SCHEDULE 14A INFORMATION

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

Filed by the Registrant / /
Filed by a Party other than the Registrant / /

Check the appropriate box:
/X/ Preliminary Proxy Statement
/ / Confidential, for Use of the Commission Only (as permitted by Rule
14a-6(e)(2))
/ / Definitive Proxy Statement
/ / Definitive Additional Materials
/ / Soliciting Material Pursuant to Section240.14a-11(c) or
Section240.14a-12

TETRA TECH, INC.
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(Name of Registrant as Specified In Its Charter)

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(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

/X/ No fee required.
/ / Fee computed on table below per Exchange Act Rules 14a-6(i)(1)
and 0-11.
(1) Title of each class of securities to which transaction applies:
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(2) Aggregate number of securities to which transaction applies:
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(3) Per unit price or other underlying value of transaction computed
pursuant to Exchange Act Rule 0-11 (set forth the amount on which the
filing fee is calculated and state how it was determined):
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(4) Proposed maximum aggregate value of transaction:
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(5) Total fee paid:
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/ / Fee paid previously with preliminary materials.
/ / Check box if any part of the fee is offset as provided by Exchange Act Rule
0-11(a)(2) and identify the filing for which the offsetting fee was paid
previously. Identify the previous filing by registration statement number,
or the Form or Schedule and the date of its filing.
(1) Amount Previously Paid:
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(2) Form, Schedule or Registration Statement No.:
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(3) Filing Party:
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(4) Date Filed:
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PRELIMINARY COPY
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TETRA TECH, INC.

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NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
TO BE HELD SEPTEMBER 14, 1998

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TO THE STOCKHOLDERS OF TETRA TECH, INC.:

A Special Meeting of the Stockholders (the "Special Meeting") of Tetra Tech,
Inc., a Delaware corporation (the "Company"), will be held on Monday, September
14, 1998 at 10:00 a.m., Pacific Time, at the Company's principal executive
offices located at 670 North Rosemead Boulevard, Pasadena, California 91107, for
the following purposes as described in the accompanying Proxy Statement:

1. To consider and act upon 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 ("Common Stock"), from 30,000,000 to
50,000,000.

2. To transact such other business as may properly come before the Special
Meeting or any adjournment or adjournments thereof.

The Board of Directors has fixed the close of business on July 27, 1998 as
the record date for the determination of stockholders entitled to vote at the
Special Meeting or any adjournment or adjournments thereof, and only record
holders of the Company's Common Stock at the close of business on that day will
be entitled to vote.

By Order of the Board of Directors

Richard A. Lemmon
VICE PRESIDENT AND SECRETARY

Pasadena, California
August 12, 1998

YOU ARE URGED TO VOTE UPON THE MATTER PRESENTED AND TO SIGN, DATE AND
PROMPTLY RETURN THE ENCLOSED PROXY IN THE ENVELOPE PROVIDED. IT IS IMPORTANT FOR
YOU TO BE REPRESENTED AT THE SPECIAL MEETING. NOT VOTING WILL HAVE THE SAME
EFFECT AS VOTING "NO" ON PROPOSAL NO. 1. PROXIES ARE REVOCABLE AT ANY TIME AND
THE EXECUTION OF YOUR PROXY WILL NOT AFFECT YOUR RIGHT TO VOTE IN PERSON IF YOU
ARE PRESENT AT THE SPECIAL MEETING.

PRELIMINARY COPY
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TETRA TECH, INC.
670 NORTH ROSEMEAD BOULEVARD
PASADENA, CALIFORNIA 91107

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PROXY STATEMENT
SPECIAL MEETING OF STOCKHOLDERS
TO BE HELD SEPTEMBER 14, 1998

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GENERAL INFORMATION

This Proxy Statement is being sent on or about August 12, 1998 in connection
with the solicitation of proxies by the Board of Directors of Tetra Tech, Inc.,
a Delaware corporation (the "Company"). The proxies are for use at a Special
Meeting of Stockholders of the Company (the "Special Meeting"), which will be
held at 10:00 a.m., Pacific Time, on Monday, September 14, 1998, at the
Company's principal executive offices located at 670 North Rosemead Boulevard,
Pasadena, California 91107, and at any meetings held upon adjournment thereof.
The record date for the Special Meeting is the close of business on July 20,
1998 (the "Record Date"), and all holders of record of the Company's common
stock, $.01 par value per share (the "Common Stock"), on the Record Date are
entitled to notice of the Special Meeting and to vote at the Special Meeting and
any meetings held upon adjournment thereof.

