County annual report · FIPS 30017
2021 Custer County, MT Power Outage Report
In 2021, customers in Custer County, MT went without power for an average of 0.6 hours, a total of 4,317 customer-hours (Montana average 5.0 hours). That ranks 48th worst of 51 Montana counties and 2780th of 2,974 nationally.
Compared with MT, the US and 2020
Coverage line is EAGLE-I's share of Montana 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 | November 13, 2021 19:30 | November 13, 2021 21:15 | 1h 45m | 676 | 1,010 |
| 2 | August 9, 2021 01:30 | August 9, 2021 03:45 | 2h 15m | 530 | 155 |
| 3 | October 10, 2021 05:45 | October 10, 2021 08:00 | 2h 15m | 300 | 413 |
| 4 | October 12, 2021 17:30 | October 13, 2021 00:15 | 6h 45m | 296 | 949 |
| 5 | October 16, 2021 12:45 | October 16, 2021 13:45 | 1h | 134 | 133 |
| 6 | July 22, 2021 19:45 | July 22, 2021 20:45 | 1h | 101 | 47 |
| 7 | November 2, 2021 06:00 | November 2, 2021 06:15 | 15m | 95 | 24 |
| 8 | May 8, 2021 03:45 | May 8, 2021 07:30 | 3h 45m | 80 | 276 |
| 9 | September 13, 2021 11:45 | September 13, 2021 13:00 | 1h 15m | 68 | 28 |
| 10 | August 4, 2021 22:15 | August 4, 2021 23:30 | 1h 15m | 55 | 69 |
Outage episodes by size in 2021: 6 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 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 |
|---|---|---|---|---|---|
| Mid-Yellowstone Elec Coop, Inc | 2018 | 4.5 hrs | 3.82 | 4.5 hrs | 3.82 |
| WAPA-- Western Area Power Administration | - | - | - | - | - |
| Montana-Dakota Utilities Co | - | - | - | - | - |
| McCone Electric Coop Inc | - | - | - | - | - |
| Tongue River Electric Coop Inc | - | - | - | - | - |
| Southeast 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 76% of Montana's customers in 2021; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 6,942 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 2017–2025.
Cite this report
MassOutage (massoutage.com), Custer County, MT 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/montana/custer-county