The Duke Energy Registrants are subject to federal, state and local regulations regarding air and water quality, hazardous and solid waste disposal, coal ash and other environmental matters. These regulations can be changed from time to time, imposing new obligations on the Duke Energy Registrants. The following environmental matters impact all Duke Energy Registrants.

In addition to Asset Retirement Obligations recorded as a result of various environmental regulations, the Duke Energy Registrants are responsible for environmental remediation at various sites. These include certain properties that are part of ongoing operations and sites formerly owned or used by Duke Energy entities. These sites are in various stages of investigation, remediation and monitoring. Managed in conjunction with relevant federal, state and local agencies, remediation activities vary based on site conditions and location, remediation requirements, complexity and sharing of responsibility. If remediation activities involve joint and several liability provisions, strict liability, or cost recovery or contribution actions, the Duke Energy Registrants could potentially be held responsible for environmental impacts caused by other potentially responsible parties and may also benefit from insurance policies or contractual indemnities that cover some or all cleanup costs. Liabilities are recorded when losses become probable and are reasonably estimable. The total costs that may be incurred cannot be estimated because the extent of environmental impact, allocation among potentially responsible parties, remediation alternatives and/or regulatory decisions have not yet been determined at all sites. Additional costs associated with remediation activities are likely to be incurred in the future and could be significant. Costs are typically expensed as Operation, maintenance and other on the Condensed Consolidated Statements of Operations unless regulatory recovery of the costs is deemed probable.

On December 20, 2024, 15 plaintiffs filed a lawsuit in Iredell County, North Carolina, against Duke Energy (Parent), Duke Energy Carolinas and Duke Energy Progress (collectively “Duke Energy”) on behalf of a putative class alleging past and ongoing environmental contamination in the Mooresville area of North Carolina. The lawsuit alleges that Duke Energy disposed of and sold coal ash as structural fill resulting in the contamination of soil, groundwater and Lake Norman. The plaintiffs claim that Duke Energy failed to properly remediate the contamination and continues to pollute, and they assert that the contamination has negatively impacted property values and led to elevated cancer rates and other health issues. The plaintiffs are seeking unspecified compensatory and punitive damages, injunctive relief to stop further contamination, remediation of contaminated areas and attorneys' fees and costs. On July 28, 2025, the plaintiffs filed an Amended Complaint, which asserts claims for negligence, negligence per se, gross negligence, private nuisance, strict liability for ultra-hazardous activities and trespass. Duke Energy's deadline to respond to the Amended Complaint is September 11, 2025. Duke Energy has informed the plaintiffs and the court that it intends to file a motion to dismiss. A hearing on the motion to dismiss is scheduled for December 15, 2025.

On July 11, 2025, plaintiffs Leo Dorrell and John Dunn filed a putative class action lawsuit in the U.S. District Court for the District of Maryland against all U.S. commercial nuclear power operators, including Duke Energy Corporation (Parent) and Progress Energy. The plaintiffs allege that the nuclear power industry engaged in a conspiracy to suppress compensation by exchanging salary information since 2003, in violation of Section 1 of the Sherman Act. Although not named as defendants, other entities are accused of having participated in the plaintiff's alleged conspiracy, including Duke Energy Carolinas and Duke Energy Progress. The lawsuit seeks unspecified monetary damages, including treble damages, on behalf of current and former employees in the nuclear power industry as well as injunctive relief. Duke Energy is evaluating the claims and intends to vigorously defend this lawsuit. A Consent Motion was filed on August 4, 2025, setting the briefing schedule in the case. The defendants' response to the complaint is due on October 15, 2025.

In November 2017, Duke Energy Carolinas entered into a standard FERC large generator interconnection agreement (LGIA) with NTE Carolinas II, LLC (NTE), a company that proposed to build a combined-cycle natural gas plant in Rockingham County, North Carolina. In September 2019, Duke Energy Carolinas filed a lawsuit in Mecklenburg County Superior Court against NTE for breach of contract, alleging that NTE's failure to pay benchmark payments for Duke Energy Carolinas' transmission system upgrades required under the interconnection agreement constituted a termination of the interconnection agreement. Duke Energy Carolinas sought a monetary judgment against NTE because NTE failed to make multiple milestone payments. The lawsuit was moved to federal court in North Carolina. NTE filed a motion to dismiss Duke Energy Carolinas’ complaint and brought counterclaims alleging anti-competitive conduct and violations of state and federal statutes. Duke Energy Carolinas filed a motion to dismiss NTE's counterclaims. Both NTE's and Duke Energy Carolinas' motions to dismiss were subsequently denied by the court.

On May 21, 2020, in response to a NTE petition challenging Duke Energy Carolinas' termination of the LGIA, FERC issued a ruling that 1) it has exclusive jurisdiction to determine whether a transmission provider may terminate an LGIA; 2) FERC approval is required to terminate a conforming LGIA if objected to by the interconnection customer; and 3) Duke Energy may not announce the termination of a conforming LGIA unless FERC has approved the termination. FERC's Office of Enforcement also initiated an investigation of Duke Energy Carolinas into matters pertaining to the LGIA. In April 2023, Duke Energy Carolinas received notice from the FERC Office of Enforcement that they have closed their non-public investigation with no further action recommended.

