from a federalFederal government agency that we are entitled
to payments in excess of our billings. However, the agency involved must
obtain specific funding approval for amounts owed to us and there can be no
assurance this funding approval will be obtained.

RISKS ASSOCIATEDOUR CONTRACTS WITH GOVERNMENTAL AUDITS

Our contractsAGENCIES 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.

In September 1995, we acquired PRC Environmental Management, Inc. (EMI).
EMI also contracts with Federal government agencies and such contracts are
also subject to the same governmental audits. TheAt the time of acquisition,
audits had not yet been completed or finalized. Accordingly, reserves were
established for potential disallowances. Since then, the DCAA has completed
audits of EMI's contracts for the fiscal years 1987 9
through 1995. As a
result of these audits and our negotiations with the DCAA, the DCAA disallowed
approximately $2.9$4.4 million in costs.

FIXED PRICEcosts which have been applied against the
established reserves.

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. Additionally, we enter into various types of
contracts with our clients, including fixed-price
contracts. In fiscal 1998, approximately 26.1% 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. If we incur lossesLosses under fixed-price
contracts itor termination of contracts at the discretion of the client could
have a material adverse effect on our business.

DEPENDENCE ONIn fiscal 1999, we had a contract change with Tele-Communications, Inc.
involving three turnkey contracts. This change was due in part to
Tele-Communications, Inc.'s change in strategy from turnkey contracts to
direct service contracts in the upgrading of their network systems.

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. Our reliance on
subcontractors varies from project to project. In fiscal 1998 and the nine
months ended July 4, 1999, subcontractor costs comprised 22.3% and 23.1%,
respectively, 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.

SIGNIFICANT COMPETITIONOUR 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 we do.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 10 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; Castle Tower Corporation; Camp,
Dresser & McKee; CH2M Hill Companies Ltd.; Dames & Moore Group; EA
Engineering, Science & Technology, Inc.; Earth Tech, Inc.; ICF Kaiser
International, Inc.; IT Group Inc.; Mastec, Inc.; Montgomery Watson; OSP
Consultants, Inc.; Roy F. Weston, Inc.; and URS Greiner Corporation.

POTENTIALOUR 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 and
professional liability insurance policies. We believe that our insurance
policies are adequate for our business operations. TheseProfessional liability
policies are "claims made" policies. Thus, only claims made during the term
of the policy are covered. IfShould we terminate our professional liability
policies and do not obtain retroactive coverage, we would be uninsured for
claims made after termination even if these claims are based on events or
acts that occurred during 10
the term of the policy. OurAdditionally, our
insurance policies may not protect us against potential liability because our policies typically havedue to
various exclusions and retentions. In
addition, ifShould we expand into new markets, we may
not be able to obtain insurance coverage for such activities or, if insurance
is obtained, the dollar amount of any liabilities incurred could exceed our
insurance coverage. A partiallyPartially or completely uninsured claim,claims, if successful
and of significant magnitude, could have a material adverse affect on our
business.

CONFLICTSWE 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.

RISKS ASSOCIATED WITH6

OUR INTERNATIONAL OPERATIONS EXPOSE US TO RISKS SUCH AS FOREIGN CURRENCY
FLUCTUATIONS

In fiscal 1998 and the nine months ended July 4, 1999, approximately
3.2% and 3.8%, respectively, 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 will also increase.
We have entered into forward exchange contracts to address certain foreign
currency fluctuations.

WE COULD EXPERIENCE BUSINESS INTERRUPTIONS RELATING TO THE YEAR 2000

We are working to resolve the potential impact of the year 2000 (Y2K) on
our business operations and the ability of our computerized information
systems to accurately process information that may be date-sensitive. Any of
our programs that recognize a date using "00" as the year 1900 rather than
the year 2000(Y2K) could result in errors or system failures.

We utilize a number of computer programs across our entire operation.
The primary information technology systems we utilize are the accounting and
financial and human resource information management systems. We began our
risk assessment in 1995. Since that time we have procured and implemented
certain accounting and financial reporting systems as well as contract
administration and billing systems that have been certified as year 2000Y2K compliant
by our vendors. Currently, approximately 72%vendors and have obtained assurances of Y2K compliance in all of our
gross revenue is recognized on
these year 2000 compliant systems. Weacquired businesses. In all cases, we believe that our financial and
accounting and human resource management information systems will be year 2000Y2K compliant in a timely manner and will not be
materially impacted by the year 2000. We may
fail, however, in updating our various systems to be year 2000 compliant in a
timely manner.Y2K.

We have extensive business with the Federal government. Should the
Federal government, especially the Department of Defense,DOD, experience significant business
interruptions relating to non-year 2000Y2K compliance, our business could be materially
impacted. To the extent that other third parties upon which we rely,
upon, such as
banking institutions, clients and vendors, are unable to address their year 2000Y2K
issues in a timely manner, our businesswe could be materially impacted. We believe that
the worst case scenario relating to the year 2000Y2K would be an extensive period of
time in which the Federal government and other third parties could not
process payments promptly, in addition to our financial institutions not
being able to supply us with our working capital needs.

Additional risks associated with non-year 2000 compliance include:

- Our inability to invoice and process payments;

- Our inability to produce accurate and timely financials;

- The impact on our profitability; and

- Our potential liability to third parties for not meeting contracted
deliverables.

IMPACT OF ANTI-TAKEOVER PROVISIONS ON OUR STOCK PRICE

Our certificateSELLING STOCKHOLDERS

On June 18, 1999, we acquired Utilities & C.C., Inc., a California
corporation ("UCCI"), through the merger of incorporationUCCI Acquisition Corporation, a
Delaware corporation and by-laws andour wholly-owned subsidiary, into UCCI. In
connection with this acquisition, we issued to the Delaware General
Corporation Law include provisions that may be deemed to have anti-takeover
effects. These anti-takeover effects could delay or prevent a takeover attempt
that you or our other stockholders might consider in your or their best
interests.

In addition, our boardUCCI shareholders an
aggregate of directors is authorized to issue, without
obtaining stockholder approval, up to 2,000,000144,482 shares of preferred stockour Common Stock (as adjusted to reflect a
post-closing purchase price adjustment).

Under a Registration Rights Agreement dated as of June 18, 1999, we
agreed to register the shares of Common Stock and to determineuse commercially
reasonable efforts to keep the price, rights, preferences and privileges of such shares without
any further stockholder action. The existence of this "blank-check" preferred
stock could make more difficult or discourage an attempt to obtain control of us
by means of a tender offer, merger, proxy contest or otherwise.

Inregistration statement effective until the
future, we may adopt other measures that may have the effect of
delaying, deferring or preventing an unsolicited takeover, even if such a change
in control were at a premium price or favored by a majority of unaffiliated
stockholders. Certain of these measures may be adopted without any further vote
or action by the stockholders.

OFFERING BENEFITS TO CERTAIN SELLING STOCKHOLDERS

Thedate on which all selling stockholders will receive substantial proceeds from sellingmay sell their shares of common stock in this offering. We will payCommon Stock
under Rule 144 promulgated under the

offering expenses7

Securities Act of 1933, as amended (the "Securities Act"), without any volume
limitation. Our registration of the selling stockholders in this offering, other than underwriting discounts
and commissions. After deducting underwriting discounts and commissions, the net
proceeds (at an assumed offering price of $26.50 per share) to the selling
stockholders, all of whom are our affiliates, are approximately $54.3 million.
These selling stockholders have granted the underwriters an over-allotment
option to purchase 326,250 shares of common stock. If the underwriters'
over-allotment option is exercised in full, the aggregate net proceeds toCommon Stock does not
necessarily mean that the selling stockholders will be approximately $62.5 million (at an assumed offering
price of $26.50 per share).

USE OF PROCEEDS

The net proceeds from the salesell all or any of the
1,000,000shares.

The shares listed below represent all of common stock
offered by us will be approximately $24.6 million (approximately $28.4 million
if the underwriters' over-allotment option is exercised in full), at an assumed
offering price of $26.50 per share, and after deducting the estimated
underwriting discounts and commissions (approximately $1.5 million) and
estimated offering expenses and other related fees (approximately $0.4 million)shares that we will pay. We will not receive any proceeds from the sale of shares of
common stock by theeach selling
stockholders.

We intend to use approximately $24.6 millionstockholder currently owns of our net proceeds for the
partial repayment of our outstanding indebtedness under our $65.0 million
revolving credit facility with Bank of America National Trust and Savings
Association. Payments made under the revolving credit facility will not result
in a reduction in the maximum amount available under the facility but will have
the effect of increasing the amount we can borrow under the facility in the
future to fund possible acquisitions of businesses and for general corporate
purposes, including working capital. We continually evaluate potential
acquisition candidates, but we have not reached any agreements, commitments or
understandings for any material future acquisitions.

Interest on borrowings under the revolving credit facility is payable at
our option (a) at a base rate (at 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%. The revolving credit facility matures on
December 15, 2000 or earlier at our discretion upon payment in full of loans and
other obligations. At October 4, 1998, borrowings totaled $47.0 million under
the revolving credit facility. The weighted average interest rate on outstanding
borrowings at October 4, 1998 was 6.34%.

Our use of proceeds may vary significantly and will depend on a number of
factors, including our future revenues and the other factors described under
"Risk Factors." Accordingly, our management has broad discretion in the
allocation of the net proceeds. Pending such uses, the net proceeds of this
offering will be invested in short-term, interest-bearing investment grade
securities.

PRICE RANGE OF COMMON STOCK

Our common stock has traded on the Nasdaq National Market under the
symbol "WATR" since December 1991. The following table sets forth, for the
periods indicated, the range of high and low sales prices for our common stock
as reported on the Nasdaq National Market. The prices have been adjusted to
reflect the effect, on a retroactive basis, of a 5-for-4 stock split, effected
in the form of a 25% stock dividend, in September 1998.

PRICE RANGE OF
COMMON STOCK
--------------------
HIGH LOW
--------- ---------

Fiscal 1994:
First Quarter............................................................. $ 6.39 $ 4.92
Second Quarter............................................................ $ 6.72 $ 5.65
Third Quarter............................................................. $ 7.54 $ 5.49
Fourth Quarter............................................................ $ 8.29 $ 5.90

Fiscal 1995:
First Quarter............................................................. $ 8.19 $ 6.70
Second Quarter............................................................ $ 8.29 $ 6.55
Third Quarter............................................................. $ 9.52 $ 7.99
Fourth Quarter............................................................ $ 12.16 $ 8.96

Fiscal 1996:
First Quarter............................................................. $ 12.16 $ 10.50
Second Quarter............................................................ $ 12.16 $ 9.99
Third Quarter............................................................. $ 14.34 $ 10.11
Fourth Quarter............................................................ $ 15.68 $ 11.04

Fiscal 1997:
First Quarter............................................................. $ 16.32 $ 11.92
Second Quarter............................................................ $ 13.28 $ 7.84
Third Quarter............................................................. $ 14.80 $ 8.80
Fourth Quarter............................................................ $ 18.08 $ 13.44

Fiscal 1998:
First Quarter............................................................. $ 17.76 $ 14.90
Second Quarter............................................................ $ 19.20 $ 15.20
Third Quarter............................................................. $ 20.20 $ 15.60
Fourth Quarter............................................................ $ 23.00 $ 15.40

Fiscal 1999:
First Quarter (through December 29, 1998)................................. $ 28.00 $ 15.63

On December 29, 1998, the last reported closing sale price of the common
stock was $26.50 per share.

DIVIDEND POLICY

Since our initial public offering, we have not paid cash dividends on our
common stock. We currently anticipate that all of our earnings will be retained
for development of our business and do not anticipate paying any cash dividends
in the foreseeable future.

CAPITALIZATION

The following table sets forth our capitalization as of October 4, 1998
on an actual basis and on a pro forma as adjusted basis to give effect to our
sale and issuance of the 1,000,000 shares of common stock at an assumed public
offering price of $26.50, after deducting the estimated underwriting discounts
and commissions and estimated offering expenses and fees, and receipt and
application of the estimated net proceeds therefrom. See "Use of Proceeds." The
data set forth below should be read in conjunction with our Consolidated
Financial Statements, including Notes thereto, included in this prospectus.

OCTOBER 4, 1998
-----------------------
PRO FORMA
ACTUAL AS ADJUSTED
---------- -----------
(IN THOUSANDS)

Long-term obligations excluding current portion.......................................... $ 33,546 $ 8,920
Stockholders' equity:
Preferred Stock -- authorized, 2,000,000 shares of $.01 par value;
no shares issued and outstanding....................................................... -- --
Exchangeable stock of subsidiary......................................................... 15,411 15,411
Common Stock -- authorized, 50,000,000 shares of $.01 par value;
issued and outstanding, 28,630,600 shares at October 4, 1998;
issued and outstanding, 29,630,600, pro forma as adjusted.............................. 287 296
Additional paid-in capital............................................................... 87,565 112,182
Retained Earnings........................................................................ 64,518 64,518
---------- -----------
Total stockholders' equity........................................................... 167,781 192,407
---------- -----------
Total capitalization............................................................. $ 201,327 $ 201,327
---------- -----------
---------- -----------

SELECTED CONSOLIDATED FINANCIAL DATA

The selected consolidated financial data set forth below with respect to
our statements of income for each of the three years in the period ended October
4, 1998 and balance sheets as of September 28, 1997 and October 4, 1998, have
been derived from our financial statements included elsewhere in this
prospectus, which have been audited by Deloitte & Touche LLP, independent
auditors, as indicated in their report included elsewhere in this prospectus.
The statements of income data for the years ended October 2, 1994 and October 1,
1995 and the balance sheet data as of October 2, 1994, October 1, 1995 and
September 29, 1996 have been derived from our audited financial statements not
included in this prospectus. The data set forth below should be read in
conjunction with our consolidated financial statements, including notes thereto,
and "Management's Discussion and Analysis of Financial Condition and Results of
Operations" included in this prospectus.

FISCAL YEAR ENDED
---------------------------------------------------------------
OCT. 2, OCT. 1, SEPT. 29, SEPT. 28, OCT. 4,
1994(2) 1995(3) 1996(4) 1997(5) 1998(6)
----------- ----------- ----------- ----------- -----------
(IN THOUSANDS, EXCEPT PER SHARE DATA)

STATEMENTS OF INCOME DATA:
Revenue:
Gross revenue............................................. $ 96,472 $ 120,034 $ 220,099 $ 246,767 $ 382,934
Subcontractor costs....................................... 28,653 32,160 59,062 55,976 85,337
----------- ----------- ----------- ----------- -----------
Net revenue................................................. 67,819 87,874 161,037 190,791 297,597
Cost of net revenue......................................... 51,069 65,484 122,084 141,019 223,871
----------- ----------- ----------- ----------- -----------
Gross profit................................................ 16,750 22,390 38,953 49,772 73,726
Selling, general and administrative expenses................ 7,589 10,634 21,218 25,173 33,913
----------- ----------- ----------- ----------- -----------
Income from operations...................................... 9,161 11,756 17,735 24,599 39,813
Net interest income (expense)............................... 354 833 (776) (20) (1,910)
----------- ----------- ----------- ----------- -----------
Income before minority interest and income tax expense...... 9,515 12,589 16,959 24,579 37,903
Minority interest........................................... -- -- -- -- 1,397
----------- ----------- ----------- ----------- -----------
Income before income tax expense............................ 9,515 12,589 16,959 24,579 36,506
Income tax expense.......................................... 3,806 5,036 6,854 10,323 15,920
----------- ----------- ----------- ----------- -----------
Net income.................................................. $ 5,709 $ 7,553 $ 10,105 $ 14,256 $ 20,586
----------- ----------- ----------- ----------- -----------
----------- ----------- ----------- ----------- -----------
Basic earnings per share(1)................................. $ 0.28 $ 0.37 $ 0.46 $ 0.61 $ 0.74
----------- ----------- ----------- ----------- -----------
----------- ----------- ----------- ----------- -----------
Diluted earnings per share(1)............................... $ 0.27 $ 0.36 $ 0.45 $ 0.58 $ 0.71
----------- ----------- ----------- ----------- -----------
----------- ----------- ----------- ----------- -----------
Weighted average common shares outstanding:(1)
Basic(1)................................................. 20,464 20,585 21,851 23,371 27,970
----------- ----------- ----------- ----------- -----------
----------- ----------- ----------- ----------- -----------
Diluted(1)............................................... 20,811 21,146 22,581 24,656 29,191
----------- ----------- ----------- ----------- -----------
----------- ----------- ----------- ----------- -----------

---------------------------------------------------------------
OCT. 2, OCT. 1, SEPT. 29, SEPT. 28, OCT. 4,
1994 1995 1996 1997 1998
----------- ----------- ----------- ----------- -----------
(IN THOUSANDS)

BALANCE SHEET DATA:
Working capital............................................. $ 24,833 $ 39,872 $ 32,739 $ 42,539 $ 77,049
Total assets................................................ 51,606 92,930 88,463 159,513 266,610
Long-term obligations, excluding current portion............ -- 19,045 -- -- 33,546
Stockholders' equity........................................ 33,507 41,496 63,269 107,641 167,781

- ------------

(1) Reflects the effect, on a retroactive basis, of a 5-for-4 stock split,
effected in the form of a 25% stock dividend, in September 1998.

