v3.26.1
Asset Retirement Obligations and Accrued Environmental Costs
3 Months Ended
Mar. 31, 2026
Asset Retirement Obligation Disclosure [Abstract]  
Asset Retirement Obligations and Accrued Environmental Costs
8. Asset Retirement Obligations and Accrued Environmental Costs
Certain subsidiaries of the Company have legal retirement obligations for the decommissioning and environmental remediation costs associated with our current and former generation sites. Most of these obligations, except remediation of some ash impoundments, are not expected to be paid until several years, or decades, in the future. The Company’s most significant obligations are associated with the: (i) decommissioning of Susquehanna, which the NDT is expected to fund; and (ii) coal ash disposal units of legacy coal-fired generation facilities which, for certain obligations, the Company has posted surety bonds (some of which have been collateralized with LCs). The carrying value of these AROs include assumptions of estimated future retirement and remediation cash expenditures, cost escalation rates, probabilistic cash flow models, and discount rates.
The Company may be required to revise or recognize new AROs as a result of regulatory changes by the NRC, EPA, Montana Department of Environmental Quality (the “MDEQ”) or other regulatory entities. Additionally, revisions may result from scope of work amendments to remediation activities as well as changes to remediation costs and other assumptions. If the assumptions underlying any ARO estimates do not materialize as expected, actual cash expenditures and costs could be materially different than currently estimated.
As of March 31, 2026, the fair values of certain conditional AROs as a result of the EPA CCR Rule cannot be determined. See Note 9 for additional information on a recent EPA proposal to rescind certain provisions of the EPA CCR Rule.
The carrying value of AROs and accrued environmental costs were:

March 31,
2026
December 31,
2025
Asset retirement obligations$522 $514 
Accrued environmental costs 20 20 
Total asset retirement obligations and accrued environmental costs 542 534 
Less: asset retirement obligations and accrued environmental costs due within one year (a)
46 40 
Asset retirement obligations and accrued environmental costs due after one year $496 $494 
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(a)Presented as “Other current liabilities” on the Consolidated Balance Sheets.
The changes of the ARO carrying value during the period were:
2026
Carrying value January 1,$514 
Obligations settled(6)
Accretion expense14 
Carrying value, March 31, $522 
The disaggregation of ARO carrying values on the Consolidated Balance Sheets was:

March 31,
2026
December 31,
2025
Nuclear (a)
$281 $272 
Non-nuclear (b)
241 242 
Carrying value $522 $514 
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(a)Obligations are expected to be settled with available funds in the NDT at the time of decommissioning. See Note 6 for additional information on the NDT.
(b)Certain obligations are: (i) partially supported by surety bonds, some of which have been collateralized with LCs; or (ii) partially prefunded under phased installment agreements.