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  <xsd:element id="bkh_EffectiveIncomeTaxReconciliationNetOperatingLossCarryback" name="EffectiveIncomeTaxReconciliationNetOperatingLossCarryback" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_EffectiveIncomeTaxReconciliationTaxBenefitRelatedtoLegalRestructuring" name="EffectiveIncomeTaxReconciliationTaxBenefitRelatedtoLegalRestructuring" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_ElectricGenerationCapacityMegawatts" name="ElectricGenerationCapacityMegawatts" nillable="true" substitutionGroup="xbrli:item" type="num:powerItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_ElectricUtilitiesMember" name="ElectricUtilitiesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_EnvironmentalMember" name="EnvironmentalMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_ExternalCustomersMember" name="ExternalCustomersMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_FixedforFloatSwapsPurchasedMember" name="FixedforFloatSwapsPurchasedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_FlowThroughAccountingMember" name="FlowThroughAccountingMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_FuelPurchasedPowerAndCostOfGasSold" name="FuelPurchasedPowerAndCostOfGasSold" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_GasSupplyContractTerminationMember" name="GasSupplyContractTerminationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_GasUtilitiesMember" name="GasUtilitiesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_IntercompanyCustomersMember" name="IntercompanyCustomersMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_MarketOffSystemSalesMember" name="MarketOffSystemSalesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_MiningMember" name="MiningMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_NaturalGasDistributionMember" name="NaturalGasDistributionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_NaturalGasPhysicalPurchasesMember" name="NaturalGasPhysicalPurchasesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_NetIncomeLossIncludingPortionAttributabletoNoncontrollingInterestExcludingIncomeLossAttributabletoRedeemableNoncontrollingInterest" name="NetIncomeLossIncludingPortionAttributabletoNoncontrollingInterestExcludingIncomeLossAttributabletoRedeemableNoncontrollingInterest" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_NoncurrentLiabilitiesHeldForSaleMember" name="NoncurrentLiabilitiesHeldForSaleMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_NumberOfOneYearExtensionOptions" name="NumberOfOneYearExtensionOptions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_OperatingExpenseMaintenanceOperationsandOtherCostsandExpense" name="OperatingExpenseMaintenanceOperationsandOtherCostsandExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_OtherRegulatoryAssetsMember" name="OtherRegulatoryAssetsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_OtherRegulatoryLiabilitiesMember" name="OtherRegulatoryLiabilitiesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_PowerGenerationMember" name="PowerGenerationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized" name="PublicUtilitiesAllowanceForFundsUsedDuringConstructionBorrowedInterestCostsCapitalized" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="bkh_RecourseLeverageRatio" name="RecourseLeverageRatio" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="bkh_RestrictedCashFairValueDisclosure" name="RestrictedCashFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="bkh_RestrictedNetAssetsForSubsidiaries" name="RestrictedNetAssetsForSubsidiaries" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="bkh_RetailMember" name="RetailMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_ScheduleOfDefinedBenefitPlansContributionsTableTextBlock" name="ScheduleOfDefinedBenefitPlansContributionsTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_ScheduleOfRegulatoryAssetsAndLiabilitiesLineItems" name="ScheduleOfRegulatoryAssetsAndLiabilitiesLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_ScheduleOfRegulatoryAssetsAndLiabilitiesTable" name="ScheduleOfRegulatoryAssetsAndLiabilitiesTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="bkh_ScheduleOfRegulatoryAssetsAndLiabilitiesTableTextBlock" name="ScheduleOfRegulatoryAssetsAndLiabilitiesTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_SeniorUnsecuredNotesDue2019Member" name="SeniorUnsecuredNotesDue2019Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_TransmissionOtherMember" name="TransmissionOtherMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_TransportationMember" name="TransportationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_UtilitiesGroupMember" name="UtilitiesGroupMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_WeightedAverageNumberOfSharesOutstandingBasicAndDilutedAbstract" name="WeightedAverageNumberOfSharesOutstandingBasicAndDilutedAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="bkh_WholesaleMember" name="WholesaleMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
</xsd:schema>