(2) We have included the results of operations and financial positions of
Simons, Li & Associates, Inc. (acquired October 4, 1993) and
Hydro-Search, Inc. (acquired June 3, 1994) from the dates set forth in
the related purchase agreements.

(3) We have included the results of operations and financial position of
Tetra Tech EM Inc., formerly known as PRC Environmental Management, Inc.
(acquired September 15, 1995) from the date set forth in the related
purchase agreement.

(4) We have included the results of operations and financial position of
KCM, Inc., (acquired November 7, 1995) from the date set forth in the
related purchase agreement.

(6) 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), McNamee, Porter & Seeley, Inc. (acquired July 8, 1998), and the
Sentrex Group of Companies (acquired September 22, 1998) from the dates
set forth in the related purchase agreements.

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 THE CONSOLIDATED FINANCIAL STATEMENTS INCLUDED ELSEWHERE IN THIS PROSPECTUS.

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 have 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 1998, we generated a net revenue compounded annual growth rate of
approximately 34.2%, and achieved a net income compounded annual growth rate of
approximately 36.4%.

We derive our gross revenues 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 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. In addition, we
include amortization of certain intangible assets resulting from acquisitions in
SG&A expenses.

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 1996 FISCAL 1997 FISCAL 1998
- --------------------------------------------- ----------- ----------- -----------

Federal government........................... 61.7% 52.3% 48.7%
State and local government................... 16.6 14.8 12.7
Private...................................... 20.1 29.2 35.4
International................................ 1.6 3.7 3.2
----- ----- -----
Total........................................ 100.0% 100.0% 100.0%
----- ----- -----
----- ----- -----

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 1998, we purchased ten companies in the
following five separate transactions:

TETRA TECH NUS, INC. -- In December 1997, we acquired, through our
wholly-owned subsidiary Tetra Tech NUS, Inc. (NUS), the assets of certain
environmental services businesses of Brown & Root, Inc. and Halliburton
Corporation. The purchase was valued at approximately $25.2 million. NUS is a
nationwide firm providing consulting, engineering and design services for the
environmental remediation of contaminated air, water and soil conditions.

WHALEN/SENTREX LLC -- In March 1998, our wholly-owned subsidiary Whalen
Service Corps Inc. agreed to participate in a partnership with Sentrex Cen-Comm
and ANTEC Corporation. The partnership purchased certain assets from ANTEC
Corporation for a price of approximately $0.6 million. The partnership,
Whalen/Sentrex LLC, a Colorado-based firm, provides nationwide design,
engineering, information management and construction services to support
advanced communication system upgrades to the broadband information transport
industries.

C.D.C. ENGINEERING, INC. -- In March 1998, we acquired C.D.C.
Engineering, Inc. (CDE). The purchase was valued at approximately $1.5 million.
CDE, a California-based consulting and engineering firm, specializes in civil
engineering, transportation engineering, structural engineering and land
surveying.

MCNAMEE, PORTER & SEELEY, INC. -- In July 1998, we acquired McNamee,
Porter & Seeley, Inc. (MPS). The purchase was valued at approximately $14.2
million. MPS, a Michigan-based firm, provides engineering services throughout
the Midwest with expertise in the areas of water, industrial wastewater and
process controls.

SENTREX GROUP OF COMPANIES -- In September 1998, we acquired, through our
wholly-owned subsidiary, Tetra Tech Canada Ltd., six Canadian corporations that
are collectively referred to as the Sentrex Group of Companies (SGOC). The
purchase was valued at approximately $19.2 million. SGOC provides engineering
and technical services to the cable television, telephony and data networking
industries. As a result of the SGOC acquisition, we now own 100% of
Whalen/Sentrex LLC.

RESULTS OF OPERATIONS

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

PERCENTAGE RELATIONSHIP TO NET
REVENUE
-------------------------------------
FISCAL YEARS ENDED
-------------------------------------
SEPT. 29, SEPT. 28, OCT. 4,
1996 1997 1998
----------- ----------- -----------

Net revenue......................................... 100.0% 100.0% 100.0%
Cost of net revenue................................. 75.8 73.9 75.2
----- ----- -----
Gross profit........................................ 24.2 26.1 24.8
Selling, general and administrative expenses........ 13.2 13.2 11.4
----- ----- -----
Income from operations.............................. 11.0 12.9 13.4
Net interest income (expense)....................... (0.5) -- (0.7)
----- ----- -----
Income before minority interest and income tax
expense........................................... 10.5 12.9 12.7
Minority interest................................... -- -- (0.5)
----- ----- -----
Income before income tax expense.................... 10.5 12.9 12.2
Income tax expense.................................. 4.2 5.4 5.3
----- ----- -----
Net income.......................................... 6.3% 7.5% 6.9%
----- ----- -----
----- ----- -----

FISCAL 1998 COMPARED TO FISCAL 1997

NET REVENUE. Net revenue increased $106.8 million, or 56.0%, to $297.6
million in fiscal 1998 from $190.8 million in fiscal 1997. All four client
sectors continued to show net revenue increases in actual dollars. These
increases were attributable to increases in our existing Federal government
contracts, the introduction of new lines of service in our communications
business and to companies acquired in fiscal 1998. As a percentage of net
revenue, increases were realized in the private sector. Net revenue from the
companies acquired in fiscal 1998 totaled $72.0 million. Excluding the net
revenue from these companies, we realized 18.2% growth in our net revenue. Gross
revenue increased $136.2 million, or 55.2%, to $382.9 million in fiscal 1998
from $246.8 million in fiscal 1997. In fiscal 1998, subcontractor costs
comprised 22.3% of gross revenue compared to 22.7% for fiscal 1997.

COST OF NET REVENUE. Cost of net revenue increased $82.9 million, or
58.8%, to $223.9 million in fiscal 1998 from $141.0 million in fiscal 1997. As a
percentage of net revenue, cost of net revenue increased from 73.9% in fiscal
1997 to 75.2% in fiscal 1998. This increase was primarily attributable to higher
costs of Federal government contracts, as well as costs incurred in connection
with the additional net revenue from the acquired companies. Professional
compensation, the largest component of our cost of net revenue, rose as the
number of our employees increased by 1,400 or 61.9%, to 3,662 in fiscal 1998
from 2,262 in fiscal 1997. Excluding the employees provided from acquired
companies, our number of employees increased by 265, or 11.7%. Gross profit
increased $24.0 million, or 48.1%, to $73.7 million in fiscal 1998 from $49.8
million in fiscal 1997. However, as a percentage of net revenue, gross profit
decreased from 26.1% in fiscal 1997 to 24.8% in fiscal 1998, primarily due to a
change in the relative mix of our Federal government contracts.

SELLING, GENERAL AND ADMINISTRATIVE EXPENSES. SG&A expenses increased
$8.7 million, or 34.7%, to $33.9 million in fiscal 1998 from $25.2 million in
fiscal 1997. This increase was primarily attributable to additional
headquarters' costs associated with centralizing corporate functions as well as
additional amortization expense relating to acquired companies. As a percentage
of net revenue, SG&A expenses decreased from 13.2% in fiscal 1997 to 11.4% in
fiscal 1998 due to operating efficiencies. The

amortization expenses related to acquisitions increased $1.4 million, or 89.1%,
to $3.0 million in fiscal 1998 from $1.6 million in fiscal 1997.

NET INTEREST EXPENSE. Net interest expense increased from less than $0.1
million to $1.9 million from fiscal 1997 to fiscal 1998. This increase was
primarily attributable to the financing and working capital needs of certain
acquisitions.

INCOME TAX EXPENSE. Income tax expense increased $5.6 million, or 54.2%
to $15.9 million in fiscal 1998 from $10.3 million in fiscal 1997. This increase
was due to higher income before income taxes and an increase in our effective
tax rate from 42.0% in fiscal 1997 to 43.6% in fiscal 1998. This increase was
primarily attributable to amortization amounts which were not tax deductible.

FISCAL 1997 COMPARED TO FISCAL 1996

NET REVENUE. Net revenue increased $29.8 million, or 18.5%, to $190.8
million in fiscal 1997 from $161.0 million in fiscal 1996. The increase in net
revenue was primarily attributable to revenue associated with companies acquired
in fiscal 1997 which totaled $24.6 million. Despite the weakened condition of
the environmental industry, which was impacted by the decrease in Federal
government activity, we attained a 3.2% growth in our net revenue, excluding
revenue related to acquired companies. Gross revenue increased $26.7 million, or
12.1%, to $246.8 million in fiscal 1997 from $220.1 million in fiscal 1996. In
fiscal 1997, subcontractor costs were 22.7% of gross revenue, compared to 26.8%
for fiscal 1996. This decrease was due to the nature of the projects undertaken.

COST OF NET REVENUE. Cost of net revenue increased $18.9 million, or
15.5%, to $141.0 million in fiscal 1997 from $122.1 million in fiscal 1996. This
increase was primarily attributable to costs incurred in connection with the
additional net revenue from the acquired companies. As a percentage of net
revenue, cost of net revenue decreased from 75.8% in fiscal 1996 to 73.9% in
fiscal 1997. Professional compensation, the largest component of our cost of net
revenue, rose as the number of employees increased by 363, or 19.1%, to 2,262 in
fiscal 1997 from 1,899 in fiscal 1996. Excluding the employees provided from
acquired companies, our number of employees remained relatively flat. Gross
profit increased $10.8 million, or 27.8%, to $49.8 million in fiscal 1997 from
$39.0 million in fiscal 1996, primarily due to efficiencies in operations,
acquisitions and higher profit margins realized in the acquired businesses in
the communications industry.

SELLING, GENERAL AND ADMINISTRATIVE EXPENSES. SG&A expenses increased
$4.0 million, or 18.6%, to $25.2 million in fiscal 1997 from $21.2 million in
fiscal 1996. However, as a percentage of net revenue, SG&A expenses remained
flat at 13.2% for fiscal 1997. The amortization of intangible assets relating to
acquisitions increased $0.4 million, or 29.8%, to $1.6 million in fiscal 1997
from $1.2 million in fiscal 1996.

NET INTEREST EXPENSE. Net interest expense decreased $0.8 million to
less than $0.1 million in fiscal 1997 due to the reduction of the average
outstanding borrowings from fiscal 1996 to fiscal 1997.

INCOME TAX EXPENSE. Income tax expense increased $3.4 million, or 50.6%,
to $10.3 million in fiscal 1997 from $6.9 million in fiscal 1996. Our effective
tax rate increased from 40.4% in fiscal 1996 to 42.0% in fiscal 1997. This
increase was primarily attributable to amortization amounts which were not tax
deductible.

UNAUDITED QUARTERLY OPERATING RESULTS

The following tables set forth certain unaudited quarterly operating
results for each of our last three fiscal years ended September 29, 1996,
September 28, 1997 and October 4, 1998. 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 1996 QUARTER ENDED FISCAL 1997 QUARTER ENDED
-------------------------------------------------- -------------------------------------
DEC. 31, MAR. 31, JUN. 30, SEP. 29, DEC. 29, MAR. 30, JUN. 29,
1995 1996 1996 1996 1996 1997 1997
----------- ----------- ----------- ----------- ----------- ----------- -----------
(In thousands)

Net revenue.................... $ 38,023 $ 40,076 $ 40,314 $ 42,624 $ 40,423 $ 43,914 $ 48,621
Cost of net revenue............ 29,483 30,676 30,479 31,446 31,051 33,367 35,660
----------- ----------- ----------- ----------- ----------- ----------- -----------
Gross profit................... 8,540 9,400 9,835 11,178 9,372 10,547 12,961
Selling, general and
administrative expenses..... 4,810 5,281 5,329 5,798 4,979 5,655 6,754
----------- ----------- ----------- ----------- ----------- ----------- -----------
Income from operations......... 3,730 4,119 4,506 5,380 4,393 4,892 6,207
Net interest income
(expense)................... (348) (291) (131) (6) 49 31 4
----------- ----------- ----------- ----------- ----------- ----------- -----------
Income before minority interest
and income tax expense...... 3,382 3,828 4,375 5,374 4,442 4,923 6,211
Minority interest.............. -- -- -- -- -- -- --
----------- ----------- ----------- ----------- ----------- ----------- -----------
Income before income tax
expense..................... 3,382 3,828 4,375 5,374 4,442 4,923 6,211
Income tax expense............. 1,353 1,531 1,750 2,220 1,846 2,051 2,567
----------- ----------- ----------- ----------- ----------- ----------- -----------
Net income..................... $ 2,029 $ 2,297 $ 2,625 $ 3,154 $ 2,596 $ 2,872 $ 3,644
----------- ----------- ----------- ----------- ----------- ----------- -----------
----------- ----------- ----------- ----------- ----------- ----------- -----------

FISCAL 1998 QUARTER ENDED
------------------------------------------------
SEP. 28, DEC. 28, MAR. 29, JUN. 28, OCT. 4,
1997 1997 1998 1998 1998
----------- ----------- ----------- ----------- ---------

Net revenue.................... $ 57,833 $ 53,664 $ 71,806 $ 75,149 $ 96,978
Cost of net revenue............ 40,941 40,339 54,786 54,405 74,341
----------- ----------- ----------- ----------- ---------
Gross profit................... 16,892 13,325 17,020 20,744 22,637
Selling, general and
administrative expenses..... 7,785 6,146 8,148 9,333 10,286
----------- ----------- ----------- ----------- ---------
Income from operations......... 9,107 7,179 8,872 11,411 12,351
Net interest income
(expense)................... (104) (73) (596) (510) (731)
----------- ----------- ----------- ----------- ---------
Income before minority interest
and income tax expense...... 9,003 7,106 8,276 10,901 11,620
Minority interest.............. -- -- 203 1,194 --
----------- ----------- ----------- ----------- ---------
Income before income tax
expense..................... 9,003 7,106 8,073 9,707 11,620
Income tax expense............. 3,859 3,055 3,552 4,214 5,099
----------- ----------- ----------- ----------- ---------
Net income..................... $ 5,144 $ 4,051 $ 4,521 $ 5,493 $ 6,521
----------- ----------- ----------- ----------- ---------
----------- ----------- ----------- ----------- ---------

Net revenue.................... 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%
Cost of net revenue............ 77.5 76.5 75.6 73.8 76.8 76.0 73.3
----- ----- ----- ----- ----- ----- -----
Gross profit................... 22.5 23.5 24.4 26.2 23.2 24.0 26.7
Selling, general and
administrative expenses..... 12.7 13.2 13.2 13.6 12.3 12.9 13.9
----- ----- ----- ----- ----- ----- -----
Income from operations......... 9.8 10.3 11.2 12.6 10.9 11.1 12.8
Net interest income
(expense)................... (0.9) (0.7) (0.3) -- 0.1 0.1 --
----- ----- ----- ----- ----- ----- -----
Income before minority interest
and income tax expense...... 8.9 9.6 10.9 12.6 11.0 11.2 12.8
Minority interest.............. -- -- -- -- -- -- --
----- ----- ----- ----- ----- ----- -----
Income before income tax
expense..................... 8.9 9.6 10.9 12.6 11.0 11.2 12.8
Income tax expense............. 3.6 3.8 4.3 5.2 4.6 4.7 5.3
----- ----- ----- ----- ----- ----- -----
Net income..................... 5.3% 5.7% 6.5% 7.4% 6.4% 6.5% 7.5%
----- ----- ----- ----- ----- ----- -----
----- ----- ----- ----- ----- ----- -----

FISCAL 1998 QUARTER ENDED
--------------------------------------------------
SEP. 28, DEC. 28, MAR. 29, JUN. 28, OCT. 4,
1997 1997 1998 1998 1998
----------- ----------- ----------- ----------- -----------

Net revenue.................... 100.0% 100.0% 100.0% 100.0% 100.0%
Cost of net revenue............ 70.8 75.2 76.3 72.4 76.7
----- ----- ----- ----- -----
Gross profit................... 29.2 24.8 23.7 27.6 23.3
Selling, general and
administrative expenses..... 13.5 11.5 11.3 12.4 10.6
----- ----- ----- ----- -----
Income from operations......... 15.7 13.4 12.4 15.2 12.7
Net interest income
(expense)................... (0.2) (0.1) (0.8) (0.7) (0.8)
----- ----- ----- ----- -----
Income before minority interest
and income tax expense...... 15.6 13.2 11.5 14.5 12.0
Minority interest.............. -- -- 0.3 1.6 --
----- ----- ----- ----- -----
Income before income tax
expense..................... 15.6 13.2 11.2 12.9 12.0
Income tax expense............. 6.7 5.7 4.9 5.6 5.3
----- ----- ----- ----- -----
Net income..................... 8.9% 7.5% 6.3% 7.3% 6.7%
----- ----- ----- ----- -----
----- ----- ----- ----- -----

Our revenues and operating results fluctuate from quarter to quarter as a
result of a number of factors, such as: (1) the seasonality of the spending
cycle of our public sector clients, notably the Federal government; (2) employee
hiring and utilization rates; (3) the number and significance of client
engagements commenced and completed during a quarter; (4) delays incurred in
connection with an engagement; (5) the ability of clients to terminate
engagements without penalties; (6) the size and scope of engagements; (7) the
timing and size of the return on investment capital; and (8) general economic
and political conditions. Variations in any of these factors can cause
significant variations in operating results from quarter to quarter and could
result in losses.

