Power Purchase Obligations. TVA has contracted with various independent power producers and LPCs for additional capacity to be made available to TVA. Several of these agreements have contractual minimum payments and are accounted for as either finance or operating leases. In total, these agreements provide 4,487 megawatts ("MW") of summer net capability. The remaining terms of the agreements range up to 12 years. Additionally, TVA has contracted with regional transmission organizations to reserve 2,792 MW of transmission service to support purchases from the market and wind PPAs. The remaining terms of these agreements range up to four years. Excluding lease-related costs, TVA incurred $301 million, $318 million, and $202 million of expense under these power purchase and transmission service agreements during 2023, 2022, and 2021, respectively.

Under federal law, TVA is obligated to purchase power from qualifying facilities (cogenerators and small power producers). As of September 30, 2023, there was a combined qualifying facility capacity of 285 MW from 955 different generation sources, from which TVA purchased power under this law.

Other Commitments. See Note 8 — Leases, Note 11 — Variable Interest Entities, Note 14 — Debt and Other Obligations, and Note 20 — Benefit Plans for the obligations and commitments attributable to leases, VIEs and membership interests of VIEs subject to mandatory redemption, leaseback obligations, and the retirement plan, respectively.

Nuclear Insurance. Section 170 of the Atomic Energy Act, commonly known as the Price-Anderson Act, provides a layered framework of financial protection to compensate for liability claims of members of the public for personal injury and property damages arising from a nuclear incident in the U.S. This financial protection consists of two layers of coverage. The primary level is private insurance underwritten by American Nuclear Insurers and provides public liability insurance coverage of $450 million for each nuclear power plant licensed to operate. If this amount is not sufficient to cover claims arising from a nuclear incident, the second level, Secondary Financial Protection, applies. Within the Secondary Financial Protection level, the licensee of each nuclear reactor has a contingent obligation to pay a retrospective premium, equal to its proportionate share of the loss in excess of the primary level, regardless of proximity to the incident of fault, up to a maximum of $138 million per reactor per incident. With TVA's seven reactors, the maximum total contingent obligation per incident is $963 million. This retrospective premium is payable at a maximum rate currently set at $20 million per year per nuclear incident per reactor. Currently, 97 reactors are participating in the Secondary Financial Protection program.

Federal law requires that each NRC power reactor licensee obtain property insurance from private sources to cover the cost of stabilizing and decontaminating a reactor and its station site after an accident. TVA carries property, decommissioning liability, and decontamination liability insurance from Nuclear Electric Insurance Limited ("NEIL") and European Mutual Association for Nuclear Insurance. The limits available for a loss are up to $2.1 billion for two of TVA's nuclear sites and up to $2.8 billion for the remaining site. Some of this insurance may require the payment of retrospective premiums up to a maximum of $114 million.

TVA purchases accidental outage (business interruption) insurance for TVA's nuclear sites from NEIL. In the event that an accident covered by this policy takes a nuclear unit offline or keeps a nuclear unit offline, NEIL will pay TVA, after a waiting period, an indemnity (a set dollar amount per week) with a maximum indemnity of $490 million per unit. This insurance policy may require the payment of retrospective premiums up to a maximum of $44 million, but only to the extent the retrospective premium is deemed necessary by the NEIL Board of Directors to pay losses unable to be covered by NEIL's surplus.

Decommissioning Costs. TVA recognizes legal obligations associated with the future retirement of certain tangible long-lived assets related primarily to nuclear generating plants, coal-fired generating plants, hydroelectric generating plants/dams, transmission structures, and other property-related assets. See Note 13 — Asset Retirement Obligations.

Nuclear Decommissioning. Provision for decommissioning costs of nuclear generating units is based on options prescribed by the NRC procedures to dismantle and decontaminate the facilities to meet the NRC criteria for license termination. At September 30, 2023, $3.8 billion, representing the discounted value of future estimated nuclear decommissioning costs, was included in nuclear AROs. The actual decommissioning costs may vary from the derived estimates because of, among other things, changes in current assumptions, such as the assumed dates of decommissioning, changes in regulatory requirements, changes in technology, and changes in the cost of labor, materials, and equipment. Utilities that own and operate nuclear plants are required to use different procedures in calculating nuclear decommissioning costs under GAAP than those that are used in calculating nuclear decommissioning costs when reporting to the NRC. The two sets of procedures produce different estimates for the costs of decommissioning primarily because of differences in the underlying assumptions. TVA bases its nuclear decommissioning estimates on site-specific cost studies. The most recent study was approved and implemented in September 2022. Site-specific cost studies are updated for each of TVA's nuclear units at least every five years.

TVA maintains an NDT to provide funding for the ultimate decommissioning of its nuclear power plants. See Note 16 — Fair Value Measurements — Investment Funds. TVA monitors the value of its NDT and believes that, over the long term and before cessation of nuclear plant operations and commencement of decommissioning activities, adequate funds from investments and additional contributions, if necessary, will be available to support decommissioning. TVA's operating nuclear power units are licensed through various dates between 2033 - 2055, depending on the unit. It may be possible to extend the operating life of some of the units with approval from the NRC. See Note 10 — Regulatory Assets and Liabilities — Nuclear Decommissioning Costs and Note 13 — Asset Retirement Obligations.

