<SEC-DOCUMENT>0001728969-25-000006.txt : 20251202
<SEC-HEADER>0001728969-25-000006.hdr.sgml : 20251202
<ACCEPTANCE-DATETIME>20251202201815
ACCESSION NUMBER:		0001728969-25-000006
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20251119
FILED AS OF DATE:		20251202
DATE AS OF CHANGE:		20251202

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hopson Preston
		CENTRAL INDEX KEY:			0001728969
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19655
		FILM NUMBER:		251544691

	MAIL ADDRESS:	
		STREET 1:		3475 E FOOTHILL BLVD
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91107

	FORMER NAME:	
		FORMER CONFORMED NAME:	Hopson Preston III
		DATE OF NAME CHANGE:	20180123

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TETRA TECH INC
		CENTRAL INDEX KEY:			0000831641
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-ENGINEERING SERVICES [8711]
		ORGANIZATION NAME:           	07 Trade & Services
		EIN:				954148514
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0928

	BUSINESS ADDRESS:	
		STREET 1:		3475 EAST FOOTHILL BOULEVARD
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91107
		BUSINESS PHONE:		6263514664

	MAIL ADDRESS:	
		STREET 1:		3475 EAST FOOTHILL BOULEVARD
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91107
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1764724692.xml
<DESCRIPTION>FORM 4
<TEXT>
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        <issuerName>TETRA TECH INC</issuerName>
        <issuerTradingSymbol>TTEK</issuerTradingSymbol>
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            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>91107</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, Chief Legal/Human Capital</officerTitle>
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                </transactionAcquiredDisposedCode>
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                <underlyingSecurityTitle>
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                    <value>2735</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <value>2024-11-30</value>
                <footnoteId id="F5"/>
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                <footnoteId id="F4"/>
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                <underlyingSecurityTitle>
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                </underlyingSecurityTitle>
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                    <value>2735</value>
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                    <value>5460</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
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                    <value>0</value>
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                    <value>D</value>
                </transactionAcquiredDisposedCode>
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                <value>2025-11-30</value>
                <footnoteId id="F6"/>
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                <footnoteId id="F4"/>
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                <sharesOwnedFollowingTransaction>
                    <value>7363</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
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        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the shares withheld to pay the related tax liability of the restricted stock units (RSUs) that vested on November 30, 2025.</footnote>
        <footnote id="F2">Represents an award of restricted stock units (RSUs), each unit of which represents a contingent right to receive one share of Tetra Tech common stock.</footnote>
        <footnote id="F3">The RSUs become vested as to 25% of the shares on November 30, 2026, and 25% annually, thereafter, until fully vested.</footnote>
        <footnote id="F4">The RSUs are exercisable at the time of vesting and do not have a set expiration date.</footnote>
        <footnote id="F5">The RSUs become vested as to 25% of the shares on November 30, 2024, and 25% annually, thereafter, until fully vested.</footnote>
        <footnote id="F6">The RSUs become vested as to 25% of the shares on November 30, 2025, and 25% annually, thereafter, until fully vested.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Preston Hopson</signatureName>
        <signatureDate>2025-12-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</SEC-DOCUMENT>
