County annual report · FIPS 46025
2021 Clark County, SD Power Outage Report
In 2021, customers in Clark County, SD went without power for an average of 3.1 hours, a total of 4,966 customer-hours (South Dakota average 3.4 hours). That ranks 27th worst of 61 South Dakota counties and 1800th 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 Clark 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 | May 24, 2021 06:00 | May 24, 2021 13:15 | 7h 15m | 385 | 1,584 |
| 2 | February 27, 2021 06:00 | February 27, 2021 07:30 | 1h 30m | 360 | 540 |
| 3 | August 26, 2021 14:15 | August 26, 2021 21:45 | 7h 30m | 348 | 959 |
| 4 | August 28, 2021 11:00 | August 28, 2021 13:45 | 2h 45m | 334 | 919 |
| 5 | May 23, 2021 21:00 | May 24, 2021 00:15 | 3h 15m | 79 | 162 |
| 6 | March 29, 2021 15:00 | March 29, 2021 20:45 | 5h 45m | 38 | 219 |
| 7 | November 2, 2021 14:30 | November 2, 2021 19:15 | 4h 45m | 18 | 86 |
| 8 | March 31, 2021 15:15 | March 31, 2021 22:30 | 7h 15m | 17 | 57 |
| 9 | August 30, 2021 14:15 | August 30, 2021 14:30 | 15m | 17 | 4 |
| 10 | September 2, 2021 21:45 | September 3, 2021 00:45 | 3h | 14 | 42 |
Outage episodes by size in 2021: 4 reached 100+ customers, 0 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 Clark 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 |
|---|---|---|---|---|---|
| NorthWestern Energy - (SD) | 2021 | 1.5 hrs | 0.95 | 81 min | 0.83 |
| Northern Electric Coop, Inc | 2021 | 2.0 hrs | 1.20 | 1.9 hrs | 1.18 |
| H-D Electric Coop Inc | 2018 | 2.6 hrs | 1.52 | 1.6 hrs | 1.14 |
| WAPA-- Western Area Power Administration | - | - | - | - | - |
| Codington-Clark Elec Coop, Inc | - | - | - | - | - |
| Kingsbury Electric Coop, Inc | - | - | - | - | - |
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 ÷ 1,587 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. Clark County has data for 2019–2025.
Cite this report
MassOutage (massoutage.com), Clark 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/clark-county