UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
SCHEDULE 13G
Under the Securities Exchange Act of 1934
(Amendment No. )*
Tetra Tech, Inc.
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(Name of Issuer)
Common Stock
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(Title of Class of Securities)
88162G103
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(CUSIP Number)
December 31, 2002
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(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:
[x] Rule 13d-1(b)
[ ] Rule 13d-1(c)
[ ] Rule 13d-1(d)
*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.
The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).
Page 1 of 9 pages
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CUSIP No. 88162G103 13G Page 2 of 9 pages
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1 NAME OF REPORTING PERSON
S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
Liberty Wanger Asset Management, L.P. 36-3820584
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2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
Not Applicable (a)[ ]
(b)[ ]
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3 SEC USE ONLY
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4 CITIZENSHIP OR PLACE OF ORGANIZATION
Delaware
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5 SOLE VOTING POWER
NUMBER OF
None
SHARES ---------------------------------------------------------
6 SHARED VOTING POWER
BENEFICIALLY
2,693,000
OWNED BY ---------------------------------------------------------
7 SOLE DISPOSITIVE POWER
EACH
None
REPORTING ---------------------------------------------------------
8 SHARED DISPOSITIVE POWER
PERSON WITH
2,693,000
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9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
2,693,000
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10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
Not Applicable [ ]
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11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
5.1%
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12 TYPE OF REPORTING PERSON*
IA
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*SEE INSTRUCTION BEFORE FILLING OUT!
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CUSIP No. 88162G103 13G Page 3 of 9 pages
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1 NAME OF REPORTING PERSON
S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
WAM Acquisition GP, Inc.
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2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
Not Applicable (a)[ ]
(b)[ ]
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3 SEC USE ONLY
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4 CITIZENSHIP OR PLACE OF ORGANIZATION
Delaware
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5 SOLE VOTING POWER
NUMBER OF
None
SHARES ---------------------------------------------------------
6 SHARED VOTING POWER
BENEFICIALLY
2,693,000
OWNED BY ---------------------------------------------------------
7 SOLE DISPOSITIVE POWER
EACH
None
REPORTING ---------------------------------------------------------
8 SHARED DISPOSITIVE POWER
PERSON WITH
2,693,000
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9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
2,693,000
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10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
Not Applicable [ ]
--------------------------------------------------------------------------------
11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
5.1%
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12 TYPE OF REPORTING PERSON*
CO
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*SEE INSTRUCTION BEFORE FILLING OUT!
Item 1(a) Name of Issuer:
Tetra Tech, Inc.
Item 1(b) Address of Issuer's Principal Executive Offices:
3475 East Foothill Blvd.
Pasadena,CA 91107
Item 2(a) Name of Person Filing:
Liberty Wanger Asset Management, L.P. ("WAM")
WAM Acquisition GP, Inc., the general partner of WAM
("WAM GP")
Item 2(b) Address of Principal Business Office:
WAM and WAM GP are each located at:
227 West Monroe Street, Suite 3000
Chicago, Illinois 60606
Item 2(c) Citizenship:
WAM is a Delaware limited partnership; WAM GP is a
Delaware corporation.
Item 2(d) Title of Class of Securities:
Common Stock
Item 2(e) CUSIP Number:
88162G103
Item 3 Type of Person:
(e) WAM is an Investment Adviser registered under
section 203 of the Investment Advisers Act of
1940; WAM GP is the General Partner of the
Investment Adviser.
Page 4 of 9 pages
Item 4 Ownership (at December 31, 2002):
(a) Amount owned "beneficially" within the meaning of
rule 13d-3:
2,693,000
(b) Percent of class:
5.1% (based on 53,319,936 shares outstanding as of
December 13, 2002, based on Form 10-Q filed on
December 30, 2002).
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the
vote: none
(ii) shared power to vote or to direct
the vote: 2,693,000
(iii) sole power to dispose or to direct
the disposition of: none
(iv) shared power to dispose or to direct
disposition of: 2,693,000
Item 5 Ownership of Five Percent or Less of a Class:
Not Applicable
Item 6 Ownership of More than Five Percent on Behalf of
Another Person:
The shares reported herein have been acquired on behalf
of discretionary clients of WAM. Persons other than WAM
and WAM GP are entitled to receive all dividends from,
and proceeds from the sale of, those shares.
Item 7 Identification and Classification of the Subsidiary Which
Acquired the Security Being Reported on by the Parent Holding
Company:
Not Applicable
Item 8 Identification and Classification of Members of the Group:
Not Applicable
Item 9 Notice of Dissolution of Group:
Not Applicable
Page 5 of 9 pages
Item 10 Certification:
By signing below I certify that, to the best of my knowledge
and belief, the securities referred to above were acquired and
are held in the ordinary course of business and were not acquired
and are not held for the purpose of or with the effect of
changing or influencing the control of the issuer of the
securities and were not acquired and are not held in connection
with or as a participant in any transaction having that purpose
or effect.
Page 6 of 9 pages
Signature
After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.
Date: February 14, 2003
The undersigned corporation, on the date above written, agrees
and consents to the joint filing on its behalf of this
Schedule 13G in connection with its beneficial ownership of
the security reported herein.
WAM Acquisition GP, Inc.
for itself and as general partner of
LIBERTY WANGER ASSET MANAGEMENT, L.P.
By: /s/ Bruce H. Lauer
---------------------------------------
Bruce H. Lauer
Senior Vice President and Secretary
Page 7 of 9 pages
Exhibit Index
Exhibit 1 Joint Filing Agreement dated as of February 14, 2003 by and among
Liberty Wanger Asset Management, L.P. and WAM Acquisition GP,
Inc.
Page 8 of 9 pages