ASSET RETIREMENT OBLIGATIONS (Tables)

12 Months Ended

Dec. 31, 2021

Asset Retirement Obligation Disclosure [Abstract]

Schedule of changes to asset retirement obligations

The following table shows changes to our AROs during the years ended December 31:

(in millions)	2021			2020			2019
Balance as of January 1	$	45.5		$	41.5		$	50.8
Accretion	1.8			1.8			2.5
Additions and revisions to estimated cash flows	8.6		(1)	8.2		(2)	(3.7)
Liabilities settled	(0.1)			(6.0)		(3)	(8.1)		(4)
Balance as of December 31	$	55.8		$	45.5		$	41.5

(1)    AROs increased $10.8 million in 2021, due to the legal requirement to dismantle, at retirement, the Badger Hollow I solar generation project. Also in 2021, AROs increased $6.8 million due to revisions made to the removal estimates for fly ash landfills and ash ponds. AROs decreased $8.9 million due to revisions made to removal estimates for wind generation projects.

(2)    This increase in AROs during 2020 was primarily due to the legal requirement to dismantle, at retirement, the Two Creeks solar generation project.

(3)    AROs decreased $3.8 million in 2020, due to the settlement of AROs for the abatement of asbestos at our generation facilities. Also in 2020, AROs decreased $2.2 million, due to the settlement of AROs for the closure of coal combustion residual landfills at certain generation facilities.

(4)    AROs decreased $8.1 million in 2019, primarily due to the settlement of AROs for the abatement of asbestos at our generation facilities.