v2.4.0.6

Jointly-Owned Electric Utility Plant

12 Months Ended

Dec. 31, 2012

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 coal-fired electric generating facilities. Each of the respective owners is responsible for the financing of its portion of the construction costs. Kilowatt-hour generation and operating expenses are primarily divided between the joint owners on the same basis as ownership. IPL’s and WPL’s shares of expenses from jointly-owned coal-fired electric generating facilities are included in the corresponding operating expenses (e.g., electric production fuel, other operation and maintenance, etc.) in their Consolidated Statements of Income. Refer to Note 1(b) for further discussion of cost of removal obligations. Information relative to IPL’s and WPL’s ownership interest in these jointly-owned coal-fired electric generating facilities at December 31, 2012 was as follows (dollars in millions):

										Accumulated				Construction				Cost of Removal
	In-service		Ownership			Plant in				Provision for				Work in				Obligations Included in
	Dates		Interest %			Service				Depreciation				Progress				Regulatory Liabilities
IPL
Ottumwa Unit 1	1981		48.0	%			$239.2				$118.8				$84.0				$12.0
George Neal Unit 4	1979		25.7	%		97.1				67.8				44.5				11.5
George Neal Unit 3	1975		28.0	%		59.1				39.1				27.2				5.6
Louisa Unit 1	1983		4.0	%		35.0				19.2				0.2				3.0
						430.4				244.9				155.9				32.1
WPL
Columbia Units 1-2	1975-1978		46.2	%		247.0				157.9				133.5				10.2
Edgewater Unit 4	1969		68.2	%		91.8				49.2				0.4				2.2
						338.8				207.1				133.9				12.4
Alliant Energy							$769.2				$452.0				$289.8				$44.5

IPL [Member]

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 coal-fired electric generating facilities. Each of the respective owners is responsible for the financing of its portion of the construction costs. Kilowatt-hour generation and operating expenses are primarily divided between the joint owners on the same basis as ownership. IPL’s and WPL’s shares of expenses from jointly-owned coal-fired electric generating facilities are included in the corresponding operating expenses (e.g., electric production fuel, other operation and maintenance, etc.) in their Consolidated Statements of Income. Refer to Note 1(b) for further discussion of cost of removal obligations. Information relative to IPL’s and WPL’s ownership interest in these jointly-owned coal-fired electric generating facilities at December 31, 2012 was as follows (dollars in millions):

										Accumulated				Construction				Cost of Removal
	In-service		Ownership			Plant in				Provision for				Work in				Obligations Included in
	Dates		Interest %			Service				Depreciation				Progress				Regulatory Liabilities
IPL
Ottumwa Unit 1	1981		48.0	%			$239.2				$118.8				$84.0				$12.0
George Neal Unit 4	1979		25.7	%		97.1				67.8				44.5				11.5
George Neal Unit 3	1975		28.0	%		59.1				39.1				27.2				5.6
Louisa Unit 1	1983		4.0	%		35.0				19.2				0.2				3.0
						430.4				244.9				155.9				32.1
WPL
Columbia Units 1-2	1975-1978		46.2	%		247.0				157.9				133.5				10.2
Edgewater Unit 4	1969		68.2	%		91.8				49.2				0.4				2.2
						338.8				207.1				133.9				12.4
Alliant Energy							$769.2				$452.0				$289.8				$44.5

WPL [Member]

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 coal-fired electric generating facilities. Each of the respective owners is responsible for the financing of its portion of the construction costs. Kilowatt-hour generation and operating expenses are primarily divided between the joint owners on the same basis as ownership. IPL’s and WPL’s shares of expenses from jointly-owned coal-fired electric generating facilities are included in the corresponding operating expenses (e.g., electric production fuel, other operation and maintenance, etc.) in their Consolidated Statements of Income. Refer to Note 1(b) for further discussion of cost of removal obligations. Information relative to IPL’s and WPL’s ownership interest in these jointly-owned coal-fired electric generating facilities at December 31, 2012 was as follows (dollars in millions):

										Accumulated				Construction				Cost of Removal
	In-service		Ownership			Plant in				Provision for				Work in				Obligations Included in
	Dates		Interest %			Service				Depreciation				Progress				Regulatory Liabilities
IPL
Ottumwa Unit 1	1981		48.0	%			$239.2				$118.8				$84.0				$12.0
George Neal Unit 4	1979		25.7	%		97.1				67.8				44.5				11.5
George Neal Unit 3	1975		28.0	%		59.1				39.1				27.2				5.6
Louisa Unit 1	1983		4.0	%		35.0				19.2				0.2				3.0
						430.4				244.9				155.9				32.1
WPL
Columbia Units 1-2	1975-1978		46.2	%		247.0				157.9				133.5				10.2
Edgewater Unit 4	1969		68.2	%		91.8				49.2				0.4				2.2
						338.8				207.1				133.9				12.4
Alliant Energy							$769.2				$452.0				$289.8				$44.5

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