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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 dA7ykXCqodhz2DZbNYR+XQ==

<SEC-DOCUMENT>0001181431-06-019492.txt : 20060323
<SEC-HEADER>0001181431-06-019492.hdr.sgml : 20060323
<ACCEPTANCE-DATETIME>20060323125256
ACCESSION NUMBER:		0001181431-06-019492
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060322
FILED AS OF DATE:		20060323
DATE AS OF CHANGE:		20060323

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NORTHWEST NATURAL GAS CO
		CENTRAL INDEX KEY:			0000073020
		STANDARD INDUSTRIAL CLASSIFICATION:	NATURAL GAS DISTRIBUTION [4924]
		IRS NUMBER:				930256722
		STATE OF INCORPORATION:			OR
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		220 NW SECOND AVE
		CITY:			PORTLAND
		STATE:			OR
		ZIP:			97209
		BUSINESS PHONE:		5032264211

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Thrasher Kenneth
		CENTRAL INDEX KEY:			0001319835

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15973
		FILM NUMBER:		06705634

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		(503) 887-8099

	MAIL ADDRESS:	
		STREET 1:		610 NW WESTOVER TERRACE
		CITY:			PORTLAND
		STATE:			OR
		ZIP:			97210
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd112029.xml
<DESCRIPTION>3/06 OPEN MARKET PURCHASE
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-03-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000073020</issuerCik>
        <issuerName>NORTHWEST NATURAL GAS CO</issuerName>
        <issuerTradingSymbol>NWN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001319835</rptOwnerCik>
            <rptOwnerName>Thrasher Kenneth</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>610 NW WESTOVER TERRACE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PORTLAND</rptOwnerCity>
            <rptOwnerState>OR</rptOwnerState>
            <rptOwnerZipCode>97210</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $3-1/6 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2006-03-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>34.1398</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>C.J. Rue,  Attorney-in-Fact</signatureName>
        <signatureDate>2006-03-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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