A proxy form is enclosed. Whether or not you plan to attend the Special
Meeting in person, please date, sign and return the enclosed proxy as promptly
as possible, in the postage prepaid envelope provided, to ensure that your
shares will be voted at the Special Meeting. Any stockholder who returns a proxy
in such form has the power to revoke it at any time prior to its effective use
by filing an instrument revoking it or a duly executed proxy bearing a later
date with the Secretary of the Company or by attending the Special Meeting and
voting in person. Unless contrary instructions are given, any such proxy, if not
revoked, will be voted at the Special Meeting for approval of the proposed
amendment to the Company's Certificate of Incorporation to increase the number
of authorized shares of Common Stock from 30,000,000 to 50,000,000 (the
"Amendment"), and as recommended by the Board of Directors with regard to all
other matters, in its discretion.

The Company has announced its intention to effect a 5-for-4 split of its
Common Stock (in the form of a 25% stock dividend), contingent upon obtaining
stockholder approval of the Amendment (the "Stock Split"). In the event the
Amendment is approved, the Stock Split will be effected on September 15, 1998
and paid to stockholders of record on July 27, 1998.

The voting securities of the Company are the outstanding shares of Common
Stock. At the Record Date, the Company had outstanding 22,861,965 shares of
Common Stock. For each share of Common Stock held on the Record Date, a
stockholder is entitled to one vote on all matters to be considered at the
Special Meeting.

Approval of the Amendment requires the affirmative vote of the holders of a
majority of the outstanding shares of Common Stock as of the Record Date
entitled to vote on this matter at the Meeting. Neither an abstention nor a
broker non-vote is an affirmative vote and, therefore, both will have the same
legal effect as a vote against the approval of the proposed Amendment. Broker
non-votes occur when a broker holding shares of Common Stock in street name
withholds its vote on certain non-routine matters because the broker has not
received instructions from the beneficial owner of those shares and does not
have discretionary authority to vote on such non-routine matters without
specific instructions. Brokers

holding shares in street name must receive specific instructions from the
beneficial owners in order to have the authority to vote, in person or by proxy,
on certain non-routine matters. When a beneficial owner does not give specific
instructions to the broker, the broker, as the holder of record, is entitled to
vote only on "routine" matters and must withhold its votes as to any
"non-routine" matters. Where a proxy solicitation includes a non-routine
proposal and the broker does not receive specific instructions from the
beneficial owner, the resulting proxy is considered a "limited proxy." Shares
represented by limited proxies are considered present for quorum purposes, but
are not considered present for purposes of determining the total number of
shares with voting power present with regard to a non-routine proposal. The
resulting broker non-vote of such a limited proxy will be treated as an
abstention on such non-routine proposal. The proposed Amendment is a non-routine
proposal.

The cost of preparing, assembling, printing and mailing this Proxy Statement
and the accompanying form of proxy, and the cost of soliciting proxies relating
to the Special Meeting, will be borne by the Company. The Company may request
banks and brokers to solicit their customers who beneficially own Common Stock
listed of record in names of nominees, and will reimburse such banks and brokers
for their reasonable out-of-pocket expenses of such solicitations. The original
solicitation of proxies by mail may be supplemented by telephone, telegram and
personal solicitation by officers, directors and regular employees of the
Company, but no additional compensation will be paid to such individuals.

The Common Stock is listed for trading under the symbol "WATR" on The Nasdaq
National Market ("Nasdaq"), which is operated by The Nasdaq Stock Market, Inc.
On August 7, 1998, the closing price for a share of Common Stock on Nasdaq was
$ .

The principal executive offices of the Company are located at 670 North
Rosemead Boulevard, Pasadena, California 91107, and the Company's telephone
number is (626) 351-4664.

PROPOSAL NO. 1
APPROVAL OF AMENDMENT TO THE COMPANY'S
CERTIFICATE OF INCORPORATION

OVERVIEW

In July 1998, the Board of Directors declared advisable and unanimously
approved an amendment of the Company's Certificate of Incorporation to increase
the number of authorized shares of Common Stock from 30,000,000 shares to
50,000,000 shares. No increase in the number of shares of Preferred Stock of the
Company, currently 2,000,000 shares, is proposed or anticipated. As more fully
set forth below, the proposed Amendment is intended to permit the proposed Stock
Split and improve the Company's flexibility in meeting its future needs for
unreserved Common Stock.

