NorthWestern Energy - (SD)
Investor Owned electric utility · South Dakota · #295 of 3,199 U.S. utilities by customers · EIA utility #13809
NorthWestern Energy - (SD) is a investor owned electric utility serving 65,396 customers in South Dakota. In 2025 it sold 1,656 gigawatt-hours of electricity for $201.48M in revenue, an average realized rate of 12.16¢ per kWh across all customer classes and 13.35¢ per kWh for residential customers. Its reported service territory covers 27 counties. EIA records its activities as: generation, transmission, buying transmission, distribution, wholesale marketing, bundled.
Customers, sales and rates by customer class (2025)
| Class | Customers | Sales (GWh) | Revenue | Avg realized rate | Share of sales |
|---|---|---|---|---|---|
| Residential | 51,787 | 583 | $77.89M | 13.35¢ | |
| Commercial | 13,551 | 687 | $89.41M | 13.02¢ | |
| Industrial | 58 | 386 | $34.17M | 8.85¢ | |
| Total | 65,396 | 1,656 | $201.48M | 12.16¢ |
Average realized rate = revenue divided by sales as reported on EIA Form 861. It blends fixed charges, demand charges and riders into one per-kWh figure; it is not the utility's tariff rate. Estimated residential bill assumes the average residential customer's actual 2025 usage (939 kWh/month).
Five-year trend
| Year | Customers | Sales (GWh) | Revenue | Residential rate |
|---|---|---|---|---|
| 2021 | 64,018 | 1,682 | $170.50M | 11.45¢ |
| 2022 | 64,386 | 1,730 | $180.74M | 11.71¢ |
| 2023 | 64,654 | 1,721 | $173.81M | 11.26¢ |
| 2024 | 64,971 | 1,665 | $185.10M | 12.56¢ |
| 2025 | 65,396 | 1,656 | $201.48M | 13.35¢ |
Reliability (2025)
Average outage time (SAIDI): 120 minutes per customer per year
Average outages (SAIFI): 1.14 per customer
Average restoration time (CAIDI): 105 minutes
As reported for South Dakota under the IEEE standard, with major event days included where the standard reports them. Lower is better; see the reliability rankings.
Energy supply (2025)
Net generation: 1,234 GWh
Wholesale power purchased: 1,973 GWh
Winter peak demand: 319 MW
Meters & rooftop solar (2025)
Smart (AMI) meters: 99.7% of 65,943 meters
Counties served
Aurora, SDBeadle, SDBon Homme, SDBrown, SDBrule, SDCharles Mix, SDClark, SDCodington, SDDavison, SDDay, SDDeuel, SDDouglas, SDEdmunds, SDFaulk, SDHamlin, SDHand, SDHanson, SDHughes, SDHutchinson, SDHyde, SDJerauld, SDKingsbury, SDMarshall, SDSanborn, SDSpink, SDTurner, SDYankton, SD
Other large utilities in South Dakota
- Black Hills Power, Inc. - 85,804 customers, residential 15.07¢
- Sioux Valley SW Elec Coop - 30,059 customers, residential 13.87¢
- Southeastern Electric Coop Inc - (SD) - 24,428 customers, residential 12.98¢
- West River Electric Assn Inc - 21,332 customers, residential 15.16¢
- Watertown Municipal Utilities - 14,497 customers, residential 9.29¢
- City of Brookings - (SD) - 12,568 customers, residential 10.69¢
- Black Hills Electric Coop, Inc - 11,478 customers, residential 14.79¢
- Butte Electric Coop, Inc - 7,472 customers, residential —
All South Dakota utilities and rates
Source: U.S. Energy Information Administration, Form EIA-861 2025 (filed by the utility; figures as published). Utility #13809 in the EIA frame.