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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 WJ3wEv550PUaLHMdtimAf+KhS7rDfpNx8H7XbdT9Y9K+a4OeJc5RHAsH7uvFF0c/
 eUvCwjC07RmLTTIRVbyhUQ==

<SEC-DOCUMENT>0001206709-03-000002.txt : 20030509
<SEC-HEADER>0001206709-03-000002.hdr.sgml : 20030509
<ACCEPTANCE-DATETIME>20030508184702
ACCESSION NUMBER:		0001206709-03-000002
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030507
FILED AS OF DATE:		20030509

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TETRA TECH INC
		CENTRAL INDEX KEY:			0000831641
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-ENGINEERING SERVICES [8711]
		IRS NUMBER:				954148514
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		3475 EAST FOOTHILL BOULEVARD
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91107
		BUSINESS PHONE:		626-351-4664

	MAIL ADDRESS:	
		STREET 1:		3475 EAST FOOTHILL BOULEVARD
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91107

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CHRISTENSEN CRAIG L
		CENTRAL INDEX KEY:			0001206709

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19655
		FILM NUMBER:		03688921

	BUSINESS ADDRESS:	
		STREET 1:		670 NORTH ROSEMEAD BLVD
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91107
		BUSINESS PHONE:		6263514664

	MAIL ADDRESS:	
		STREET 1:		670 NORTH ROSEMEAD BLVD
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91107
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

<documentType>4</documentType><periodOfReport>2003-05-07</periodOfReport>
<issuer><issuerCik>0000831641</issuerCik>
        <issuerName>TETRA TECH INC</issuerName>
<issuerTradingSymbol>TTEK</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001206709</rptOwnerCik>
            <rptOwnerName>CHRISTENSEN CRAIG L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
<reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>VICE PRESIDENT</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeSecurity><securityTitle><value>COMMON STOCK</value></securityTitle><transactionDate><value>2003-05-07</value></transactionDate><deemedExecutionDate><value>2003-05-07</value></deemedExecutionDate><transactionCoding><transactionFormType>5</transactionFormType><transactionCode>G</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>500</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>716</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnershi
p><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeSecurity><derivativeSecurity><securityTitle><value>STOCK OPTION</value></securityTitle><conversionOrExercisePrice><value>8.725</value></conversionOrExercisePrice><transactionDate><value>2003-05-07</value></transactionDate><deemedExecutionDate><value>2003-05-07</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>500</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2000-11-15</value></exerciseDate><expirationDate><value>2009-11-15</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>COMMON STOCK</value></underlyingSecurityTitle><underlyingSecurityShares><value>500</v
alue></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>52359</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><footnotes/><ownerSignature><signatureName>Janis B. Salin for Craig L. Christensen</signatureName><signatureDate>2003-05-08</signatureDate></ownerSignature></ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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