Jointly-Owned Electric Utility Plant (Tables)

12 Months Ended

Dec. 31, 2012

Jointly Owned Utility Plant Interests [Line Items]

Components of Jointly-Owned Electric Utility Plants

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 Utility Plant Interests [Line Items]

Components of Jointly-Owned Electric Utility Plants

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 Utility Plant Interests [Line Items]

Components of Jointly-Owned Electric Utility Plants

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

- Definition

Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants.

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