Commitments, Guarantees and Contingencies	9 Months Ended
Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments, Guarantees and Contingencies	COMMITMENTS, GUARANTEES AND CONTINGENCIES Power Purchase and Sale Agreements. Our long-term PPAs have been evaluated under the accounting guidance for variable interest entities. We have determined that either we have no variable interest in the PPAs or, where we do have variable interests, we are not the primary beneficiary; therefore, consolidation is not required. These conclusions are based on the fact that we do not have both control over activities that are most significant to the entity and an obligation to absorb losses or receive benefits from the entity’s performance. Our financial exposure relating to these PPAs is limited to our capacity and energy payments. Our PPAs are summarized in Note 9. Commitments, Guarantees and Contingencies to the Consolidated Financial Statements in our 2022 Form 10-K, with additional disclosure provided in the following paragraphs. Square Butte PPA. As of September 30, 2023, Square Butte had total debt outstanding of $176.9 million. Fuel expenses are recoverable through Minnesota Power’s fuel adjustment clause and include the cost of coal purchased from BNI Energy under a long-term contract. Minnesota Power’s cost of power purchased from Square Butte during the nine months ended September 30, 2023, was $64.8 million ($63.8 million for the same period in 2022). This reflects Minnesota Power’s pro rata share of total Square Butte costs based on the 50 percent output entitlement. Included in this amount was Minnesota Power’s pro rata share of interest expense of $4.1 million ($3.7 million for the same period in 2022). Minnesota Power’s payments to Square Butte are approved as a purchased power expense for ratemaking purposes by both the MPUC and the FERC. Minnkota Power PSA. Minnesota Power has a PSA with Minnkota Power, which commenced in 2014. Under the PSA, Minnesota Power is selling a portion of its entitlement from Square Butte to Minnkota Power, resulting in Minnkota Power’s net entitlement increasing and Minnesota Power’s net entitlement decreasing until Minnesota Power’s share is eliminated at the end of 2025. Of Minnesota Power’s 50 percent output entitlement, Minnesota Power sold to Minnkota Power approximately 37 percent in 2023 and 32 percent in 2022. Coal, Rail and Shipping Contracts. Minnesota Power has coal supply agreements providing for the purchase of a significant portion of its coal requirements through December 2025. Minnesota Power also has coal transportation agreements in place for the delivery of a significant portion of its coal requirements through December 2024. The costs of fuel and related transportation costs for Minnesota Power’s generation are recoverable from Minnesota Power’s retail and municipal utility customers through the fuel adjustment clause. Environmental Matters. Our businesses are subject to regulation of environmental matters by various federal, state and local authorities. A number of regulatory changes to the Clean Air Act, the Clean Water Act and various waste management requirements have been promulgated by both the EPA and state authorities over the past several years. Minnesota Power’s facilities are subject to additional requirements under many of these regulations. Minnesota Power is reshaping its generation portfolio, over time, to reduce its reliance on coal, has installed cost-effective emission control technology, and advocates for sound science and policy during rulemaking implementation. NOTE 6. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued) Environmental Matters (Continued) We consider our businesses to be in substantial compliance with currently applicable environmental regulations and believe all necessary permits have been obtained. We anticipate that with many state and federal environmental regulations and requirements finalized, or to be finalized in the near future, potential expenditures for future environmental matters may be material and require significant capital investments. Minnesota Power has evaluated various environmental compliance scenarios using possible outcomes of environmental regulations to project power supply trends and impacts on customers. We review environmental matters on a quarterly basis. Accruals for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated based on current law and existing technologies. Accruals are adjusted as assessment and remediation efforts progress, or as additional technical or legal information becomes available. Accruals for environmental liabilities are included in the Consolidated Balance Sheet at undiscounted amounts and exclude claims for recoveries from insurance or other third parties. Costs related to environmental contamination treatment and cleanup are expensed unless recoverable in rates from customers. Air. The electric utility industry is regulated both at the federal and state level to address air emissions. Minnesota Power’s thermal generating facilities mainly burn low-sulfur western sub-bituminous coal. All of Minnesota Power’s coal-fired generating facilities are equipped with pollution control equipment such as scrubbers, baghouses and low NOX technologies. Under currently applicable environmental regulations, these facilities are substantially compliant with emission requirements. Cross-State Air Pollution Rule (CSAPR). The CSAPR requires certain states, including Minnesota, to reduce power plant emissions that contribute to ozone or fine particulate pollution in other states. The CSAPR does not require installation of controls but does require facilities have sufficient allowances to cover their emissions on an annual basis. These allowances are allocated to facilities from each state’s annual budget, and can be bought and sold. Minnesota Power continues to monitor ongoing CSAPR rulemakings and compliance implementation, including the EPA’s Good Neighbor Plan published June 5, 2023, modifying certain aspects of the CSAPR’s program scope and extent. National Ambient Air Quality Standards (NAAQS). The EPA is required to review the NAAQS every five years. If the EPA determines that a state’s air quality is not in compliance with the NAAQS, the state is required to adopt plans describing how it will reduce emissions to attain the NAAQS. Minnesota Power actively monitors NAAQS developments and compliance costs for existing standards or proposed NAAQS revisions are not currently expected to be material. The EPA is currently reviewing the secondary NAAQS for NOx and SO2, as well as particulate matter. In June 2021, the EPA announced it would reconsider the December 2020 final rule retaining the 2012 particulate matter NAAQS. On January 6, 2023, the EPA announced a proposed rule to revise the primary annual particulate matter NAAQS from its current level while retaining the other primary and secondary particulate matter NAAQS. The rule was advanced to the White House Office of Management and Budget (OMB) on September 22, 2023 and a final rule is tentatively expected by the end of the year. The EPA also announced in October 2021 that it was reconsidering the 2020 Ozone NAAQS rule finalized in December 2020, and issued an initial draft policy assessment on April 28, 2022, recommending retention of the current standard. A second version of the draft policy assessment was then published for public comment on March 1, 2023. Subsequently on August 21, 2023, the EPA announced it would cease reconsideration of the Ozone NAAQS and initiate a new review instead. This new NAAQS review is expected to take several years, during which time the existing 2020 ozone NAAQS will remain in place. Anticipated timelines and compliance costs related to the proposed and expected NAAQS revisions cannot yet be estimated; however, costs could be material. Minnesota Power would seek recovery of additional costs through a rate proceeding. EPA Good Neighbor Plan for 2015 Ozone NAAQS. On June 5, 2023, the EPA published a final Federal Implementation Plan (FIP) rule in the Federal Register, the Good Neighbor Plan, to address regional ozone transport for the 2015 Ozone NAAQS by reducing NOx emissions during the period of May 1 through September 30 (ozone season). This rule addresses certain good neighbor or interstate transport provisions of the Clean Air Act relative to the 2015 Ozone NAAQS. In the justification for the final rule, the EPA asserts that 23 states, including Minnesota, are modeled as significant contributors to downwind states’ challenges in attaining or maintaining ozone NAAQS compliance within their state borders. The Good Neighbor Plan is designed to resolve this interstate transport issue by implementing a variety of NOx reduction strategies, including federal implementation plan requirements, NOx emission limitations, and ozone season allowance program requirements, beginning with the 2023 ozone season. The final rule imposes restrictions on fossil-fuel fired power plants in 22 states and on certain industrial sources in 20 states. Implementation of the rule will occur in part through changes to the existing CSAPR program for power plants. NOTE 6. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued) Environmental Matters (Continued) Minnesota Power previously submitted public comments to the EPA on the April 2022 proposed Good Neighbor Plan. Concerns noted by Minnesota Power and other entities included the technical accuracy of the EPA’s assumptions and methods used to identify Minnesota as a significant contributor state, as well as the proposed rule’s intended timeline. On February 13, 2023, the EPA also published its final rule to partially disapprove the Good Neighbor State Implementation Plans (SIPs) for the states of Minnesota and Wisconsin, and to disapprove 19 other SIP submissions. The SIP final action subjects Minnesota to the final Good Neighbor Plan and associated compliance costs will be known when the final SIP rule evaluation and implementation has been completed. On April 14, 2023, Minnesota Power and a coalition of other Minnesota utilities and industry (the parties) co-filed challenges to the EPA’s final Minnesota SIP disapproval, submitting a petition for reconsideration and stay to the EPA and a petition for judicial review to the U.S. Court of Appeals for the Eighth Circuit (Eighth Circuit Court). The parties are challenging and requesting reconsideration of certain technical components of the EPA’s review and subsequent partial disapproval of the state of Minnesota’s SIP, including the rulemaking process, air modeling practices and other emissions inventory aspects. On May 31, 2023, the parties filed a motion to stay the SIP disapproval with the Eighth Circuit Court, which granted the stay on July 5, 2023, which prevents the Good Neighbor Plan from taking effect in Minnesota while the stay remains in effect. On