LIQUIDITY AND CAPITAL RESOURCES

We expect that internally generated funds, our existing cash balances,
proceeds from this offering and availability under the Credit Agreement will be
sufficient to meet our capital requirements through the end of fiscal 1999.

As of October 4, 1998, our working capital was $77.0 million, an increase
of $34.5 million from $42.5 million on September 28, 1997, of which cash and
cash equivalents totaled $4.9 million. In fiscal 1998, we augmented cash used in
operations with borrowings under our credit facility. In fiscal 1998, $6.6
million was used in operating activities and $41.3 million was used in investing
activities, of which $37.8 million was related to business acquisitions. In
fiscal 1997, we generated $1.1 million from operating activities and used $3.8
million in investing activities, of which $1.2 million was related to business
acquisitions. The decreases in cash from operating activities in fiscal 1998 and
fiscal 1997 primarily resulted from the payment of liabilities assumed in
connection with fiscal 1998 acquisitions of approximately $6.4 million as well
as the acquisitions of Whalen & Company, Inc. in fiscal 1997 and McNamee, Porter
& Seeley, Inc. in fiscal 1998. In these acquisitions we agreed that we would not
acquire the accounts receivable. As a result, we experienced a lag in cash flow
to fund the business' operations. As an ongoing effort, we attempt to increase
our efficiencies in the timing of billings and the collection of receivables.
Our capital expenditures during fiscal years 1996, 1997, and 1998 were
approximately $2.4 million, $2.6 million and $3.5 million, respectively. The
expenditures were primarily for computer equipment, leasehold improvements and
office expansion.

We have a credit agreement with a bank (the "Credit Agreement") which, as
of October 4, 1998, provided us with a revolving credit facility (the
"Facility") of $70.0 million. The Credit Agreement provides for mandatory
reductions of $5.0 million on December 15, 1998 and December 15, 1999. We
amended the Credit Agreement during fiscal 1998 in order to accommodate the
fiscal 1998 acquisitions as well as to position ourselves to pursue future
acquisitions. The Facility matures on December 15, 2000 or earlier at our
discretion upon payment in full of loans and other obligations. Throughout
fiscal 1998, maximum borrowings under the Facility were $49.0 million. At
October 4, 1998, borrowings and standby letters of credit totaled $47.0 million
and $2.2 million, respectively.

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. However, 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,
we do not expect to be materially adversely affected by inflation or changing
prices.

RECENTLY ISSUED FINANCIAL STANDARDS

In February 1997, the Financial Accounting Standards Board (FASB) issued
Statement of Financial Accounting Standard (SFAS) No. 128, EARNINGS PER SHARE,
which we adopted in fiscal year 1998. The Statement replaces the presentation of
primary EPS with a presentation of basic EPS, which excludes dilution and is
computed by dividing income available to common stockholders by the weighted
average number of common shares outstanding for the period. The Statement also
requires the dual presentation of basic and diluted EPS on the face of the
income statement for all companies with complex capital structures and requires
a reconciliation of the numerator and denominator of the basic EPS computation
to the numerator and denominator of the diluted EPS computation. Diluted EPS is
computed similarly to fully diluted EPS pursuant to APB Opinion No. 15. EPS has
been retroactively restated to reflect the requirements of SFAS No. 128.

In June 1997, the FASB issued SFAS No. 130, REPORTING COMPREHENSIVE
INCOME. The Statement is effective for fiscal years beginning after December 15,
1997. The Statement establishes standards for reporting and display of
comprehensive income and its components (revenues, expenses, gains and losses)
in a full set of general-purpose financial statements. This Statement requires
that all items that are required to be recognized under accounting standards as
components of comprehensive income be reported in a financial statement that is
displayed with the same prominence as other financial statements. We will adopt
this Statement in fiscal year 1999.

In June 1997, the FASB issued SFAS No. 131, DISCLOSURES ABOUT SEGMENTS OF
AN ENTERPRISE AND RELATED INFORMATION. The Statement is effective for fiscal
years beginning after December 15, 1997. The Statement establishes standards for
the way that public business enterprises report information about operating
segments as well as related disclosures about products and services, geographic
areas, and major clients. The Statement also requires that a public business
report descriptive information about the way that the operating segments were
determined, the products and services provided by the operating segments,
differences between the measurements used in reporting segment information and
those used in the enterprise's general-purpose financial statements, and changes
in the measurement of segment amounts from period to period. The Statement need
not be applied to interim financial statements in the initial year of its
application. We have not completed our analysis of the effect of SFAS No. 131 on
our financial statements. We will adopt this Statement in fiscal year 1999.

In June 1998, the FASB issued SFAS No. 133, ACCOUNTING FOR DERIVATIVES
AND HEDGING ACTIVITIES. The Statement is effective for all fiscal quarters of
fiscal years beginning after June 15, 1999. The Statement requires companies to
recognize all derivative instruments on their balance sheet as either assets or
liabilities measured at fair value. The Statement also specifies a new method of
accounting for hedging transactions, prescribes the type of items and
transactions that may be hedged, and specifies detailed criteria to be met to
qualify for hedge accounting. We will adopt this Statement in fiscal year 2001.

MARKET RISKS

We currently utilize no 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 debt. 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 anytime 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 December 15,
2000 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 debt based on anticipated payments within and beyond
one year's period of time. Without giving effect to the use of the proceeds we
receive from the sale of our common stock in this offering, we presently
anticipate repaying our long-term debt in the amounts of $14,065,000,
$15,546,000 and $18,000,000 in fiscal 1999, 2000 and 2001, respectively.
Assuming we pay our long-term debt in such amounts ratably throughout the year,
and our average interest rate on our long-term debt increases or decreases by
one percentage point, our interest expense would increase or decrease by
$406,000, $258,000 and $90,000 in fiscal 1999, 2000 and 2001, respectively.
However, there can be no assurance that we will, or will be able to, repay our
long-term debt in the manner described. For example, we could incur additional
debt under the Facility or our operating results could be worse than we expect.

YEAR 2000

We are working to resolve the potential impact of the year 2000 on our
business operations and the ability of our computerized information systems to
accurately process information that may be date-sensitive.

Any of our programs that recognize a date using "00" as the year 1900 rather
than the year 2000 could result in errors or system failures.

We utilize a number of computer programs across our entire operation. The
primary information technology (IT) systems we utilize are (1) the accounting
and financial systems which include general ledger, accounts payable, accounts
receivable, billing and collection, fixed assets, job cost accounting and
payroll and (2) human resource information management systems. We do not believe
we have a material amount of non-IT systems on which we rely.

We have established both a year 2000 review committee and a year 2000
action team. The purpose of the review committee is to develop and communicate
our year 2000 plan to achieve our year 2000 compliance mission. The purpose of
the action team is to identify, remediate and implement plans to resolve our
year 2000 related issues. Through the review committee and the action team, we
are in the process of completing our full assessment of all issues relating to
the year 2000. We have developed questionnaires regarding year 2000 readiness to
be used internally and externally. We have completed our internal assessment and
we are in the process of assessing the year 2000 issues of our clients and
vendors. Based on the information collected to date, we do not believe that the
cost of addressing our year 2000 issues will have a material adverse impact on
our financial position. We plan to devote all resources required to resolve any
significant year 2000 issues in a timely manner.

STATE OF READINESS

We began our risk assessment in 1995. Since that time we have procured
and implemented certain accounting and financial reporting systems as well as
contract administration and billing systems that have been certified as year
2000 compliant by our vendors. Currently, approximately 72% of our gross revenue
is recognized on these year 2000 compliant systems. We have successfully
converted seven of our 18 operating units to these year 2000 compliant systems.
We are planning to convert four additional operating units by July 1999. The
operating units that will not be converted to the systems currently in place are
in the process of upgrading their existing systems to a year 2000 compliant
version or will procure and implement year 2000 compliant software. In all
cases, we believe that our financial and accounting systems will be year 2000
compliant in a timely manner and will not be materially impacted by the year
2000.

We are currently installing a year 2000 compliant human resource
information management system. Ten operating units including our corporate units
will be supported by this system. The anticipated completion date is April 1999.
We plan to convert the remaining operating units following April 1999. In all
cases, we believe that our human resource management information systems will be
year 2000 compliant in a timely manner and will not be materially impacted by
the year 2000.

We have expended or obligated approximately $2.6 million on the
procurement of these systems, the conversion of data from legacy systems to
these systems, and on the implementation and testing of these systems.

We have extensive business with the Federal government. Should the
Federal government, specifically the Department of Defense, experience
significant business interuptions relating to non-year 2000 compliance, we could
be materially impacted. To the extent that other third parties upon which we
rely, such as banking institutions, clients and vendors, are unable to address
their year 2000 issues in a timely manner, we could be materially impacted. We
believe that the worst case scenario relating to the year 2000 would be an
extensive period of time in which the Federal government and other third parties
could not process payments promptly.

RISKS

We believe the risks associated with non-year 2000 compliance include:

- Our inability to invoice and process payments;

- Our inability to produce accurate and timely financials;

- The impact on our cash flow and working capital needs;

- The impact on our profitability; and

- Our potential liability to third parties for not meeting contracted
deliverables.

CONTINGENCY PLANS

We currently do not have formal contingency plans for the failure of our
financial and accounting systems. We have substantial experience in the
conversion process from multiple legacy systems to our current year 2000
certified systems. We have an experienced and dedicated staff to perform the
functions identified and are reasonably confident that the projected conversions
will be accomplished as projected.

We currently do not have formal contingency plans for the failure of our
human resource information management system. Our implementation strategy is to
install the system as simply as possible, with little customization. Our vendor
supports our implementation strategy and has agreed to a financial penalty if
the implementation is not achieved within three months, or by April 1999. If the
implementation is not achieved by April 1999, we believe there will still be
sufficient time to meet the year 2000 deadline.

We maintain, as a matter of policy and practice, mitigation plans in the
event of systems failure which include regular backup of historical information.

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. We have more than 3,600
employees worldwide, 3,500 of whom are located in North America in more than 100
locations. In addition, we have established a presence in Asia, South America
and Europe. From fiscal 1991 through fiscal 1998, we generated a net revenue
compounded annual growth rate of approximately 34.2%, and achieved a net income
compounded annual growth rate of approximately 36.4%.

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. According to the ENVIRONMENTAL BUSINESS JOURNAL, the
size of the consulting, engineering services and wastewater treatment
segments of the water management industry totaled more than $30 billion in
1997.

- 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. Recently, the
Federal government has committed approximately $15 billion to various
environmental initiatives in an attempt to curb pollution, accelerate
toxic waste cleanups and

combat other forms of pollution. 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 costs savings through increased operating
efficiencies.

INFRASTRUCTURE. Continued population and economic growth places
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. According to
the ENGINEERING NEWS-RECORD, the market opportunity in the United States for
technical services in infrastructure development including water and wastewater,
transportation, hazardous waste, and educational, recreational and correctional
facilities, ranges from $15 to $20 billion.

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,
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.

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 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, the Philippines, Argentina, Chile, Brazil and the Czech
Republic.

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 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 comprehensive 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 1,000 active 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;

- CONSTRUCTION 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 is driving demand for our services.
Over the past 32 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.

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.

Nuclear Environmental Projects: The DOE's nuclear weapons plants and
research laboratories face a wide variety of environmental challenges
including groundwater and surface water contamination, hazardous waste
management and environmental compliance. Our services include
environmental impact analyses and documentation, environmental audits and
risk assessments, regulatory compliance support, groundwater
characterization, remedial investigation/feasibility studies, and project
management and oversight. Our environmental analyses provide the DOE with
information it requires in order to make decisions regarding the storage
or disposition of surplus materials from dismantled nuclear weapon
components.

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
multi-story facilities. We have completed engineering and construction
projects for a wide range of clients with specialized needs such as
security systems, clean rooms, laboratories 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 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 aquarium projects worldwide.

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 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. 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 in both the broadband
and wireless sectors. 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 projects in our
three primary business areas:

- --------------------------- --------------------------------------------------------

BUSINESS AREA
- --------------------------- REPRESENTATIVE PROJECTS
--------------------------------------------------------
RESOURCE MANAGEMENT - Currently conducting a remedial design/remedial action
for contaminated groundwater at a Superfund site in
Hendersonville, North Carolina for a private
corporation.

- 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.

INFRASTRUCTURE - Completed the development and analysis of alternative
flood control measures for the Los Angeles River.

- Currently providing 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.

- Selected by Texas Parks and Wildlife Department as the
prime contractor to plan and develop a new,
state-of-the-art, marine fish hatchery and visitor
center at Lake Jackson, Texas. Provided design and
construction administration, and engineering and
bioengineering for all life support systems.

COMMUNICATIONS - Provided site acquisition, obtained entitlements,
supervised construction and installation of equipment,
and provided program management services for a
Canadian corporation.

- Supported the initiative to enhance Emergency 911
services and to improve the dispatch of emergency
services to Henrico County near Richmond, Virginia.
Assisted in the buildout of the Emergency 911
communications network through installation of
antennas, coaxial cables, microwave dishes and
elliptical waveguides.

- Currently redesigning and reconstructing 25% of Tele-
Communications Inc.'s U.S. cable TV networks under a
turnkey contract.

CLIENTS

We have developed a diverse client base of over 700 clients both in the
public and private sectors. During fiscal 1998, the DOD, EPA and DOE accounted
for 26.2%, 17.1% and 3.5%, 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 1998.

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 SECTOR
- ------------------ -------------------------- -------------------------- --------------------------

RESOURCE U.S. Environmental California Department of Lockheed Martin
MANAGEMENT Protection Agency; U.S. Health Services; Corporation; Merck & Co.;
Air Force; U.S. Navy; U.S. Washington Department of General Electric Company;
Army; U.S. Coast Guard; Ecology; Prince Georges Westwood Squibb
U.S. Forest Service County, Maryland; Clarmont Pharmaceuticals, Inc.
County, Ohio; City of San
Jose, California

INFRASTRUCTURE U.S. Army Corps of City of Tucson, Arizona; Universal Studios, Inc.;
Engineers; U.S. Bureau of City of Breckenridge, Boeing Corporation; E.I.
Reclamation; U.S. Air Colorado; Washington DuPont de Nemours and
Force; Federal Emergency Department of Company; Ford Motor
Management Agency Transportation; City of Company
Detroit, Michigan; City of
Portland, Oregon; Texas
Parks and Wildlife
Department; King County,
Washington; Delaware
Department of
Transportation; Delaware
Department of Corrections

COMMUNICATIONS Henrico County, Virginia AT&T Wireless Services;
Nextel Communications,
Inc.; AirTouch
Communications, Inc.;
Motorola, Inc.; Sprint
Communications Company;
TCI

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 1998,
26.1%, 33.5% and 40.4% 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 allowability and 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 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 improperly accounted for such costs in a manner inconsistent
with Cost Accounting Standards. Under a government contract, 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.

In September 1995, we acquired PRC Environmental Management, Inc. (EMI).
The Defense Contract Audit Agency recently completed an audit of EMI for the
fiscal years 1987 through 1995. As a result of the completed audit and our
negotiations with the DCAA, the DCAA disallowed approximately $2.9 million in
costs. Because we were aware of these issues prior to completing the
acquisition, we established a sufficient reserve and, consequently, the
disallowance did not have a material adverse effect on our business.

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 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
and media relations.

We also perform marketing activities through our local offices. We
believe that these offices have a greater understanding of local environmental
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 regulatory 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 10 to 100 firms, depending upon the relative value of the project,
the financial terms and risks associated with the work, and any restrictions
placed upon competition by the client. Historically, clients have chosen among
competing firms 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; Castle Tower Corporation; Camp, Dresser &
McKee; CH2M Hill Companies Ltd., Dames & Moore Group; EA Engineering, Science &
Technology, Inc.; Earth Tech, Inc.; ICF Kaiser International, Inc.; IT Group
Inc.; Mastec, Inc.; Montgomery Watson; OSP Consultants, Inc.; Roy F. Weston,
Inc.; and URS Greiner Corporation.

BACKLOG

At October 4, 1998, our gross revenue backlog was approximately $405.0
million, compared to $217.5 million at September 28, 1997. 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 $329.6
million of the gross revenue backlog at October 4, 1998 will be recognized
during fiscal 1999. 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 would not recognize 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; 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. 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 liability insurance policies. These policies are "claims made"
policies. This means that only claims made during the term of the policy are
covered. If we terminate our 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
engineering 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, we may not be
able to obtain insurance coverage for such activities or, if insurance is
obtained, the dollar amount of any liabilities incurred could exceed our
insurance coverage.

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 October 4, 1998, we had 3,662 total employees or 3,077 full-time
equivalent employees. Of the 3,662 total employees, 2,144 are professionals. 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. Three
employees of one of our subsidiaries will be represented by a labor
organization. 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.

