County annual report · FIPS 30093
2021 Silver Bow County, MT Power Outage Report
In 2021, customers in Silver Bow County, MT went without power for an average of 1.4 hours, a total of 34K customer-hours (Montana average 5.0 hours). That ranks 45th worst of 51 Montana counties and 2496th 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 Silver Bow 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 | July 20, 2021 15:45 | July 20, 2021 21:30 | 5h 45m | 5,468 | 13K |
| 2 | March 2, 2021 01:00 | March 2, 2021 05:00 | 4h | 1,761 | 961 |
| 3 | August 13, 2021 18:45 | August 13, 2021 21:30 | 2h 45m | 723 | 1,648 |
| 4 | January 20, 2021 20:15 | January 20, 2021 21:30 | 1h 15m | 671 | 839 |
| 5 | September 8, 2021 16:45 | September 9, 2021 06:45 | 14h | 566 | 2,158 |
| 6 | March 29, 2021 08:15 | March 30, 2021 21:15 | 1d 13h | 515 | 2,255 |
| 7 | June 17, 2021 04:00 | June 17, 2021 08:15 | 4h 15m | 465 | 1,406 |
| 8 | January 18, 2021 21:45 | January 18, 2021 23:15 | 1h 30m | 333 | 450 |
| 9 | June 30, 2021 16:00 | June 30, 2021 19:15 | 3h 15m | 248 | 806 |
| 10 | June 8, 2021 22:00 | June 9, 2021 01:15 | 3h 15m | 221 | 325 |
Outage episodes by size in 2021: 15 reached 100+ customers, 2 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 Silver Bow 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 LLC - (MT) | 2021 | 2.5 hrs | 1.37 | 2.1 hrs | 1.18 |
| Bonneville Power Administration | - | - | - | - | - |
| NorthWestern Energy | - | - | - | - | - |
| Vigilante 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 ÷ 24,074 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. Silver Bow County has data for 2019–2025.
Cite this report
MassOutage (massoutage.com), Silver Bow 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/silver-bow-county