September 29, 2023, the EPA issued an updated final interim rule addressing the stays in Minnesota and five other states, formally staying the effectiveness of the final FIP for states with active stays in place. The state of Minnesota was therefore not subject to compliance obligations for the 2023 ozone season, which would have gone into effect on August 4, 2023. Future compliance obligations will depend on the eventual resolution of the stay and appeal. Additionally, challenges have been filed against the final SIP rule by the Minnesota coalition parties and other entities. Anticipated compliance costs related to final Good Neighbor Plan compliance cannot yet be estimated due to uncertainties about SIP approval status, implementation timing, and allowance costs and facility emissions during the ozone season. However, the costs could be material, including costs of additional NOx controls, emission allowance program participation, or operational changes, if any are required. Minnesota Power would seek recovery of additional costs through a rate proceeding. EPA National Emission Standards for Hazardous Air Pollutants for Major Sources: Industrial, Commercial and Institutional Boilers and Process Heaters (Industrial Boiler MACT) Rule. A final rule issued by the EPA for Industrial Boiler MACT became effective in 2013 with compliance required at major existing sources in 2016. Minnesota Power’s Hibbard Renewable Energy Center and Rapids Energy Center are subject to this rule. Compliance with the Industrial Boiler MACT Rule consisted largely of adjustments to fuels and operating practices and compliance costs were not material. Subsequent to this initial rulemaking, litigation from 2016 through 2018 resulted in court orders directing that the EPA reconsider certain aspects of the regulation including the basis for and numerical value of several different emission limits. On October 6, 2022, the EPA published a final rule in the Federal Register incorporating these changes. The rule became effective on December 5, 2022, imposing a compliance deadline of October 6, 2025. Minnesota Power’s review of this new rule indicates that the revisions should not significantly impact its affected units. As such, compliance costs associated with the new Industrial Boiler MACT Rule are not currently expected to be material; however, Minnesota Power would seek recovery of additional costs through a rate proceeding. EPA Mercury and Air Toxics Standards (MATS) Rule. On April 24, 2023, the EPA published a proposed revision to the existing MATS Rule as part of its mandatory 2020 MATS review. In this proposed rule, the EPA is proposing to alter certain compliance and operational requirements, and to lower several emission limits including filterable particulate matter as well as mercury for lignite units. Compliance would be due in the 2026 to 2027 timeframe. The MATS regulation applies at Minnesota Power’s Boswell facility, which is currently well-controlled for these emissions and is in full compliance with existing requirements. Initial review of this draft regulation indicates that compliance costs should not be material based on the proposed revision. The EPA expects to issue the final rule in March 2024. Compliance costs cannot yet be estimated; however, recovery of any additional costs would be sought through a rate proceeding. NOTE 6. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued) Environmental Matters (Continued) Climate Change. The scientific community generally accepts that emissions of GHGs are linked to global climate change which creates physical and financial risks. Physical risks could include, but are not limited to: increased or decreased precipitation and water levels in lakes and rivers; increased or other changes in temperatures; increased risk of wildfires; and changes in the intensity and frequency of extreme weather events. These all have the potential to affect the Company’s business and operations. We are addressing climate change by taking the following steps that also ensure reliable and environmentally compliant generation resources to meet our customers’ requirements: •Expanding renewable power supply for both our operations and the operations of others; •Providing energy conservation initiatives for our customers and engaging in other demand side management efforts; •Improving efficiency of our generating facilities; •Supporting research of technologies to reduce carbon emissions from generating facilities and carbon sequestration efforts; •Evaluating and developing less carbon intensive future generating assets such as efficient and flexible natural gas‑fired generating facilities; •Managing vegetation on right-of-way corridors to reduce potential wildfire or storm damage risks; and •Practicing sound forestry management in our service territories to create landscapes more resilient to disruption from climate-related changes, including planting and managing long-lived conifer species. EPA Regulation of GHG Emissions. On May 23, 2023, the EPA published in the Federal Register a proposal for five separate regulatory actions under Section 111 of the Clean Air Act (CAA) addressing greenhouse gas (GHG) emissions from fossil fuel-fired electric generating units (EGUs). The EPA is proposing revised new source performance standards (NSPS) for new, modified and reconstructed EGUs (Section 111(b) of the CAA) as well as emission guidelines for certain existing (Section 111(d) of the CAA) EGUs. The EPA also proposed in this action to officially repeal the predecessor regulation “Affordable Clean Energy Rule”, first issued in 2019 and later vacated in 2021. The draft rules were open for public comment until August 8, 2023, and the EPA’s Spring 2023 unified agenda identifies the EPA’s goal of issuing final regulations in April 2024. The Company will continue to monitor this GHG rulemaking and analyze potential impacts to our existing and proposed thermal generating facilities from the draft Section 111 rules, which would apply to several Company assets including existing EGUs at the Boswell and Laskin facilities as well as the proposed combined cycle natural gas-fired generating facility, NTEC. Minnesota Power continues implementing its EnergyForward strategic plan that provides for significant emissions reductions and diversifying its electricity generation mix to include more renewable and natural gas energy. We are unable to predict compliance costs due to the draft status of the rules and the need for a state implementation plan for Section 111(d) existing units; however, the costs could be material. Minnesota Power would seek recovery of additional costs through a rate proceeding. Water. The Clean Water Act requires NPDES permits be obtained from the EPA (or, when delegated, from individual state pollution control agencies) for any wastewater discharged into navigable waters. We have obtained all necessary NPDES permits, including NPDES storm water permits for applicable facilities, to conduct our operations. Steam Electric Power Generating Effluent Limitations Guidelines. In 2015, the EPA issued revised federal effluent limitation guidelines (ELG) for steam electric power generating stations under the Clean Water Act. It set effluent limits and prescribed BACT for several wastewater streams, including flue gas desulphurization (FGD) water, bottom ash transport water and coal combustion landfill leachate. In 2017, the EPA announced a two-year postponement of the ELG compliance date of November 1, 2018, to November 1, 2020, while the agency reconsidered the bottom ash transport water (BATW) and FGD wastewater provisions. On April 12, 2019, the U.S. Court of Appeals for the Fifth Circuit vacated and remanded back to the EPA portions of the ELG that allowed for continued discharge of legacy wastewater and leachate. On October 13, 2020, the EPA published a final ELG Rule allowing re-use of bottom ash transport water in FGD scrubber systems with limited discharges related to maintaining system water balance. The rule sets technology standards and numerical pollutant limits for discharges of bottom ash transport water and FGD wastewater. Compliance deadlines depend on subcategory, with compliance generally required as soon as possible, beginning after October 13, 2021, but no later than December 31, 2025, or December 31, 2028, in some specific cases. The rule also established new subcategories for retiring high-flow and low-utilization units, and established a voluntary incentives program for FGD wastewater. In accordance with the January 2021 Executive Order 13990, the EPA was mandated to conduct a review of actions and polices taken during the prior administration, including the 2020 ELG Rule. On September 14, 2021, the EPA published a notice of availability for its preliminary effluent guidelines program plan. In the plan, the EPA confirmed the agency is initiating a rulemaking process to strengthen wastewater pollution limitations from FGD and bottom ash transport water discharges while the 2020 ELG Rule remains in effect. NOTE 6. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued) Environmental Matters (Continued) On March 29, 2023, the EPA published a proposed new ELG rule in the Federal Register to update the 2020 ELGs; the public comment period was open until May 30, 2023. In the proposed rule, the EPA is revising ELGs for existing sources, including establishing zero discharge limitations for BATW and FGD wastewater; new limits for combustion residual leachate; and allowing states to set discharge limits for legacy wastewater in surface impoundments based on best professional judgment. The rule proposes to preserve flexibility and maintain exemptions for units permanently ceasing coal combustion by 2028, and adds a new category for units that have already complied with the 2020 ELG rule and which will retire by 2032. Additionally, the EPA is encouraging state permitting authorities to conduct functional equivalency tests for facilities with landfills or CCR surface impoundments to identify groundwater to surface water point source discharges. More stringent limitations would apply where point source discharges occur. Bottom ash transport and FGD wastewater ELGs are not expected to have a significant impact on Minnesota Power operations. Boswell, where these ELGs are applicable, completed conversion to dry bottom ash handling and installed a FGD dewatering system in September 2022. The dry conversion projects eliminated bottom ash transport water and minimized wastewater from the FGD system. Re-use and onsite consumption is planned for the remaining FGD waste stream and for dewatering legacy wastewater from Boswell’s existing impoundments. The EPA’s reconsideration of legacy wastewater and leachate discharge requirements has the potential to impact dewatering associated with the closed impoundment at Laskin and the closed Taconite Harbor