<SEC-DOCUMENT>0001174947-25-000503.txt : 20250403
<SEC-HEADER>0001174947-25-000503.hdr.sgml : 20250403
<ACCEPTANCE-DATETIME>20250403161223
ACCESSION NUMBER:		0001174947-25-000503
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250401
FILED AS OF DATE:		20250403
DATE AS OF CHANGE:		20250403

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kooper Jay L
		CENTRAL INDEX KEY:			0001603213
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-00422
		FILM NUMBER:		25809573

	MAIL ADDRESS:	
		STREET 1:		1500 RONSON ROAD
		CITY:			ISELIN
		STATE:			NJ
		ZIP:			08830

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MIDDLESEX WATER CO
		CENTRAL INDEX KEY:			0000066004
		STANDARD INDUSTRIAL CLASSIFICATION:	WATER SUPPLY [4941]
		ORGANIZATION NAME:           	01 Energy & Transportation
		EIN:				221114430
		STATE OF INCORPORATION:			NJ
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		485C ROUTE 1 SOUTH
		STREET 2:		SUITE 400
		CITY:			ISELIN
		STATE:			NJ
		ZIP:			08830
		BUSINESS PHONE:		7326341500

	MAIL ADDRESS:	
		STREET 1:		485C ROUTE 1 SOUTH
		STREET 2:		SUITE 400
		CITY:			ISELIN
		STATE:			NJ
		ZIP:			08830
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>ownership.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-04-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000066004</issuerCik>
        <issuerName>MIDDLESEX WATER CO</issuerName>
        <issuerTradingSymbol>MSEX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001603213</rptOwnerCik>
            <rptOwnerName>Kooper Jay L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>485C ROUTE 1 SOUTH</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>ISELIN</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, Gen. Counsel &amp; Secretary</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock (Restricted Stock Book)</value>
            </securityTitle>
            <transactionDate>
                <value>2025-04-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1607</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>64.10</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5685</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock (Restricted Stock Book)</value>
            </securityTitle>
            <transactionDate>
                <value>2025-04-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>832</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>64.10</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4853</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock (Book)</value>
            </securityTitle>
            <transactionDate>
                <value>2025-04-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>369</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>64.10</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>528</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents the number of shares of Restricted Stock awarded for current year.</footnote>
        <footnote id="F2">Represents the number of shares of Restricted Stock originally awarded that have now vested.</footnote>
        <footnote id="F3">Represents the number of shares released to the awardee after choosing to surrender shares back to Issuer to satisfy the tax withholding obligations that arose in connection with the vesting of the Restricted Stock.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Jay L. Kooper</signatureName>
        <signatureDate>2025-04-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