PROPERTIES

Our corporate headquarters facilities are located in Pasadena,
California. These facilities contain approximately 25,000 square feet of office
space and are subject to leases which expire beyond the year 2001. We lease
office space in approximately 110 locations in the United States. 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 additional or substitute space will be available as needed
to accommodate any expansion of operations.

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. We believe that the
resolution of these claims will not have a material effect on our financial
position or results of operations.

MANAGEMENT

DIRECTORS AND EXECUTIVE OFFICERS

The following table sets forth certain information concerning our
directors and executive officers:

NAME AGE POSITION
- ------------------------------- --- ---------------------------------------------------------

Li-San Hwang................... 63 Chairman of the Board of Directors, President and Chief
Executive Officer

Thomas D. Brisbin.............. 46 Executive Vice President, Chief Operating Officer

James M. Jaska................. 47 Vice President, Chief Financial Officer and Treasurer

Daniel A. Whalen............... 51 Director, Executive Vice President

William R. Brownlie............ 45 Senior Vice President

Steven A. Gherini.............. 53 Vice President

Arkan Say...................... 63 Vice President

Charles R. Faust............... 53 Vice President

Richard A. Lemmon.............. 39 Vice President and Secretary

J. Christopher Lewis........... 42 Director

Patrick C. Haden............... 45 Director

James J. Shelton............... 82 Director

Our executive officers are elected by and serve at the discretion of the
Board of Directors. Set forth below is a brief description of the business
experience of all executive officers and directors.

LI-SAN HWANG joined our predecessor in 1967 and has held his present
positions since our acquisition of the Water Management Group of Tetra Tech,
Inc., a subsidiary of Honeywell Inc., in March 1988 (the "Acquisition"). Dr.
Hwang was named our Director of Engineering in 1972 and a Vice President in
1974. Prior to the Acquisition, Dr. Hwang was Senior Vice President of
Operations. He has served as an advisor to numerous government and professional
society committees and has published extensively in the field of hydrodynamics.
Dr. Hwang is a graduate of the National Taiwan University, Michigan State
University and the California Institute of Technology, holding B.S., M.S. and
Ph.D. degrees, respectively, in Civil Engineering, specializing in water
resources.

THOMAS D. BRISBIN was named our Executive Vice President and Chief
Operating Officer in 1996 after we acquired Tetra Tech EM Inc. (formerly known
as PRC Environmental Management, Inc.). Dr. Brisbin joined Planning Research
Corporation (PRC), a wholly-owned subsidiary of The Black & Decker Corporation,
in 1978 and was co-founder and President of PRC Environmental Management, Inc.
(PRC EMI). During his 17 year tenure at PRC, he was involved in all aspects of
marketing, operations and finance. Before joining PRC, he was a research
associate at Argonne National Laboratory and an adjunct professor at the
Illinois Institute of Technology. Dr. Brisbin holds a B.S. degree from Northern
Illinois University and a Ph.D. in Environmental Engineering from the Illinois
Institute of Technology. He also completed Harvard Business School's Advanced
Management Program in 1988.

JAMES M. JASKA joined us in 1994 as Vice President, Chief Financial
Officer and Treasurer. From 1991 to 1994, Mr. Jaska held several operations and
management positions at Alliant Techsystems, Inc., in addition to leading the
environmental business venture and having operational responsibility for large
government defense plants. From 1988 to 1990, he served as the Director of
Finance and Business Management at Honeywell Inc.'s Precision Weapons
Operations. From 1981 to

1987, he was responsible for environmental affairs at Honeywell Inc. From 1977
to 1981, he managed regulatory affairs dealing with the production of specialty
chemicals at Ecolab, Inc. Mr. Jaska also served as an advisor to numerous
governmental and professional committees. Mr. Jaska holds B.S. and M.S. degrees
from Western Illinois University and completed an executive management program
through Harvard University.

DANIEL A. WHALEN, currently on a leave of absence from his position as
our Executive Vice President of Telecommunications Services and President of
Whalen & Company, Inc. (WAC), joined us and the Board upon our merger with WAC
in June 1997. Prior to founding WAC in 1987, Mr. Whalen co-founded and served as
an executive officer of First Cellular Group, Inc., The Microwave Group, Inc.,
Network Building & Consulting, Inc., and Cellular Development Company. Earlier
he was Vice President-Operations of American TeleServices, Inc. and Director of
Operations of NYNEX Mobile Services. Mr. Whalen earned a B.S. degree from St.
John's University and M.A. and M.B.A. degrees from Stanford University.

WILLIAM R. BROWNLIE joined us in 1981, has been a Vice President since
1988 and was named a Senior Vice President in December 1993. Dr. Brownlie has
managed several large government environmental support programs and serves as
one of our Division Managers. Dr. Brownlie is a registered Civil Engineer with a
technical background in hydrology, hydraulics, water quality analysis and
numerical modeling. Dr. Brownlie holds B.S. and M.S. degrees in Civil
Engineering at the State University of New York at Buffalo, and earned a Ph.D.
in Civil Engineering from the California Institute of Technology.

STEVEN A. GHERINI joined us in 1976. Mr. Gherini has served as Program
Manager on a variety of contracts involving chemistry, water quality control and
water quality modeling, and served as Division Vice President prior to being
named as Vice President in 1988. He is the author of numerous technical
publications and is the developer of several models for pollutant fate and
transport. He has served on two National Academy of Science panels. Mr. Gherini
is a registered engineer with B.S. and M.S. degrees in Civil Engineering from
Stanford University, and a M.S. degree in Aquatic Chemistry from Harvard
University.

ARKAN SAY joined Edward H. Richardson & Associates (a firm that our
predecessor acquired in 1981 and which became one of our divisions in 1991) in
1958 and was named to his present position in 1988. Mr. Say has authored several
publications on site development, engineering and storm drainage. Mr. Say holds
a B.S. in Civil Engineering from Robert College in Istanbul, Turkey and a M.S.
in Civil Engineering from the University of Delaware.

CHARLES R. FAUST, Vice President since 1988 and President of HSI
GeoTrans, Inc. (HSG), one of our subsidiaries, co-founded GeoTrans, Inc., a
predecessor of HSG, in 1979. In addition to his management responsibilities, Mr.
Faust is engaged in the quantitative assessment and investigation of highly
technical groundwater problems. He has published 23 articles and has co-authored
a book on groundwater modeling. Dr. Faust holds B.S. and Ph.D. degrees in
Geology from Pennsylvania State University.

RICHARD A. LEMMON, Vice President and Secretary, joined us in 1981. Until
1985, he served in several technical capacities. Mr. Lemmon transferred to
Corporate Human Resources, and was promoted to Corporate Manager of Human
Resources in 1987. Following our divestiture from Honeywell, Inc., Mr. Lemmon
structured and managed our Risk Management, Human Resource and Office Leasing
programs. In 1990, he was promoted to Director of Administration and in 1994
assumed responsibility for contracts administration and was elected as our
Secretary. In November 1995, Mr. Lemmon became a Vice President. Mr. Lemmon
holds a B.A. degree in Business Administration.

J. CHRISTOPHER LEWIS has been a member of our Board of Directors since
February 1988. Since 1982, Mr. Lewis has been a general partner of Riordan,
Lewis & Haden, a Los Angeles-based partnership which invests equity in
high-growth middle market companies. Mr. Lewis also serves as a

director of Data Processing Resources Corporation, a provider of specialty
information technology staffing services, SM&A Corporation, a provider of
proposal management, systems engineering and information technology services,
California Beach Restaurants, Inc., an owner and operator of restaurants, PIA
Merchandising Services, Inc., a supplier of in-store merchandising and sales
services, and several privately-held companies.

PATRICK C. HADEN has been a member of our Board of Directors since
December 1, 1992. Mr. Haden is a general partner of Riordan, Lewis & Haden,
which he joined in 1987. Mr. Haden also serves as a director of PIA
Merchandising Services, Inc., a supplier of in-store merchandising and sales
services, Data Processing Resources Corporation, a provider of specialty
information technology staffing services, and several privately-held companies.

JAMES J. SHELTON has been a member of our Board of Directors since March
1995. Mr. Shelton is a self-employed investor and venture capitalist. He is the
former (retired) President of the Baker Drilling Equipment Co., and formerly
served as the Director of Corporate Relations and a director of Baker Hughes
Incorporated (formerly Baker International Corp.).

EXECUTIVE COMPENSATION

The following table sets forth the cash compensation that we paid or
accrued to the Chief Executive Officer and to each of the four additional most
highly compensated executive officers for each of the fiscal years in the
three-year period ended October 4, 1998:

SUMMARY COMPENSATION TABLE

LONG-TERM COMPENSATION
--------------------------------
ANNUAL COMPENSATION AWARDS
------------------------------------------------ --------------------------------
OTHER RESTRICTED SECURITIES
ANNUAL STOCK UNDERLYING
NAME AND SALARY BONUS COMPENSATION AWARD(S) OPTIONS/SARS
PRINCIPAL POSITION YEAR ($) ($) ($)(1) ($) ($)
- ---------------------------------- --------- --------- --------- --------------- --------------- ---------------

Li-San Hwang ..................... 1998 185,000 85,000 601(2) -- 12,500
Chairman, Chief Executive 1997 185,000 80,000 1,087 -- 7,813
Officer and President 1996 185,000 80,000 1,975 -- 9,766

Thomas D. Brisbin ................ 1998 150,000 95,000(4) 3,600(5) -- 3,750
Executive Vice President, Chief 1997 150,000 50,000 -- -- --
Operating Officer 1996 150,000 -- -- -- 83,985

James M. Jaska ................... 1998 120,000 60,000 4,950(7) -- 2,500
Vice President, Chief Financial 1997 110,000 50,000 5,400 -- 18,750
Officer and Treasurer 1996 110,000 27,000 5,400 -- 3,906

William R. Brownlie .............. 1998 117,000 35,000 5,400(9) -- 3,125
Senior Vice President 1997 115,000 30,000 5,400 -- 3,125
1996 114,000 25,000 5,400 -- 4,883

Charles R. Faust ................. 1998 120,000 25,000 5,400(11) -- 5,000
Vice President 1997 120,000 -- 5,400 -- 5,469
1996 115,000 15,000 5,400 -- 2,930

PAYOUTS
-------------
LTIP ALL OTHER
NAME AND PAYOUTS COMPENSATION
PRINCIPAL POSITION ($) ($)
- ---------------------------------- ------------- ---------------

Li-San Hwang ..................... -- 10,266(3)
Chairman, Chief Executive -- 10,317
Officer and President -- 10,746
Thomas D. Brisbin ................ -- 9,079(6)
Executive Vice President, Chief -- 34,058
Operating Officer -- 9,337
James M. Jaska ................... -- 7,060(8)
Vice President, Chief Financial -- 5,826
Officer and Treasurer -- 6,378
William R. Brownlie .............. -- 6,890(10)
Senior Vice President -- 6,043
-- 6,668
Charles R. Faust ................. -- 9,405(12)
Vice President -- 8,637
-- 8,758

- ---------

(1) No named executive officer received other annual compensation in excess
of the lesser of $50,000 or 10% of such officer's compensation in fiscal
1998.

(2) Comprised of $601 in automobile allowances.

(3) Comprised of $7,850 of contributions to our Retirement Plan and $2,416
benefits and premiums we paid to Dr. Hwang pursuant to the Executive
Medical Reimbursement Plan.

(4) Includes $50,000 of bonus paid in fiscal 1998 relating to bonus earned
in fiscal 1996.

(5) Comprised of $3,600 in automobile allowances.

(6) Comprised of $9,079 of contributions to our Retirement Plan.

(7) Comprised of $4,950 in automobile allowances.

(8) Comprised of $7,060 of contributions to our Retirement Plan.

(9) Comprised of $5,400 in automobile allowances.

(10) Comprised of $6,890 of contributions to our Retirement Plan.

(11) Comprised of $5,400 in automobile allowances.

(12) Comprised of $7,155 of HSI GeoTrans' contributions to HSI GeoTrans'
Retirement Plan and $2,250 in life insurance premiums we paid on behalf
of Dr. Faust.

The following table sets forth information concerning options granted to
each of the named executive officers during fiscal 1998:

OPTION/SAR GRANTS IN LAST FISCAL YEAR

POTENTIAL REALIZABLE
VALUE AT ASSUMED
INDIVIDUAL GRANTS ANNUAL RATES OF
------------------------------------------------------------ STOCK PRICE
NUMBER OF % OF TOTAL APPRECIATION FOR
SECURITIES OPTIONS/SARS EXERCISE OPTION TERM
UNDERLYING GRANTED TO OR BASE --------------------
OPTIONS/SARS EMPLOYEES IN PRICE EXPIRATION 5% 10%
NAME GRANTED (#)(1) FISCAL YEAR ($/SH) DATE ($)(2) ($)(2)
- ---------------------------------- --------------- --------------- ------------- ----------- --------- ---------

Li-San Hwang...................... 12,500 2.19 16.00 12/18/07 125,779 318,748
Thomas D. Brisbin................. 3,750 0.66 16.00 12/18/07 37,734 95,625
James M. Jaska.................... 2,500 0.44 16.00 12/18/07 25,156 63,750
William R. Brownlie............... 3,125 0.55 16.00 12/18/07 31,445 79,687
Charles R. Faust.................. 5,000 0.88 16.00 12/18/07 50,312 127,499

- ---------

(1) All options are incentive stock options and were granted under our 1992
Incentive Stock Plan. Such options vest over four year periods at an
annual rate of 25% beginning on the first anniversary of the date of
grant.

(2) Potential realizable value is determined by multiplying the exercise or
base price per share by the stated annual appreciation rate compounded
annually for the term of the option (10 years), subtracting the exercise
or base price per share from the product, and multiplying the remainder by
the number of options granted. Actual gains, if any, on stock option
exercises and common stock holdings are dependent on the future
performance of the common stock and overall stock market conditions. There
can be no assurance that the amounts reflected in this table will be
achieved.

The following table sets forth information concerning the aggregate
number of options exercised during fiscal 1998 by each of the named executive
officers:

OPTION/SAR EXERCISES IN LAST FISCAL YEAR AND
FISCAL YEAR END OPTION/SAR VALUES

NUMBER OF VALUE OF UNEXERCISED
UNEXERCISED OPTIONS/ IN-THE-MONEY OPTIONS/
SARS AT FY-END SARS AT FY-END
SHARES VALUE --------------------------- -----------------------------
ACQUIRED ON REALIZED EXERCISABLE/UNEXERCISABLE EXERCISABLE/UNEXERCISABLE
NAME EXERCISE (#) ($) (#) ($)(1)
- -------------------------- ------------- ----------- --------------------------- -----------------------------

Li-San Hwang.............. -- -- 15,991/26,296 144,642/237,853
Thomas D. Brisbin......... -- -- 55,175/18,517 662,216/222,243
James M. Jaska............ 12,500 147,095 45,898/41,837 430,229/392,163
William R. Brownlie....... -- -- 35,649/10,963 473,362/145,571
Charles R. Faust.......... -- -- 16,048/12,400 202,993/359,842

- ---------

(1) Value is determined by subtracting the exercise price from the fair
market value of $20.84 per share (the closing price for our common stock
as reported by the Nasdaq National Market as of October 2, 1998) and
multiplying the remainder by the number of underlying shares of common
stock.

PRINCIPAL AND SELLING STOCKHOLDERS

The following table sets forth certain information regarding the
beneficial ownership of our common stock at December 18, 1998 and after giving
effect to our sale of 1,000,000 shares of common stock and the sale by the
selling stockholders of 2,175,000 shares of common stock in this offering and
assuming no exercise of the Underwriters' over-allotment option, by: (1) each
director and executive officer; (2) each person we know to beneficially own more
than 5% of the outstanding shares of our common stock; (3) all officers and
directors as a group; and (4) the selling stockholders.Common Stock. Except as otherwise noted,
we know of no agreements among our stockholders which relate to voting or
investment power over our Common Stock. Except as otherwise noted, the
address of each person named below has an address in care of our principal executive
offices.

SHARESselling stockholder is c/o Utilities & C.C., Inc., 1555
Bedell Court, Roseville, California 95747.