dry ash landfill. At this time, we estimate no additional material compliance costs for ELG bottom ash water and FGD requirements. Compliance costs we might incur related to other ELG waste streams (e.g., leachate) or other potential future water discharge regulations at Minnesota Power facilities cannot be estimated; however, the costs could be material, including costs associated with wastewater treatment and re-use. Minnesota Power would seek recovery of additional costs through a rate proceeding. Permitted Water Discharges – Sulfate. In 2017, the MPCA released a draft water quality standard in an attempt to update Minnesota’s existing 10 mg/L sulfate limit for waters used for the production of wild rice with the proposed rulemaking heard before an administrative law judge (ALJ). In 2018, the ALJ rejected significant portions of the proposed rulemaking and the MPCA subsequently withdrew the rulemaking. The existing 10 mg/L limit remains in place, but the MPCA is currently prohibited under state law from listing wild rice waters as impaired or requiring sulfate reduction technology. In April 2021, the MPCA’s proposed list of impaired waters submitted pursuant to the Clean Water Act was partially rejected by the EPA due to the absence of wild rice waters listed for sulfate impairment. The EPA transmitted a final list of 32 EPA-added wild rice waters to the MPCA in November 2021. This list could subsequently be used to set sulfate limits in discharge permits for power generation facilities and municipal and industrial customers, including paper and pulp facilities, and mining operations. At this time, we are unable to determine the specific impacts these developments may have on Minnesota Power operations, if any. Minnesota Power would seek recovery of additional costs through a rate proceeding. Solid and Hazardous Waste. The Resource Conservation and Recovery Act of 1976 regulates the management and disposal of solid and hazardous wastes. We are required to notify the EPA of hazardous waste activity and, consequently, routinely submit reports to the EPA. Coal Ash Management Facilities. Minnesota Power produces the majority of its coal ash at Boswell, with small amounts of ash generated at Hibbard Renewable Energy Center. Ash storage and disposal methods include storing ash in clay-lined onsite impoundments (ash ponds), disposing of dry ash in a lined dry ash landfill, applying ash to land as an approved beneficial use, and trucking ash to state permitted landfills. Coal Combustion Residuals from Electric Utilities (CCR). In 2015, the EPA published the final rule (2015 Rule) regulating CCR as nonhazardous waste under Subtitle D of the Resource Conservation and Recovery Act (RCRA) in the Federal Register. The rule includes additional requirements for new landfill and impoundment construction as well as closure activities related to certain existing impoundments. Costs of compliance for Boswell and Laskin are expected to be incurred primarily over the next 12 years and be between approximately $65 million and $120 million. Compliance costs for CCR at Taconite Harbor are not expected to be material. Minnesota Power would seek recovery of additional costs through a rate proceeding. NOTE 6. COMMITMENTS, GUARANTEES AND CONTINGENCIES (Continued) Environmental Matters (Continued) Minnesota Power continues to work on minimizing costs through evaluation of beneficial re-use and recycling of CCR and CCR-related waters. In 2017, the EPA announced its intention to formally reconsider the CCR rule under Subtitle D of the RCRA. In March 2018, the EPA published the first phase of the proposed rule revisions in the Federal Register. In 2018, the EPA finalized revisions to elements of the CCR rule, including extending certain deadlines by two years, the establishment of alternative groundwater protection standards for certain constituents and the potential for risk-based management options at facilities based on site characteristics. In 2018, a U.S. District Court for the District of Columbia decision vacated specific provisions of the CCR rule. The court decision resulted in a change to the status of three existing clay-lined impoundments at Boswell that must now be considered unlined. The EPA proposed additional rule revisions in 2019 to address outstanding issues from litigation and closure timelines for unlined impoundments, respectively. The first of these rules, CCR Part A Rule, was finalized in September 2020. The Part A Rule revision requires unlined impoundments to cease disposal of waste as soon as technically feasible but no later than April 11, 2021. Upon completion of dry ash conversion activities, Boswell ceased disposal in both impoundments in September 2022. Both impoundments are now inactive and have initiated closure. On May 17, 2023, the EPA released a proposed rule for CCR legacy surface impoundments. The proposal expands the scope of units regulated under the CCR rule to include legacy ponds (inactive surface impoundments at inactive facilities) and creates a new category of units called CCR management units, which includes inactive and closed impoundments and landfills as well as other non-containerized accumulations of CCR. The proposed rule was published in the Federal Register on May 18, 2023, and the 60-day public comment period ended on July 17, 2023. The EPA is proposing to require that all generating facilities evaluate and identify all past deposits of CCR materials on their sites and close or re-close existing CCR units to meet current closure standards, as well as install groundwater monitoring systems, conduct groundwater monitoring and implement groundwater corrective actions as necessary. This rule has the potential to impact Boswell and Laskin. Compliance costs for Minnesota Power facilities cannot be estimated at this time; however, the costs could be material. Minnesota Power would seek recovery of additional costs through a rate proceeding. Additionally, the EPA released a proposed CCR Part B rulemaking in February 2020 addressing options for beneficial reuse of CCR materials, alternative liner demonstrations and other CCR regulatory revisions. Portions of the Part B rule addressing alternative liner equivalency standards were finalized in November 2020. According to the EPA’s updated spring 2023 regulatory agenda, finalization of the remainder of the proposed Part B rule has been moved to the agency’s long-term agenda. The final federal permit rule is still expected in late-2023. The final federal permit rule will finalize procedures for implementing a CCR federal permit program. Other Environmental Matters. Manufactured Gas Plant Site. SWL&P continues working with the Wisconsin Department of Natural Resources (WDNR) to address and remediate environmental conditions at a former manufactured gas plant site located in Superior, Wisconsin, and formerly operated by SWL&P. As of September 30, 2023, we have recorded a liability of approximately $4 million for remediation costs at this site. SWL&P has also recorded an associated regulatory asset as we expect recovery of these remediation costs to be allowed by the PSCW. Remediation costs are expected to be incurred through 2025. Other Matters. Letters of Credit and Surety Bonds. We have multiple credit facility agreements in place that provide the ability to issue standby letters of credit to satisfy contractual security requirements across our businesses. As of September 30, 2023, we had $163.6 million of outstanding letters of credit issued, including those issued under our revolving credit facility. Regulated Operations. As of September 30, 2023, we had $24.2 million outstanding in standby letters of credit at our Regulated Operations which are pledged as security to MISO, the NDPSC and a state agency. ALLETE Clean Energy. ALLETE Clean Energy’s wind energy facilities have various PSAs in place for some or all of their output that expire in various years between 2024 and 2039. As of September 30, 2023, ALLETE Clean Energy has $105.3 million outstanding in standby letters of credit, the majority of which are pledged as security under these PSAs and PSAs for wind energy facilities developed for others. ALLETE Clean Energy does not believe it is likely that any of these outstanding letters of credit will be drawn upon. Corporate and Other. BNI Energy. As of September 30, 2023, BNI Energy had surety bonds outstanding of $82.4 million related to the reclamation liability for closing costs associated with its mine and mine facilities. Although its coal supply agreements obligate the customers to provide for the closing costs, additional assurance is required by federal and state regulations. BNI Energy’s total reclamation liability is currently estimated at $82.1 million. BNI Energy does not believe it is likely that any of these outstanding surety bonds will be drawn upon. Investment in Nobles 2. The Nobles 2 wind energy facility requires standby letters of credit as security for certain contractual obligations. As of September 30, 2023, ALLETE South Wind has $10.1 million outstanding in standby letters of credit, related to its portion of the security requirements relative to its ownership in Nobles 2. We do not believe it is likely that any of these outstanding letters of credit will be drawn upon. South Shore Energy. As of September 30, 2023, South Shore Energy had $23.9 million outstanding in standby letters of credit pledged as security in connection with the development of NTEC. South Shore Energy does not believe it is likely that any of these outstanding letters of credit will be drawn upon. Legal Proceedings. We are involved in litigation arising in the normal course of business. Also in the normal course of business, we are involved in tax, regulatory and other governmental audits, inspections, investigations and other proceedings that involve state and federal taxes, safety, and compliance with regulations, rate base and cost of service issues, among other things. We do not expect the outcome of these matters to have a material effect on our financial position, results of operations or cash flows. In the first quarter of 2023, an ALLETE Clean Energy subsidiary initiated arbitration proceedings seeking damages against a counterparty for non-performance under a contract. Arbitration hearings were held in June and July 2023, and a final arbitration ruling was issued in favor of ALLETE Clean Energy’s subsidiary in September 2023. The final arbitration ruling awarded $68.3 million to ALLETE Clean Energy’s subsidiary, which included prejudgment interest of $5.1 million, recovery of $3.6 million of arbitration-related costs, and resulted in the recognition of a $58.4 million pre-tax gain in the third quarter of 2023. The arbitration ruling also resulted in the receipt of approximately $60 million of cash, net of distribution to non-controlling interest, in the third quarter of 2023.

