ASSET RETIREMENT OBLIGATIONS

Recognized AROs relate to legal obligations for the removal, closure or dismantlement of several assets including, but not limited to, wind farms, ash ponds, active ash landfills, above ground storage tanks, coal yards and solar generation. Recognized AROs also include legal obligations for the management and final disposition of asbestos and polychlorinated biphenyls. AROs are recorded in “Other current liabilities” and “Other liabilities” on the balance sheets. Refer to Note 2 for information regarding regulatory assets related to AROs. A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):


	Alliant Energy		IPL		WPL
	2020	2019	2020	2019	2020	2019
Balance, January 1	$196	$177	$134	$118	$62	$59
Revisions in estimated cash flows	13	(6)	9	(7)	4	1
Liabilities settled	(13)	(8)	(9)	(8)	(4)	—
Liabilities incurred (a)	48	26	38	26	10	—
Accretion expense	7	7	5	5	2	2
Balance, December 31	$251	$196	$177	$134	$74	$62

(a)In 2020, IPL placed in service the Whispering Willow North, Golden Plains and Richland wind sites, and WPL placed in service the Kossuth wind site. As a result, Alliant Energy, IPL and WPL recognized additional AROs in 2020, which resulted in corresponding increases in property, plant and equipment, net on the respective balance sheets.

Schedule of Asset Retirement Obligations [Line Items]

Asset Retirement Obligations (AROs)

ASSET RETIREMENT OBLIGATIONS

Recognized AROs relate to legal obligations for the removal, closure or dismantlement of several assets including, but not limited to, wind farms, ash ponds, active ash landfills, above ground storage tanks, coal yards and solar generation. Recognized AROs also include legal obligations for the management and final disposition of asbestos and polychlorinated biphenyls. AROs are recorded in “Other current liabilities” and “Other liabilities” on the balance sheets. Refer to Note 2 for information regarding regulatory assets related to AROs. A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):


	Alliant Energy		IPL		WPL
	2020	2019	2020	2019	2020	2019
Balance, January 1	$196	$177	$134	$118	$62	$59
Revisions in estimated cash flows	13	(6)	9	(7)	4	1
Liabilities settled	(13)	(8)	(9)	(8)	(4)	—
Liabilities incurred (a)	48	26	38	26	10	—
Accretion expense	7	7	5	5	2	2
Balance, December 31	$251	$196	$177	$134	$74	$62

(a)In 2020, IPL placed in service the Whispering Willow North, Golden Plains and Richland wind sites, and WPL placed in service the Kossuth wind site. As a result, Alliant Energy, IPL and WPL recognized additional AROs in 2020, which resulted in corresponding increases in property, plant and equipment, net on the respective balance sheets.