Investor Presentaiton

L Appendix 59 2020 System Statistics Owned Energy Supply Transmission Distribution Electric (MW) MT SD Total Trans for Others MT SD Total Demand MT SD/NE (1) Total Base load coal 222 210 432 Electric (GWh) 11,432 26 11,457 Daily MWs 750 200 950 Wind 51 80 131 Natural Gas (Bcf) 42.0 31.2 73.2 Peak MWs 1,200 328 1,528 Hydro 448 448 Other resources (2) 150 121 271 Annual GWhs Annual Bcf 6,600 1,750 8,350 21.3 10.3 31.7 871 411 1,282 System (miles) MT SD Total Electric Natural Gas (Bcf) MT SD Total Natural gas 6,809 1,308 2,165 55 8,117 Customers 2,220 Electric Proven reserves Annual production Storage 43.1 3.5 43.1 3.5 Total 8,974 1,363 10,337 Natural gas MT 384,700 203,700 SD/NE Total Total 588,400 63,900 448,600 90,700 294,400 154,600 743,000 17.8 17.8 System (miles) Electric Natural gas MT SD/NE Total 18,068 4,892 2,314 20,382 2,523 Total 22,960 4,837 Note: Statistics above are as of 12/31/2020 except for electric transmission for others which is 2019 data (1) Nebraska is a natural gas only jurisdiction (2) Dave Gates Generating Station (DGGS) in Montana is a 150 MW nameplate facility but consider it a 105 MW (60 MW FERC & 45MW MPSC jurisdictions) peaker 7,415 27,797 NorthWestern Energy Delivering a Bright Future

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