Power Purchase and Sale Agreements. Our long-term PPAs have been evaluated under the accounting guidance for variable interest entities. We have determined that either we have no variable interest in the PPAs or, where we do have variable interests, we are not the primary beneficiary; therefore, consolidation is not required. These conclusions are based on the fact that we do not have both control over activities that are most significant to the entity and an obligation to absorb losses or receive benefits from the entity’s performance. Our financial exposure relating to these PPAs is limited to our capacity and energy payments.

Square Butte PPA. As of September 30, 2023, Square Butte had total debt outstanding of $176.9 million. Fuel expenses are recoverable through Minnesota Power’s fuel adjustment clause and include the cost of coal purchased from BNI Energy under a long-term contract. Minnesota Power’s cost of power purchased from Square Butte during the nine months ended September 30, 2023, was $64.8 million ($63.8 million for the same period in 2022). This reflects Minnesota Power’s pro rata share of total Square Butte costs based on the 50 percent output entitlement. Included in this amount was Minnesota Power’s pro rata share of interest expense of $4.1 million ($3.7 million for the same period in 2022). Minnesota Power’s payments to Square Butte are approved as a purchased power expense for ratemaking purposes by both the MPUC and the FERC.

Minnkota Power PSA. Minnesota Power has a PSA with Minnkota Power, which commenced in 2014. Under the PSA, Minnesota Power is selling a portion of its entitlement from Square Butte to Minnkota Power, resulting in Minnkota Power’s net entitlement increasing and Minnesota Power’s net entitlement decreasing until Minnesota Power’s share is eliminated at the end of 2025. Of Minnesota Power’s 50 percent output entitlement, Minnesota Power sold to Minnkota Power approximately 37 percent in 2023 and 32 percent in 2022.