Following completion of discovery, Duke Energy Carolinas filed a motion for summary judgment seeking a ruling in its favor as to some of its affirmative claims against NTE and to all of NTE’s counterclaims. On June 24, 2022, the court issued an order partially granting Duke Energy Carolinas' motion by dismissing NTE's counterclaims that Duke Energy Carolinas engaged in anti-competitive behavior in violation of state and federal statutes. In October 2022, the parties executed a settlement agreement with respect to the remaining breach of contract claims in the litigation and a Stipulation of Dismissal was filed with the court.

In November 2022, NTE filed its Notice of Appeal to the U.S. Court of Appeals for the Fourth Circuit as to the district court's summary judgment ruling in Duke Energy Carolinas' favor on NTE's antitrust and unfair competition claims. On August 5, 2024, the U.S. Court of Appeals for the Fourth Circuit reversed the district court's grant of summary judgment and remanded the case back to the district court for further proceedings. In August 2024, Duke Energy Carolinas filed a petition for rehearing, which was denied on November 26, 2024. On February 21, 2025, Duke Energy Carolinas filed a petition seeking review by the U.S. Supreme Court. On June 2, 2025, the U.S. Supreme Court invited the Solicitor General to file a brief reflecting the views of the U.S. as it relates to this matter.

Duke Energy Carolinas has experienced numerous claims for indemnification and medical cost reimbursement related to asbestos exposure. These claims relate to damages for bodily injuries alleged to have arisen from exposure to or use of asbestos in connection with construction and maintenance activities conducted on its electric generation plants prior to 1985.

Duke Energy Carolinas has recognized asbestos-related reserves of $379 million at June 30, 2025, and $396 million at December 31, 2024. These reserves are classified in Other within Other Noncurrent Liabilities and Other within Current Liabilities on the Condensed Consolidated Balance Sheets. These reserves are based on Duke Energy Carolinas' best estimate for current and future asbestos claims through 2044 and are recorded on an undiscounted basis. In light of the uncertainties inherent in a longer-term forecast, management does not believe they can reasonably estimate the indemnity and medical costs that might be incurred after 2044 related to such potential claims. It is possible Duke Energy Carolinas may incur asbestos liabilities in excess of the recorded reserves.

Duke Energy Carolinas has third-party insurance to cover certain losses related to asbestos-related injuries and damages above an aggregate self-insured retention. Receivables for insurance recoveries were $540 million at June 30, 2025, and $539 million at December 31, 2024. These amounts are classified in Other within Other Noncurrent Assets and Receivables within Current Assets on the Condensed Consolidated Balance Sheets. Any future payments up to the policy limit will be reimbursed by the third-party insurance carrier. Duke Energy Carolinas is not aware of any uncertainties regarding the legal sufficiency of insurance claims. Duke Energy Carolinas believes the insurance recovery asset is probable of recovery as the insurance carrier continues to have a strong financial strength rating.

The reserve for credit losses for insurance receivables is $9 million as of June 30, 2025, and December 31, 2024, for both Duke Energy and Duke Energy Carolinas. The insurance receivable is evaluated based on the risk of default and the historical losses, current conditions and expected conditions around collectability. Management evaluates the risk of default annually based on payment history, credit rating and changes in the risk of default from credit agencies.

In June 2022, Duke Energy Indiana filed a civil action in Indiana Superior Court against various insurance companies seeking declaratory relief with respect to insurance coverage for coal combustion residuals-related expenses and liabilities covered by third-party liability insurance policies. The insurance policies cover the 1969-1972 and 1984-1985 periods and provide third-party liability insurance for claims and suits alleging property damage, bodily injury and personal injury (or a combination thereof). In June 2024, Duke Energy Indiana filed an amended complaint adding several additional insurance companies as defendants to the litigation. During 2023 through 2025, Duke Energy Indiana reached confidential settlements with various insurance companies, the results of which were not material to Duke Energy. All settlement payments have been received and the case has been dismissed. In July 2025, Duke Energy Indiana began refunding retail customers their share of coal ash insurance settlement proceeds, after expenses, over one year.

The Duke Energy Registrants are involved in other legal, tax and regulatory proceedings arising in the ordinary course of business, some of which involve significant amounts. The Duke Energy Registrants believe the final disposition of these proceedings will not have a material effect on their results of operations, cash flows or financial position. Reserves are classified on the Condensed Consolidated Balance Sheets in Other within Other Noncurrent Liabilities and Other within Current Liabilities.

As part of their normal business, the Duke Energy Registrants are party to various financial guarantees, performance guarantees and other contractual commitments to extend guarantees of credit and other assistance to various subsidiaries, investees and other third parties. These guarantees involve elements of performance and credit risk, which are not fully recognized on the Condensed Consolidated Balance Sheets and have uncapped maximum potential payments. However, the Duke Energy Registrants do not believe these guarantees will have a material effect on their results of operations, cash flows or financial position.

In addition, the Duke Energy Registrants enter into various fixed-price, non-cancelable commitments to purchase or sell power or natural gas, take-or-pay arrangements, transportation, or throughput agreements and other contracts that may or may not be recognized on their respective Condensed Consolidated Balance Sheets. Some of these arrangements may be recognized at fair value on their respective Condensed Consolidated Balance Sheets if such contracts meet the definition of a derivative and the NPNS exception does not apply. In most cases, the Duke Energy Registrants’ purchase obligation contracts contain provisions for price adjustments, minimum purchase levels and other financial commitments.