<SEC-DOCUMENT>0001950047-25-005801.txt : 20250814
<SEC-HEADER>0001950047-25-005801.hdr.sgml : 20250814
<ACCEPTANCE-DATETIME>20250814160148
ACCESSION NUMBER:		0001950047-25-005801
CONFORMED SUBMISSION TYPE:	144
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20250814
DATE AS OF CHANGE:		20250814

SUBJECT COMPANY:	

	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

	FILING VALUES:
		FORM TYPE:		144
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	000-19655
		FILM NUMBER:		251218488

	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

REPORTING-OWNER:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Birkenbeuel Gary
		CENTRAL INDEX KEY:			0001748476
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		144

	MAIL ADDRESS:	
		STREET 1:		3475 EAST FOOTHILL BOULEVARD
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91107
</SEC-HEADER>
<DOCUMENT>
<TYPE>144
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:ns2="http://www.sec.gov/edgar/common">
    <headerData>
        <submissionType>144</submissionType>
        <filerInfo>
            <filer>
                <filerCredentials>
                    <cik>0001748476</cik>
                    <ccc>XXXXXXXX</ccc>
                </filerCredentials>
            </filer>
            <liveTestFlag>LIVE</liveTestFlag>



        </filerInfo>
    </headerData>
    <formData>
        <issuerInfo>
            <issuerCik>0000831641</issuerCik>
            <issuerName>TETRA TECH, INC.</issuerName>
            <secFileNumber>000-19655</secFileNumber>
            <issuerAddress>
                <ns2:street1>3475 East Foothill Boulevard</ns2:street1>
                <ns2:city>PASADENA</ns2:city>
                <ns2:stateOrCountry>CA</ns2:stateOrCountry>
                <ns2:zipCode>91107</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>(626) 351-4664</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>GARY R BIRKENBEUEL</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Director</relationshipToIssuer>
            </relationshipsToIssuer>
        </issuerInfo>
        <securitiesInformation>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>8th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>2390</noOfUnitsSold>
            <aggregateMarketValue>86050.04</aggregateMarketValue>
            <noOfUnitsOutstanding>262773412</noOfUnitsOutstanding>
            <approxSaleDate>08/14/2025</approxSaleDate>
            <securitiesExchangeName>NASDAQ</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>11/23/2021</acquiredDate>
            <natureOfAcquisitionTransaction>Performance Shares</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>2390</amountOfSecuritiesAcquired>
            <paymentDate>11/23/2021</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <noticeSignature>
            <noticeDate>08/14/2025</noticeDate>
            <planAdoptionDates/>
            <signature>/s/ Gary Birkenbeuel</signature>
        </noticeSignature>
    </formData>
</edgarSubmission>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
