Property, Plant and Equipment

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

(5)          Property, Plant and Equipment

The following table presents the major classifications of our property, plant and equipment (in thousands):

	Estimated Useful Life	December 31,
		2019			2018
	(years)	(in thousands)
Land, land rights and easements	50 – 96	$	156,069		$	149,636
Building and improvements	23 – 73	278,164			264,205
Transmission, distribution, and storage	15 – 85	3,569,141			3,341,001
Generation	23 – 71	1,222,796			1,193,117
Plant acquisition adjustment (1)	25 – 50	686,328			686,328
Other	2 – 45	545,009			541,741
Construction work in process	–—	96,421			110,076
Total property, plant and equipment		6,553,928			6,286,104
Less accumulated depreciation		(1,853,004		)	(1,764,786		)
Net property, plant and equipment		$	4,700,924		$	4,521,318

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(1) The plant acquisition adjustment balance above includes our Beethoven wind project acquired in 2015, our hydro generating assets acquired in 2014, and the inclusion of our interest in Colstrip Unit 4 in rate base in 2009. The acquisition adjustment is amortized on a straight-line basis over the estimated remaining useful life of each related asset in depreciation expense.

Net plant and equipment under finance lease were $13.3 million and $15.4 million as of December 31, 2019 and 2018, respectively, which included $13.1 million and $15.1 million as of December 31, 2019 and 2018, respectively, related to a long-term power supply contract with the owners of a natural gas fired peaking plant, which has been accounted for as a finance lease.

Jointly Owned Electric Generating Plant

We have an ownership interest in four base-load electric generating plants, all of which are coal fired and operated by other companies. We have an undivided interest in these facilities and are responsible for our proportionate share of the capital and operating costs while being entitled to our proportionate share of the power generated. Our interest in each plant is reflected in the Consolidated Balance Sheets on a pro rata basis and our share of operating expenses is reflected in the Consolidated Statements of Income. The participants each finance their own investment.

Information relating to our ownership interest in these facilities is as follows (in thousands):

	Big Stone (SD)			Neal #4 (IA)			Coyote (ND)			Colstrip Unit 4 (MT)
December 31, 2019
Ownership percentages	23.4		%	8.7		%	10.0		%	30.0		%
Plant in service	$	155,662		$	62,565		$	52,448		$	311,399
Accumulated depreciation	40,988			32,853			38,310			97,563
December 31, 2018
Ownership percentages	23.4		%	8.7		%	10.0		%	30.0		%
Plant in service	$	155,359		$	60,758		$	50,325		$	309,163
Accumulated depreciation	42,235			31,542			37,955			88,985