If the Amendment is approved by the stockholders, it will become effective
upon the filing of a Certificate of Amendment of Certificate of Incorporation
(the "Certificate of Amendment") with the Delaware Secretary of State. The text
of the second paragraph of Article IV of the Company's Certificate of
Incorporation will read as follows:

"The total number of shares of stock that the Corporation shall
have authority to issue is fifty-two million (52,000,000),
consisting of fifty million (50,000,000) shares of common stock,
par value $0.01, and two million (2,000,000) shares of preferred
stock, par value $0.01. The designations and the powers,
preferences and rights, and the qualifications, limitations or
restrictions thereof are as follows:"

As of the close of business on the Record Date, of the 30,000,000 shares
authorized, 22,856,933 shares of Common Stock of the Company were issued and
outstanding, 3,424,891 shares of Common Stock were reserved for issuance upon
exercise of outstanding stock options and 487,784 shares were reserved for
future issuance under the Company's stock benefit plans. Accordingly, only
3,230,392 shares of Common Stock unreserved on the Record Date.

REASONS FOR AND POSSIBLE EFFECTS OF THE PROPOSED AMENDMENT

STOCK SPLIT

In July 1998, the Board of Directors declared advisable and unanimously
approved a 5-for-4 split of the Common Stock (to be effected in the form of a
25% stock dividend), contingent upon stockholder approval of the Amendment at
the Special Meeting. In the event the Amendment is approved, the Stock Split
will be effected on September 15, 1998 and paid to stockholders of record on
July 27, 1998.

FLEXIBILITY IN SHARE ISSUANCE

As indicated above, the Company has only 3,230,392 authorized but unreserved
and unissued shares of Common Stock available for future issuance. This severely
limits the ability of the Board of Directors to issue shares of Common Stock
without seeking stockholder approval. Obtaining stockholder approval is a time
consuming, expensive process and could delay or prevent the Company from taking
such actions as potential acquisitions, financings, stock splits, stock
dividends or additional compensation plans.

If the Amendment is approved, 23,230,392 authorized, unreserved and unissued
shares of Common Stock will be available for issue from time to time for such
purposes as the Board of Directors may approve. After giving effect to the Stock
Split, 8,537,990 authorized, unreserved and unissued shares of Common Stock will
be so available. No further vote of the stockholders of the Company will be
required, except as provided under Delaware law or under the rules of Nasdaq or
any other national securities exchange on which shares of Common Stock of the
Company are then listed. The availability of additional shares for issue,
without the delay and expense of obtaining the approval of stockholders at a
subsequent

special meeting, will afford the Company greater flexibility in acting upon
proposed transactions in which shares of Common Stock may be issued.

POSSIBLE EFFECTS

The additional shares of Common Stock to be authorized by adoption of the
Amendment would have rights identical to the currently outstanding shares of
Common Stock of the Company. Adoption of the proposed Amendment and issuance of
the Common Stock would not affect the rights of the holders of currently
outstanding shares of Common Stock, except for effects incidental to increasing
the number of outstanding shares of Common Stock such as dilution of the
earnings per share and voting rights of current holders of Common Stock.

Stockholders should note, however, that authorized but unissued stock could
be issued by the Board of Directors for the purpose of countering an unsolicited
takeover or other proposal that is opposed by the Board. Accordingly, an effect
of the increase in the number of authorized shares may be to deter a future
takeover attempt which holders of Common Stock may deem to be in their best
interest or in which holders of Common Stock are offered a premium for their
shares over the market price. The Board is not currently aware of any attempt to
takeover or acquire the Company, and has no current plans to issue additional
shares of Common Stock other than pursuant to the exercise of outstanding stock
options and stock options that might be granted in the future under the
Company's employee benefit plans, or pursuant to a possible split of the Common
Stock. In addition, the Company continuously evaluates the marketplace for
strategic acquisition opportunities to position itself to address existing and
emerging markets. The Company views acquisitions as a key component of its
growth strategy, and intends to use both securities and cash, as it deems
appropriate, to fund such acquisitions.

The Board of Directors believes that the benefits of providing the Company
with the flexibility to issue shares without delay for any purpose outweighs the
possible disadvantages discussed above, and that it is prudent and in the best
interests of the stockholders to provide the greater flexibility that will
result from the approval of the proposed increase in authorized shares.

VOTE REQUIRED

The approval of the Amendment requires the affirmative vote of a majority of
the outstanding shares of Common Stock as of the Record Date entitled to vote on
this matter at the Special Meeting. Neither an abstention nor a broker non-vote
is an affirmative vote and, therefore, both will have the same effect as a vote
against the Amendment. See "General Information."