Non-Nuclear Decommissioning. At September 30, 2023, $3.7 billion, representing the discounted value of future estimated non-nuclear decommissioning costs, was included in non-nuclear AROs. This decommissioning cost estimate involves estimating the amount and timing of future expenditures and making judgments concerning whether or not such costs are considered a legal obligation. Estimating the amount and timing of future expenditures includes, among other things, making projections of the timing and duration of the asset retirement process and how costs will escalate with inflation. The actual decommissioning costs may vary from the derived estimates because of changes in current assumptions, such as the assumed dates of decommissioning, changes in regulatory requirements, changes in technology, and changes in the cost of labor, materials, and equipment. TVA updates its underlying assumptions for non-nuclear decommissioning AROs at least every five years. However, material changes in underlying assumptions that impact the amount and timing of undiscounted cash flows are continuously monitored and incorporated into ARO balances in the period identified.

TVA maintains an ART to help fund the ultimate decommissioning of its non-nuclear power assets. See Note 16 — Fair Value Measurements — Investment Funds. Estimates involved in determining if additional funding will be made to the ART include inflation rate, rate of return projections on the fund investments, and the planned use of other sources to fund decommissioning costs. See Note 10 — Regulatory Assets and Liabilities — Non-Nuclear Decommissioning Costs and Note 13 — Asset Retirement Obligations.

Environmental Matters. TVA's generation activities, like those across the utility industry and in other industrial sectors, are subject to federal, state, and local environmental laws and regulations. Major areas of regulation affecting TVA's activities include air quality control, greenhouse gas ("GHG") emissions, water quality control, and management and disposal of solid and hazardous wastes. Regulations in these major areas continue to become more stringent and have, and will continue to have, a particular emphasis on climate change, renewable generation, and energy efficiency.

TVA has incurred, and expects to continue to incur, substantial capital and operating and maintenance costs to comply with evolving environmental requirements primarily associated with, but not limited to, the operation of TVA's coal-fired and natural gas-fired generating units in general and emissions of pollutants from those units. Environmental requirements placed on the operation of coal-fired and other generating units using fossil fuels such as oil and natural gas will likely continue to become more restrictive over time. Failure to comply with environmental and safety requirements can result in enforcement actions and litigation, which can lead to the imposition of significant civil liability, including fines and penalties, criminal sanctions, and/or temporary or permanent closure of non-compliant facilities. Historical non-compliance can also lead to difficulty in renewing existing permits, as well as difficulty in obtaining permits to bring new generation facilities online. Other obstacles to renewal or permitting of new facilities include a proliferation of non-government organizations seeking to use litigation tools to delay or stop altogether permitting of new fossil fuel facilities in favor of renewable energy projects.

From 1970 to 2023, TVA spent $6.8 billion to reduce emissions from its power plants, including $25 million, $16 million, and $17 million in 2023, 2022, and 2021, respectively, on clean air controls. TVA estimates that compliance with existing Clean Air Act ("CAA") requirements (excluding GHG requirements and new or proposed regulations) could lead to costs of $252 million from 2024 to 2028, which include existing controls capital projects and air operations and maintenance projects. TVA also estimates additional expenditures of $1.6 billion from 2024 to 2028 relating to TVA's CCR Program, as well as expenditures of $190 million from 2024 to 2028 relating to compliance with Clean Water Act ("CWA") requirements. Future costs could differ from these estimates if new environmental laws or regulations become applicable to TVA or the facilities it operates, or if existing environmental laws or regulations are revised or reinterpreted. There could also be costs that cannot reasonably be predicted at this time, due to uncertainty of actions, that could increase these estimates, and these estimates do not include expenditures expected to be incurred after 2028.

Compliance with the EPA's CCR Rule required implementation of a groundwater monitoring program, additional engineering, and ongoing analysis. As further analyses are performed, including evaluation of monitoring results, there is the potential for additional costs for investigation and/or remediation. These costs cannot reasonably be predicted until a final remedy is selected where required.

Liability for releases, natural resource damages, and required cleanup of hazardous substances is primarily regulated by the federal Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"), the Resource Conservation and Recovery Act ("RCRA"), and other federal and parallel state statutes. In a manner similar to many other governmental entities, industries, and power systems, TVA has generated or used hazardous substances over the years. TVA operations at some facilities have resulted in releases of contaminants that TVA has addressed or is addressing consistent with state and federal requirements. At September 30, 2023 and 2022, TVA's estimated liability for required cleanup and similar environmental work for those sites for which sufficient information is available to develop a cost estimate was $16 million and $17

million, respectively, on a non-discounted basis, and was included in Accounts payable and accrued liabilities and Other long-term liabilities on the Consolidated Balance Sheets. Additionally, the potential inclusion of new hazardous substances under CERCLA and RCRA jurisdiction could significantly affect TVA's future liability for remediating historical releases.

