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  <xs:element id="nwn_CCICreditsLiability" abstract="false" name="CCICreditsLiability" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_CCIDeferredCosts" abstract="false" name="CCIDeferredCosts" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_IncreaseDecreaseInCloudBasedSoftwareCapitalExpenditure" abstract="false" name="IncreaseDecreaseInCloudBasedSoftwareCapitalExpenditure" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_OilAndGasGasReservesValue" abstract="false" name="OilAndGasGasReservesValue" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_SiEnergyGasUtilityMember" abstract="true" name="SiEnergyGasUtilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NWNWaterUtilityMember" abstract="true" name="NWNWaterUtilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_OtherMember" abstract="true" name="OtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NWNGasUtilityMember" abstract="true" name="NWNGasUtilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NWNaturalOtherMember" abstract="true" name="NWNaturalOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_ATMEquityProgramMember" abstract="true" name="ATMEquityProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_CumulativeProceedsReceivedOnAllTransactions" abstract="false" name="CumulativeProceedsReceivedOnAllTransactions" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_SaleOfStockConsiderationReceived" abstract="false" name="SaleOfStockConsiderationReceived" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_SaleOfStockCommissionsAndFeesPaid" abstract="false" name="SaleOfStockCommissionsAndFeesPaid" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_AtTheMarketEquityProgramAvailableForIssuance" abstract="false" name="AtTheMarketEquityProgramAvailableForIssuance" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_NWNWaterMember" abstract="true" name="NWNWaterMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NaturalGasSalesMember" abstract="true" name="NaturalGasSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_GasStorageRevenueNetofRegulatorySharingMember" abstract="true" name="GasStorageRevenueNetofRegulatorySharingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_AssetManagementRevenueNetofRegulatorySharingMember" abstract="true" name="AssetManagementRevenueNetofRegulatorySharingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_WaterAndWastewaterRevenueMember" abstract="true" name="WaterAndWastewaterRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_GasApplianceCenterRevenueMember" abstract="true" name="GasApplianceCenterRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_RenewableNaturalGasSalesMember" abstract="true" name="RenewableNaturalGasSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_OtherrevenueMember" abstract="true" name="OtherrevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_AlternativerevenueMember" abstract="true" name="AlternativerevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_LeasingrevenueMember" abstract="true" name="LeasingrevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NorthMistLeaseMember" abstract="true" name="NorthMistLeaseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_OtherImmaterialLeasesMember" abstract="true" name="OtherImmaterialLeasesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_CompressedNaturalGasLeaseMember" abstract="true" name="CompressedNaturalGasLeaseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_RevenueOverTimePerformanceObligationNumber" abstract="false" name="RevenueOverTimePerformanceObligationNumber" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_LesseeOperatingLeaseMaximumTermOfShortTermLeasesNotRecordedOnTheBalanceSheet" abstract="false" name="LesseeOperatingLeaseMaximumTermOfShortTermLeasesNotRecordedOnTheBalanceSheet" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nwn_ShortTermLeaseCostBenefit" abstract="false" name="ShortTermLeaseCostBenefit" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract" abstract="true" name="RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nwn_A20242026AwardMember" abstract="true" name="A20242026AwardMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_A20252027AwardMember" abstract="true" name="A20252027AwardMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_A20262028AwardMember" abstract="true" name="A20262028AwardMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_LongTermIncentivePlanMember" abstract="true" name="LongTermIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_ShareBasedCompensationArrangementsByShareBasedPaymentAwardConversionRatioPercentOfTarget" abstract="false" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardConversionRatioPercentOfTarget" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nwn_ShareBasedCompensationAwardTargetShare" abstract="false" name="ShareBasedCompensationAwardTargetShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="nwn_ShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceMetricROICPeriod" abstract="false" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceMetricROICPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nwn_ShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceMetricCumulativeEBITDAPeriod" abstract="false" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceMetricCumulativeEBITDAPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nwn_SiEnergyHoldingsCreditAgreementMember" abstract="true" name="SiEnergyHoldingsCreditAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NaturalFirstMortgageBondsMember" abstract="true" name="NaturalFirstMortgageBondsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_DelayedDrawTermLoanFacilityMember" abstract="true" name="DelayedDrawTermLoanFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_SiEnergySecuredSeniorNotesMember" abstract="true" name="SiEnergySecuredSeniorNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