<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019df3eb-40a8-7e0e-a884-9eaac569551f,g:3a2290f0-6a15-4b14-bb92-61a9cbd60599-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="https://xbrl.org/2023/arcrole/summation-item" xlink:type="simple" xlink:href="https://www.xbrl.org/2023/calculation-1.1.xsd#summation-item"/>
  <link:roleRef roleURI="http://www.tristategt.org/role/ConsolidatedStatementsofFinancialPosition" xlink:type="simple" xlink:href="tris-20260331.xsd#ConsolidatedStatementsofFinancialPosition"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/ConsolidatedStatementsofFinancialPosition" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7dc2-9d2c-5ea8f29c6966" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019df3eb-4254-79af-9e9f-320f02022ad2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7dc2-9d2c-5ea8f29c6966" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019df3eb-4254-79af-9e9f-320f02022ad2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019df3eb-4254-776c-90fa-362d52baa7d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7dc2-9d2c-5ea8f29c6966" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019df3eb-4254-776c-90fa-362d52baa7d4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_019df3eb-4254-774f-a5d5-d6f729409402" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MinorityInterest"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7dc2-9d2c-5ea8f29c6966" xlink:to="loc_us-gaap_MinorityInterest_019df3eb-4254-774f-a5d5-d6f729409402" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOtherNet_019df3eb-4179-7579-8f5c-8e2e8fbc9840" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentOtherNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOther_019df3eb-4179-7def-8bc9-b2a694abe095" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentOther"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentOtherNet_019df3eb-4179-7579-8f5c-8e2e8fbc9840" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOther_019df3eb-4179-7def-8bc9-b2a694abe095" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipmentOther_019df3eb-4179-7fad-952d-3e8c7c4f2f95" xlink:href="tris-20260331.xsd#tris_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipmentOther"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentOtherNet_019df3eb-4179-7579-8f5c-8e2e8fbc9840" xlink:to="loc_tris_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipmentOther_019df3eb-4179-7fad-952d-3e8c7c4f2f95" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_CapitalizationLongTermDebtNoncurrentAndEquity_019df3eb-4179-7aab-a611-9c7a8b996a09" xlink:href="tris-20260331.xsd#tris_CapitalizationLongTermDebtNoncurrentAndEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4179-75c9-a518-683883868ad6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_CapitalizationLongTermDebtNoncurrentAndEquity_019df3eb-4179-7aab-a611-9c7a8b996a09" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4179-75c9-a518-683883868ad6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019df3eb-4179-7087-8de3-34e556fcf19d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_CapitalizationLongTermDebtNoncurrentAndEquity_019df3eb-4179-7aab-a611-9c7a8b996a09" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019df3eb-4179-7087-8de3-34e556fcf19d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019df3eb-4179-766e-b7fa-f6bacb1b3b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_CapitalizationLongTermDebtNoncurrentAndEquity_019df3eb-4179-7039-a68d-8090fd413250" xlink:href="tris-20260331.xsd#tris_CapitalizationLongTermDebtNoncurrentAndEquity"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019df3eb-4179-766e-b7fa-f6bacb1b3b9d" xlink:to="loc_tris_CapitalizationLongTermDebtNoncurrentAndEquity_019df3eb-4179-7039-a68d-8090fd413250" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-7651-a00d-a1fe951fc584" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019df3eb-4179-766e-b7fa-f6bacb1b3b9d" xlink:to="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-7651-a00d-a1fe951fc584" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities_019df3eb-4179-7048-a5ca-1f1e88aeed15" xlink:href="tris-20260331.xsd#tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019df3eb-4179-766e-b7fa-f6bacb1b3b9d" xlink:to="loc_tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities_019df3eb-4179-7048-a5ca-1f1e88aeed15" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesCurrentAndNoncurrent_019df3eb-4179-7133-a653-47f01ac459d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesCurrentAndNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019df3eb-4179-766e-b7fa-f6bacb1b3b9d" xlink:to="loc_us-gaap_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesCurrentAndNoncurrent_019df3eb-4179-7133-a653-47f01ac459d2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_OtherAssetsAndInvestments_019df3eb-4179-79bd-b253-909209ea1ef4" xlink:href="tris-20260331.xsd#tris_OtherAssetsAndInvestments"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_019df3eb-4179-703c-a0b1-3cae3929e639" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherAssetsAndInvestments_019df3eb-4179-79bd-b253-909209ea1ef4" xlink:to="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_019df3eb-4179-703c-a0b1-3cae3929e639" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_InvestmentsInAndAdvancesToCoalMines_019df3eb-4179-70b2-a4a5-59f58f82dea6" xlink:href="tris-20260331.xsd#tris_InvestmentsInAndAdvancesToCoalMines"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherAssetsAndInvestments_019df3eb-4179-79bd-b253-909209ea1ef4" xlink:to="loc_tris_InvestmentsInAndAdvancesToCoalMines_019df3eb-4179-70b2-a4a5-59f58f82dea6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndInvestmentsNoncurrent_019df3eb-4179-78b8-8f63-444c052ad0af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndInvestmentsNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherAssetsAndInvestments_019df3eb-4179-79bd-b253-909209ea1ef4" xlink:to="loc_us-gaap_RestrictedCashAndInvestmentsNoncurrent_019df3eb-4179-78b8-8f63-444c052ad0af" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019df3eb-4179-78b2-97cc-12f77fa3ed0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherAssetsAndInvestments_019df3eb-4179-79bd-b253-909209ea1ef4" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019df3eb-4179-78b2-97cc-12f77fa3ed0b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatedEntityOtherAssetsNoncurrent_019df3eb-4179-73d3-9489-78eed7cfb1ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatedEntityOtherAssetsNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherAssetsAndInvestments_019df3eb-4179-79bd-b253-909209ea1ef4" xlink:to="loc_us-gaap_RegulatedEntityOtherAssetsNoncurrent_019df3eb-4179-73d3-9489-78eed7cfb1ac" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019df3eb-4179-7a2c-879b-97cc17d0b359" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialsSuppliesAndOther_019df3eb-4179-7e8a-8d0e-242e2cf7c659" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MaterialsSuppliesAndOther"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019df3eb-4179-7a2c-879b-97cc17d0b359" xlink:to="loc_us-gaap_MaterialsSuppliesAndOther_019df3eb-4179-7e8a-8d0e-242e2cf7c659" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019df3eb-4179-7c8e-9347-da205d1d1f4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019df3eb-4179-7a2c-879b-97cc17d0b359" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019df3eb-4179-7c8e-9347-da205d1d1