Asset Retirement Obligations

During the six months ended March 31, 2020, TVA's total asset retirement obligations ("ARO") liability increased $159 million as a result of periodic accretion and revisions in estimate, partially offset by settlement projects that were conducted during the period. The nuclear and non-nuclear accretion amounts were deferred as regulatory assets. During the six months ended March 31, 2020, $84 million of the related regulatory assets were amortized into expense as these amounts were collected in rates. See Note 8 — Regulatory Assets and Liabilities. TVA maintains investment trusts to help fund its decommissioning obligations. See Note 15 — Fair Value Measurements — Investment Funds and Note 20 — Contingencies and Legal Proceedings — Contingencies — Decommissioning Costs for disclosure of the current balances of the trusts and a discussion of the trusts' objectives.



Asset Retirement Obligation Activity⁽¹⁾
	Nuclear		Non-Nuclear			Total
Balance at September 30, 2019	$	3,136	$	2,480		$	5,616
Settlements	—		(62		)	(62		)
Revisions in estimate	—		120			120
Accretion (recorded as regulatory asset)	70		31			101
Balance at March 31, 2020	$	3,206	$	2,569		$	5,775

Note

(1) The current portions of the ARO liability in the amounts of $193 million and $163 million at March 31, 2020, and September 30, 2019, respectively, are included in Accounts payable and accrued liabilities.

The revisions in non-nuclear estimates increased $120 million for the six months ended March 31, 2020. In November 2019, the Tennessee Department of Environment and Conservation ("TDEC") released amendments to its regulations which govern solid waste disposal facilities, including TVA's active Coal Combustion Residuals ("CCR") facilities covered by a solid waste disposal permit and those which closed pursuant to a TDEC approved closure plan. Such facilities are generally subject to a 30-year post-closure care period during which the owner or operator must undertake certain activities, including monitoring and maintaining the facility. The amendments will, among other things, add an additional 50-year period after the end of the post-closure care period, require TVA to submit recommendations as to what activities must be performed during this 50-year period to protect human health and the environment, and require TVA to submit revised closure plans every 10 years. This regulatory revision resulted in an increase of $129 million, of which $38 million was related to operating CCR facilities and $91 million was related to inactive or closed CCR facilities.