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    <ReturnTs>2026-03-28T16:30:06-07:00</ReturnTs>
    <TaxPeriodEndDt>2023-12-31</TaxPeriodEndDt>
    <ReturnTypeCd>990EZ</ReturnTypeCd>
    <TaxPeriodBeginDt>2023-12-01</TaxPeriodBeginDt>
    <Filer>
      <EIN>030502889</EIN>
      <BusinessName>
        <BusinessNameLine1Txt>RIO MESA MUTUAL WATER COMPANY</BusinessNameLine1Txt>
      </BusinessName>
      <BusinessNameControlTxt>RIOM</BusinessNameControlTxt>
      <PhoneNum>7147261981</PhoneNum>
      <USAddress>
        <AddressLine1Txt>11201 RIO MESA DR</AddressLine1Txt>
        <CityNm>BAKERSFIELD</CityNm>
        <StateAbbreviationCd>CA</StateAbbreviationCd>
        <ZIPCd>93308</ZIPCd>
      </USAddress>
    </Filer>
    <BusinessOfficerGrp>
      <PersonNm>MARGARET FRANTZ</PersonNm>
      <PersonTitleTxt>FINANCE</PersonTitleTxt>
      <PhoneNum>7147261981</PhoneNum>
      <SignatureDt>2024-06-11</SignatureDt>
    </BusinessOfficerGrp>
    <IRSResponsiblePrtyInfoCurrInd>1</IRSResponsiblePrtyInfoCurrInd>
    <TaxYr>2023</TaxYr>
    <BuildTS>2025-03-06 01:10:19Z</BuildTS>
  </ReturnHeader>
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    <IRS990EZ accountingPeriodChangeCd="CHANGE OF ACCOUNTING PERIOD" accountingPeriodChangeApprvCd="REVENUE PROCEDURE 85-58 RULES APPLY" documentId="R000001" referenceDocumentId="R000002" softwareId="23018249" softwareVersionNum="v1.00">
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      <ScheduleBNotRequiredInd>X</ScheduleBNotRequiredInd>
      <Organization501cInd organization501cTypeTxt="12">X</Organization501cInd>
      <TypeOfOrganizationOtherInd>X</TypeOfOrganizationOtherInd>
      <TypeOfOrganizationOtherDesc>MUTUAL WATER</TypeOfOrganizationOtherDesc>
      <GrossReceiptsAmt>4108</GrossReceiptsAmt>
      <ContributionsGiftsGrantsEtcAmt>4108</ContributionsGiftsGrantsEtcAmt>
      <ProgramServiceRevenueAmt>0</ProgramServiceRevenueAmt>
      <MembershipDuesAmt>0</MembershipDuesAmt>
      <InvestmentIncomeAmt>0</InvestmentIncomeAmt>
      <SaleOfAssetsGrossAmt>0</SaleOfAssetsGrossAmt>
      <CostOrOtherBasisExpenseSaleAmt>0</CostOrOtherBasisExpenseSaleAmt>
      <GainOrLossFromSaleOfAssetsAmt>0</GainOrLossFromSaleOfAssetsAmt>
      <GamingGrossIncomeAmt>0</GamingGrossIncomeAmt>
      <FundraisingGrossIncomeAmt fndrsngEventContriPrevRptAmt="0">0</FundraisingGrossIncomeAmt>
      <SpecialEventsDirectExpensesAmt>0</SpecialEventsDirectExpensesAmt>
      <SpecialEventsNetIncomeLossAmt>0</SpecialEventsNetIncomeLossAmt>
      <GrossSalesOfInventoryAmt>0</GrossSalesOfInventoryAmt>
      <CostOfGoodsSoldAmt>0</CostOfGoodsSoldAmt>
      <GrossProfitLossSlsOfInvntryAmt>0</GrossProfitLossSlsOfInvntryAmt>
      <OtherRevenueTotalAmt>0</OtherRevenueTotalAmt>
      <TotalRevenueAmt>4108</TotalRevenueAmt>
      <GrantsAndSimilarAmountsPaidAmt>0</GrantsAndSimilarAmountsPaidAmt>
      <BenefitsPaidToOrForMembersAmt>0</BenefitsPaidToOrForMembersAmt>
      <SalariesOtherCompEmplBnftAmt>0</SalariesOtherCompEmplBnftAmt>
      <FeesAndOtherPymtToIndCntrctAmt>842</FeesAndOtherPymtToIndCntrctAmt>
      <OccupancyRentUtltsAndMaintAmt>660</OccupancyRentUtltsAndMaintAmt>
      <PrintingPublicationsPostageAmt>0</PrintingPublicationsPostageAmt>
      <OtherExpensesTotalAmt>0</OtherExpensesTotalAmt>
      <TotalExpensesAmt>1502</TotalExpensesAmt>
      <ExcessOrDeficitForYearAmt>2606</ExcessOrDeficitForYearAmt>
      <NetAssetsOrFundBalancesBOYAmt>54859</NetAssetsOrFundBalancesBOYAmt>
      <OtherChangesInNetAssetsAmt>0</OtherChangesInNetAssetsAmt>