f4a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndInvestmentsCurrent_019df3eb-4179-732a-b413-c8d1a954e6ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndInvestmentsCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019df3eb-4179-7a2c-879b-97cc17d0b359" xlink:to="loc_us-gaap_RestrictedCashAndInvestmentsCurrent_019df3eb-4179-732a-b413-c8d1a954e6ed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedInventoryCoal_019df3eb-4179-78ba-977e-011dd6178b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnergyRelatedInventoryCoal"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019df3eb-4179-7a2c-879b-97cc17d0b359" xlink:to="loc_us-gaap_EnergyRelatedInventoryCoal_019df3eb-4179-78ba-977e-011dd6178b9d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019df3eb-4179-7851-9f14-466d9db227d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019df3eb-4179-7a2c-879b-97cc17d0b359" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019df3eb-4179-7851-9f14-466d9db227d6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherReceivablesNetCurrent_019df3eb-4179-796d-8736-288966e6c539" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherReceivablesNetCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019df3eb-4179-7a2c-879b-97cc17d0b359" xlink:to="loc_us-gaap_OtherReceivablesNetCurrent_019df3eb-4179-796d-8736-288966e6c539" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_DepositsAndAdvancesCurrent_019df3eb-4179-7fa4-bb19-11f19a290503" xlink:href="tris-20260331.xsd#tris_DepositsAndAdvancesCurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019df3eb-4179-7a2c-879b-97cc17d0b359" xlink:to="loc_tris_DepositsAndAdvancesCurrent_019df3eb-4179-7fa4-bb19-11f19a290503" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019df3eb-4254-7203-944f-a98cfc487659" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019df3eb-4254-75c6-8499-e93fd0e4768e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_019df3eb-4254-7203-944f-a98cfc487659" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019df3eb-4254-75c6-8499-e93fd0e4768e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOtherNet_019df3eb-4254-74bc-80a4-3ee03bb66491" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentOtherNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_019df3eb-4254-7203-944f-a98cfc487659" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOtherNet_019df3eb-4254-74bc-80a4-3ee03bb66491" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities_019df3eb-4179-74db-a2de-232c019c413f" xlink:href="tris-20260331.xsd#tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilities_019df3eb-4179-733f-ba45-009e08a19268" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities_019df3eb-4179-74db-a2de-232c019c413f" xlink:to="loc_us-gaap_RegulatoryLiabilities_019df3eb-4179-733f-ba45-009e08a19268" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019df3eb-4179-739b-8b30-c8299920a4be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities_019df3eb-4179-74db-a2de-232c019c413f" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019df3eb-4179-739b-8b30-c8299920a4be" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesNoncurrent_019df3eb-4179-7f6a-9082-541c8689da21" xlink:href="tris-20260331.xsd#tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities_019df3eb-4179-74db-a2de-232c019c413f" xlink:to="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesNoncurrent_019df3eb-4179-7f6a-9082-541c8689da21" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4179-735a-b716-9b3cb70c1e2d" xlink:href="tris-20260331.xsd#tris_OtherDeferredCreditsAndOtherLiabilities"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_DeferredCreditsRegulatoryLiabilitiesAndOtherLiabilities_019df3eb-4179-74db-a2de-232c019c413f" xlink:to="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4179-735a-b716-9b3cb70c1e2d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019df3eb-4179-7f61-8844-32ef4d74e7dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_019df3eb-4179-7c23-991d-97f987e54153" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019df3eb-4179-7f61-8844-32ef4d74e7dc" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_019df3eb-4179-7c23-991d-97f987e54153" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation_019df3eb-4179-7b93-9ecf-fa9ff47c2fa6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019df3eb-4179-7f61-8844-32ef4d74e7dc" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation_019df3eb-4179-7b93-9ecf-fa9ff47c2fa6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_PrepaidExpenseRegulatoryAssetsAndDeferredChargesCurrent_019df3eb-4179-778c-8aa3-cf6bea65a1f2" xlink:href="tris-20260331.xsd#tris_PrepaidExpenseRegulatoryAssetsAndDeferredChargesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_019df3eb-4179-794c-a0a3-c308ddd4f670" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssets"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_PrepaidExpenseRegulatoryAssetsAndDeferredChargesCurrent_019df3eb-4179-778c-8aa3-cf6bea65a1f2" xlink:to="loc_us-gaap_RegulatoryAssets_019df3eb-4179-794c-a0a3-c308ddd4f670" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_019df3eb-4179-7b41-9e84-b11864b40d58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_PrepaidExpenseRegulatoryAssetsAndDeferredChargesCurrent_019df3eb-4179-778c-8aa3-cf6bea65a1f2" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_019df3eb-4179-7b41-9e84-b11864b40d58" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCurrentAndNoncurrent_019df3eb-4179-7681-99a2-63d86782c260" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCostsCurrentAndNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_PrepaidExpenseRegulatoryAssetsAndDeferredChargesCurrent_019df3eb-4179-778c-8aa3-cf6bea65a1f2" xlink:to="loc_us-gaap_DeferredCostsCurrentAndNoncurrent_019df3eb-4179-7681-99a2-63d86782c260" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_019df3eb-4179-7ce5-97ed-08dd6603dfd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceExcludingConstructionWorkInProgress_019df3eb-4179-7587-898d-7e0dd459890a" xlink:href="tris-20260331.xsd#tris_PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceExcludingConstructionWorkInProgress"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_019df3eb-4179-7ce5-97ed-08dd6603dfd1" xlink:to="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceExcludingConstructionWorkInProgress_019df3eb-4179-7587-898d-7e0dd459890a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress_019df3eb-4179-7570-a05c-50f796492d00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_019df3eb-4179-7ce5-97ed-08dd6603dfd1" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress_019df3eb-4179-7570-a05c-50f796492d00" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_MemberAdvancesCurrent_019df3eb-4179-707f-b359-90130e181902" xlink:href="tris-20260331.xsd#tris_MemberAdvancesCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:to="loc_tris_MemberAdvancesCurrent_019df3eb-4179-707f-b359-90130e181902" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019df3eb-4179-7f2e-acb7-04c0366d8a94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:to="loc_us-gaap_AccountsPayableCurrent_019df3eb-4179-7f2e-acb7-04c0366d8a94" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_019df3eb-4179-7508-a5b5-4122e1a25fe7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermBorrowings"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:to="loc_us-gaap_ShortTermBorrowings_019df3eb-4179-7508-a5b5-4122e1a