RECOMMENDATION OF THE BOARD OF DIRECTORS

FOR ALL OF THE FOREGOING REASONS, THE BOARD BELIEVES THAT THE AMENDMENT IS
IN THE BEST INTERESTS OF THE COMPANY AND ITS STOCKHOLDERS AND UNANIMOUSLY
RECOMMENDS A VOTE "FOR" APPROVAL THEREOF. PROXIES WILL BE VOTED FOR THIS
PROPOSAL UNLESS OTHERWISE SPECIFICALLY INDICATED.

SECURITY OWNERSHIP OF PRINCIPAL STOCKHOLDERS,
DIRECTORS AND EXECUTIVE OFFICERS

The following table sets forth information regarding the ownership of the
Company's Common Stock as of July 15, 1998 by (i) all those persons known by the
Company to own beneficially more than 5% of the Company's Common Stock, (ii)
each director and certain executive officers of the Company, and (iii) all
executive officers and directors as a group. Except as otherwise noted, the
Company knows of no agreements among its stockholders which relate to voting or
investment power over its Common Stock.

NUMBER OF PERCENTAGE OF
SHARES SHARES
BENEFICIALLY BENEFICIALLY
NAME OF BENEFICIAL OWNER(1) OWNED OWNED(1)
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Li-San Hwang(2) ................................................... 1,338,481 6.0%
Tetra Tech, Inc.
670 N. Rosemead Blvd.
Pasadena, California 91107

Daniel A. Whalen(3) ............................................... 3,642,920 16.3
Whalen & Company, Inc.
3675 Mt. Diablo Blvd.
Suite 360
Lafayette, California 94549

Pilgrim Baxter & Associates, Ltd.(4) .............................. 2,298,565 10.3
Harold J. Baxter
Gary I. Pilgrim
1255 Drummers Lane
Wayne, Pennsylvania 19087

J. Christopher Lewis(5)............................................ 63,126 *

Patrick C. Haden(6)................................................ 19,464 *

James J. Shelton(7)................................................ 12,083 *

Thomas D. Brisbin(8)............................................... 37,334 *

Charles R. Faust(9)................................................ 35,054 *

James M. Jaska(10)................................................. 42,454 *

All directors and executive officers
as a group (12 persons)(11)...................................... 5,502,376 24.6

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* Amount represents less than 1% of the Company's Common Stock.

(1) Unless otherwise indicated, the persons named in the table have sole voting
and sole investment power with respect to all shares of Common Stock shown
as beneficially owned by them, subject to community property rules where
applicable and the information contained in this table and these notes.

(2) Excludes an aggregate of 20,991 shares of Common Stock owned by Dr. Hwang's
adult children as to which Dr. Hwang disclaims beneficial ownership.
Includes 12,792 shares issuable with respect to stock options exercisable
within 60 days after July 15, 1998.

(3) Includes 3,003,307 shares of Common Stock held by Daniel A. Whalen and
Katherine C. Whalen as Trustees for the Whalen Family Trust U/A/D 4/30/92,
(ii) 500,000 shares of Common Stock held by Daniel A. Whalen and Katherine
C. Whalen as Trustees for the Whalen 1997 Charitable Remainder Unitrust,
(iii) 22,748 shares of Common Stock held by Daniel A. Whalen and Katharine
C. Whalen as

Trustees for the MJW Whalen Trust 1997 - D, (iv) 22,748 shares of Common
Stock held by Daniel A. Whalen and Katharine C. Whalen as Trustees for the
ACW Whalen Trust 1997 - D, (v) 22,748 shares of Common Stock held by Daniel
A. Whalen and Katharine C. Whalen as Trustees for the MCW Whalen Trust 1997
- D, (vi) 22,748 shares of Common Stock held by Daniel A. Whalen and
Katharine C. Whalen as Trustees for the MJW Whalen Trust 1997 - K, (vii)
22,748 shares of Common Stock held by Daniel A. Whalen and Katharine C.
Whalen as Trustees for the ACW Whalen Trust 1997 - K, and (viii) 22,748
shares of Common Stock held by Daniel A. Whalen and Katharine C. Whalen as
Trustees for the MCW Whalen Trust 1997 - K. All information regarding share
ownership is taken from and furnished in reliance upon the Schedule 13D
(Amendment No. 1), dated as of February 17, 1998, filed by Daniel A. Whalen.
Also includes 3,125 shares issuable with respect to stock options
exercisable within 60 days after July 15, 1998.

(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 12,204 shares issuable with respect to stock options exercisable
within 60 days after July 15, 1998.

