Power outages in South Dakota
In 2025, the average South Dakota customer had 268.5 minutes (4.5 hours) of outages. That is a little above the US median of 258.7 minutes (4.3 hours) across 50 states compared.
Trend
SAIDI was low in 2020, 2021, 2023 and 2024 (77.0 to 105.6 minutes), then rose to 268.5 minutes in 2025. The worst year was 2022, with 327.1 minutes (5.5 hours).
Utilities in 2025
The best utility by SAIDI in 2025 was Watertown Municipal Utilities at 4.25 minutes. The worst was Black Hills Electric Coop, Inc at 2,486.8 minutes (41.4 hours).
| Utility | Customers | Hours / yr | Interruptions |
|---|---|---|---|
| Black Hills Electric Coop, Inc | 11,466 | 41.4 | 3.4 |
| Black Hills Power, Inc. | 82,900 | 9.0 | 2.3 |
| Otter Tail Power Co | 12,464 | 3.2 | 1.7 |
| Northern States Power Co - Minnesota | 107,525 | 2.7 | 0.9 |
| NorthWestern Energy - (SD) | 64,904 | 2.0 | 1.1 |
| Sioux Valley SW Elec Coop | 26,620 | 1.0 | 1.6 |
| West River Electric Assn Inc | 21,246 | 0.4 | 0.3 |
| Southeastern Electric Coop Inc - (SD) | 24,550 | 0.4 | — |
| City of Brookings - (SD) | 12,388 | 0.2 | 0.1 |
| Watertown Municipal Utilities | 14,608 | 0.1 | 0.1 |
What this means for backup power
For everyday outages, enter 3.4 hours in the calculator, which is the average length of one interruption. To ride out a year like 2022, size for 5.5 hours, the total outage time that year.
FAQ
What does SAIDI mean for my home?
SAIDI is the total outage time the average customer had in a year. It is not the length of one outage. In South Dakota, 2025 SAIDI was 268.5 minutes (4.5 hours).
How long does a typical outage last in South Dakota?
One interruption lasts about 3.4 hours on average. Customers had about 1.335 interruptions in 2025. Use 3.4 hours in the calculator for everyday outages.
How much backup runtime should I plan for?
For a typical outage, plan for about 3.4 hours. If you want to cover a year like 2022, the worst in the data, plan for 5.5 hours of total outage time.
Utility pages
Source: U.S. EIA Form 861 Reliability file. Data snapshot 2026-11-05.