25fe7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_019df3eb-4179-700f-908e-c701bc7bbc3d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_019df3eb-4179-700f-908e-c701bc7bbc3d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationCurrent_019df3eb-4179-7211-bb99-999a7662e2b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligationCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:to="loc_us-gaap_AssetRetirementObligationCurrent_019df3eb-4179-7211-bb99-999a7662e2b5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrent_019df3eb-4179-70cc-aec8-f280038f006a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:to="loc_us-gaap_InterestPayableCurrent_019df3eb-4179-70cc-aec8-f280038f006a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccrualForTaxesOtherThanIncomeTaxesCurrent_019df3eb-4179-7e82-be1c-6c900cddb29d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccrualForTaxesOtherThanIncomeTaxesCurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:to="loc_us-gaap_AccrualForTaxesOtherThanIncomeTaxesCurrent_019df3eb-4179-7e82-be1c-6c900cddb29d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019df3eb-4179-7617-ad9f-5d4155f5bc5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019df3eb-4179-74a7-a223-d5912f7e8795" xlink:to="loc_us-gaap_LongTermDebtCurrent_019df3eb-4179-7617-ad9f-5d4155f5bc5b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019df3eb-4179-7b72-a5f6-d749453a1c17" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019df3eb-4179-7b50-a969-d718f03e5c85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019df3eb-4179-7b72-a5f6-d749453a1c17" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019df3eb-4179-7b50-a969-d718f03e5c85" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_OtherAssetsAndInvestments_019df3eb-4179-782a-b211-dae094f01557" xlink:href="tris-20260331.xsd#tris_OtherAssetsAndInvestments"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019df3eb-4179-7b72-a5f6-d749453a1c17" xlink:to="loc_tris_OtherAssetsAndInvestments_019df3eb-4179-782a-b211-dae094f01557" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019df3eb-4179-7d90-b3de-e3f897c8d98b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019df3eb-4179-7b72-a5f6-d749453a1c17" xlink:to="loc_us-gaap_AssetsCurrent_019df3eb-4179-7d90-b3de-e3f897c8d98b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_PrepaidExpenseRegulatoryAssetsAndDeferredChargesCurrent_019df3eb-4179-70ca-9e3d-a3b5b149d0a7" xlink:href="tris-20260331.xsd#tris_PrepaidExpenseRegulatoryAssetsAndDeferredChargesCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019df3eb-4179-7b72-a5f6-d749453a1c17" xlink:to="loc_tris_PrepaidExpenseRegulatoryAssetsAndDeferredChargesCurrent_019df3eb-4179-70ca-9e3d-a3b5b149d0a7" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/ConsolidatedStatementsofOperationsUnaudited" xlink:type="simple" xlink:href="tris-20260331.xsd#ConsolidatedStatementsofOperationsUnaudited"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/ConsolidatedStatementsofOperationsUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tris_InterestExpenseNetOfCapitalizedInterest_019df3eb-4254-7fe9-85d0-57fccfbdc6b8" xlink:href="tris-20260331.xsd#tris_InterestExpenseNetOfCapitalizedInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019df3eb-4254-7dc5-bbad-a4f3a211165b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_InterestExpenseNetOfCapitalizedInterest_019df3eb-4254-7fe9-85d0-57fccfbdc6b8" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019df3eb-4254-7dc5-bbad-a4f3a211165b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_CapitalizedInterestCostsConstructionProjects_019df3eb-4254-79b6-98f4-ba5f83749146" xlink:href="tris-20260331.xsd#tris_CapitalizedInterestCostsConstructionProjects"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_InterestExpenseNetOfCapitalizedInterest_019df3eb-4254-7fe9-85d0-57fccfbdc6b8" xlink:to="loc_tris_CapitalizedInterestCostsConstructionProjects_019df3eb-4254-79b6-98f4-ba5f83749146" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019df3eb-4254-7a60-8121-8ea44ccf0db4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019df3eb-4254-7169-adec-6588dc3fea55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ProfitLoss_019df3eb-4254-7a60-8121-8ea44ccf0db4" xlink:to="loc_us-gaap_OperatingIncomeLoss_019df3eb-4254-7169-adec-6588dc3fea55" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019df3eb-4254-7c94-a46f-bc232c9aed0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ProfitLoss_019df3eb-4254-7a60-8121-8ea44ccf0db4" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019df3eb-4254-7c94-a46f-bc232c9aed0e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_InterestExpenseNetOfCapitalizedInterest_019df3eb-4254-7146-bb0b-f7efde8e2c1e" xlink:href="tris-20260331.xsd#tris_InterestExpenseNetOfCapitalizedInterest"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ProfitLoss_019df3eb-4254-7a60-8121-8ea44ccf0db4" xlink:to="loc_tris_InterestExpenseNetOfCapitalizedInterest_019df3eb-4254-7146-bb0b-f7efde8e2c1e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019df3eb-4254-7ce4-ab69-7da3d0428ceb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ProfitLoss_019df3eb-4254-7a60-8121-8ea44ccf0db4" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019df3eb-4254-7ce4-ab69-7da3d0428ceb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019df3eb-4254-7ec6-809e-e6cae5b254d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019df3eb-4254-7d38-a6c3-e47e76861ec7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_019df3eb-4254-7ec6-809e-e6cae5b254d5" xlink:to="loc_us-gaap_Revenues_019df3eb-4254-7d38-a6c3-e47e76861ec7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7054-a51a-7920029634cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostsAndExpenses"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_019df3eb-4254-7ec6-809e-e6cae5b254d5" xlink:to="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7054-a51a-7920029634cc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostsAndExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpensePurchasedPower_019df3eb-4254-791f-8d8a-89260e667d98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpensePurchasedPower"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:to="loc_us-gaap_UtilitiesOperatingExpensePurchasedPower_019df3eb-4254-791f-8d8a-89260e667d98" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpenseFuelUsed_019df3eb-4254-7958-84ce-f603ca8f70ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpenseFuelUsed"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:to="loc_us-gaap_UtilitiesOperatingExpenseFuelUsed_019df3eb-4254-7958-84ce-f603ca8f70ac" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_UtilitiesOperatingExpenseProduction_019df3eb-4254-7bf4-acdd-9a09b7dffd69" xlink:href="tris-20260331.xsd#tris_UtilitiesOperatingExpenseProduction"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:to="loc_tris_UtilitiesOperatingExpenseProduction_019df3eb-4254-7bf4-acdd-9a09b7dffd69" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_UtilitiesOperatingExpenseTransmission_019df3eb-4254-757f-aa6b-d5331726f4c1" xlink:href="tris-20260331.xsd#tris_UtilitiesOperatingExpenseTransmission"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:to="loc_tris_UtilitiesOperatingExpenseTransmission_019df3eb-4254-757f-aa6b-d5331726f4c1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019df3eb-4254-798a-b602-a6feb1bf6729" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