Our businesses are subject to regulation of environmental matters by various federal, state and local authorities. A number of regulatory changes to the Clean Air Act, the Clean Water Act and various waste management requirements have been promulgated by both the EPA and state authorities over the past several years. Minnesota Power’s facilities are subject to additional requirements under many of these regulations. Minnesota Power is reshaping its generation portfolio, over time, to reduce its reliance on coal, has installed cost-effective emission control technology, and advocates for sound science and policy during rulemaking implementation.

We consider our businesses to be in substantial compliance with currently applicable environmental regulations and believe all necessary permits have been obtained. We anticipate that with many state and federal environmental regulations and requirements finalized, or to be finalized in the near future, potential expenditures for future environmental matters may be material and require significant capital investments. Minnesota Power has evaluated various environmental compliance scenarios using possible outcomes of environmental regulations to project power supply trends and impacts on customers.

We review environmental matters on a quarterly basis. Accruals for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated based on current law and existing technologies. Accruals are adjusted as assessment and remediation efforts progress, or as additional technical or legal information becomes available. Accruals for environmental liabilities are included in the Consolidated Balance Sheet at undiscounted amounts and exclude claims for recoveries from insurance or other third parties. Costs related to environmental contamination treatment and cleanup are expensed unless recoverable in rates from customers.

Air. The electric utility industry is regulated both at the federal and state level to address air emissions. Minnesota Power’s thermal generating facilities mainly burn low-sulfur western sub-bituminous coal. All of Minnesota Power’s coal-fired generating facilities are equipped with pollution control equipment such as scrubbers, baghouses and low NOX technologies. Under currently applicable environmental regulations, these facilities are substantially compliant with emission requirements.

Cross-State Air Pollution Rule (CSAPR). The CSAPR requires certain states, including Minnesota, to reduce power plant emissions that contribute to ozone or fine particulate pollution in other states. The CSAPR does not require installation of controls but does require facilities have sufficient allowances to cover their emissions on an annual basis. These allowances are allocated to facilities from each state’s annual budget, and can be bought and sold. Minnesota Power continues to monitor ongoing CSAPR rulemakings and compliance implementation, including the EPA’s Good Neighbor Plan published June 5, 2023, modifying certain aspects of the CSAPR’s program scope and extent.

