County annual report · FIPS 30057
2021 Madison County, MT Power Outage Report
In 2021, customers in Madison County, MT went without power for an average of 9.0 hours, a total of 56K customer-hours (Montana average 5.0 hours). That ranks 14th worst of 51 Montana counties and 856th 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 Madison 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 | October 11, 2021 06:45 | October 11, 2021 18:45 | 12h | 2,860 | 11K |
| 2 | May 19, 2021 08:15 | May 19, 2021 12:45 | 4h 30m | 1,511 | 4,865 |
| 3 | September 22, 2021 00:45 | September 22, 2021 02:30 | 1h 45m | 1,140 | 1,994 |
| 4 | October 5, 2021 16:00 | October 5, 2021 20:00 | 4h | 908 | 3,502 |
| 5 | May 8, 2021 09:00 | May 8, 2021 19:30 | 10h 30m | 867 | 1,071 |
| 6 | June 9, 2021 14:30 | June 9, 2021 16:00 | 1h 30m | 867 | 1,107 |
| 7 | June 28, 2021 16:00 | June 29, 2021 03:00 | 11h | 800 | 8,402 |
| 8 | February 12, 2021 13:15 | February 12, 2021 16:45 | 3h 30m | 678 | 2,373 |
| 9 | April 1, 2021 10:30 | April 1, 2021 13:30 | 3h | 591 | 1,478 |
| 10 | January 13, 2021 18:15 | January 13, 2021 20:45 | 2h 30m | 587 | 681 |
Outage episodes by size in 2021: 25 reached 100+ customers, 3 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 Madison 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 |
| 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 ÷ 6,199 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. Madison County has data for 2018–2025.
Cite this report
MassOutage (massoutage.com), Madison 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/madison-county