019df3eb-4254-798a-b602-a6feb1bf6729" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_DepreciationDepletionAndAmortizationExcludingIntangibleAssets_019df3eb-4254-72b8-a2d8-8657b8308f89" xlink:href="tris-20260331.xsd#tris_DepreciationDepletionAndAmortizationExcludingIntangibleAssets"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:to="loc_tris_DepreciationDepletionAndAmortizationExcludingIntangibleAssets_019df3eb-4254-72b8-a2d8-8657b8308f89" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_OperatingExpenseCoalMining_019df3eb-4254-744e-9746-48c6d38586b5" xlink:href="tris-20260331.xsd#tris_OperatingExpenseCoalMining"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:to="loc_tris_OperatingExpenseCoalMining_019df3eb-4254-744e-9746-48c6d38586b5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UtilitiesOperatingExpenseOther_019df3eb-4254-7a35-91eb-6b850ad1fc9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UtilitiesOperatingExpenseOther"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019df3eb-4254-7bfb-942d-3c7dcddcc94a" xlink:to="loc_us-gaap_UtilitiesOperatingExpenseOther_019df3eb-4254-7a35-91eb-6b850ad1fc9d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019df3eb-4254-7259-8fe1-fcbf0bd5d1cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019df3eb-4254-7606-9e78-e674befc2d65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019df3eb-4254-7259-8fe1-fcbf0bd5d1cb" xlink:to="loc_us-gaap_ProfitLoss_019df3eb-4254-7606-9e78-e674befc2d65" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019df3eb-4254-716d-88aa-9a0f77af030c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019df3eb-4254-7259-8fe1-fcbf0bd5d1cb" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019df3eb-4254-716d-88aa-9a0f77af030c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019df3eb-4254-71e7-b844-d4747a83b55d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_019df3eb-4254-7608-891c-865d25e901f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_019df3eb-4254-71e7-b844-d4747a83b55d" xlink:to="loc_us-gaap_InvestmentIncomeInterest_019df3eb-4254-7608-891c-865d25e901f1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_CapitalCreditsFromCooperatives_019df3eb-4254-7078-829f-5d5aebc64bd1" xlink:href="tris-20260331.xsd#tris_CapitalCreditsFromCooperatives"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_019df3eb-4254-71e7-b844-d4747a83b55d" xlink:to="loc_tris_CapitalCreditsFromCooperatives_019df3eb-4254-7078-829f-5d5aebc64bd1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019df3eb-4254-754a-b448-0ab666bc4d64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_019df3eb-4254-71e7-b844-d4747a83b55d" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019df3eb-4254-754a-b448-0ab666bc4d64" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019df3eb-4254-749a-a839-2cd9baaddf59" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019df3eb-4254-77d0-ad84-f29e8fd60389" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_019df3eb-4254-749a-a839-2cd9baaddf59" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019df3eb-4254-77d0-ad84-f29e8fd60389" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_OtherOperatingRevenueIncludingRevenueFromContractWithCustomer_019df3eb-4254-7c73-ac53-2d208c5278fa" xlink:href="tris-20260331.xsd#tris_OtherOperatingRevenueIncludingRevenueFromContractWithCustomer"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_019df3eb-4254-749a-a839-2cd9baaddf59" xlink:to="loc_tris_OtherOperatingRevenueIncludingRevenueFromContractWithCustomer_019df3eb-4254-7c73-ac53-2d208c5278fa" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/ConsolidatedStatementsofComprehensiveIncomeLossUnaudited" xlink:type="simple" xlink:href="tris-20260331.xsd#ConsolidatedStatementsofComprehensiveIncomeLossUnaudited"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/ConsolidatedStatementsofComprehensiveIncomeLossUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7699-a9ea-0e8da17aded2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019df3eb-4254-7dfa-a357-617605659744" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7699-a9ea-0e8da17aded2" xlink:to="loc_us-gaap_ProfitLoss_019df3eb-4254-7dfa-a357-617605659744" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019df3eb-4254-701e-b51a-6499e0905700" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7699-a9ea-0e8da17aded2" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019df3eb-4254-701e-b51a-6499e0905700" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019df3eb-4254-7d4c-b188-d08fbf6ab640" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_019df3eb-4254-70e1-a7f7-778c02177066" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019df3eb-4254-7d4c-b188-d08fbf6ab640" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_019df3eb-4254-70e1-a7f7-778c02177066" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax_019df3eb-4254-740a-868f-ff0aceb258ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019df3eb-4254-7d4c-b188-d08fbf6ab640" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax_019df3eb-4254-740a-868f-ff0aceb258ea" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_019df3eb-4254-7c52-a488-2a178254988c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7358-97f3-908b3d006cf9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_019df3eb-4254-7c52-a488-2a178254988c" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019df3eb-4254-7358-97f3-908b3d006cf9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest_019df3eb-4254-7244-8c06-d9c4e61ea9b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_019df3eb-4254-7c52-a488-2a178254988c" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest_019df3eb-4254-7244-8c06-d9c4e61ea9b3" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/ConsolidatedStatementsofCashFlowsUnaudited" xlink:type="simple" xlink:href="tris-20260331.xsd#ConsolidatedStatementsofCashFlowsUnaudited"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/ConsolidatedStatementsofCashFlowsUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_ProceedsFromPaymentsAppliedMemberAdvances_019df3eb-4254-7867-955e-0cb8465f505e" xlink:href="tris-20260331.xsd#tris_ProceedsFromPaymentsAppliedMemberAdvances"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:to="loc_tris_ProceedsFromPaymentsAppliedMemberAdvances_019df3eb-4254-7867-955e-0cb8465f505e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_019df3eb-4254-76ba-8d4a-06f5c708f3e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_019df3eb-4254-76ba-8d4a-06f5c708f3e2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019df3eb-4254-70c8-9a2a-961bb6f4fa17" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019df3eb-4254-70c8-9a2a-961bb6f4fa17" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019df3eb-4254-7826-b45a-007d1b1687ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019df3eb-4254-7826-b45a-007d1b1687ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromRepaymentsOfShortTermDebt_019df3eb-4254-718d-8e22-8d0b8282b987" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromRepaymentsOfShortTermDebt"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:to="loc_us-gaap_ProceedsFromRepaymentsOfShortTermDebt_019df3eb-4254-718d-8e22-8d0b8282b987" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_PaymentsForRetirementOfPatronageCapital_019df3eb-4254-7a52-87a8-ea0b42418dd5" xlink:href="tris-20260331.xsd#tris_PaymentsForRetirementOfPatronageCapital"