County annual report · FIPS 30039
2020 Granite County, MT Power Outage Report
In 2020, customers in Granite County, MT went without power for an average of 13.2 hours, a total of 30K customer-hours (Montana average 5.6 hours). That ranks 11th worst of 50 Montana counties and 621st of 3,019 nationally.
Compared with MT, the US and 2019
Coverage line is EAGLE-I's share of Montana customers tracked each year.
Biggest outages in Granite County, 2020
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 15, 2020 11:45 | May 16, 2020 04:15 | 16h 30m | 1,673 | 7,263 |
| 2 | June 13, 2020 22:00 | June 14, 2020 09:30 | 11h 30m | 1,218 | 1,793 |
| 3 | June 8, 2020 05:15 | June 8, 2020 09:45 | 4h 30m | 1,062 | 4,569 |
| 4 | June 14, 2020 21:30 | June 15, 2020 03:00 | 5h 30m | 1,044 | 3,393 |
| 5 | June 15, 2020 04:00 | June 15, 2020 05:00 | 1h | 522 | 522 |
| 6 | October 14, 2020 03:30 | October 14, 2020 12:15 | 8h 45m | 521 | 2,790 |
| 7 | February 19, 2020 23:15 | February 20, 2020 00:15 | 1h | 417 | 417 |
| 8 | August 6, 2020 23:45 | August 7, 2020 04:00 | 4h 15m | 163 | 402 |
| 9 | May 17, 2020 19:15 | May 17, 2020 20:30 | 1h 15m | 153 | 126 |
| 10 | August 7, 2020 06:00 | August 7, 2020 11:45 | 5h 45m | 145 | 834 |
Outage episodes by size in 2020: 11 reached 100+ customers, 4 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 Granite County reported on EIA Form 861 for 2020, 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) | 2020 | 2.8 hrs | 1.13 | 2.0 hrs | 1.02 |
| Missoula Electric Coop, Inc | 2020 | 6.0 hrs | 2.00 | 6.0 hrs | 2.00 |
| Bonneville Power Administration | - | - | - | - | - |
| NorthWestern Energy | - | - | - | - | - |
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 2020; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 2,293 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. Granite County has data for 2019–2025.
Cite this report
MassOutage (massoutage.com), Granite County, MT annual power outage report, 2020, 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/2020/montana/granite-county