SHARES
BENEFICIALLY NUMBER OF BENEFICIALLY
OWNED PRIOR SHARES OWNED AFTER
NAMES TO OFFERING %(1) OFFERED OFFERING %(1)
- ----------------------------------------------------- ------------ --- ----------- ------------ -----

Li-San Hwang(2)...................................... 1,629,961 5.7% -- 1,629,961 5.5%
Daniel A. Whalen(3).................................. 3,713,649 13.0 2,175,000(3) 1,538,649 5.2
Whalen & Company, Inc.
3675 Mt. Diablo Blvd.
Suite 360
Lafayette, California 94549
Pilgrim Baxter &Associates, Ltd.(4).................. 2,873,206 10.0 -- 2,873,206 9.7
Harold J. Baxter
Gary I. Pilgrim
1255 Drummers Lane
Wayne, Pennsylvania 19087
J. Christopher Lewis(5).............................. 76,472 * -- 76,472 *
Patrick C. Haden(6).................................. 28,145 * -- 28,145 *
James J. Shelton(7).................................. 20,869 * -- 20,869 *
Thomas D. Brisbin(8)................................. 47,603 * -- 47,603 *
Charles R. Faust(9).................................. 48,998 * -- 48,998 *
James M. Jaska(10)................................... 58,209 * -- 58,209 *
William R. Brownlie(11).............................. 147,068 * -- 147,068 *
Steven A. Gherini(12)................................ 170,262 * -- 170,262 *
Arkan Say(13)........................................ 39,157 * -- 39,157 *
Richard A. Lemmon(14)................................ 38,841 * -- 38,841 *
All directors and executive officers as a group 21.0%
(12 persons)(15).................................. 6,019,234 -- 3,844,234 13.0%

- ----------------------------------------- ------------ ---- ---------

Kenneth L. Shelton....................... 92,468 * 92,468
Lonny B. Cunningham...................... 52,014 * 52,014

- --------------

* Represents less than 1% of the outstanding shares of common stock.

(1) Applicable percentagesCommon Stock.

All selling stockholders are employees of ownership prior to the offering are based on
28,666,131 shares of common stock outstanding on December 18, 1998,
adjusted as required by the rules promulgated by the SecuritiesUCCI, and Exchange Commission (SEC). Applicable percentages of ownership after the
offering are based on 29,666,131 shares of common stock outstanding. This
table is based upon information supplied by officers, directors and
principal stockholders and Schedules 13D and 13G (if any) filed with the
SEC. Unless otherwise indicated, and subject to community property laws
where applicable, we believe that each of the stockholders named in this
tableno selling
stockholder has sole voting and investment power with respect to the shares
indicated as beneficially owned. Any security thathad any person named above
has the right to acquire within 60 days is deemed to be outstanding for
purposes of calculating the percentage ownership of such person, but is
not deemed to be outstanding for purposes of calculating the ownership
percentage of any other person.

(2) Includes 26,563 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998.

(3) Includes 3,906 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998. Also includes (a)
2,890,821 shares of common stock held by Daniel A. Whalen and Katharine
C. Whalen, as Trustees for the Whalen Family Trust U/A/D 4/30/92 (the
"Family Trust"), (b) 31,000 shares of common stock held by Brown
Investment Advisory & Trust Company, as Trustee for the Whalen 1997
Charitable Remainder Unitrust, (c) 488,295 shares of common stock held by
DKW/CRT Investments ("DKW/CRT"), and (d) 299,627 shares of common stock
held by D-K-W Ventures LP ("D-K-W"). Of the shares being offered hereby,
1,709,422 will be sold by the Family Trust, 288,797 will be sold by
DKW/CRT and 176,781 will be sold by D-K-W.

(4) All information regarding share ownership is taken from and furnished
in reliance upon the Schedule 13G (Amendment No. 6), dated as of April 9,
1998, jointly filed by Pilgrim Baxter & Associates, Ltd., Harold J.
Baxter and Gary I. Pilgrim.

(5) Includes 19,070 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998.

(6) Excludes an aggregate of 2,683 shares of common stock owned by Mr.
Haden's wife as to which Mr. Haden disclaims beneficial ownership.
Includes 19,070 shares issuable with respect to stock options exercisable
within 60 days after December 18, 1998.

(7) Includes 5,613 shares held by James J. Shelton, Sarah Belle Shelton and
James J. Shelton, Jr., Trustees of the James J. Shelton and Sarah Belle
Shelton Family Trust dated August 19, 1987, and 15,256 shares issuable
with respect to stock options exercisable within 60 days after December
18, 1998.

(8) Includes 46,835 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998.

(9) Includes 21,230 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998. Additionally, Charles
R. Faust's minor children own an aggregate of 2,882 shares of common
stock as to which Charles R. Faust disclaims beneficial ownership.

(10) Includes 57,558 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998.

(11) Includes 41,484 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998. Also includes an
aggregate of 400 shares of common stock owned by Dr. Brownlie's minor
children.

(12) Includes 27,090 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998.

(13) Includes 14,157 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998.

(14) Includes 11,945 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998.

(15) Includes 304,164 shares issuable with respect to stock options
exercisable within 60 days after December 18, 1998.

UNDERWRITING

The Underwriters named below, acting through their representatives,
BancBoston Robertson Stephens Inc., NationsBanc Montgomery Securities LLC,
Cleary Gull & Reiland Inc., and First Analysis Securities Corporation (the
"Representatives"), have severally agreedmaterial relationship with us, andor any of our
predecessors or affiliates, other than as an employee. Because the selling
stockholders subjectmay sell all or part of their shares of Common Stock offered
hereby, no estimate can be given as to the terms and conditions of the Underwriting Agreement, to purchase the number of shares of common stock set forth oppositeCommon Stock
that will be held by any selling stockholder upon termination of any offering
made hereby.

PLAN OF DISTRIBUTION

We are registering the shares of Common Stock on behalf of the selling
stockholders. As used herein, "selling stockholders" includes donees and
pledgees selling shares received from a named selling shareholder after the
date of this Prospectus. This Prospectus may also be used by transferees of
the selling stockholders or by other persons acquiring shares, including
brokers who borrow the shares to settle short sales of shares of Common
Stock. We will bear all costs, expenses and fees in connection with the
registration of the shares offered hereby. The selling stockholders will
bear brokerage commissions and any similar selling expenses associated with
the sale of shares.

The selling stockholders may offer their respective names
below.shares of Common Stock at
various times in one or more of the following transactions:

- on the Nasdaq National Market;

- in the over-the-counter market;

- in transactions other than on the Nasdaq National Market or in the
over-the-counter market;

- in connection with short sales of the shares of Common Stock;

- by pledge to secure debts and other obligations;

- in connection with the writing of non-traded and exchange-traded call
options, in hedge transactions and in settlement of other transactions
in standardized or over-the-counter options; or

- in any combination of any of the above transactions.

In connection with hedging transactions, broker-dealers or other
financial institutions may engage in short sales of the Common Stock in the
course of hedging the positions they assume with selling stockholders. The
Underwriters are committedselling stockholders may also enter into options or other transactions with
broker-dealers or other financial institutions, which require the delivery to
purchase and paysuch broker-dealer or other financial institution of the shares offered
hereby, which shares may be resold pursuant to this prospectus (as
supplemented or amended to reflect such transaction).

The selling stockholders may sell their shares at market prices
prevailing at the time of sale, at prices related to such prevailing market
prices, at negotiated prices or at fixed prices. The selling shareholders
may use broker-dealers to sell their shares. If this happens, broker-dealers
will either receive discounts or commissions from purchasers of shares for
those shares, if
any are purchased.

NUMBER OF
UNDERWRITER SHARES
- ----------------------------------------------------------------------------------------------------- ----------

BancBoston Robertson Stephens Inc....................................................................
NationsBanc Montgomery Securities LLC................................................................
Cleary Gull & Reiland Inc............................................................................
First Analysis Securities Corporation................................................................

----------
Total............................................................................................ 3,175,000
----------
----------
whom they acted as agents.

The Representativesselling stockholders have advised us that they have not entered into
any agreements, understandings or arrangements with any underwriters or
broker-dealers regarding the sale of their securities, nor is there an
underwriter or coordinating broker acting in connection with the proposed
sale of shares by the selling stockholders.

The selling stockholders and any broker-dealers that act in connection
with the sale of shares might be deemed to be "underwriters" within the
meaning of Section 2(11) of the Securities Act, and any commissions received
by such broker-dealers and any profit on the resale of the shares sold by
them while acting as principals might be deemed to be underwriting discounts
or commissions under the Securities Act. We have agreed to indemnify each
selling stockholder against certain liabilities, including liabilities
arising under the Securities Act. The selling stockholders may agree to
indemnify any agent, dealer or broker-dealer that participates in
transactions involving sales of the shares against certain liabilities,
including liabilities arising under the Securities Act.

Because the selling stockholders may be deemed to be "underwriters"
within the meaning of Section 2(11) of the Securities Act, the selling
stockholders will be subject to the prospectus delivery requirements of the
Securities Act. We have informed the selling stockholders that the
Underwriters propose to offer the sharesanti-manipulative provisions of common stock to the public at the
public offering price set forth on the cover page of this prospectus and to
certain dealers at such price less a concession of not more than $ per
share, of which $ may be reallowed to other dealers. After the
completion of this offering, the public offering price, concession and
reallowance to dealers may be reduced by the Representatives. No such reduction
shall change the amount of proceeds we and the selling stockholders will receive
as set forth on the cover page of this prospectus.

OVER-ALLOTMENT OPTION. We and certain of the selling stockholders have
granted to the Underwriters an option, exercisable during the 30-day period
after the date of this prospectus, to purchase up to 476,250 additional shares
of common stock at the same price per share as we and the selling stockholders
will receive for the 3,175,000 shares that the Underwriters have agreed to
purchase from us and the selling stockholders. To the extent that the
Underwriters exercise such option, each of the Underwriters will have a firm
commitment to purchase approximately the same percentage of such additional
shares that the number of shares of common stock to be purchased by it shown in
the above table represents as a percentage of the total number of shares offered
hereby. If purchased, such additional shares will be sold by the Underwriters on
the same terms as those on which the shares are being sold.

INDEMNITY. The Underwriting Agreement contains covenants of indemnity
among the Underwriters, the selling stockholders and us against certain civil
liabilities, including liabilities under the Securities Act of 1933 and
liabilities arising from breaches of representations and warranties contained in
the Underwriting Agreement.

LOCK-UP AGREEMENTS. Pursuant to the terms of lock-up agreements, the
holders of shares of common stock, have agreed, for a period of up to 90
days after the date of this prospectus, and the selling stockholders have
agreed, for a period of up to 90 days after the date of this prospectus, that,
subject to certain exceptions, they will not contract to sell or otherwise
dispose of any shares of common stock, any options to purchase shares of common
stock or any securities convertible into, or exchangeable for, shares of common
stock, owned directly by such holders or with respect to which they have the
power of disposition, without the prior written consent of BancBoston Robertson

Stephens Inc. However, BancBoston Robertson Stephens Inc. may, in its sole
discretion, and at any time or from time to time, without notice, release all or
any portion of the securities subject to those lock-up agreements. All of the
shares of common stock subject to the lock-up agreements will be eligible for
sale in the public market upon the expiration of the lock-up agreements, subject
in the case of shares held by affiliates, to Rule 144.

FUTURE SALES. In addition, we have agreed that until 90 days after the
date of this prospectus, we will not, without the prior written consent of
BancBoston Robertson Stephens Inc., subject to certain exceptions, offer, sell,
contract to sell or otherwise dispose of any shares of our common stock, any
options to purchase any shares of our common stock or any securities convertible
into, exercisable for or exchangeable for shares of our common stock other than
our sale of shares in this offering, the issuance of shares of our common stock
upon the exercise of outstanding options and the grant of options to purchase
shares of our common stock under existing employee stock option or stock
purchase plans.

The Underwriters do not intend to confirm sales to any accounts over
which they exercise discretionary authority.

STABILIZATION. The Representatives have advised us that, pursuant to
Regulation M promulgated under the Securities
Exchange Act of 1934, certain persons
participatingas amended (the "Exchange Act"), may apply to their
sales in the offeringmarket.

The selling stockholders also may engage in transactions, including stabilizing
bids, syndicate covering transactionsresell all or the imposition of penalty bids which
may have the effect of stabilizing or maintaining the market price of our common
stock at a level above that which might otherwise prevail in the open market. A
"stabilizing bid" is a bid for or the purchaseportion of the common stock on behalf of
the Underwriters for the purpose of fixing or maintaining the price of the
common stock. A "syndicate covering transaction" is the bid for or the purchase
of the common stock on behalf of the Underwriters to reduce a short position
incurred by the Underwritersshares
in connection with the offering. A "penalty bid" is
an arrangement permitting the Representatives to reclaim the selling concession
otherwise accruing to an Underwriter or syndicate member in connection with the
offering if the common stock originally sold by such Underwriter or syndicate
member is purchased by the Representatives in a syndicate covering transaction
and has therefore not been effectively placed by such Underwriter or syndicate
member. The Representatives have advised us that such transactions may be
effected on the Nasdaq National Market or otherwise and, if commenced, may be
discontinued at any time.

PASSIVE MARKET MAKING. In connection with this offering, certain
Underwriter and syndicate selling group members, if any, who are qualifiedopen market makers on the Nasdaq National Market may engage in passive market making transactions in the common stock on the Nasdaq National Market in accordance
withreliance upon Rule 103 of Regulation M144 under the Securities
Exchange Act, of 1934, duringprovided they meet the business day priorcriteria and conform to the pricingrequirements of such
Rule.

Upon being notified by a selling stockholder that any material
arrangement has been entered into with a broker-dealer for the sale of shares
through a block trade, special offering, exchange distribution or secondary
distribution or a purchase by a broker or dealer, we will file a supplement
to this Prospectus, if required, pursuant to Rule 424(b) under the Securities
Act, disclosing (i) the name of each such selling stockholder and of the
offering, beforeparticipating broker-dealer(s), (ii) the commencementnumber of offersshares involved, (iii) the
price at which such shares were sold, (iv) the commissions paid or sales of our common stock. Passive market makers must comply withdiscounts
or concessions allowed to such broker-dealer(s), where applicable, volume and price limitations and must be identified as such.(v)
other facts material to the transaction. In general,addition, upon being notified by
a passive market maker must display its bid atselling stockholder that a price not in excess of
the highest independent bid for such security; if all independent bids are
lowered below the passive market maker's bid, however, such bid must then be
lowered when certain purchase limits are exceeded.

46donee or pledgee intends to sell more than 500
shares, we will file a supplement to this Prospectus.

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and special reports, proxy statements and
other information with the Securities and Exchange Commission (SEC). You may
read and copy any document we file at the SEC's public reference room at
450 Fifth Street, N.W., Washington, D.C. 20549. Please call the SEC at
1-800-SEC-0330 for further information on the public reference room. Our SEC
filings are also available to the public from the SEC's Website at "http://
//www.sec.gov."

The SEC allows us to "incorporate by reference" the information we file
with them, which means that we can disclose important information to you by
referring you to those documents. The information incorporated by reference
is considered to be part of this prospectus, and information that we file
later with the SEC will automatically update and supersede this information.
We incorporate by reference the documents listed below and any future filings
we will make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the
Securities Exchange Act of 1934:Act:

1. Annual Report on Form 10-K for the fiscal year ended October 4,
1998, as filed with the SEC on December 31, 1998;

2. Annual Report on Form 10-K/A (Amendment No. 1) for the fiscal year
ended October 4, 1998, as filed with the SEC on February 2, 1999;

3. Annual Report on Form 10-K/A (Amendment No. 2) for the fiscal year
ended October 4, 1998, as filed with the SEC on March 5, 1999;

4. Quarterly Report on Form 10-Q for the fiscal quarter ended January
3, 1999, as filed with the SEC on February 16, 1999;

5. Quarterly Report on Form 10-Q for the fiscal quarter ended April 4,
1999, as filed with the SEC on May 19, 1999;

6. Quarterly Report on Form 10-Q for the fiscal quarter ended July 4,
1999, as filed with the SEC on August 18, 1999;

7. Current Report on Form 8-K for the event of September 22, 1998, as
filed with the SEC on October 7, 1998;

3.8. Current Report on Form 8-K/A for event of September 22, 1998, as
filed with the SEC on December 1, 1998;

4.9. Definitive Proxy Statement, as filed with the SEC on December 31,
1998, for the 1999 Annual Meeting of Stockholders;

10. Definitive Proxy Statement (Amendment No. 1), as filed with the SEC
on January 12, 1999, for the 1999 Annual Meeting of Stockholders; and

5.11. The description of the common stockCommon Stock set forth in the Registration
Statement on Form 8-A dated November 13, 1991, including any
amendments or reports filed for the purpose of updating such
description.

You may request a copy of these filings, at no cost, by writing or
telephoning James M. Jaska our Vice President and Chief Financial Officer, at
the following address:as follows:

Tetra Tech, Inc.
Attention: Investor Relations
670 North Rosemead Boulevard
Pasadena, CACalifornia 91107
(626) 351-4664

This prospectus is part of a registration statement we filed with the
SEC. You should rely only on the information or representations provided in
this prospectus. We have authorized no one to provide you with different
information. We are not making an offer of these securities in any state
where the offer is not permitted. You should not assume that the information
in this prospectus is accurate as of any date other than the date on the
front of the document.

LEGAL MATTERS

Certain legal matters with respect to theThe validity of the shares of
common stockCommon Stock offered hereby will be passed uponon for the Companyus
by Riordan & McKinzie, a Professional Corporation, Los Angeles, California.
Certain principals of Riordan & McKinzie own, in the aggregate, approximately
162,140160,000 shares of Tetra Tech common stock. Certain legal matters related to the offering
will be passed upon for the Underwriters by Wilson Sonsini Goodrich & Rosati, a
Professional Corporation, Palo Alto, California.