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:to="loc_tris_PaymentsForRetirementOfPatronageCapital_019df3eb-4254-7a52-87a8-ea0b42418dd5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToMinorityShareholders_019df3eb-4254-759b-8946-6f84b4da30ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToMinorityShareholders"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:to="loc_us-gaap_PaymentsToMinorityShareholders_019df3eb-4254-759b-8946-6f84b4da30ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_019df3eb-4254-754b-be72-731ab26da984" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-74c4-bf3e-d28401984620" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_019df3eb-4254-754b-be72-731ab26da984" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019df3eb-4254-7716-b631-3c66206d1fc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019df3eb-4254-7363-a0c9-a9642727fc8c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019df3eb-4254-7716-b631-3c66206d1fc9" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019df3eb-4254-7363-a0c9-a9642727fc8c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_ProceedsFromSaleOfElectricPlantAssets_019df3eb-4254-7297-bde1-2f6a4045eaef" xlink:href="tris-20260331.xsd#tris_ProceedsFromSaleOfElectricPlantAssets"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019df3eb-4254-7716-b631-3c66206d1fc9" xlink:to="loc_tris_ProceedsFromSaleOfElectricPlantAssets_019df3eb-4254-7297-bde1-2f6a4045eaef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_ProceedsFromSaleOfNonUtilityAssets_019df3eb-4254-700f-b5db-72daeef5b16c" xlink:href="tris-20260331.xsd#tris_ProceedsFromSaleOfNonUtilityAssets"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019df3eb-4254-7716-b631-3c66206d1fc9" xlink:to="loc_tris_ProceedsFromSaleOfNonUtilityAssets_019df3eb-4254-700f-b5db-72daeef5b16c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredChargesInvesting_019df3eb-4254-7e32-8146-d3f27c5c5813" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInDeferredChargesInvesting"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019df3eb-4254-7716-b631-3c66206d1fc9" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredChargesInvesting_019df3eb-4254-7e32-8146-d3f27c5c5813" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019df3eb-4254-7931-b732-4ed3656495ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_ProfitLoss_019df3eb-4254-7931-b732-4ed3656495ca" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_DepreciationDepletionAndAmortizationExcludingIntangibleAssets_019df3eb-4254-7bbf-92c5-313bd81bc50b" xlink:href="tris-20260331.xsd#tris_DepreciationDepletionAndAmortizationExcludingIntangibleAssets"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_tris_DepreciationDepletionAndAmortizationExcludingIntangibleAssets_019df3eb-4254-7bbf-92c5-313bd81bc50b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019df3eb-4254-7928-8166-f09aece653bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019df3eb-4254-7928-8166-f09aece653bb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_AmortizationOfRetirementAndSecurityPlanPrepayment_019df3eb-4254-7b8b-aaf1-a2ce3f0c37ef" xlink:href="tris-20260331.xsd#tris_AmortizationOfRetirementAndSecurityPlanPrepayment"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_tris_AmortizationOfRetirementAndSecurityPlanPrepayment_019df3eb-4254-7b8b-aaf1-a2ce3f0c37ef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_019df3eb-4254-7105-95ef-92c608588eea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfFinancingCosts"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_019df3eb-4254-7105-95ef-92c608588eea" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationAccretionExpense_019df3eb-4254-7512-aaa3-fddf54308f16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetRetirementObligationAccretionExpense"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_AssetRetirementObligationAccretionExpense_019df3eb-4254-7512-aaa3-fddf54308f16" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_DepositsForGenerationInterconnectionStudies_019df3eb-4254-7b95-a98d-afe7cdccfd58" xlink:href="tris-20260331.xsd#tris_DepositsForGenerationInterconnectionStudies"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_tris_DepositsForGenerationInterconnectionStudies_019df3eb-4254-7b95-a98d-afe7cdccfd58" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_DeferredRevenueRecognized_019df3eb-4254-7a4a-9e19-4b908c8ceb91" xlink:href="tris-20260331.xsd#tris_DeferredRevenueRecognized"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_tris_DeferredRevenueRecognized_019df3eb-4254-7a4a-9e19-4b908c8ceb91" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_CapitalCreditAllocationsFromCooperativesAndIncomeFromCoalMinesUnderOverRefundDistribution_019df3eb-4254-7d12-abc0-f20bc06f24c3" xlink:href="tris-20260331.xsd#tris_CapitalCreditAllocationsFromCooperativesAndIncomeFromCoalMinesUnderOverRefundDistribution"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_tris_CapitalCreditAllocationsFromCooperativesAndIncomeFromCoalMinesUnderOverRefundDistribution_019df3eb-4254-7d12-abc0-f20bc06f24c3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_AmortizationOfTransmissionCredits_019df3eb-4254-7c5c-8600-3da101192f28" xlink:href="tris-20260331.xsd#tris_AmortizationOfTransmissionCredits"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_tris_AmortizationOfTransmissionCredits_019df3eb-4254-7c5c-8600-3da101192f28" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInReceivables_019df3eb-4254-71c3-8cb9-687c5f9db250" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInReceivables"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_IncreaseDecreaseInReceivables_019df3eb-4254-71c3-8cb9-687c5f9db250" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInCoalInventories_019df3eb-4254-796b-a0ca-e17afe298c47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInCoalInventories"/>
    <link:calculationArc order="12" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_IncreaseDecreaseInCoalInventories_019df3eb-4254-796b-a0ca-e17afe298c47" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInMaterialsAndSupplies_019df3eb-4254-79be-8790-ea704795c447" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInMaterialsAndSupplies"/>
    <link:calculationArc order="13" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_IncreaseDecreaseInMaterialsAndSupplies_019df3eb-4254-79be-8790-ea704795c447" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019df3eb-4254-7538-95b7-9463dbeeedf1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019df3eb-4254-7538-95b7-9463dbeeedf1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInterestPayableNet_019df3eb-4254-7f1e-808a-307496916ed4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInInterestPayableNet"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_IncreaseDecreaseInInterestPayableNet_019df3eb-4254-7f1e-808a-307496916ed4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPropertyAndOtherTaxesPayable_019df3eb-4254-72b7-81f3-d72ef2a2329b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInPropertyAndOtherTaxesPayable"/>
    <link:calculationArc order="16" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_IncreaseDecreaseInPropertyAndOtherTaxesPayable_019df3eb-4254-72b7-81f3-d72ef2a2329b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAssetRetirementObligations_019df3eb-4254-73db-82a4-3ffaf53cefd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAssetRetirementObligations"/>
