| December 31, | ||||||||||||||||||||||||||||||||||||
| 2023 | 2022 | 2021 | ||||||||||||||||||||||||||||||||||
| Liability at January 1, | $ | 40,894 | $ | 40,631 | $ | 45,355 | Accretion expense | 1,899 | 1,853 | 2,233 | Liabilities incurred | — | — | — | Liabilities settled | (1,244) | (4,004) | (2,906) | Revisions to cash flows | (125) | 2,414 | (4,051) | Liability at December 31, | $ | 41,424 | $ | 40,894 | $ | 40,631 | |||||||
| Generation Facilities | Fuel Source | Ownership Interest | Owned MW | ||||||||
| Big Stone Plant, located near Big Stone City in northeastern South Dakota | Sub-bituminous coal | 23.4% | 111 | ||||||||
| Aberdeen Generating Units No. 1 and 2, located near Aberdeen, South Dakota | Natural gas & Liquid Fuel | 100.0% | 80 | ||||||||
| Beethoven Wind Project, located near Tripp, South Dakota | Wind | 100.0% | 80 | ||||||||
| BGGS, located near Huron, South Dakota | Natural Gas | 100.0% | 58 | ||||||||
| Neal Electric Generating Unit No. 4, located near Sioux City, Iowa | Sub-bituminous coal | 8.7% | 57 | ||||||||
| Coyote Electric Generating Station, located near Beulah, North Dakota | Lignite coal | 10.0% | 43 | ||||||||
| Miscellaneous combustion turbine units and small diesel units (used only during peak periods) | Combination of fuel oil and natural gas | 100.0% | 17 | ||||||||
| Total | 446 | ||||||||||
| Other Facilities | Fuel Source | Ownership Interest | Owned MW | ||||||||
| Colstrip Unit 4, located near Colstrip in southeastern Montana | Sub-bituminous coal | 30% | 222 | ||||||||
| DGGS, located near Anaconda, Montana | Natural Gas & Liquid Fuel | 100% | 150 | ||||||||
| Spion Kop Wind, located in Judith Basin County in Montana | Wind | 100% | 40 | ||||||||
| Two Dot Wind, located in Wheatland County in Montana | Wind | 100% | 11 | ||||||||