National Ambient Air Quality Standards (NAAQS). The EPA is required to review the NAAQS every five years. If the EPA determines that a state’s air quality is not in compliance with the NAAQS, the state is required to adopt plans describing how it will reduce emissions to attain the NAAQS. Minnesota Power actively monitors NAAQS developments and compliance costs for existing standards or proposed NAAQS revisions are not currently expected to be material. The EPA is currently reviewing the secondary NAAQS for NOx and SO2, as well as particulate matter. In June 2021, the EPA announced it would reconsider the December 2020 final rule retaining the 2012 particulate matter NAAQS. On January 6, 2023, the EPA announced a proposed rule to revise the primary annual particulate matter NAAQS from its current level while retaining the other primary and secondary particulate matter NAAQS. The rule was advanced to the White House Office of Management and Budget (OMB) on September 22, 2023 and a final rule is tentatively expected by the end of the year. The EPA also announced in October 2021 that it was reconsidering the 2020 Ozone NAAQS rule finalized in December 2020, and issued an initial draft policy assessment on April 28, 2022, recommending retention of the current standard. A second version of the draft policy assessment was then published for public comment on March 1, 2023. Subsequently on August 21, 2023, the EPA announced it would cease reconsideration of the Ozone NAAQS and initiate a new review instead. This new NAAQS review is expected to take several years, during which time the existing 2020 ozone NAAQS will remain in place. Anticipated timelines and compliance costs related to the proposed and expected NAAQS revisions cannot yet be estimated; however, costs could be material. Minnesota Power would seek recovery of additional costs through a rate proceeding.

EPA Good Neighbor Plan for 2015 Ozone NAAQS. On June 5, 2023, the EPA published a final Federal Implementation Plan (FIP) rule in the Federal Register, the Good Neighbor Plan, to address regional ozone transport for the 2015 Ozone NAAQS by reducing NOx emissions during the period of May 1 through September 30 (ozone season). This rule addresses certain good neighbor or interstate transport provisions of the Clean Air Act relative to the 2015 Ozone NAAQS. In the justification for the final rule, the EPA asserts that 23 states, including Minnesota, are modeled as significant contributors to downwind states’ challenges in attaining or maintaining ozone NAAQS compliance within their state borders. The Good Neighbor Plan is designed to resolve this interstate transport issue by implementing a variety of NOx reduction strategies, including federal implementation plan requirements, NOx emission limitations, and ozone season allowance program requirements, beginning with the 2023 ozone season. The final rule imposes restrictions on fossil-fuel fired power plants in 22 states and on certain industrial sources in 20 states. Implementation of the rule will occur in part through changes to the existing CSAPR program for power plants.

Minnesota Power previously submitted public comments to the EPA on the April 2022 proposed Good Neighbor Plan. Concerns noted by Minnesota Power and other entities included the technical accuracy of the EPA’s assumptions and methods used to identify Minnesota as a significant contributor state, as well as the proposed rule’s intended timeline. On February 13, 2023, the EPA also published its final rule to partially disapprove the Good Neighbor State Implementation Plans (SIPs) for the states of Minnesota and Wisconsin, and to disapprove 19 other SIP submissions. The SIP final action subjects Minnesota to the final Good Neighbor Plan and associated compliance costs will be known when the final SIP rule evaluation and implementation has been completed. On April 14, 2023, Minnesota Power and a coalition of other Minnesota utilities and industry (the parties) co-filed challenges to the EPA’s final Minnesota SIP disapproval, submitting a petition for reconsideration and stay to the EPA and a petition for judicial review to the U.S. Court of Appeals for the Eighth Circuit (Eighth Circuit Court). The parties are challenging and requesting reconsideration of certain technical components of the EPA’s review and subsequent partial disapproval of the state of Minnesota’s SIP, including the rulemaking process, air modeling practices and other emissions inventory aspects. On May 31, 2023, the parties filed a motion to stay the SIP disapproval with the Eighth Circuit Court, which granted the stay on July 5, 2023, which prevents the Good Neighbor Plan from taking effect in Minnesota while the stay remains in effect.

On September 29, 2023, the EPA issued an updated final interim rule addressing the stays in Minnesota and five other states, formally staying the effectiveness of the final FIP for states with active stays in place. The state of Minnesota was therefore not subject to compliance obligations for the 2023 ozone season, which would have gone into effect on August 4, 2023. Future compliance obligations will depend on the eventual resolution of the stay and appeal. Additionally, challenges have been filed against the final SIP rule by the Minnesota coalition parties and other entities. Anticipated compliance costs related to final Good Neighbor Plan compliance cannot yet be estimated due to uncertainties about SIP approval status, implementation timing, and allowance costs and facility emissions during the ozone season. However, the costs could be material, including costs of additional NOx controls, emission allowance program participation, or operational changes, if any are required. Minnesota Power would seek recovery of additional costs through a rate proceeding.

EPA National Emission Standards for Hazardous Air Pollutants for Major Sources: Industrial, Commercial and Institutional Boilers and Process Heaters (Industrial Boiler MACT) Rule. A final rule issued by the EPA for Industrial Boiler MACT became effective in 2013 with compliance required at major existing sources in 2016. Minnesota Power’s Hibbard Renewable Energy Center and Rapids Energy Center are subject to this rule. Compliance with the Industrial Boiler MACT Rule consisted largely of adjustments to fuels and operating practices and compliance costs were not material. Subsequent to this initial rulemaking, litigation from 2016 through 2018 resulted in court orders directing that the EPA reconsider certain aspects of the regulation including the basis for and numerical value of several different emission limits. On October 6, 2022, the EPA published a final rule in the Federal Register incorporating these changes. The rule became effective on December 5, 2022, imposing a compliance deadline of October 6, 2025. Minnesota Power’s review of this new rule indicates that the revisions should not significantly impact its affected units. As such, compliance costs associated with the new Industrial Boiler MACT Rule are not currently expected to be material; however, Minnesota Power would seek recovery of additional costs through a rate proceeding.

EPA Mercury and Air Toxics Standards (MATS) Rule. On April 24, 2023, the EPA published a proposed revision to the existing MATS Rule as part of its mandatory 2020 MATS review. In this proposed rule, the EPA is proposing to alter certain compliance and operational requirements, and to lower several emission limits including filterable particulate matter as well as mercury for lignite units. Compliance would be due in the 2026 to 2027 timeframe. The MATS regulation applies at Minnesota Power’s Boswell facility, which is currently well-controlled for these emissions and is in full compliance with existing requirements. Initial review of this draft regulation indicates that compliance costs should not be material based on the proposed revision. The EPA expects to issue the final rule in March 2024. Compliance costs cannot yet be estimated; however, recovery of any additional costs would be sought through a rate proceeding.

