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Jointly owned facilities | 12 Months Ended
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Dec. 31, 2020
Regulated Operations [Abstract] |
Jointly owned facilities | Jointly Owned Facilities The consolidated financial statements include the Company's ownership interests in three coal-fired electric generating facilities (Big Stone Station, Coyote Station and Wygen III) and one major transmission line (BSSE). Each owner of the jointly owned facilities is responsible for financing its investment. The Company's share of the jointly owned facilities operating expenses was reflected in the appropriate categories of operating expenses (electric fuel and purchased power; operation and maintenance; and taxes, other than income) in the Consolidated Statements of Income. At December 31, the Company's share of the cost of utility plant in service, construction work in progress and related accumulated depreciation for the jointly owned facilities was as follows:
| Ownership Percentage | 2020 | 2019
|  | (In thousands)
Big Stone Station: | 22.7 | % |  |
Utility plant in service |  | $ | 155,967 |  | $ | 152,836 |
Construction work in progress |  | 104 |  | 518 |
Less accumulated depreciation |  | 45,435 |  | 46,266 |
|  | $ | 110,636 |  | $ | 107,088 |
BSSE: | 50.0 | % |  |
Utility plant in service |  | $ | 107,442 |  | $ | 105,767 |
Construction work in progress |  | — |  | — |
Less accumulated depreciation |  | 2,682 |  | 1,232 |
|  | $ | 104,760 |  | $ | 104,535 |
Coyote Station: | 25.0 | % |  |
Utility plant in service |  | $ | 159,784 |  | $ | 160,235 |
Construction work in progress |  | 323 |  | 21 |
Less accumulated depreciation |  | 108,852 |  | 107,638 |
|  | $ | 51,255 |  | $ | 52,618 |
Wygen III: | 25.0 | % |  |
Utility plant in service |  | $ | 66,101 |  | $ | 67,869 |
Construction work in progress |  | 232 |  | 112 |
Less accumulated depreciation |  | 10,038 |  | 10,482 |
|  | $ | 56,295 |  | $ | 57,499 |

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