47
Common Stock.

EXPERTS

The financial statements included in this prospectus have been audited by
Deloitte & Touche LLP, independent auditors, as stated in their report appearing
herein, and are included in reliance upon the report of such firm given upon
their authority as experts in accounting and auditing.

The financial statements and the related financial statement schedule
incorporated in this prospectus by reference from the Company'sour Annual Report on
Form 10-K for the year ended October 4, 1998 have been audited by Deloitte &
Touche LLP, independent auditors, as stated in their reports, which are
incorporated herein by reference, and have been so incorporated in reliance
upon the reports of such firm given upon their authority as experts in
accounting and auditing.

INDEX TO TETRA TECH, INC. FINANCIAL STATEMENTS

PAGE
-----

INDEPENDENT AUDITORS' REPORT............................................................................... F-2

CONSOLIDATED BALANCE SHEETS................................................................................ F-3

CONSOLIDATED STATEMENTS OF INCOME.......................................................................... F-4

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY............................................................ F-5

CONSOLIDATED STATEMENTS OF CASH FLOWS...................................................................... F-6

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS................................................................. F-8

F-1

INDEPENDENT AUDITORS' REPORT

Tetra Tech, Inc.:

We have audited the accompanying consolidated balance sheets of Tetra
Tech, Inc. and its subsidiaries as of October 4, 1998 and September 28, 1997,
and the related consolidated statements of income, stockholders' equity, and
cash flows for each of the three years in the period ended October 4, 1998.
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 generally accepted auditing
standards. 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 October 4, 1998 and September 28, 1997, and the results of
their operations and their cash flows for each of the three years in the period
ended October 4, 1998 in conformity with generally accepted accounting
principles.

DELOITTE & TOUCHE LLP

Los Angeles, California
November 13, 1998

F-2

TETRA TECH, INC.

CONSOLIDATED BALANCE SHEETS

SEPT. 28, OCT. 4,
1997 1998
-------------- --------------

ASSETS
Current Assets:
Cash and cash equivalents...................................................... $ 12,262,000 $ 4,889,000
Accounts receivable--net....................................................... 30,089,000 68,834,000
Unbilled receivables--net...................................................... 35,145,000 59,888,000
Prepaid and other current assets............................................... 2,522,000 4,955,000
Deferred income taxes.......................................................... 867,000 3,766,000
-------------- --------------
Total Current Assets......................................................... 80,885,000 142,332,000
-------------- --------------
Property and Equipment:
Equipment, furniture and fixtures.............................................. 16,838,000 25,616,000
Leasehold improvements......................................................... 1,177,000 1,348,000
-------------- --------------
Total........................................................................ 18,015,000 26,964,000
Accumulated depreciation and amortization...................................... (9,592,000) (13,219,000)
-------------- --------------
Property and Equipment--Net...................................................... 8,423,000 13,745,000
-------------- --------------
Intangible Assets--Net........................................................... 69,439,000 108,638,000
Other Assets..................................................................... 766,000 1,895,000
-------------- --------------
Total Assets..................................................................... $ 159,513,000 $ 266,610,000
-------------- --------------
-------------- --------------

LIABILITIES AND STOCKHOLDERS' EQUITY
Current Liabilities:
Accounts payable............................................................... $ 11,621,000 $ 24,027,000
Accrued compensation........................................................... 10,981,000 15,614,000
Other current liabilities...................................................... 6,386,000 8,283,000
Income taxes payable........................................................... 1,358,000 3,294,000
Current portion of long-term obligations....................................... 8,000,000 14,065,000
-------------- --------------
Total Current Liabilities.................................................... 38,346,000 65,283,000
-------------- --------------
Long-term Obligations............................................................ -- 33,546,000
-------------- --------------
Commitments and Contingencies (Notes 9 and 11)
Redeemable Preferred Stock....................................................... 13,526,000 --
-------------- --------------
Stockholders' Equity:
Preferred stock--authorized, 2,000,000 shares of $.01 par value; issued and
outstanding 1,231,840 at September 28, 1997 and 0 at October 4, 1998......... -- --
Exchangeable stock of a subsidiary............................................. -- 15,411,000
Common stock--authorized, 50,000,000 shares of $.01 par value; issued and
outstanding 25,892,818 shares at September 28, 1997 and 28,630,600 at October
4, 1998...................................................................... 259,000 287,000
Additional paid-in capital..................................................... 63,450,000 87,565,000
Retained earnings.............................................................. 43,932,000 64,518,000
-------------- --------------
Total Stockholders' Equity....................................................... 107,641,000 167,781,000
-------------- --------------
Total Liabilities and Stockholders' Equity....................................... $ 159,513,000 $ 266,610,000
-------------- --------------
-------------- --------------

See accompanying Notes to Consolidated Financial Statements.

F-3

TETRA TECH, INC.

CONSOLIDATED STATEMENTS OF INCOME

FISCAL YEAR ENDED
----------------------------------------------

SEPT. 29, SEPT. 28, OCT. 4,
1996 1997 1998
-------------- -------------- --------------
Revenue:
Gross revenue................................................. $ 220,099,000 $ 246,767,000 $ 382,934,000
Subcontractor costs........................................... 59,062,000 55,976,000 85,337,000
-------------- -------------- --------------
Net Revenue..................................................... 161,037,000 190,791,000 297,597,000
Cost of Net Revenue............................................. 122,084,000 141,019,000 223,871,000
-------------- -------------- --------------
Gross Profit.................................................... 38,953,000 49,772,000 73,726,000
Selling, General and Administrative Expenses.................... 21,218,000 25,173,000 33,913,000
-------------- -------------- --------------
Income From Operations.......................................... 17,735,000 24,599,000 39,813,000
Interest Expense................................................ 1,076,000 320,000 2,329,000
Interest Income................................................. 300,000 300,000 419,000
-------------- -------------- --------------
Income Before Minority Interest and Income Tax Expense.......... 16,959,000 24,579,000 37,903,000
Minority Interest............................................... -- -- 1,397,000
-------------- -------------- --------------
Income Before Income Tax Expense................................ 16,959,000 24,579,000 36,506,000
Income Tax Expense.............................................. 6,854,000 10,323,000 15,920,000
-------------- -------------- --------------
Net Income...................................................... $ 10,105,000 $ 14,256,000 $ 20,586,000
-------------- -------------- --------------
-------------- -------------- --------------
Basic Earnings Per Share........................................ $ 0.46 $ 0.61 $ 0.74
-------------- -------------- --------------
-------------- -------------- --------------
Diluted Earnings Per Share...................................... $ 0.45 $ 0.58 $ 0.71
-------------- -------------- --------------
-------------- -------------- --------------
Weighted Average Common Shares Outstanding:
Basic......................................................... 21,851,000 23,371,000 27,970,000
-------------- -------------- --------------
-------------- -------------- --------------
Diluted....................................................... 22,581,000 24,656,000 29,191,000
-------------- -------------- --------------
-------------- -------------- --------------

See accompanying Notes to Consolidated Financial Statements.

F-4

TETRA TECH, INC.

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY

EXCHANGEABLE STOCK COMMON STOCK ADDITIONAL
--------------------- -------------------- PAID-IN RETAINED
SHARES AMOUNT SHARES AMOUNT CAPITAL EARNINGS TOTAL
--------- ---------- --------- --------- ---------- ---------- -----------

BALANCE, OCTOBER 1, 1995 as previously
reported............................. -- $ -- 16,544,136 $ 165,000 $21,760,000 $19,571,000 $41,496,000
5-for-4 common stock split (see Note
7)................................ -- -- 4,136,034 42,000 (42,000)
--------- ---------- --------- --------- ---------- ---------- -----------
BALANCE, OCTOBER 1, 1995................ -- -- 20,680,170 207,000 21,718,000 19,571,000 41,496,000
Net income........................... -- -- -- 10,105,000 10,105,000
Payment for fractional shares........ -- -- (264) (3,000) -- (3,000)
Shares issued in acquisition......... -- -- 1,234,744 12,000 10,301,000 -- 10,313,000
Stock options exercised.............. -- -- 158,790 2,000 682,000 -- 684,000
Tax benefit for disqualifying
dispositions of stock options..... -- -- -- -- 674,000 -- 674,000
--------- ---------- --------- --------- ---------- ---------- -----------
BALANCE, SEPTEMBER 29, 1996............. -- -- 22,073,440 221,000 33,372,000 29,676,000 63,269,000
Net income........................... -- -- 14,256,000 14,256,000
Shares issued in acquisitions........ -- -- 3,439,330 34,000 27,016,000 -- 27,050,000
Stock options exercised.............. -- -- 225,949 2,000 1,308,000 -- 1,310,000
Shares issued in Employee Stock
Purchase Plan..................... -- -- 154,099 2,000 1,280,000 -- 1,282,000
Tax benefit for disqualifying
dispositions of stock options..... -- -- -- -- 474,000 -- 474,000
--------- ---------- --------- --------- ---------- ---------- -----------
BALANCE, SEPTEMBER 28, 1997............. -- -- 25,892,818 259,000 63,450,000 43,932,000 107,641,000
Net income........................... -- -- 20,586,000 20,586,000
Shares issued in acquisitions........ -- -- 345,948 4,000 5,520,000 -- 5,524,000
Stock options exercised.............. -- -- 352,265 4,000 2,613,000 -- 2,617,000
Payment for fractional shares........ -- -- (726) (7,000) (7,000)
Shares issued in Employee Stock
Purchase Plan..................... -- -- 115,545 1,000 1,505,000 -- 1,506,000
Preferred shares converted to common
stock............................. -- -- 1,924,750 19,000 13,507,000 -- 13,526,000
Exchangeable shares of a subsidiary
issued in acquisitions............ 920,354 15,411,000 -- -- -- -- 15,411,000
Tax benefit for disqualifying
dispositions of stock options..... -- -- -- -- 977,000 -- 977,000
--------- ---------- --------- --------- ---------- ---------- -----------
BALANCE, OCTOBER 4, 1998................ 920,354 $15,411,000 28,630,600 $ 287,000 $87,565,000 $64,518,000 $167,781,000
--------- ---------- --------- --------- ---------- ---------- -----------
--------- ---------- --------- --------- ---------- ---------- -----------

See accompanying Notes to Consolidated Financial Statements.

F-5

TETRA TECH, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

FISCAL YEAR ENDED
----------------------------------------------
SEPT. 29, SEPT. 28, OCT. 4,
1996 1997 1998
-------------- -------------- --------------

CASH FLOWS FROM OPERATING ACTIVITIES:
Net income..................................................... $ 10,105,000 $ 14,256,000 $ 20,586,000
Adjustments to reconcile net income to net cash provided by
(used in) operating activities:
Depreciation and amortization................................ 3,613,000 4,514,000 6,595,000
Deferred income taxes........................................ (519,000) 1,490,000 (2,899,000)
Changes in operating assets and liabilities, net of effects of
acquisitions:
Accounts receivable.......................................... 18,043,000 (3,776,000) (23,561,000)
Unbilled receivables......................................... (5,916,000) (8,037,000) (11,537,000)
Prepaid and other current assets............................. 246,000 1,823,000 (1,375,000)
Accounts payable............................................. (4,080,000) (3,551,000) 10,203,000
Accrued compensation......................................... (1,431,000) (3,909,000) (32,000)
Other current liabilities.................................... (192,000) (1,412,000) (6,548,000)
Income taxes payable......................................... 1,255,000 (254,000) 1,948,000
-------------- -------------- --------------
Net Cash Provided By (Used In) Operating Activities....... 21,124,000 1,144,000 (6,620,000)
-------------- -------------- --------------
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures........................................... (2,385,000) (2,640,000) (3,511,000)
Proceeds from sale of property and equipment................... 71,000 44,000 --
Payments for business acquisitions, net of cash acquired....... (6,441,000) (1,237,000) (37,778,000)
-------------- -------------- --------------
Net Cash Used In Investing Activities..................... (8,755,000) (3,833,000) (41,289,000)
-------------- -------------- --------------
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments on long-term obligations.............................. (25,048,000) (6,797,000) (39,580,000)
Proceeds from issuance of long-term obligations................ 5,003,000 13,000,000 76,000,000
Payments on obligations under capital leases................... (6,000) -- --
Proceeds from issuance of common stock......................... 681,000 2,619,000 4,116,000
-------------- -------------- --------------
Net Cash (Used In) Provided By Financing Activities....... (19,370,000) 8,822,000 40,536,000
-------------- -------------- --------------
Net (Decrease) Increase in Cash and Cash Equivalents............. (7,001,000) 6,133,000 (7,373,000)
Cash and Cash Equivalents at Beginning of Year................... 13,130,000 6,129,000 12,262,000
-------------- -------------- --------------
Cash and Cash Equivalents at End of Year......................... $ 6,129,000 $ 12,262,000 $ 4,889,000
-------------- -------------- --------------
-------------- -------------- --------------
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid during the year for:
Interest..................................................... $ 1,149,000 $ 309,000 $ 2,129,000
-------------- -------------- --------------
-------------- -------------- --------------
Income taxes................................................. $ 6,123,000 $ 9,407,000 $ 17,195,000
-------------- -------------- --------------
-------------- -------------- --------------

(Continued)

F-6

TETRA TECH, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

FISCAL YEAR ENDED
----------------------------------------------
SEPT. 29, SEPT. 28, OCT. 4,
1996 1997 1998
-------------- -------------- --------------

SUPPLEMENTAL NON-CASH INVESTING AND FINANCING ACTIVITIES:
In fiscal 1996, the Company purchased all of the capital stock
of KCM, Inc. In conjunction with this acquisition,
liabilities were assumed as follows:
Fair value of assets acquired............................. $ 20,393,000
Cash paid................................................. (2,645,000)
Issuance of common stock.................................. (10,313,000)
Other acquisition costs................................... (415,000)
--------------
Liabilities assumed..................................... $ 7,020,000
--------------
--------------

In fiscal 1997, the Company purchased all of the capital stock
of IWA Engineers, FLO Engineering, Inc., SCM Consultants,
Inc., Whalen & Company, Inc., Whalen Service Corps Inc. and
CommSite Development Corporation. In conjunction with these
acquisitions, liabilities were assumed as follows:
Fair value of assets acquired............................. $ 66,386,000
Cash paid................................................. (8,811,000)
Purchase price payable.................................... (729,000)
Issuance of common and preferred stock.................... (40,577,000)
Other acquisition costs................................... (2,111,000)
--------------
Liabilities assumed..................................... $ 14,158,000
--------------
--------------

In fiscal 1998, the Company purchased all of the capital stock
of C.D.C. Engineering, Inc., McNamee, Porter & Seeley, Inc.
and the Sentrex Group of Companies. The Company also
purchased certain assets of Brown & Root, Inc. and
Halliburton Corporation. In conjunction with these
acquisitions, liabilities were assumed as follows:
Fair value of assets acquired............................. $ 79,639,000
Cash paid................................................. (37,778,000)
Issuance of common and exchangeable stock................. (20,935,000)
Other acquisition costs................................... (985,000)
--------------
Liabilities assumed..................................... $ 19,941,000
--------------
--------------

(Concluded)
See accompanying Notes to Consolidated Financial Statements.

F-7

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

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. As a specialized
management consultant, the Company assists its clients in defining problems and
developing innovative and cost-effective solutions. 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 and its wholly-owned subsidiaries. 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 1996 and 1997 contained
52 weeks. Fiscal year 1998 contained 53 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 are 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.

Contract revenue under Federal government contracts and subcontracts
accounted for approximately 61.7%, 52.3% and 48.7% of net contract revenue for
the years ended September 29, 1996, September 28, 1997 and October 4, 1998,
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 reviews the recoverability of long-lived
assets to determine if there has been any impairment. 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

F-8

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

1. SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
without interest charges) are less than the carrying value, a writedown would be
recorded to reduce the related asset to its estimated fair value. Long-lived
assets as of September 28, 1997 and October 4, 1998 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 28, 1997 and October 4, 1998 was $3,522,000 and
$6,490,000, 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--Due to the Company's complex capital structure, the
Company presents both basic and diluted Earnings Per Share (EPS). Basic 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 net income 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, the weighted average number of
shares of redeemable preferred stock and the weighted average dilutive effects
of outstanding stock options. The exchangeable stock of a subsidiary is non-
voting and is exchangeable share for share for the Company's common stock. The
redeemable preferred stock has voting and dividend rights substantially similar
to those of common. The redeemable preferred stock outstanding at September 28,
1997 was converted to common stock during the fiscal year ended October 4, 1998.
Basic and diluted EPS reflect, on a retroactive 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 September 15, 1998 for each four shares outstanding as of
the record date of July 27, 1998.

FAIR VALUE OF FINANCIAL INSTRUMENTS--

CASH AND CASH EQUIVALENTS, ACCOUNTS RECEIVABLE, UNBILLED RECEIVABLES
AND ACCOUNTS PAYABLE--The carrying amounts approximate fair value because of
the short maturities of these instruments.

REVOLVING CREDIT FACILITY--The carrying amount approximates fair
value because the interest rates are based upon variable reference rates.