    <link:calculationArc order="17" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_IncreaseDecreaseInAssetRetirementObligations_019df3eb-4254-73db-82a4-3ffaf53cefd3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_IncreaseDecreaseInDeferredMembershipWithdrawal_019df3eb-4254-79a9-ae63-b9c752079ad0" xlink:href="tris-20260331.xsd#tris_IncreaseDecreaseInDeferredMembershipWithdrawal"/>
    <link:calculationArc order="18" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_tris_IncreaseDecreaseInDeferredMembershipWithdrawal_019df3eb-4254-79a9-ae63-b9c752079ad0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_019df3eb-4254-7635-a4e2-cbeff2f08e27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:calculationArc order="19" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-747b-b5d2-3aaec07ae4ae" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_019df3eb-4254-7635-a4e2-cbeff2f08e27" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_019df3eb-4254-79fc-bf7f-a5dde8ee4be2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-79d9-9010-47faae9852e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_019df3eb-4254-79fc-bf7f-a5dde8ee4be2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019df3eb-4254-79d9-9010-47faae9852e1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019df3eb-4254-7b3a-b97d-96efac2d5153" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_019df3eb-4254-79fc-bf7f-a5dde8ee4be2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019df3eb-4254-7b3a-b97d-96efac2d5153" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-776c-98dd-e59d4f35244b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_019df3eb-4254-79fc-bf7f-a5dde8ee4be2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019df3eb-4254-776c-98dd-e59d4f35244b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/ACCOUNTINGFORRATEREGULATIONDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#ACCOUNTINGFORRATEREGULATIONDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/ACCOUNTINGFORRATEREGULATIONDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetRegulatoryAssets_019df3eb-4254-7017-8fed-f5f56e2eefaf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetRegulatoryAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_019df3eb-4254-7766-b1f0-b0c7a05a75ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryAssets"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetRegulatoryAssets_019df3eb-4254-7017-8fed-f5f56e2eefaf" xlink:to="loc_us-gaap_RegulatoryAssets_019df3eb-4254-7766-b1f0-b0c7a05a75ff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilities_019df3eb-4254-7481-9142-90a9152d01ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RegulatoryLiabilities"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetRegulatoryAssets_019df3eb-4254-7017-8fed-f5f56e2eefaf" xlink:to="loc_us-gaap_RegulatoryLiabilities_019df3eb-4254-7481-9142-90a9152d01ad" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/PROPERTYPLANTANDEQUIPMENTElectricPlantDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#PROPERTYPLANTANDEQUIPMENTElectricPlantDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/PROPERTYPLANTANDEQUIPMENTElectricPlantDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentExcludingConstructionInProcessNet_019df3eb-4254-7daa-a2eb-ceb1de18baec" xlink:href="tris-20260331.xsd#tris_PublicUtilitiesPropertyPlantAndEquipmentExcludingConstructionInProcessNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceExcludingConstructionInProgress_019df3eb-4254-7a8f-aa72-ad066dc00e08" xlink:href="tris-20260331.xsd#tris_PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceExcludingConstructionInProgress"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentExcludingConstructionInProcessNet_019df3eb-4254-7daa-a2eb-ceb1de18baec" xlink:to="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceExcludingConstructionInProgress_019df3eb-4254-7a8f-aa72-ad066dc00e08" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation_019df3eb-4254-7968-886e-e58d3cf1ac82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentExcludingConstructionInProcessNet_019df3eb-4254-7daa-a2eb-ceb1de18baec" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation_019df3eb-4254-7968-886e-e58d3cf1ac82" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019df3eb-4254-7815-9a8d-40f67bdca133" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentExcludingConstructionInProcessNet_019df3eb-4254-72bf-8566-43f1c1331b55" xlink:href="tris-20260331.xsd#tris_PublicUtilitiesPropertyPlantAndEquipmentExcludingConstructionInProcessNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019df3eb-4254-7815-9a8d-40f67bdca133" xlink:to="loc_tris_PublicUtilitiesPropertyPlantAndEquipmentExcludingConstructionInProcessNet_019df3eb-4254-72bf-8566-43f1c1331b55" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress_019df3eb-4254-7d4f-aa82-7df2808447c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_019df3eb-4254-7815-9a8d-40f67bdca133" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress_019df3eb-4254-7d4f-aa82-7df2808447c1" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/CASHCASHEQUIVALENTSANDRESTRICTEDCASHANDINVESTMENTSDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#CASHCASHEQUIVALENTSANDRESTRICTEDCASHANDINVESTMENTSDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/CASHCASHEQUIVALENTSANDRESTRICTEDCASHANDINVESTMENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tris_CashCashEquivalentsRestrictedCashRestrictedCashEquivalentsAndInvestments_019df3eb-4254-76ea-887a-8ffcce5dd2c0" xlink:href="tris-20260331.xsd#tris_CashCashEquivalentsRestrictedCashRestrictedCashEquivalentsAndInvestments"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndInvestmentsNoncurrent_019df3eb-4254-7421-8fa6-1ebf1f6803ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndInvestmentsNoncurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_CashCashEquivalentsRestrictedCashRestrictedCashEquivalentsAndInvestments_019df3eb-4254-76ea-887a-8ffcce5dd2c0" xlink:to="loc_us-gaap_RestrictedCashAndInvestmentsNoncurrent_019df3eb-4254-7421-8fa6-1ebf1f6803ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019df3eb-4254-7059-b331-f44b54011a31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_CashCashEquivalentsRestrictedCashRestrictedCashEquivalentsAndInvestments_019df3eb-4254-76ea-887a-8ffcce5dd2c0" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019df3eb-4254-7059-b331-f44b54011a31" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndInvestmentsCurrent_019df3eb-4254-7ff5-a990-7728d62e6527" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndInvestmentsCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_CashCashEquivalentsRestrictedCashRestrictedCashEquivalentsAndInvestments_019df3eb-4254-76ea-887a-8ffcce5dd2c0" xlink:to="loc_us-gaap_RestrictedCashAndInvestmentsCurrent_019df3eb-4254-7ff5-a990-7728d62e6527" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/OTHERDEFERREDCHARGESDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#OTHERDEFERREDCHARGESDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/OTHERDEFERREDCHARGESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCurrentAndNoncurrent_019df3eb-4254-79b3-a15a-82e10a681b0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCostsCurrentAndNoncurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_PreliminarySurveysPlansAndInvestigations_019df3eb-4254-7e5d-ac33-22baeb8448eb" xlink:href="tris-20260331.xsd#tris_PreliminarySurveysPlansAndInvestigations"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredCostsCurrentAndNoncurrent_019df3eb-4254-79b3-a15a-82e10a681b0a" xlink:to="loc_tris_PreliminarySurveysPlansAndInvestigations_019df3eb-4254-7e5d-ac33-22baeb8448eb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_DueFromJointVenturePartners_019df3eb-4254-78d9-ac70-def2d04ddb9e" xlink:href="tris-20260331.xsd#tris_DueFromJointVenturePartners"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredCostsCurrentAndNoncurrent_019df3eb-4254-79b3-a15a-82e10a681b0a" xlink:to="loc_tris_DueFromJointVenturePartners_019df3eb-4254-78d9-ac70-def2d04ddb9e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_LeaseRightOfUseAsset_019df3eb-4254-74ba-b28e-1e3fff231380" xlink:href="tris-20260331.xsd#tris_LeaseRightOfUseAsset"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredCostsCurrentAndNoncurrent_019df3eb-4254-79b3-a15a-82e10a681b0a" xlink:to="loc_tris_LeaseRightOfUseAsset_019df3eb-4254-74ba-b28e-1e3fff231380" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDeferredCostsNet_019df3eb-4254-7b15-8f9f-532685462325" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherDeferredCostsNet"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredCostsCurrentAndNoncurrent_019df3eb-4254-79b3-a15a-82e10a681b0a" xlink:to="loc_us-gaap_OtherDeferredCostsNet_019df3eb-4254-7b15-8f9f-532685462325" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/LONGTERMDEBTSummaryDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#LONGTERMDEBTSummaryDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/LONGTERMDEBTSummaryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019df3eb-4254-7d6a-89a1-9148190de433" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019df3eb-4254-70fa-b1f2-eda3ce0c0a69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_019df3eb-4254-7d6a-89a1-9148190de433" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019df3eb-4254-70fa-b1f2-eda3ce0c0a69" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_019df3eb-4254-780f-82bd-60225714b1da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_019df3eb-4254-7d6a-89a1-9148190de433" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_019df3eb-4254-780f-82bd-60225714b1da" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedPremium_019df3eb-4254-7b2a-b51a-1a2823e48c74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedPremium"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_019df3eb-4254-7d6a-89a1-9148190de433" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedPremium_019df3eb-4254-7b2a-b51a-1a2823e48c74" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_019df3eb-4254-7885-932d-e9042ab9ed94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_019df3eb-4254-7d6a-89a1-9148190de433" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_019df3eb-4254-7885-932d-e9042ab9ed94" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/LONGTERMDEBTSummaryDetails_1" xlink:type="simple" xlink:href="tris-20260331.xsd#LONGTERMDEBTSummaryDetails_1"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/LONGTERMDEBTSummaryDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019df3eb-4254-7470-8fe4-b4e6cad46a99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019df3eb-4254-7554-ae64-e31bc6fed30b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_019df3eb-4254-7470-8fe4-b4e6cad46a99" xlink:to="loc_us-gaap_LongTermDebtCurrent_019df3eb-4254-7554-ae64-e31bc6fed30b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019df3eb-4254-7b87-910a-b82ec2065096" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_019df3eb-4254-7470-8fe4-b4e6cad46a99" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019df3eb-4254-7b87-910a-b82ec2065096" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/ASSETRETIREMENTANDENVIRONMENTALREMEDIATIONOBLIGATIONSSummaryDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#ASSETRETIREMENTANDENVIRONMENTALREMEDIATIONOBLIGATIONSSummaryDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/ASSETRETIREMENTANDENVIRONMENTALREMEDIATIONOBLIGATIONSSummaryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingencies_019df3eb-4254-74f6-bb21-baabc2346fcf" xlink:href="tris-20260331.xsd#tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingencies"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesCurrent_019df3eb-4254-77eb-8021-80d2f4696a7a" xlink:href="tris-20260331.xsd#tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingencies_019df3eb-4254-74f6-bb21-baabc2346fcf" xlink:to="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesCurrent_019df3eb-4254-77eb-8021-80d2f4696a7a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesNoncurrent_019df3eb-4254-79f7-b163-c37a06c0bc86" xlink:href="tris-20260331.xsd#tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingencies_019df3eb-4254-74f6-bb21-baabc2346fcf" xlink:to="loc_tris_AssetRetirementObligationAndAccrualForEnvironmentalLossContingenciesNoncurrent_019df3eb-4254-79f7-b163-c37a06c0bc86" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/OTHERDEFERREDCREDITSANDOTHERLIABILITIESSummaryDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#OTHERDEFERREDCREDITSANDOTHERLIABILITIESSummaryDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/OTHERDEFERREDCREDITSANDOTHERLIABILITIESSummaryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4254-7e6a-b525-47f01ddf1327" xlink:href="tris-20260331.xsd#tris_OtherDeferredCreditsAndOtherLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_EasementRightOfWayPresentValueOfPaymentsDue_019df3eb-4254-7c76-8635-d0a2c51ba424" xlink:href="tris-20260331.xsd#tris_EasementRightOfWayPresentValueOfPaymentsDue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4254-7e6a-b525-47f01ddf1327" xlink:to="loc_tris_EasementRightOfWayPresentValueOfPaymentsDue_019df3eb-4254-7c76-8635-d0a2c51ba424" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_TransmissionDeposits_019df3eb-4254-7d49-83f2-2f51232a4fbb" xlink:href="tris-20260331.xsd#tris_TransmissionDeposits"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4254-7e6a-b525-47f01ddf1327" xlink:to="loc_tris_TransmissionDeposits_019df3eb-4254-7d49-83f2-2f51232a4fbb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_019df3eb-4254-7cd4-8b36-9973ab436423" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4254-7e6a-b525-47f01ddf1327" xlink:to="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_019df3eb-4254-7cd4-8b36-9973ab436423" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_CustomerDepositsToBeReturned_019df3eb-4254-7a60-ad9a-108120274449" xlink:href="tris-20260331.xsd#tris_CustomerDepositsToBeReturned"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4254-7e6a-b525-47f01ddf1327" xlink:to="loc_tris_CustomerDepositsToBeReturned_019df3eb-4254-7a60-ad9a-108120274449" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_019df3eb-4254-7bfa-a3a1-85c176abe4da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4254-7e6a-b525-47f01ddf1327" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_019df3eb-4254-7bfa-a3a1-85c176abe4da" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_LeaseLiabilityNoncurrent_019df3eb-4254-7e54-aa46-f407ca0c3f25" xlink:href="tris-20260331.xsd#tris_LeaseLiabilityNoncurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4254-7e6a-b525-47f01ddf1327" xlink:to="loc_tris_LeaseLiabilityNoncurrent_019df3eb-4254-7e54-aa46-f407ca0c3f25" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_019df3eb-4254-7b4f-89a6-0cb226752342" