Our property, plant and equipment consists of electric plant and other plant. Both of these are discussed below and are included on our consolidated statements of financial position.

ELECTRIC PLANT: As of June 30, 2024, 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):


	Annual Depreciation Rate					Plant In Service		Accumulated Depreciation		Net Book Value
Generation plant	0.89	%	to	6.27	%	$	3,089,810	$	(1,699,258)	$	1,390,552
Transmission plant	1.11	%	to	2.09	%	1,895,240		(701,422)		1,193,818
General plant	1.46	%	to	9.53	%	448,016		(274,586)		173,430
Other	2.75	%	to	10.00	%	240,737		(97,015)		143,722
Electric plant in service (at cost)						$	5,673,803	$	(2,772,281)	2,901,522
Construction work in progress										256,301
Electric plant										$	3,157,823

In March 2024, we executed an asset purchase agreement to purchase the 145 MW Axial Basin Solar project being developed in northwestern Colorado. Concurrent with execution of the purchase agreement, we also executed an engineering, procurement and construction contract with an affiliate of the developer of the project. In April 2024, we closed on the acquisition of Axial Basin Solar project and issued a notice to proceed with construction to the contractor.

In April 2024, we executed an asset purchase agreement to purchase the 110 MW Dolores Canyon Solar project being developed in southwestern Colorado. Concurrent with execution of the purchase agreement, we also executed an engineering, procurement and construction contract with an affiliate of the developer of the project. In May 2024, we closed on the acquisition of Dolores Canyon Solar project and issued a notice to proceed with construction to the contractor.

Both acquisitions were accounted for as an asset acquisition in accordance with the accounting requirements for business combinations since we purchased the project assets and not a business. As such, the asset acquisitions and subsequent

facility development costs are being capitalized which is included in construction work in progress as of June 30, 2024. Both projects are expected to achieve commercial operation in the second half of 2025.

As of December 31, 2023, 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):


	Annual Depreciation Rate					Plant In Service		Accumulated Depreciation		Net Book Value
Generation plant	0.89	%	to	6.27	%	$	3,082,133	$	(1,669,941)	$	1,412,192
Transmission plant	1.11	%	to	2.09	%	1,983,629		(708,412)		1,275,217
General plant	1.46	%	to	9.53	%	410,856		(266,013)		144,843
Other	2.75	%	to	10.00	%	246,061		(95,558)		150,503
Electric plant in service (at cost)						$	5,722,679	$	(2,739,924)	2,982,755
Construction work in progress										163,954
Electric plant										$	3,146,709

JOINTLY OWNED FACILITIES: Our share in each jointly owned facility is as follows as of June 30, 2024 (these electric plant in service, accumulated depreciation and construction work in progress amounts are included in the electric plant table above) (dollars in thousands):


	Tri-State Share		Electric Plant in Service		Accumulated Depreciation		Construction Work In Progress
Yampa Project - Craig Generating Station Units 1 and 2	24.00	%	$	392,510	$	362,750	$	—
MBPP - Laramie River Station	28.50	%	537,127		349,594		7,047
Total			$	929,637	$	712,344	$	7,047

OTHER PLANT: Other plant consists of mine assets (discussed below) and non‑utility assets which consist of facilities not in service, land and irrigation equipment.

We own 100 percent of Elk Ridge Mining and Reclamation, LLC (“Elk Ridge”), organized for the purpose of acquiring coal reserves and supplying coal to us. Elk Ridge is the owner of the Colowyo Mine, a surface coal mine near Craig, Colorado, and the New Horizon Mine near Nucla, Colorado. The New Horizon Mine is in post-reclamation monitoring and no longer produces coal. The expenses related to the Colowyo Mine coal used by us are included in fuel expense on our consolidated statements of operations.


	June 30, 2024		December 31, 2023
Colowyo Mine assets	$	395,438	$	396,441
New Horizon Mine assets	6,320		6,448

Accumulated depreciation and depletion	(199,278)		(184,239)
Net mine assets	202,480		218,650
Non-utility assets	549,224		549,430
Accumulated depreciation	(527,604)		(527,658)
Net non-utility assets	21,620		21,772
Net other plant	$	224,100	$	240,422