JOINTLY-OWNED ELECTRIC UTILITY PLANT

Under joint ownership agreements with other utilities, IPL and WPL have undivided ownership interests in jointly-owned EGUs. Each of the respective owners is responsible for the financing of its portion of the construction costs. IPL’s and WPL’s shares of expenses from jointly-owned EGUs are included in the corresponding operating expenses (e.g., electric production fuel, other operation and maintenance, etc.) in the income statements. Information relative to IPL’s and WPL’s ownership interest in these jointly-owned EGUs at December 31, 2023 was as follows (dollars in millions):


	Ownership	Electric	Accumulated Provision	Construction
	Interest %	Plant	for Depreciation	Work in Progress
IPL
Ottumwa Unit 1	48.0%	$632	$264	$7
George Neal Unit 4	25.7%	196	107	6
George Neal Unit 3	28.0%	181	85	8
Louisa Unit 1	4.0%	44	22	—
		1,053	478	21
WPL
Columbia Units 1-2	53.5%	818	361	6
West Riverside Energy Center and Solar Facility (a)	73.8%	581	60	6
Forward Wind Energy Center	42.6%	118	53	—
		1,517	474	12
Alliant Energy		$2,570	$952	$33

(a)In 2023, Madison Gas and Electric Company and WEC Energy Group, Inc. acquired partial ownership interests in West Riverside. The related proceeds are included in “Proceeds from sales of partial ownership interests in West Riverside” in investing activities in Alliant Energy’s and WPL’s cash flows statements in 2023.

Jointly-Owned Electric Utility Plant

JOINTLY-OWNED ELECTRIC UTILITY PLANT

Under joint ownership agreements with other utilities, IPL and WPL have undivided ownership interests in jointly-owned EGUs. Each of the respective owners is responsible for the financing of its portion of the construction costs. IPL’s and WPL’s shares of expenses from jointly-owned EGUs are included in the corresponding operating expenses (e.g., electric production fuel, other operation and maintenance, etc.) in the income statements. Information relative to IPL’s and WPL’s ownership interest in these jointly-owned EGUs at December 31, 2023 was as follows (dollars in millions):


	Ownership	Electric	Accumulated Provision	Construction
	Interest %	Plant	for Depreciation	Work in Progress
IPL
Ottumwa Unit 1	48.0%	$632	$264	$7
George Neal Unit 4	25.7%	196	107	6
George Neal Unit 3	28.0%	181	85	8
Louisa Unit 1	4.0%	44	22	—
		1,053	478	21
WPL
Columbia Units 1-2	53.5%	818	361	6
West Riverside Energy Center and Solar Facility (a)	73.8%	581	60	6
Forward Wind Energy Center	42.6%	118	53	—
		1,517	474	12
Alliant Energy		$2,570	$952	$33

(a)In 2023, Madison Gas and Electric Company and WEC Energy Group, Inc. acquired partial ownership interests in West Riverside. The related proceeds are included in “Proceeds from sales of partial ownership interests in West Riverside” in investing activities in Alliant Energy’s and WPL’s cash flows statements in 2023.

Jointly-Owned Electric Utility Plant

JOINTLY-OWNED ELECTRIC UTILITY PLANT

Under joint ownership agreements with other utilities, IPL and WPL have undivided ownership interests in jointly-owned EGUs. Each of the respective owners is responsible for the financing of its portion of the construction costs. IPL’s and WPL’s shares of expenses from jointly-owned EGUs are included in the corresponding operating expenses (e.g., electric production fuel, other operation and maintenance, etc.) in the income statements. Information relative to IPL’s and WPL’s ownership interest in these jointly-owned EGUs at December 31, 2023 was as follows (dollars in millions):


	Ownership	Electric	Accumulated Provision	Construction
	Interest %	Plant	for Depreciation	Work in Progress
IPL
Ottumwa Unit 1	48.0%	$632	$264	$7
George Neal Unit 4	25.7%	196	107	6
George Neal Unit 3	28.0%	181	85	8
Louisa Unit 1	4.0%	44	22	—
		1,053	478	21
WPL
Columbia Units 1-2	53.5%	818	361	6
West Riverside Energy Center and Solar Facility (a)	73.8%	581	60	6
Forward Wind Energy Center	42.6%	118	53	—
		1,517	474	12
Alliant Energy		$2,570	$952	$33

(a)In 2023, Madison Gas and Electric Company and WEC Energy Group, Inc. acquired partial ownership interests in West Riverside. The related proceeds are included in “Proceeds from sales of partial ownership interests in West Riverside” in investing activities in Alliant Energy’s and WPL’s cash flows statements in 2023.