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilities"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_tris_OtherDeferredCreditsAndOtherLiabilities_019df3eb-4254-7e6a-b525-47f01ddf1327" xlink:to="loc_us-gaap_OtherLiabilities_019df3eb-4254-7b4f-89a6-0cb226752342" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/EMPLOYEEBENEFITPLANSNRECAExecutiveBenefitRestorationPlanObligationsDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#EMPLOYEEBENEFITPLANSNRECAExecutiveBenefitRestorationPlanObligationsDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/EMPLOYEEBENEFITPLANSNRECAExecutiveBenefitRestorationPlanObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_019df3eb-4254-7707-973d-67ca621dda5a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_019df3eb-4254-7bce-8ff1-b9089a414893" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_019df3eb-4254-7707-973d-67ca621dda5a" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_019df3eb-4254-7bce-8ff1-b9089a414893" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_019df3eb-4254-76c9-988b-11b8b3741f21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_019df3eb-4254-7707-973d-67ca621dda5a" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_019df3eb-4254-76c9-988b-11b8b3741f21" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/LEASESLeaseComponentsDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#LEASESLeaseComponentsDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/LEASESLeaseComponentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAsset_019df3eb-4254-7a5f-a456-f3dec98a0661" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeaseRightOfUseAsset"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAccumulatedAmortization_019df3eb-4254-704d-b800-365e0ced93df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeaseRightOfUseAssetAccumulatedAmortization"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAsset_019df3eb-4254-7a5f-a456-f3dec98a0661" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAccumulatedAmortization_019df3eb-4254-704d-b800-365e0ced93df" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_019df3eb-4254-7b69-9790-aa3dec697cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAsset_019df3eb-4254-7a5f-a456-f3dec98a0661" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_019df3eb-4254-7b69-9790-aa3dec697cb5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_019df3eb-4254-7d3d-8d77-b8eabd3e10ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019df3eb-4254-74f2-9396-ce9e39030b4e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseLiability_019df3eb-4254-7d3d-8d77-b8eabd3e10ae" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019df3eb-4254-74f2-9396-ce9e39030b4e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_019df3eb-4254-7819-99ed-6d77b1308d42" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseLiability_019df3eb-4254-7d3d-8d77-b8eabd3e10ae" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_019df3eb-4254-7819-99ed-6d77b1308d42" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_019df3eb-4254-77c5-9ef7-f2cfb72fae5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_019df3eb-4254-7b5b-9a55-37318ce76fd5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiability_019df3eb-4254-77c5-9ef7-f2cfb72fae5c" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_019df3eb-4254-7b5b-9a55-37318ce76fd5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_019df3eb-4254-7231-8419-25372b7d9fcb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiability_019df3eb-4254-77c5-9ef7-f2cfb72fae5c" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_019df3eb-4254-7231-8419-25372b7d9fcb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019df3eb-4254-7567-b467-95c359c48ad2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_OperatingLeaseRightOfUseAssetGross_019df3eb-4254-78c6-8fae-03955df51d52" xlink:href="tris-20260331.xsd#tris_OperatingLeaseRightOfUseAssetGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseRightOfUseAsset_019df3eb-4254-7567-b467-95c359c48ad2" xlink:to="loc_tris_OperatingLeaseRightOfUseAssetGross_019df3eb-4254-78c6-8fae-03955df51d52" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_tris_AccumulatedAmortizationOperatingLeaseRightOfUseAsset_019df3eb-4254-7948-b834-5ec71e94240f" xlink:href="tris-20260331.xsd#tris_AccumulatedAmortizationOperatingLeaseRightOfUseAsset"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseRightOfUseAsset_019df3eb-4254-7567-b467-95c359c48ad2" xlink:to="loc_tris_AccumulatedAmortizationOperatingLeaseRightOfUseAsset_019df3eb-4254-7948-b834-5ec71e94240f" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/LEASESFutureMinimumLeaseCommitmentsDetails" xlink:type="simple" xlink:href="tris-20260331.xsd#LEASESFutureMinimumLeaseCommitmentsDetails"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/LEASESFutureMinimumLeaseCommitmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7460-b86b-7e276f47895b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_019df3eb-4254-7a29-bb4d-97a9c0eadfb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7460-b86b-7e276f47895b" xlink:to="loc_us-gaap_OperatingLeaseLiability_019df3eb-4254-7a29-bb4d-97a9c0eadfb8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_019df3eb-4254-7a31-b7ab-fdc586b31fca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7460-b86b-7e276f47895b" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_019df3eb-4254-7a31-b7ab-fdc586b31fca" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.tristategt.org/role/LEASESFutureMinimumLeaseCommitmentsDetails_1" xlink:type="simple" xlink:href="tris-20260331.xsd#LEASESFutureMinimumLeaseCommitmentsDetails_1"/>
  <link:calculationLink xlink:role="http://www.tristategt.org/role/LEASESFutureMinimumLeaseCommitmentsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7dd1-a368-8b7b9cee5cc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths_019df3eb-4254-7825-b5cf-15b8e6a6d7d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7dd1-a368-8b7b9cee5cc5" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths_019df3eb-4254-7825-b5cf-15b8e6a6d7d8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo_019df3eb-4254-700f-9c80-8efabee9cba6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7dd1-a368-8b7b9cee5cc5" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo_019df3eb-4254-700f-9c80-8efabee9cba6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree_019df3eb-4254-7016-8491-7445b5ed5d27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7dd1-a368-8b7b9cee5cc5" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree_019df3eb-4254-7016-8491-7445b5ed5d27" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour_019df3eb-4254-7a56-88ba-c98731d3b693" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7dd1-a368-8b7b9cee5cc5" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour_019df3eb-4254-7a56-88ba-c98731d3b693" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive_019df3eb-4254-7765-b729-b9a7afa7af91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7dd1-a368-8b7b9cee5cc5" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive_019df3eb-4254-7765-b729-b9a7afa7af91" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive_019df3eb-4254-7182-963b-3f097286c807" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_019df3eb-4254-7dd1-a368-8b7b9cee5cc5" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive_019df3eb-4254-7182-963b-3f097286c807" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