CONCENTRATION OF CREDIT RISK--Financial instruments which subject the
Company to credit risk consist primarily of temporary cash investments and
accounts receivable. 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 October 4,
1998, approximately 44% 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.

F-9

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

1. SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
USE OF ESTIMATES--The preparation of financial statements in conformity
with generally accepted accounting principles 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.

ACCOUNTING PRONOUNCEMENTS--In February 1997, the Financial Accounting
Standards Board (FASB) issued Statement of Financial Accounting Standard (SFAS)
No. 128, EARNINGS PER SHARE, which the Company adopted in fiscal year 1998. The
Statement replaces the presentation of primary EPS with a presentation of basic
EPS, which excludes dilution and is computed by dividing income available to
common stockholders by the weighted average number of common shares outstanding
for the period. The Statement also requires the dual presentation of basic and
diluted EPS on the face of the income statement for all companies with complex
capital structures and requires a reconciliation of the numerator and
denominator of the basic EPS computation to the numerator and denominator of the
diluted EPS computation. Diluted EPS is computed similarly to fully diluted EPS
pursuant to APB Opinion No. 15. EPS has been retroactively restated to reflect
the requirements of SFAS No. 128.

In June 1997, the FASB issued SFAS No. 131, DISCLOSURES ABOUT SEGMENTS OF
AN ENTERPRISE AND RELATED INFORMATION. This Statement is effective for fiscal
years beginning after December 15, 1997. This Statement establishes standards
for the way that public business enterprises report information about operating
segments as well as related disclosures about products and services, geographic
areas, and major clients. The Statement also requires that a public business
report descriptive information about the way that the operating segments were
determined, the products and services provided by the operating segments,
differences between the measurements used in reporting segment information and
those used in the enterprise's general-purpose financial statements, and changes
in the measurement of segment amounts from period to period. The Statement need
not be applied to interim financial statements in the initial year of its
application. The Company has not yet completed its analysis of the effect of
SFAS No. 131 on its financial statements. The Company will adopt this Statement
in fiscal year 1999.

In June 1998, the FASB issued SFAS No. 133, ACCOUNTING FOR DERIVATIVES
AND HEDGING ACTIVITIES. The Statement is effective for all fiscal quarters of
all fiscal years beginning after June 15, 1999. The Statement requires companies
to recognize all derivative instruments on their balance sheet as either assets
or liabilities measured at fair value. The Statement also specifies a new method
of accounting for hedging transactions, prescribes the type of items and
transactions that may be hedged, and specifies detailed criteria to be met to
qualify for hedge accounting. The Company does not anticipate that the adoption
of SFAS No. 133 will have a material effect on the Company's financial
statements. The Company will adopt this Statement in fiscal year 2001.

F-10

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

2. MERGERS AND ACQUISITIONS

On November 7, 1995, the Company acquired 100% of the capital stock of
KCM, Inc. (KCM), an engineering services firm specializing in areas of water
quality, water and wastewater systems, surface water management, fisheries and
facilities. The purchase was valued at approximately $13,373,000, consisting of
cash and 1,234,744 shares of Company common stock issued in a private placement.

On December 11 1996, the Company acquired 100% of the capital stock of
IWA Engineers (IWA), an architecture and engineering firm providing a wide range
of planning, engineering, and design capabilities in water, wastewater, and
facility design, and serving state and local government and private clients. The
purchase was valued at approximately $1,632,000, consisting of cash and 119,593
shares of Company common stock, as adjusted based upon IWA's Net Asset Value on
December 29, 1996 as described in the related purchase agreement.

On December 18, 1996, the Company acquired 100% of the capital stock of
FLO Engineering, Inc. (FLO), a consulting and engineering firm specializing in
water resource engineering involving hydraulic engineering and hydrographic data
collection. The purchase was valued at approximately $724,000, consisting of
cash and 50,172 shares of Company common stock, as adjusted based upon FLO's Net
Asset Value on December 29, 1996 as described in the related purchase agreement.

On March 20, 1997, the Company acquired 100% of the capital stock of SCM
Consultants, Inc. (SCM), a consulting and engineering firm providing design of
irrigation, water and wastewater systems, as well as facility and infrastructure
engineering services, to state and local government, private and industrial
clients. The purchase was valued at approximately $2,431,000, consisting of cash
and 246,965 shares of Company common stock, as adjusted based upon SCM's Net
Asset Value on March 30, 1997 as described in the related purchase agreement.

On June 11, 1997, the Company acquired 100% of the capital stock of
Whalen & Company, Inc. and Whalen Service Corps Inc. (collectively, WAC). WAC, a
wireless telecommunications firm, provides a full range of wireless
telecommunications site development services for PCS, cellular, ESMR,
air-to-ground, microwave, paging, fiber optic and switching centers technology.
The purchase has been valued at approximately $41,738,000, consisting of cash
and 4,549,750 shares of Company common stock. Initially, the Company issued
1,231,840 shares of redeemable preferred stock. The shares of redeemable
preferred stock were subsequently converted into common stock prior to the stock
split which occurred on December 1, 1997. The common and preferred stock were
issued in a private placement and had a combined value of $31,972,000. On the
business day prior to the merger, WAC distributed to its stockholders (i) cash
in the amount of $4,138,000 and (ii) accounts receivable having a net value of
$18,456,000.

On July 11, 1997, the Company acquired 100% of the capital stock of
CommSite Development Corporation (CDC), a wireless telecommunications site
development service firm. The purchase has been valued at approximately
$5,702,000, consisting of cash and 397,598 shares of Company common stock, as
adjusted based on CDC's Net Asset Value on July 11, 1997 as described in the
related purchase agreement.

On December 31, 1997, the Company acquired, through its wholly-owned
subsidiary Tetra Tech NUS, Inc., the assets of certain environmental services
businesses of Brown & Root, Inc. and Halliburton Corporation, both of which are
subsidiaries of Halliburton Company (collectively, NUS). NUS provides
consulting, engineering and design services for the environmental remediation of

F-11

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

2. MERGERS AND ACQUISITIONS (CONTINUED)
contaminated air, water and soil conditions. The purchase price was valued at
approximately $25,217,000, as adjusted, and consisted of cash.

On March 2, 1998, Whalen Service Corps Inc. (WSC) agreed to participate
in a partnership with Sentrex Cen-Comm and ANTEC Corporation to provide design,
engineering, information management and construction services to support
advanced communication system upgrades to the broadband information transport
industries. The agreement required the purchase of certain assets of TANCO LLC
from ANTEC Corporation for a price in cash of approximately $623,000. WSC
initially held a 51% majority interest in Whalen/Sentrex LLC, a California
limited liability company while LAL Corp. held the remaining 49% minority
interest.

On March 26, 1998, the Company acquired 100% of the capital stock of
C.D.C. Engineering, Inc. (CDE), a consulting and engineering firm specializing
in civil engineering, transportation engineering, structural engineering and
land surveying. The purchase has been valued at approximately $1,502,000,
consisting of cash and 71,060 shares of Company common stock.

On July 8, 1998, the Company acquired 100% of the capital stock of
McNamee, Porter & Seeley, Inc. (MPS), a provider of engineering services with
expertise in the areas of water, industrial wastewater and process controls. The
purchase was valued at approximately $14,247,000, consisting of cash and 274,888
shares of Company common stock. Simultaneously with the acquisition, MPS
distributed to its former stockholders accounts receivable having a net value of
$8,040,000.

On September 22, 1998, the Company acquired, through its wholly-owned
subsidiary Tetra Tech Canada Ltd. (TtC), 100% of the capital stock of 1056584
Ontario Limited, 1056585 Ontario Limited, Venture Cable Limited, Cen-Comm
Communications, Inc., Sentrex Electronics Inc. and LAL Corp., (collectively, the
Sentrex Group of Companies (SGOC)), providers of engineering and technical
services to the cable television, telephony and data networking industries. The
purchase has been valued at approximately $19,227,000, consisting of cash and
920,354 shares of TtC exchangeable stock. The TtC exchangeable stock is
exchangeable, share for share, for Company common stock as described in the
related purchase agreement. Upon completion of the SGOC acquisition, the Company
beneficially owns 100% of Whalen/Sentrex LLC.

All of the acquisitions above have been accounted for as purchases and,
accordingly the purchase prices of the businesses acquired have been allocated
to the assets and liabilities acquired based upon their fair market 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 balance sheets. The Company values stock
exchanged in acquisitions based on extended restriction periods and economic
factors specific to the Company's circumstances. During fiscal 1996, stock
exchanged in the acquisition was discounted by 26%. During fiscal 1997, the
discount on stock exchanged in acquisitions ranged from 16% to 28%. During
fiscal 1998, stock exchanged in acquisitions was discounted 15%. The results of
operations of each of the companies acquired have been included in the Company's
financial statements from their respective acquisition effective dates as set
forth in the related purchase agreements.

The effect of unaudited pro forma operating results of the SGOC, CDE,
SCM, FLO and IWA acquisitions, had they been acquired on September 30, 1996, is
not material.

F-12

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

2. MERGERS AND ACQUISITIONS (CONTINUED)
The following table presents summarized unaudited pro forma operating
results assuming that the Company had acquired MPS, NUS, CDC and WAC on
September 30, 1996:

FISCAL YEAR ENDED
------------------------
SEPT. 28, OCT. 4,
1997 1998
----------- -----------

Gross revenue.................................... $420,294,000 $429,591,000
Income before income tax expense................. 33,637,000 37,958,000
Net income....................................... 19,510,000 21,446,000
Basic earnings per share......................... $ 0.72 $ 0.76
Diluted earnings per share....................... 0.69 0.73
Weighted average common shares outstanding:
Basic.......................................... 26,977,000 28,176,000
Diluted........................................ 28,262,000 29,397,000

3. ACCOUNTS RECEIVABLE

Accounts receivable consisted of the following at September 28, 1997 and
October 4, 1998:

SEPT. 28, OCT. 4,
1997 1998
---------- -----------

Billed accounts receivable........................ $31,435,000 $71,745,000
---------- -----------
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.......... 31,626,000 58,384,000
Costs and fee retention billable upon audit of
total contract costs.......................... 13,326,000 11,278,000
---------- -----------
Total unbilled accounts receivable................ 44,952,000 69,662,000
---------- -----------
Allowance for uncollectible accounts:
Allowance for doubtful accounts................. (1,346,000) (2,911,000)
Allowance for disallowed costs.................. (9,807,000) (9,774,000)
---------- -----------
Total allowance for uncollectible accounts........ (11,153,000) (12,685,000)
---------- -----------
Total............................................. $65,234,000 $128,722,000
---------- -----------
---------- -----------

The accounts receivable valuation allowance includes amounts to provide
for doubtful accounts and for the potential disallowance of billed and unbilled
costs. The Company's contracts with the Federal government 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 audit, the DCAA may disallow costs if it determines
that the Company improperly accounted for such costs in a manner inconsistent
with Cost Accounting Standards. Historically, the Company has not had any
material cost disallowances by the DCAA as a result of audit, however, 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).

F-13

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

3. ACCOUNTS RECEIVABLE (CONTINUED)
EMI likewise contracts with the Federal government. At the time of acquisition,
audits had not been performed for years beyond 1986. As of September 1998,
audits and negotiations relating to the EMI contracts for years 1987 through
1995 had been completed, and cost disallowances as a result of audits totaled
approximately $2,900,000. It has been determined by the Federal government that
for these periods the Company is entitled to payments, however, the
collectibility of such payments cannot be assured as each agency must obtain
separate funding approval. 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 has
been 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.

As of October 4, 1998, the Company had approximately $5,200,000 under
retainage provisions of contracts and approximately $2,166,000 of accounts
receivable which may not be realized within one year.

4. INCOME TAXES

Income tax expense for the fiscal years ended September 29, 1996,
September 28, 1997 and October 4, 1998 consisted of the following:

FISCAL YEAR ENDED
------------------------------------------
SEPT. 29, SEPT. 28, OCT. 4,
1996 1997 1998
------------ ------------- -------------

Current:
Federal........................................ $ 5,849,000 $ 9,220,000 $ 15,284,000
State.......................................... 1,462,000 2,291,000 3,535,000
Deferred......................................... (457,000) (1,188,000) (2,899,000)
------------ ------------- -------------
Total income tax expense......................... $ 6,854,000 $ 10,323,000 $ 15,920,000
------------ ------------- -------------
------------ ------------- -------------

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

SEPT. 28, OCT. 4,
1997 1998
---------- ----------

Allowance for doubtful accounts.................... $2,513,000 $3,662,000
Cash to accrual.................................... (2,275,000) (1,250,000)
Accrued vacation................................... 495,000 1,247,000
State taxes........................................ (21,000) 1,038,000
Prepaid expense.................................... (104,000) (632,000)
Depreciation....................................... (369,000) (299,000)
Other.............................................. 628,000 --
---------- ----------
Net deferred income tax asset...................... $ 867,000 $3,766,000
---------- ----------
---------- ----------

F-14

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

4. INCOME TAXES (CONTINUED)
Total income tax expense was different than the amount computed by
applying the federal statutory rate as follows:

FISCAL YEAR ENDED
---------------------------------------------------------------------------
SEPT. 29, 1996 SEPT. 28, 1997 OCT. 4, 1998
----------------------- ------------------------ ------------------------
AMOUNT % AMOUNT % AMOUNT %
------------ --------- ------------- --------- ------------- ---------

Tax at federal statutory rate.............. $ 5,936,000 35.0% $ 8,603,000 35.0% $ 12,777,000 35.0%
State taxes, net of federal benefit........ 933,000 5.5 1,348,000 5.5 1,898,000 5.2
Goodwill................................... 384,000 2.3 528,000 2.1 990,000 2.7
Other...................................... (399,000) (2.4) (156,000) (0.6) 255,000 0.7
------------ --- ------------- --- ------------- ---
Total income tax expense................... $ 6,854,000 40.4% $ 10,323,000 42.0% $ 15,920,000 43.6%
------------ --- ------------- --- ------------- ---
------------ --- ------------- --- ------------- ---

5. LONG-TERM OBLIGATIONS

The Company has a credit agreement (as amended, the "Credit Agreement")
with a bank to support its working capital and acquisition needs. At October 4,
1998, the Credit Agreement provided a revolving credit facility of $70,000,000.
The Credit Agreement provides for mandatory reductions of $5,000,000 on December
15, 1998 and December 15, 1999.

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 at October 4, 1998 was 6.34375%.

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

The Credit Agreement contains 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).

The Credit Agreement matures on December 15, 2000 or earlier at the
discretion of the Company upon payment in full of loans and other obligations.
As of October 4, 1998, outstanding borrowings totaled $47,000,000 and standby
letters of credit totaled $2,207,000.

6. EXCHANGEABLE STOCK OF A SUBSIDIARY

In connection with the SGOC acquisition, the Company issued 920,354
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 whereas a holder of Exchangeable Shares shall be 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 causing to be
delivered to such holder one share of the Company's common stock for each
Exchangeable Share presented and surrendered, plus (b) a dividend amount, if
any. The Exchangeable Shares cannot be put back to the Company for cash.

F-15

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

7. STOCKHOLDERS' EQUITY

On September 14, 1998, a Special Meeting of the Stockholders (the
"Special Meeting") was held. During the Special Meeting, the stockholders
approved a proposal to amend the Company's Certificate of Incorporation to
increase the number of authorized shares of common stock, $.01 par value per
share, from 30,000,000 to 50,000,000. On September 15, 1998, the Company paid a
5-for-4 split of the Company's common stock, effected in the form of a 25% stock
dividend, to the stockholders of record on July 27, 1998. All agreements
concerning stock options and other commitments payable in shares of the
Company's common stock are affected by the 5-for-4 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.

Pursuant to the Company's 1989 Stock Option Plan, key employees may be
granted options to purchase an aggregate of 953,672 shares of the Company's
common stock at prices ranging from 85% to 100% of the market value on the date
of grant. All options granted to date by the Company have been at 100% of the
market value as determined 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 also has a 1992 Incentive Stock Plan under which key
employees may be granted options to purchase an aggregate of 4,609,375 shares of
the Company's common stock at prices not less than 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.