Potential Liability Associated with Workers' Exposure to CCR Materials. In response to the 2008 ash spill at Kingston, TVA hired Jacobs Engineering Group, Inc. ("Jacobs") to oversee aspects of the cleanup. After the cleanup was completed, Jacobs was sued in the U.S. District Court for the Eastern District of Tennessee ("Eastern District") by employees of a contractor involved in the cleanup and family members of some of the employees. The plaintiffs alleged that Jacobs failed to take or provide proper health precautions and misled workers about the health risks associated with exposure to coal fly ash, which is a CCR material. The plaintiffs also alleged that exposure to the fly ash caused significant illnesses, including in some cases death. Other contractor employees and family members also filed lawsuits against Jacobs in the Eastern District. In the third quarter of 2023, Jacobs announced that it reached a global settlement that resolved all of these lawsuits. While TVA was not a party to any of these lawsuits, TVA may potentially have an indemnity obligation to reimburse Jacobs in some circumstances. TVA does not expect any potential liability to have a material adverse impact on its results of operations or financial condition.

From time to time, TVA is party to or otherwise involved in lawsuits, claims, proceedings, investigations, and other legal matters ("Legal Proceedings") that have arisen in the ordinary course of conducting TVA's activities, as a result of a catastrophic event or otherwise.

General. At September 30, 2023, TVA had accrued $28 million of probable losses with respect to Legal Proceedings. Of the accrued amount, $10 million is included in Other long-term liabilities and $18 million is included in Accounts payable and accrued liabilities. No assurance can be given that TVA will not be subject to significant additional claims and liabilities. If actual liabilities significantly exceed the estimates made, TVA's results of operations, liquidity, and financial condition could be materially adversely affected.

Environmental Agreements. On April 14, 2011, TVA entered into two substantively similar agreements, one with the EPA and the other with Alabama, Kentucky, North Carolina, Tennessee, and three environmental advocacy groups (collectively, the "Environmental Agreements"). To resolve alleged New Source Review claims, TVA committed under the Environmental Agreements to, among other things, take now-completed actions regarding coal units and invest $290 million in certain TVA environmental projects. Of this amount, TVA had spent approximately $283 million as of September 30, 2023. Additionally, TVA holds restricted cash in an interest earning trust to fund the remaining project commitments. Any interest earned through the trust must also be spent on agreed upon environmental projects. The total remaining committed costs, including interest earned through the trust, were approximately $8 million as of September 30, 2023.

The liabilities related to the Environmental Agreements are included in Accounts payable and accrued liabilities and Other long-term liabilities on the September 30, 2023, Consolidated Balance Sheets. In conjunction with the approval of the Environmental Agreements, the TVA Board determined that it was appropriate to record TVA's obligations under the Environmental Agreements as regulatory assets, and they are included as such on the September 30, 2023, Consolidated Balance Sheets and will be recovered in rates in future periods.

Case Involving Johnsonville Aeroderivative Combustion Turbine Project. On December 22, 2022, the Southern Environmental Law Center filed a lawsuit in the U.S. District Court for the Middle District of Tennessee on behalf of the Sierra Club, alleging that TVA violated the National Environmental Policy Act ("NEPA") in deciding to build a new aeroderivative combustion turbine project at its Johnsonville facility.

The Sierra Club claims that TVA violated NEPA by failing to adequately analyze the climate consequences of the project, adequately address GHG mitigation in light of EOs to decarbonize the power sector, consider a reasonable range of alternatives to the project, and prepare an environmental impact statement ("EIS").

The Sierra Club requests the federal court to enter a declaratory judgment that TVA's environmental assessment ("EA") violates NEPA and that TVA's decision to issue a finding of no significant impact ("FONSI") was arbitrary, vacate the EA and FONSI, order TVA to prepare an EIS, and prohibit further construction and operation of the combustion turbines until TVA has complied with NEPA. On March 20, 2023, TVA moved to dismiss the case, and that motion remains pending before the court. In addition, on October 23, 2023, TVA and the plaintiffs filed cross-motions for summary judgment. TVA cannot predict the outcome of this litigation.

Case Involving Cumberland Combined Cycle Plant. On June 14, 2023, Appalachian Voices, the Center for Biological Diversity, and the Sierra Club filed a lawsuit in the United States District Court for the Middle District of Tennessee alleging that TVA violated NEPA in deciding to build a 1,450 MW combined cycle plant at its Cumberland facility. The plaintiffs request the court, among other things, to enter a declaratory judgment that the Cumberland EIS violated NEPA and TVA's decision to issue the Cumberland Record of Decision was arbitrary, capricious, and/or not in accordance with law; enter a declaratory judgment that TVA’s failure to supplement the Cumberland EIS violated NEPA and was arbitrary, capricious, and/or not in accordance with law; vacate the Cumberland EIS and the Cumberland Record of Decision; order TVA to prepare a revised draft EIS or