PROPERTY, PLANT AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2019

PROPERTY, PLANT AND EQUIPMENT

Schedule of jointly owned facilities

JOINTLY OWNED FACILITIES:  Our share in each jointly owned facility is as follows as of December 31, 2019 (these electric plant in service, accumulated depreciation and construction work in progress amounts are included in the electric plant table above) (dollars in thousands):

			Electric				Construction
	Tri-State		Plant in		Accumulated		Work In
	Share		Service		Depreciation		Progress
Yampa Project - Craig Generating Station Units 1 and 2	24.00	%	$	396,292	$	245,723	$	21
MBPP - Laramie River Station	27.13	%		490,156		298,465		1,491
Total			$	886,448	$	544,188	$	1,512

Schedule of other plant assets (excluding utility assets)

Other plant assets are as follows (dollars in thousands):

	December 31,		December 31,
	2019		2018
Colowyo Mine assets	$	356,612	$	326,838
New Horizon Mine assets		38,949		44,589
Fort Union Mine assets		846		846
Accumulated depreciation and depletion		(106,337)		(104,031)
Net mine assets		290,070		268,242
Non-utility assets		12,644		12,377
Accumulated depreciation		(7,270)		(6,908)
Net non-utility assets		5,374		5,469
Net other plant	$	295,444	$	273,711

Electric Plant

PROPERTY, PLANT AND EQUIPMENT

Schedule of investment in plant

ELECTRIC PLANT:  At December 31, 2019, our investment in electric plant and the related annual rates of depreciation or amortization calculated using the straight‑line method are as follows (dollars in thousands):

						Plant In			Accumulated		Net Book
	Annual Depreciation Rate					Service			Depreciation		Value
Generation plant	0.89	%	to	6.27	%	$	3,681,886	$	(1,599,528)	$	2,082,358
Transmission plant	1.11	%	to	2.09	%		1,679,534		(600,740)		1,078,794
General plant	1.46	%	to	9.53	%		472,592		(321,304)		151,288
Other	2.75	%	to	10.00	%		256,380		(119,898)		136,482
Electric plant in service (at cost)						$	6,090,392	$	(2,641,470)		3,448,922
Construction work in progress											164,924
Electric plant										$	3,613,846

At December 31, 2018, our investment in electric plant and the related annual rates of depreciation or amortization calculated using the straight‑line method are as follows (dollars in thousands):

						Plant In			Accumulated		Net Book
	Annual Depreciation Rate					Service			Depreciation		Value
Generation plant	0.89	%	to	6.27	%	$	3,601,911	$	(1,504,802)	$	2,097,109
Transmission plant	1.11	%	to	2.09	%		1,556,860		(562,216)		994,644
General plant	1.46	%	to	9.53	%		492,991		(316,233)		176,758
Other	2.75	%	to	10.00	%		247,366		(116,125)		131,241
Electric plant in service (at cost)						$	5,899,128	$	(2,499,376)		3,399,752
Construction work in progress											207,732
Electric plant										$	3,607,484