      <NetAssetsOrFundBalancesEOYAmt>57465</NetAssetsOrFundBalancesEOYAmt>
      <CashSavingsAndInvestmentsGrp>
        <BOYAmt>54859</BOYAmt>
        <EOYAmt>57465</EOYAmt>
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      <LandAndBuildingsGrp>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </LandAndBuildingsGrp>
      <OtherAssetsTotalDetail>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </OtherAssetsTotalDetail>
      <Form990TotalAssetsGrp>
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        <EOYAmt>57465</EOYAmt>
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      <SumOfTotalLiabilitiesGrp>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
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      <NetAssetsOrFundBalancesGrp>
        <BOYAmt>54859</BOYAmt>
        <EOYAmt>57465</EOYAmt>
      </NetAssetsOrFundBalancesGrp>
      <PrimaryExemptPurposeTxt>PROVIDING WATER UTILITIES</PrimaryExemptPurposeTxt>
      <ProgramSrvcAccomplishmentGrp>
        <DescriptionProgramSrvcAccomTxt>PROVIDE WATER SERVICES TO PROPERTY OWNERS</DescriptionProgramSrvcAccomTxt>
      </ProgramSrvcAccomplishmentGrp>
      <TotalProgramServiceExpensesAmt>0</TotalProgramServiceExpensesAmt>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>BRENDA STORY</PersonNm>
        <TitleTxt>PRESIDENT</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>1</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>ROBERT PAULK</PersonNm>
        <TitleTxt>SECRETARY</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>1</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>MARGARET FRANTZ</PersonNm>
        <TitleTxt>TREASURER</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>1</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <ActivitiesNotPreviouslyRptInd>0</ActivitiesNotPreviouslyRptInd>
      <ChgMadeToOrgnzngDocNotRptInd>0</ChgMadeToOrgnzngDocNotRptInd>
      <OrganizationHadUBIInd>0</OrganizationHadUBIInd>
      <SubjectToProxyTaxInd>0</SubjectToProxyTaxInd>
      <OrganizationDissolvedEtcInd>0</OrganizationDissolvedEtcInd>
      <DirectIndirectPltclExpendAmt>0</DirectIndirectPltclExpendAmt>
      <Form1120PolFiledInd>0</Form1120PolFiledInd>
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      <ProhibitedTaxShelterTransInd>0</ProhibitedTaxShelterTransInd>
      <StatesWhereCopyOfReturnIsFldCd>CA</StatesWhereCopyOfReturnIsFldCd>
      <BooksInCareOfDetail>
        <PersonNm>MARGARET FRANTZ</PersonNm>
        <USAddress>
          <AddressLine1Txt>11201 RIO MESA DR</AddressLine1Txt>
          <CityNm>BAKERSFIELD</CityNm>
          <StateAbbreviationCd>CA</StateAbbreviationCd>
          <ZIPCd>93308</ZIPCd>
        </USAddress>
        <PhoneNum>7147261981</PhoneNum>
      </BooksInCareOfDetail>
      <ForeignFinancialAccountInd>0</ForeignFinancialAccountInd>
      <ForeignOfficeInd>0</ForeignOfficeInd>
      <DonorAdvisedFndsInd>0</DonorAdvisedFndsInd>
      <OperateHospitalInd>0</OperateHospitalInd>
      <TanningServicesProvidedInd>0</TanningServicesProvidedInd>
      <RelatedOrganizationCtrlEntInd>0</RelatedOrganizationCtrlEntInd>
      <TransactionWithControlEntInd>0</TransactionWithControlEntInd>
      <PoliticalCampaignActyInd>0</PoliticalCampaignActyInd>
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    <ReasonableCauseExplanation documentId="R000002" softwareId="23018249" softwareVersionNum="v1.00">
      <ExplanationTxt>CHANGING OUR CALENDER YEAR FROM DEC THRU NOVEMBER TO CALENDAR YEAR AND THIS IS TO MAKE UP FOR THAT ONE MISSING MONTH</ExplanationTxt>
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