(6) Excludes an aggregate of 2,147 shares of Common Stock owned by Mr. Haden's
wife as to which Mr. Haden disclaims beneficial ownership. Includes 12,204
shares issuable with respect to stock options exercisable within 60 days
after July 15, 1998.

(7) Includes 2,930 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 9,153 shares issuable with
respect to stock options exercisable within 60 days after July 15, 1998.

(8) Includes 36,719 shares issuable with respect to stock options exercisable
within 60 days after July 15, 1998.

(9) Includes 12,839 shares issuable with respect to stock options exercisable
within 60 days after July 15, 1998. Additionally, Dr. Faust's minor children
own an aggregate of 1,758 shares of Common Stock as to which Dr. Faust
disclaims beneficial ownership.

(10) Includes 41,933 shares issuable with respect to stock options exercisable
within 60 days after July 15, 1998.

(11) Includes 204,049 shares issuable with respect to stock options exercisable
within 60 days after July 15, 1998.

INDEPENDENT PUBLIC ACCOUNTANTS

Deloitte & Touche LLP, certified public accountants, is acting as the
Company's independent auditors for the fiscal year ending October 4, 1998. The
Company has been advised that Deloitte & Touche LLP is independent with respect
to the Company within the meaning of the Securities Act of 1933, as amended, and
the applicable published rules and regulations thereunder. Due to the nature of
the matters being considered, a representative of that firm is not expected to
be available at the Special Meeting.

STOCKHOLDER PROPOSAL FOR 1999 ANNUAL MEETING

Any stockholder who wishes to present a proposal for action at the 1999
Annual Meeting of Stockholders and who wishes to have it set forth in the
corresponding proxy statement and identified in the corresponding form of proxy
prepared by management must notify the Company no later than September 1, 1998
in such form as required under the rules and regulations promulgated by the
Securities and Exchange Commission.

OTHER MATTERS

The Board of Directors does not know of any other matters to be presented at
the Special Meeting, but, if other matters do properly come before the Special
Meeting, it is intended that the persons named as proxies in the proxy will vote
on them in accordance with their best judgment.

By Order of the Board of Directors
Richard A. Lemmon
VICE PRESIDENT AND SECRETARY

Pasadena, California
August 10, 1998

PRELIMINARY COPY

COMMON STOCK
PROXY TETRA TECH, INC.
BOARD OF DIRECTORS

The undersigned hereby appoints Li-San Hwang and Richard A. Lemmon, or
either of them, the true and lawful attorneys and proxies of the undersigned,
with full power of substitution, to vote all shares of the Common Stock, $.01
par value ("Common Stock"), of TETRA TECH, INC. which the undersigned is
entitled to vote, at a Special Meeting of the Stockholders of TETRA TECH, INC.
to be held at the principal executive offices of TETRA TECH, INC., 670 N.
Rosemead Boulevard, Pasadena, California 91107 on Monday, September 14, 1998 at
10:00 a.m., Pacific Time, and at any and all adjournments thereof, on the
proposals set forth below and any other matters properly brought before the
Meeting.

1. PROPOSAL TO APPROVE THE AMENDMENT TO THE COMPANY'S CERTIFICATE OF
INCORPORATION:

/ / FOR / / AGAINST / / ABSTAIN

2. Such other matters as may properly come before the Meeting.

THE DIRECTORS RECOMMEND A VOTE FOR APPROVAL OF THE AMENDMENT TO THE
COMPANY'S CERTIFICATE OF INCORPORATION.

(CONTINUED AND TO BE SIGNED ON THE OTHER SIDE)

(CONTINUED FROM OTHER SIDE)

Unless a contrary direction is indicated, this Proxy will be voted FOR
approval of the Amendment to the Company's Certificate of Incorporation; if
specific instructions are indicated, this Proxy will be voted in accordance
therewith.

All proxies to vote at said Meeting or any adjournment thereof heretofore
given by the undersigned are hereby revoked. Receipt of the Notice of Annual
Meeting and Proxy Statement dated August 12, 1998 is acknowledged.

Please mark, sign, date and return this Proxy in the accompanying prepaid
envelope. THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS OF TETRA
TECH, INC.
Dated: _______________, 1998

____________________________
(Signature)
____________________________
(Signature)

Please sign exactly as your
name appears hereon. When
shares are held by joint
tenants, both should sign.
When signing as attorney, as
executor, administrator,
trustee or guardian, please
give full title as such. If a
corporation, please sign in
full corporate name by
President or other authorized
officer. If a partnership,
please sign in partnership
name by authorized person.