County annual report · FIPS 30099
2021 Teton County, MT Power Outage Report
In 2021, customers in Teton County, MT went without power for an average of 17.6 hours, a total of 36K customer-hours (Montana average 5.0 hours). That ranks 5th worst of 51 Montana counties and 484th 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 Teton 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 | June 5, 2021 09:45 | June 5, 2021 22:45 | 13h | 1,936 | 8,267 |
| 2 | May 20, 2021 10:15 | May 21, 2021 05:15 | 19h | 1,436 | 7,072 |
| 3 | December 1, 2021 00:45 | December 2, 2021 07:30 | 1d 6h | 1,401 | 5,913 |
| 4 | July 21, 2021 00:45 | July 21, 2021 04:30 | 3h 45m | 898 | 2,032 |
| 5 | April 23, 2021 09:45 | April 23, 2021 20:45 | 11h | 843 | 1,905 |
| 6 | April 20, 2021 18:30 | April 21, 2021 02:00 | 7h 30m | 377 | 980 |
| 7 | July 11, 2021 23:15 | July 12, 2021 04:30 | 5h 15m | 368 | 1,409 |
| 8 | November 24, 2021 00:00 | November 24, 2021 02:15 | 2h 15m | 354 | 797 |
| 9 | January 3, 2021 15:15 | January 4, 2021 00:15 | 9h | 350 | 1,838 |
| 10 | January 9, 2021 16:00 | January 9, 2021 17:30 | 1h 30m | 344 | 348 |
Outage episodes by size in 2021: 17 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 Teton 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 |
| WAPA-- Western Area Power Administration | - | - | - | - | - |
| Sun River 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 ÷ 2,050 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. Teton County has data for 2020–2025.
Cite this report
MassOutage (massoutage.com), Teton 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/teton-county