Climate Change. The scientific community generally accepts that emissions of GHGs are linked to global climate change which creates physical and financial risks. Physical risks could include, but are not limited to: increased or decreased precipitation and water levels in lakes and rivers; increased or other changes in temperatures; increased risk of wildfires; and changes in the intensity and frequency of extreme weather events. These all have the potential to affect the Company’s business and operations. We are addressing climate change by taking the following steps that also ensure reliable and environmentally compliant generation resources to meet our customers’ requirements:

EPA Regulation of GHG Emissions. On May 23, 2023, the EPA published in the Federal Register a proposal for five separate regulatory actions under Section 111 of the Clean Air Act (CAA) addressing greenhouse gas (GHG) emissions from fossil fuel-fired electric generating units (EGUs). The EPA is proposing revised new source performance standards (NSPS) for new, modified and reconstructed EGUs (Section 111(b) of the CAA) as well as emission guidelines for certain existing (Section 111(d) of the CAA) EGUs. The EPA also proposed in this action to officially repeal the predecessor regulation “Affordable Clean Energy Rule”, first issued in 2019 and later vacated in 2021. The draft rules were open for public comment until August 8, 2023, and the EPA’s Spring 2023 unified agenda identifies the EPA’s goal of issuing final regulations in April 2024. The Company will continue to monitor this GHG rulemaking and analyze potential impacts to our existing and proposed thermal generating facilities from the draft Section 111 rules, which would apply to several Company assets including existing EGUs at the Boswell and Laskin facilities as well as the proposed combined cycle natural gas-fired generating facility, NTEC. Minnesota Power continues implementing its EnergyForward strategic plan that provides for significant emissions reductions and diversifying its electricity generation mix to include more renewable and natural gas energy. We are unable to predict compliance costs due to the draft status of the rules and the need for a state implementation plan for Section 111(d) existing units; however, the costs could be material. Minnesota Power would seek recovery of additional costs through a rate proceeding.

Steam Electric Power Generating Effluent Limitations Guidelines. In 2015, the EPA issued revised federal effluent limitation guidelines (ELG) for steam electric power generating stations under the Clean Water Act. It set effluent limits and prescribed BACT for several wastewater streams, including flue gas desulphurization (FGD) water, bottom ash transport water and coal combustion landfill leachate. In 2017, the EPA announced a two-year postponement of the ELG compliance date of November 1, 2018, to November 1, 2020, while the agency reconsidered the bottom ash transport water (BATW) and FGD wastewater provisions. On April 12, 2019, the U.S. Court of Appeals for the Fifth Circuit vacated and remanded back to the EPA portions of the ELG that allowed for continued discharge of legacy wastewater and leachate. On October 13, 2020, the EPA published a final ELG Rule allowing re-use of bottom ash transport water in FGD scrubber systems with limited discharges related to maintaining system water balance. The rule sets technology standards and numerical pollutant limits for discharges of bottom ash transport water and FGD wastewater. Compliance deadlines depend on subcategory, with compliance generally required as soon as possible, beginning after October 13, 2021, but no later than December 31, 2025, or December 31, 2028, in some specific cases. The rule also established new subcategories for retiring high-flow and low-utilization units, and established a voluntary incentives program for FGD wastewater. In accordance with the January 2021 Executive Order 13990, the EPA was mandated to conduct a review of actions and polices taken during the prior administration, including the 2020 ELG Rule. On September 14, 2021, the EPA published a notice of availability for its preliminary effluent guidelines program plan. In the plan, the EPA confirmed the agency is initiating a rulemaking process to strengthen wastewater pollution limitations from FGD and bottom ash transport water discharges while the 2020 ELG Rule remains in effect.

On March 29, 2023, the EPA published a proposed new ELG rule in the Federal Register to update the 2020 ELGs; the public comment period was open until May 30, 2023. In the proposed rule, the EPA is revising ELGs for existing sources, including establishing zero discharge limitations for BATW and FGD wastewater; new limits for combustion residual leachate; and allowing states to set discharge limits for legacy wastewater in surface impoundments based on best professional judgment. The rule proposes to preserve flexibility and maintain exemptions for units permanently ceasing coal combustion by 2028, and adds a new category for units that have already complied with the 2020 ELG rule and which will retire by 2032. Additionally, the EPA is encouraging state permitting authorities to conduct functional equivalency tests for facilities with landfills or CCR surface impoundments to identify groundwater to surface water point source discharges. More stringent limitations would apply where point source discharges occur.

Bottom ash transport and FGD wastewater ELGs are not expected to have a significant impact on Minnesota Power operations. Boswell, where these ELGs are applicable, completed conversion to dry bottom ash handling and installed a FGD dewatering system in September 2022. The dry conversion projects eliminated bottom ash transport water and minimized wastewater from the FGD system. Re-use and onsite consumption is planned for the remaining FGD waste stream and for dewatering legacy wastewater from Boswell’s existing impoundments.

At this time, we estimate no additional material compliance costs for ELG bottom ash water and FGD requirements. Compliance costs we might incur related to other ELG waste streams (e.g., leachate) or other potential future water discharge regulations at Minnesota Power facilities cannot be estimated; however, the costs could be material, including costs associated with wastewater treatment and re-use. Minnesota Power would seek recovery of additional costs through a rate proceeding.

Permitted Water Discharges – Sulfate. In 2017, the MPCA released a draft water quality standard in an attempt to update Minnesota’s existing 10 mg/L sulfate limit for waters used for the production of wild rice with the proposed rulemaking heard before an administrative law judge (ALJ). In 2018, the ALJ rejected significant portions of the proposed rulemaking and the MPCA subsequently withdrew the rulemaking. The existing 10 mg/L limit remains in place, but the MPCA is currently prohibited under state law from listing wild rice waters as impaired or requiring sulfate reduction technology.

In April 2021, the MPCA’s proposed list of impaired waters submitted pursuant to the Clean Water Act was partially rejected by the EPA due to the absence of wild rice waters listed for sulfate impairment. The EPA transmitted a final list of 32 EPA-added wild rice waters to the MPCA in November 2021. This list could subsequently be used to set sulfate limits in discharge permits for power generation facilities and municipal and industrial customers, including paper and pulp facilities, and mining operations. At this time, we are unable to determine the specific impacts these developments may have on Minnesota Power operations, if any. Minnesota Power would seek recovery of additional costs through a rate proceeding.