NWNWaterUnsecuredSeniorNotesMember" abstract="true" name="NWNWaterUnsecuredSeniorNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NWNWaterTermLoanDue2026Member" abstract="true" name="NWNWaterTermLoanDue2026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_OtherWaterDebtMember" abstract="true" name="OtherWaterDebtMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NWHoldingsUnsecuredSeniorBondsMember" abstract="true" name="NWHoldingsUnsecuredSeniorBondsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_TermLoanMember" abstract="true" name="TermLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_JuniorSubordinatedDebenturesMember" abstract="true" name="JuniorSubordinatedDebenturesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_SecuredSeniorANotesMember" abstract="true" name="SecuredSeniorANotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_SecuredSeniorBNotesMember" abstract="true" name="SecuredSeniorBNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_SeriesFNotesMember" abstract="true" name="SeriesFNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_SeriesGNotesMember" abstract="true" name="SeriesGNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_LongTermDebtCurrentMaturitiesGross" abstract="false" name="LongTermDebtCurrentMaturitiesGross" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_SeriesESeniorNotesMember" abstract="true" name="SeriesESeniorNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_DefinedBenefitPlanAmountAllocatedToConstruction" abstract="false" name="DefinedBenefitPlanAmountAllocatedToConstruction" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_DefinedBenefitPlanNetPeriodicBenefitCostChargedToExpense" abstract="false" name="DefinedBenefitPlanNetPeriodicBenefitCostChargedToExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_AmortizationOfRegulatoryBalancingAccount" abstract="false" name="AmortizationOfRegulatoryBalancingAccount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_DefinedBenefitPlanNetAmountChargedToExpense" abstract="false" name="DefinedBenefitPlanNetAmountChargedToExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_NonQualifiedPensionPlansDefinedBenefitMember" abstract="true" name="NonQualifiedPensionPlansDefinedBenefitMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_AccumulatedOtherComprehensiveIncomeLossNetOfTaxRollForward" abstract="true" name="AccumulatedOtherComprehensiveIncomeLossNetOfTaxRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="nwn_OtherTaxExpenseBenefitDifferencesToBeFlowedThroughByRegulatoryCommissions" abstract="false" name="OtherTaxExpenseBenefitDifferencesToBeFlowedThroughByRegulatoryCommissions" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_PropertyPlantEquipmentNonCash" abstract="false" name="PropertyPlantEquipmentNonCash" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_AvionWaterMember" abstract="true" name="AvionWaterMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_TotalCumulativeGasReservesInvestment" abstract="false" name="TotalCumulativeGasReservesInvestment" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_DeferredTaxesRelatedToGasReserves" abstract="false" name="DeferredTaxesRelatedToGasReserves" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_EquityMethodInvestmentNumberOfCustomerConnections" abstract="false" name="EquityMethodInvestmentNumberOfCustomerConnections" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_EquityMethodInvestmentNumberOfEmployees" abstract="false" name="EquityMethodInvestmentNumberOfEmployees" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_EquityMethodInvestmentAdditionalUnderlyingEquityInNetAssets" abstract="false" name="EquityMethodInvestmentAdditionalUnderlyingEquityInNetAssets" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_PinesMember" abstract="true" name="PinesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_SiEnergyAndPinesMember" abstract="true" name="SiEnergyAndPinesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_InlineUtilitiesLLCMember" abstract="true" name="InlineUtilitiesLLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_OtherinsignificantacquisitionsMember" abstract="true" name="OtherinsignificantacquisitionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_BusinessCombinationCustomersOfBusinessAcquired" abstract="false" name="BusinessCombinationCustomersOfBusinessAcquired" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_BusinessCombinationCommunitiesOfBusinessAcquired" abstract="false" name="BusinessCombinationCommunitiesOfBusinessAcquired" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_BusinessCombinationProFormaInformationTaxRateForAdjustments" abstract="false" name="BusinessCombinationProFormaInformationTaxRateForAdjustments" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nwn_FinancialMember" abstract="true" name="FinancialMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_PhysicalMember" abstract="true" name="PhysicalMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_NaturalGasThermsMember" abstract="true" name="NaturalGasThermsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_GasYearAxis" abstract="true" name="GasYearAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="nwn_GasYearDomain" abstract="true" name="GasYearDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_GasYear20252026Member" abstract="true" name="GasYear20252026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_CollateralPostedwithNWNaturalCounterpartiesMember" abstract="true" name="CollateralPostedwithNWNaturalCounterpartiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_TargetHedgeAchieved" abstract="false" name="TargetHedgeAchieved" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nwn_IncrementalCostOrBenefitToCollectOrRefundToCustomers" abstract="false" name="IncrementalCostOrBenefitToCollectOrRefundToCustomers" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_NorthwestHoldingsandNorthwestNaturalMember" abstract="true" name="NorthwestHoldingsandNorthwestNaturalMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_A20252044GuaranteeMember" abstract="true" name="A20252044GuaranteeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_CommitmentsAndContingenciesNumberOfProductionFacilities" abstract="false" name="CommitmentsAndContingenciesNumberOfProductionFacilities" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_IncreaseDecreaseInRNGFacilityPrepaidOperatingAssets" abstract="false" name="IncreaseDecreaseInRNGFacilityPrepaidOperatingAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_UnrecordedUnconditionalPurchaseObligationToBePaidAfterYearFour" abstract="false" name="UnrecordedUnconditionalPurchaseObligationToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_GuarantorObligationsPercentOfContractedTherms" abstract="false" name="GuarantorObligationsPercentOfContractedTherms" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nwn_PortlandHarborMember" abstract="true" name="PortlandHarborMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_GascoSiltronicSedimentsMember" abstract="true" name="GascoSiltronicSedimentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_PortlandHarborOtherMember" abstract="true" name="PortlandHarborOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_GascoUplandsMember" abstract="true" name="GascoUplandsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_GascoUplandSiteMember" abstract="true" name="GascoUplandSiteMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_GascoUplandsIRAMMember" abstract="true" name="GascoUplandsIRAMMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_FrontStreetMember" abstract="true" name="FrontStreetMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_YakamaNationMember" abstract="true" name="YakamaNationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_RemediationRecoveryPercentage" abstract="false" name="RemediationRecoveryPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nwn_SiteContingencyNumberOfMiles" abstract="false" name="SiteContingencyNumberOfMiles" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_SiteContingencyNumberOfPotentiallyResponsibleParties" abstract="false" name="SiteContingencyNumberOfPotentiallyResponsibleParties" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_ProposedRemediationPlanCleanUpCosts" abstract="false" name="ProposedRemediationPlanCleanUpCosts" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_ProposedRemediationPlanPercentageofCleanUpCosts" abstract="false" name="ProposedRemediationPlanPercentageofCleanUpCosts" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nwn_SiteContingencyNumberOfRemediationProjects" abstract="false" name="SiteContingencyNumberOfRemediationProjects" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_TrusteeCouncilMembersNumberofClaimants" abstract="false" name="TrusteeCouncilMembersNumberofClaimants" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_SiteContingencyNumberOfOtherThirdPartyDefendants" abstract="false" name="SiteContingencyNumberOfOtherThirdPartyDefendants" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_NRDLiabilityClaimYakamaNation" abstract="false" name="NRDLiabilityClaimYakamaNation" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_NumberOfAmendedComplaintsFiled" abstract="false" name="NumberOfAmendedComplaintsFiled" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_SiteContingencyNumberOfManagementPieces" abstract="false" name="SiteContingencyNumberOfManagementPieces" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="nwn_EnvironmentalExitCostsAnticipatedCostPeriod" abstract="false" name="EnvironmentalExitCostsAnticipatedCostPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nwn_CostIncurredStudiesAndDesignCosts" abstract="false" name="CostIncurredStudiesAndDesignCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_AnnualTariffRiderCollection" abstract="false" name="AnnualTariffRiderCollection" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_AnnualInsuranceProceedsToApplyAgainstRemediationCosts" abstract="false" name="AnnualInsuranceProceedsToApplyAgainstRemediationCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_TotalAnnualRemediationExpenseAndInterest" abstract="false" name="TotalAnnualRemediationExpenseAndInterest" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_ContingencyEnrolledCustomersDuringTimePeriodPeriod" abstract="false" name="ContingencyEnrolledCustomersDuringTimePeriodPeriod" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="nwn_GascoSiltronicUplandMember" abstract="true" name="GascoSiltronicUplandMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_OregonSteelMillsMember" abstract="true" name="OregonSteelMillsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_RegulatoryAssetsEnvironmentalRegulatoryDeferredCostAndInterest" abstract="false" name="RegulatoryAssetsEnvironmentalRegulatoryDeferredCostAndInterest" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_RegulatoryAssetsEnvironmentalRegulatoryAccruedSiteLiabilities" abstract="false" name="RegulatoryAssetsEnvironmentalRegulatoryAccruedSiteLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_EnvironmentalRegulatoryInsuranceProceedsAndInterest" abstract="false" name="EnvironmentalRegulatoryInsuranceProceedsAndInterest" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="nwn_RemediationNonRecoveryPercentage" abstract="false" name="RemediationNonRecoveryPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="nwn_YearOneMember" abstract="true" name="YearOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_YearTwoMember" abstract="true" name="YearTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_YearThreeMember" abstract="true" name="YearThreeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="nwn_PublicUtilitiesRequestedRateDepreciationAmount" abstract="false" name="PublicUtilitiesRequestedRateDepreciationAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
