County annual report · FIPS 46033
2021 Custer County, SD Power Outage Report
In 2021, customers in Custer County, SD went without power for an average of 6.1 hours, a total of 27K customer-hours (South Dakota average 3.4 hours). That ranks 9th worst of 61 South Dakota counties and 1130th of 2,974 nationally.
Compared with SD, the US and 2020
Coverage line is EAGLE-I's share of South Dakota customers tracked each year.
Biggest outages in Custer County, 2021
The 10 outage episodes with the most customers out at once. Times are UTC.
| # | Started (UTC) | Ended (UTC) | Duration | Peak out | Customer-hours |
|---|---|---|---|---|---|
| 1 | March 13, 2021 22:00 | March 14, 2021 02:15 | 4h 15m | 1,564 | 3,310 |
| 2 | May 23, 2021 22:00 | May 25, 2021 21:45 | 1d 23h | 971 | 5,666 |
| 3 | August 9, 2021 14:15 | August 9, 2021 14:30 | 15m | 804 | 201 |
| 4 | August 13, 2021 13:00 | August 13, 2021 14:30 | 1h 30m | 741 | 776 |
| 5 | October 13, 2021 00:45 | October 13, 2021 23:15 | 22h 30m | 683 | 3,759 |
| 6 | March 14, 2021 16:45 | March 16, 2021 01:00 | 1d 8h | 488 | 7,137 |
| 7 | July 7, 2021 14:00 | July 7, 2021 21:00 | 7h | 263 | 155 |
| 8 | April 20, 2021 17:45 | April 20, 2021 18:00 | 15m | 225 | 56 |
| 9 | March 29, 2021 15:00 | March 29, 2021 21:45 | 6h 45m | 125 | 394 |
| 10 | March 6, 2021 22:15 | March 8, 2021 13:45 | 1d 15h | 102 | 302 |
Outage episodes by size in 2021: 10 reached 100+ customers, 1 reached 1,000+ customers, 0 reached 10,000+ customers.
Utility reliability filed with the EIA
SAIDI (average outage time per customer) and SAIFI (average interruptions per customer) that utilities serving Custer County reported on EIA Form 861 for 2021, or their most recent earlier filing. Utility-wide figures, not county-specific.
| Utility | EIA year | SAIDI | SAIFI | SAIDI excl. major events | SAIFI excl. major events |
|---|---|---|---|---|---|
| Black Hills Power, Inc. | 2021 | 2.6 hrs | 1.17 | 41 min | 0.32 |
| Black Hills Electric Coop, Inc | 2021 | 6.6 hrs | 1.67 | 2.2 hrs | 1.02 |
| WAPA-- Western Area Power Administration | - | - | - | - | - |
About this data
- Outage figures come from DOE/ORNL EAGLE-I, which records customers out by county every 15 minutes. EAGLE-I tracked about 79% of South Dakota's customers in 2021; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 4,481 customers (ORNL modeled county customer count), including major storm days. It is comparable across counties but is not the SAIDI a utility files.
- An outage event is a continuous stretch with customers out; counts at 100, 1,000 and 10,000+ use its peak.
- Years loaded: 2015–2025. Custer County has data for 2016–2025.
Cite this report
MassOutage (massoutage.com), Custer County, SD annual power outage report, 2021, data as of Oct 3, 2026 02:41 UTC, sources: DOE EAGLE-I (https://eagle-i.doe.gov/); EAGLE-I modeled customer counts (MCC) (https://figshare.com/); EIA Form 861 (utility reliability) (https://www.eia.gov/electricity/data/eia861/). https://massoutage.com/reports/2021/south-dakota/custer-county