Coal Ash Management Facilities. Minnesota Power produces the majority of its coal ash at Boswell, with small amounts of ash generated at Hibbard Renewable Energy Center. Ash storage and disposal methods include storing ash in clay-lined onsite impoundments (ash ponds), disposing of dry ash in a lined dry ash landfill, applying ash to land as an approved beneficial use, and trucking ash to state permitted landfills.

Coal Combustion Residuals from Electric Utilities (CCR). In 2015, the EPA published the final rule (2015 Rule) regulating CCR as nonhazardous waste under Subtitle D of the Resource Conservation and Recovery Act (RCRA) in the Federal Register. The rule includes additional requirements for new landfill and impoundment construction as well as closure activities related to certain existing impoundments. Costs of compliance for Boswell and Laskin are expected to be incurred primarily over the next 12 years and be between approximately $65 million and $120 million. Compliance costs for CCR at Taconite Harbor are not expected to be material. Minnesota Power would seek recovery of additional costs through a rate proceeding.

Minnesota Power continues to work on minimizing costs through evaluation of beneficial re-use and recycling of CCR and CCR-related waters. In 2017, the EPA announced its intention to formally reconsider the CCR rule under Subtitle D of the RCRA. In March 2018, the EPA published the first phase of the proposed rule revisions in the Federal Register. In 2018, the EPA finalized revisions to elements of the CCR rule, including extending certain deadlines by two years, the establishment of alternative groundwater protection standards for certain constituents and the potential for risk-based management options at facilities based on site characteristics. In 2018, a U.S. District Court for the District of Columbia decision vacated specific provisions of the CCR rule. The court decision resulted in a change to the status of three existing clay-lined impoundments at Boswell that must now be considered unlined. The EPA proposed additional rule revisions in 2019 to address outstanding issues from litigation and closure timelines for unlined impoundments, respectively. The first of these rules, CCR Part A Rule, was finalized in September 2020. The Part A Rule revision requires unlined impoundments to cease disposal of waste as soon as technically feasible but no later than April 11, 2021. Upon completion of dry ash conversion activities, Boswell ceased disposal in both impoundments in September 2022. Both impoundments are now inactive and have initiated closure.

On May 17, 2023, the EPA released a proposed rule for CCR legacy surface impoundments. The proposal expands the scope of units regulated under the CCR rule to include legacy ponds (inactive surface impoundments at inactive facilities) and creates a new category of units called CCR management units, which includes inactive and closed impoundments and landfills as well as other non-containerized accumulations of CCR. The proposed rule was published in the Federal Register on May 18, 2023, and the 60-day public comment period ended on July 17, 2023. The EPA is proposing to require that all generating facilities evaluate and identify all past deposits of CCR materials on their sites and close or re-close existing CCR units to meet current closure standards, as well as install groundwater monitoring systems, conduct groundwater monitoring and implement groundwater corrective actions as necessary. This rule has the potential to impact Boswell and Laskin. Compliance costs for Minnesota Power facilities cannot be estimated at this time; however, the costs could be material. Minnesota Power would seek recovery of additional costs through a rate proceeding.

Additionally, the EPA released a proposed CCR Part B rulemaking in February 2020 addressing options for beneficial reuse of CCR materials, alternative liner demonstrations and other CCR regulatory revisions. Portions of the Part B rule addressing alternative liner equivalency standards were finalized in November 2020. According to the EPA’s updated spring 2023 regulatory agenda, finalization of the remainder of the proposed Part B rule has been moved to the agency’s long-term agenda. The final federal permit rule is still expected in late-2023. The final federal permit rule will finalize procedures for implementing a CCR federal permit program.

Manufactured Gas Plant Site. SWL&P continues working with the Wisconsin Department of Natural Resources (WDNR) to address and remediate environmental conditions at a former manufactured gas plant site located in Superior, Wisconsin, and formerly operated by SWL&P. As of September 30, 2023, we have recorded a liability of approximately $4 million for remediation costs at this site. SWL&P has also recorded an associated regulatory asset as we expect recovery of these remediation costs to be allowed by the PSCW. Remediation costs are expected to be incurred through 2025.

ALLETE Clean Energy. ALLETE Clean Energy’s wind energy facilities have various PSAs in place for some or all of their output that expire in various years between 2024 and 2039. As of September 30, 2023, ALLETE Clean Energy has $105.3 million outstanding in standby letters of credit, the majority of which are pledged as security under these PSAs and PSAs for wind energy facilities developed for others. ALLETE Clean Energy does not believe it is likely that any of these outstanding letters of credit will be drawn upon.

BNI Energy. As of September 30, 2023, BNI Energy had surety bonds outstanding of $82.4 million related to the reclamation liability for closing costs associated with its mine and mine facilities. Although its coal supply agreements obligate the customers to provide for the closing costs, additional assurance is required by federal and state regulations. BNI Energy’s total reclamation liability is currently estimated at $82.1 million. BNI Energy does not believe it is likely that any of these outstanding surety bonds will be drawn upon.

Investment in Nobles 2. The Nobles 2 wind energy facility requires standby letters of credit as security for certain contractual obligations. As of September 30, 2023, ALLETE South Wind has $10.1 million outstanding in standby letters of credit, related to its portion of the security requirements relative to its ownership in Nobles 2. We do not believe it is likely that any of these outstanding letters of credit will be drawn upon.

We are involved in litigation arising in the normal course of business. Also in the normal course of business, we are involved in tax, regulatory and other governmental audits, inspections, investigations and other proceedings that involve state and federal taxes, safety, and compliance with regulations, rate base and cost of service issues, among other things. We do not expect the outcome of these matters to have a material effect on our financial position, results of operations or cash flows.

In the first quarter of 2023, an ALLETE Clean Energy subsidiary initiated arbitration proceedings seeking damages against a counterparty for non-performance under a contract. Arbitration hearings were held in June and July 2023, and a final arbitration ruling was issued in favor of ALLETE Clean Energy’s subsidiary in September 2023. The final arbitration ruling awarded $68.3 million to ALLETE Clean Energy’s subsidiary, which included prejudgment interest of $5.1 million, recovery of $3.6 million of arbitration-related costs, and resulted in the recognition of a $58.4 million pre-tax gain in the third quarter of 2023. The arbitration ruling also resulted in the receipt of approximately $60 million of cash, net of distribution to non-controlling interest, in the third quarter of 2023.