F-16

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

7. STOCKHOLDERS' EQUITY (CONTINUED)

Pursuant to the Company's 1992 Non-employee Director Plan, non-employee
directors may be granted options to purchase an aggregate of 114,438 shares of
the Company's common stock at prices not less than 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
878,906 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 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 October 4, 1998, option
activity was as follows:

NUMBER WEIGHTED AVERAGE
OF OPTIONS EXERCISE PRICE
---------- -----------------

Balance, October 1, 1995....................................... 1,565,270 $ 5.82
Granted...................................................... 644,667 11.36
Exercised.................................................... (158,791) 4.30
Cancelled.................................................... (81,901) 7.11
---------- ------
Balance, September 29, 1996.................................... 1,969,245 7.70
Granted...................................................... 762,692 12.56
Exercised.................................................... (225,948) 5.80
Cancelled.................................................... (167,614) 9.62
---------- ------
Balance, September 28, 1997.................................... 2,338,375 9.33
Granted...................................................... 569,566 16.89
Exercised.................................................... (352,265) 7.43
Cancelled.................................................... (187,206) 12.61
---------- ------
Outstanding at October 4, 1998................................. 2,368,470 $ 11.17
---------- ------
---------- ------
Exercisable at October 4, 1998................................. 1,086,166 $ 8.04
---------- ------
---------- ------

F-17

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

7. STOCKHOLDERS' EQUITY (CONTINUED)
The following table summarizes information concerning currently
outstanding and exercisable options:

OPTIONS OUTSTANDING OPTIONS EXERCISABLE
--------------------------------------- ----------------------
WEIGHTED
AVERAGE WEIGHTED WEIGHTED
REMAINING AVERAGE AVERAGE
RANGE OF NUMBER CONTRACTUAL EXERCISE NUMBER EXERCISE
EXERCISE PRICE OUTSTANDING LIFE PRICE EXERCISABLE PRICE
- -------------------------- ----------- ------------- ----------- --------- -----------

$0.69- $1.18............. 47,711 2.47 $ 1.08 47,711 $ 1.08
$3.14- $6.96............. 431,888 5.13 5.57 419,678 5.53
$7.01-$12.32............. 921,779 7.14 10.11 525,724 9.78
$12.80-$15.70............. 660,917 8.79 13.95 93,053 13.08
$16.00-$20.88............. 306,175 9.49 17.85 -- --
----------- --- ----------- --------- -----------
2,368,470.. 7.44 $ 11.17 1,086,166 $ 8.04
----------- --- ----------- --------- -----------
----------- --- ----------- --------- -----------

The Company applies APB Opinion No. 25, ACCOUNTING FOR STOCK ISSUED TO
EMPLOYEES, and related interpretations in accounting for its employee stock
option plans. Accordingly, no compensation expense has been recognized for its
stock-based compensation plans. Pro forma net income and net income per share
had the Company accounted for stock options issued to employees in accordance
with SFAS No. 123, ACCOUNTING FOR STOCK-BASED COMPENSATION, are as follows:

FISCAL YEAR ENDED
----------------------------------
SEPT. 29, SEPT. 28, OCT. 4,
1996 1997 1998
---------- ---------- ----------

Net income-as reported................................ $10,105,000 $14,256,000 $20,586,000
Net income-pro forma.................................. 9,598,000 13,059,000 18,980,000
Basic earnings per share-as reported.................. $ 0.46 $ 0.61 $ 0.74
Diluted earnings per share-as reported................ 0.45 0.58 0.71
Basic earnings per share-pro forma.................... 0.44 0.56 0.68
Diluted earnings per share-pro forma.................. 0.43 0.53 0.65

The pro forma effects of applying SFAS No. 123 may not be representative
of the effects on reported net income and net income per share for future years
since options vest over several years and additional awards are made each year.

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 1996, 1997 and 1998 are $3.65, $4.13 and
$5.79, respectively. The following assumptions were used in completing the
model:

FISCAL YEAR ENDED
----------------------------------
SEPT. 29, SEPT. 28, OCT. 4,
1996 1997 1998
---------- ---------- ----------

Dividend yield........................................... 0.0% 0.0% 0.0%
Expected volatility...................................... 39.1% 40.5% 42.5%
Risk-free rate of return, annual......................... 6.4% 6.4% 6.4%
Expected life............................................ 2.76 yrs. 2.76 yrs. 3.11 yrs.

F-18

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

8. EARNINGS PER SHARE

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

FISCAL YEAR ENDED
-------------------------------------------
SEPT. 29, SEPT. 28,
1996 1997 OCT. 4, 1998
------------- ------------- -------------

Numerator:
Net income........................................................ $ 10,105,000 $ 14,256,000 $ 20,586,000
------------- ------------- -------------
Denominator:
Denominator for basic earnings per share--weighted-average
shares........................................................ 21,851,000 23,371,000 27,970,000
Effect of dilutive securities:
Stock options................................................. 730,000 709,000 1,040,000
Redeemable preferred stock.................................... -- 576,000 151,000
Exchangeable stock of a subsidiary............................ -- -- 30,000
------------- ------------- -------------
Dilutive potential common shares.................................. 730,000 1,285,000 1,221,000
Denominator for diluted earnings per share--adjusted
weighted-average shares and assumed conversions............... 22,581,000 24,656,000 29,191,000
------------- ------------- -------------
------------- ------------- -------------
Basic earnings per share............................................ $ 0.46 $ 0.61 $ 0.74
------------- ------------- -------------
------------- ------------- -------------
Diluted earnings per share.......................................... $ 0.45 $ 0.58 $ 0.71
------------- ------------- -------------
------------- ------------- -------------

9. LEASES

The Company leases land, buildings and equipment under various operating
leases. Rent expense under all operating leases was approximately $9,462,000,
$10,204,000 and $13,458,000 for the fiscal years ended September 29, 1996,
September 28, 1997 and October 4, 1998, respectively. Amounts payable under
noncancelable operating lease commitments are as follows during the fiscal years
ending in:

1999........................................................... $14,838,000
2000........................................................... 11,979,000
2001........................................................... 9,569,000
2002........................................................... 5,697,000
2003........................................................... 3,903,000
Thereafter..................................................... 4,036,000
----------
Total.......................................................... $50,022,000
----------
----------

10. 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 29, 1996, September 28, 1997 and October 4, 1998 employer
contributions relating to the plans were approximately $4,002,000, $3,536,000
and $3,952,000, respectively.

F-19

TETRA TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

11. 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 statements.

12. QUARTERLY FINANCIAL INFORMATION--UNAUDITED

In the opinion of management, the following unaudited quarterly data for
the years ended September 28, 1997 and October 4, 1998 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)

FIRST SECOND THIRD FOURTH
FISCAL 1997 QUARTER QUARTER QUARTER QUARTER
- ---------------------------------------------------------------------- --------- --------- --------- ---------

Gross revenue......................................................... $ 54,938 $ 55,545 $ 60,922 $ 75,362
Net revenue........................................................... 40,423 43,914 48,621 57,833
Gross profit.......................................................... 9,372 10,547 12,961 16,892
Income from operations................................................ 4,393 4,892 6,207 9,107
Net income............................................................ 2,596 2,872 3,644 5,144
Basic earnings per share.............................................. $ 0.12 $ 0.13 $ 0.16 $ 0.20
Diluted earnings per share............................................ 0.11 0.13 0.15 0.18
Weighted average common shares outstanding:
Basic............................................................... 22,110 22,306 23,178 25,811
Diluted............................................................. 22,951 22,865 24,065 28,656

FIRST SECOND THIRD FOURTH
FISCAL 1998 QUARTER QUARTER QUARTER QUARTER
- --------------------------------------------------------------------- --------- --------- --------- ----------

Gross revenue........................................................ $ 66,438 $ 92,727 $ 98,231 $ 125,538
Net revenue.......................................................... 53,664 71,806 75,149 96,978
Gross profit......................................................... 13,325 17,020 20,744 22,637
Income from operations............................................... 7,179 8,872 11,411 12,351
Net income........................................................... 4,051 4,521 5,493 6,521
Basic earnings per share............................................. $ 0.15 $ 0.16 $ 0.20 $ 0.23
Diluted earnings per share........................................... 0.14 0.16 0.19 0.22
Weighted average common shares outstanding:
Basic.............................................................. 27,217 27,905 28,147 28,567
Diluted............................................................ 28,834 28,956 29,201 29,719

F-20

[LOGO]

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.

The following is a statement of estimated expenses to be paid by the
Registrant in connection with the issuance and distribution of the securities
being registered.

SEC registration fee......................................... $ 26,772
Nasdaq National Market fee for listing additional shares..... 17,500
NASD fee..................................................... 10,130
Legal fees and expenses...................................... 125,000
Accountants' fees............................................ 50,000
Blue Sky qualification fees and expenses..................... 5,000
Transfer Agents fees......................................... 2,500
Printing and engraving fees.................................. 100,000
Miscellaneous................................................ 13,098
---------
Total.................................................... $ 350,000
---------
---------
SEC registration fee....................... $ 602
Legal fees................................. 5,000
Accountants' fees.......................... 2,000
Blue Sky qualification fees and expenses... 1,000
Transfer Agent fees........................ 1,000
Miscellaneous.............................. 1,000
-------
Total................................ $10,602
=======

All of the above amounts, except for the SEC registration fee, the Nasdaq
National Market fee for listing additional shares and the NASD fee arehave been
estimates.

ITEM 15. INDEMNIFICATION OF DIRECTORS AND OFFICERS

Section 145 of the Delaware General Corporation Law provides that a Delaware
corporation may indemnify any person against expenses, judgments, fines and
settlements actually and reasonably incurred by any such person in connection
with a threatened, pending or completed action, suit or proceeding in which
he is involved by reason of the fact that he is or was a director, officer,
employee or agent of such corporation, provided that (i) he acted in good
faith and in a manner reasonably believed to be in or not opposed to the best
interests of the corporation and (ii) with respect to any criminal action or
proceeding, he had no reasonable cause to believe his conduct was unlawful.
If the action or suit is by or in the name of the corporation, the
corporation may indemnify any such person against expense actually and
reasonably incurred by him in connection with the defense or settlement of
such action or suit if he acted in good faith and in a manner he reasonably
believed to be in or not opposed to the best interests of the corporation,
except that no indemnification may be made in respect to any claim, issue or
matter as to which such person shall have been adjudged to be liable to the
corporation for negligence or misconduct in the performance of his duty to
the corporation, unless and only to the extent that the Delaware Court of
Chancery or the court in which the action or suit is brought determines upon
application that, despite the adjudication of liability but in view of all of
the circumstances of the case, such person is fairly and reasonably entitled
to indemnity for such expense as the court deems proper.

The Company's By-Laws provides for indemnification of persons to the
fullest extent permitted by the Delaware General Corporation Law.

In accordance with the Delaware General Corporation Law, the Company's
Certificate of Incorporation, as amended, limits the personal liability of
its directors for violations of their fiduciary duty. The Certificate of
Incorporation eliminates each director's liability to the Company or its
stockholders for monetary damages except (i) for any breach of the director's
duty of loyalty to the Company or its stockholders, (ii) for acts or
omissions not in good faith or which involve intentional misconduct or a
knowing violation of law, (iii) under the section of the Delaware law
providing for liability of directors for unlawful payment of dividends or
unlawful stock purchases or redemptions, or II-1
(iv) for any transaction from
which a director derived any improper personal benefit. The effect of this
provision is to eliminate the personal liability of directors for monetary
damages for actions involving a

II-1

breach of their fiduciary duty of care, including any such actions involving
gross negligence. This provision will not, however, limit in any way the
liability of directors for violations of the Federal securities laws.

ITEM 16. EXHIBITS.

EXHIBIT
NUMBER DESCRIPTION
- ----------- ---------------------------------------------------------------------------------

1.1 Form of Underwriting Agreement.
5.1 Opinion of Riordan & McKinzie, a Professional Corporation.*
23.1 Consent of Deloitte & Touche LLP.
23.2 Consent of Riordan & McKinzie (included in Exhibit 5.1)Exhibit
Number Description
5 Opinion of Riordan & McKinzie, a Professional Corporation.
23.1 Consent of Deloitte & Touche LLP.
23.3 Consent of Riordan & McKinzie (included in Exhibit 5).
24 Powers of Attorney with respect to the Company
(included on page II-4).
24.1 Powers of Attorney with respect to the Company (included in Part II).*

- ---------

* Previously filed.

ITEM 17. UNDERTAKINGS.

The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the
Securities Act;

(ii) To reflect in the prospectus any facts or events arising
after the effective date of the registration statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the
registration statement;

(iii) To include any material information with respect to the plan
of distribution not previously disclosed in the registration statement or any
material change to such information in the registration statement.

PROVIDED, HOWEVER, that paragraphs (1)(i) and (1)(ii) do not apply if the
information required to be included in a post-effective amendment by those
paragraphs is contained in periodic reports filed with or furnished to the
Commission by the registrant pursuant to Section 13 or Section 15(d) of the
Securities Exchange Act of 1934 that are incorporated by reference in the
registration statement.

(2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a
new registration statement relating to the securities offered therein, and
the offering of such securities at that time shall be deemed to be the
initial BONA FIDE offering thereof.

(3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination
of the offering.

(4) That, for purposes of determining any liability under the
Securities Act, each filing of the registrant's annual report pursuant to
Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and,
where applicable, each filing of an employee benefit plan's annual report
pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is
incorporated by reference in the registration statement shall be deemed to be
a new registration statement relating to the securities offered therein, and
the offering of such securities at that time shall be deemed to be the
initial BONA FIDE offering thereof.

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Insofar as indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
registrant pursuant to the foregoing provisions, or otherwise, the registrant
has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act and is, therefore, unenforceable. In the event that a claim
for indemnification against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer, or
controlling person of the registrant in the successful defense of any action,
suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the registrant
will, unless in the opinion of its counsel the matter has been settled by
controlling precedent, submit to a court of appropriate jurisdiction the
question whether such indemnification by it is against public policy as
expressed in the Securities Act and will be governed by the final
adjudication of such issue.

The undersigned Registrant hereby undertakes:

(1) That, for purposes of determining any liability under the
Securities Act, each filing of the registrant's annual report pursuant to
Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934
(and, where applicable, each filing of an employee benefit plan's annual
report pursuant to Section 15(d) of the Securities Exchange Act of 1934)
that is incorporated by reference in the registration statement shall be
deemed to be a new registration statement relating to the securities
offered therein, and the offering of such securities at that time shall be
deemed to be the initial bona fide offering thereof;

(2) That, for purposes of determining any liability under the
Securities Act, the information omitted from the form of prospectus filed
as part of this registration statement in reliance upon Rule 430A and
contained in a form of prospectus filed by the registrant pursuant to Rule
424(b)(1) or (4) or 497(h) under the Securities Act shall be deemed to be
part of this Registration Statement as of the time it was declared
effective; and

(3) That, for the purpose of determining any liability under the
Securities Act of 1933, each post-effective amendment that contains a form
of prospectus shall be deemed to be a new registration statement relating
to the securities offered therein, and the offering of such securities at
that time shall be deemed to be the initial bona fide offering thereof.

II-2II-3

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the
Registrant has duly caused this Amendment No. 1 to Registration Statement to be signed on its
behalf by the undersigned, thereunto duly authorized in the City of Pasadena,
State of California on the 8th19th day of January,October, 1999.

TETRA TECH, INC.

By: /s/ LI-SAN HWANG
-----------------------------------------
Li-San Hwang
CHAIRMAN OF THE BOARD, CHIEF EXECUTIVE
OFFICER AND PRESIDENT
TETRA TECH, INC.

By: /s/ Li-San Hwang
-----------------------------
Li-San Hwang
Chairman of the Board,
Chief Executive Officer and
President

KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Li-San Hwang and James M. Jaska, and each of
them his true and lawful attorneys-in-fact and agents with full power of
substitution and resubstitution, for him and in his name, place and stead, in
any and all capacities, to sign any and all amendments to this Registration
Statement, including any post-effective amendments as well as any related
registration statement (or amendment thereto) filed in reliance upon Rule
462(b) under the Securities Act of 1933, and to file the same, with all
exhibits thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorney-in-fact and
agents, and each of them, full power and authority to do and perform each and
every act and thing requisite or necessary to be done in and about the
premises, as fully to all intents and purposes as he might or could do in
person, hereby ratifying and confirming all that said attorneys-in-fact and
agents or any of them, or their or his substitute or substitutes, may
lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.

SIGNATURE TITLE DATE
- ------------------------------ -------------------------- -------------------

Chairman of the Board,
/s/ LI-SAN HWANG Chief Executive Officer
- ------------------------------ and President (Principal January 8, 1999
Li-San Hwang Executive Officer)

Vice President, Chief
Financial Officer and
* Treasurer (Principal
- ------------------------------ Financial Officer and January 8, 1999
James M. Jaska Principal Accounting
Officer)

*
- ------------------------------ Director January 8,SIGNATURE TITLE DATE

/s/ Li-San Hwang Chairman of the Board, Chief October 19, 1999
- ------------------------ Executive Officer and President
Li-San Hwang (Principal Executive Officer)

/s/ James M. Jaska Vice President, Chief October 19, 1999
- ------------------------ Financial Officer and Treasurer
James M. Jaska (Principal Financial Officer and
Principal Accounting Officer)

/s/ J. Christopher Lewis Director October 19, 1999
- ------------------------
J. Christopher Lewis

/s/ Patrick C. Haden Director October 19, 1999
- ------------------------
Patrick C. Haden

/s/ Joseph J. Shelton Director October 19, 1999
- ------------------------
Joseph J. Shelton

Director
- ------------------------
Daniel A. Whalen

*
- ------------------------------ Director January 8, 1999
J. Christopher Lewis

*
- ------------------------------ Director January 8, 1999
Patrick C. Haden

*
- ------------------------------ Director January 8, 1999
Joseph J. Shelton

*By: /s/ LI-SAN
HWANG
- ------------------------------ January 8, 1999
Li-San Hwang
ATTORNEY-IN-FACT

II-3