County annual report · FIPS 17199
2021 Williamson County, IL Power Outage Report
In 2021, customers in Williamson County, IL went without power for an average of 2.0 hours, a total of 72K customer-hours (Illinois average 2.3 hours). That ranks 65th worst of 102 Illinois counties and 2218th of 2,974 nationally.
Compared with IL, the US and 2020
Coverage line is EAGLE-I's share of Illinois customers tracked each year.
Biggest outages in Williamson 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 10, 2021 09:15 | July 12, 2021 11:15 | 2d 2h | 6,630 | 16K |
| 2 | November 26, 2021 19:00 | November 26, 2021 21:45 | 2h 45m | 2,596 | 3,357 |
| 3 | January 6, 2021 13:30 | January 6, 2021 20:30 | 7h | 1,284 | 2,304 |
| 4 | June 2, 2021 00:15 | June 2, 2021 19:15 | 19h | 1,099 | 13K |
| 5 | May 24, 2021 12:15 | May 24, 2021 12:30 | 15m | 1,091 | 273 |
| 6 | December 6, 2021 05:00 | December 6, 2021 12:00 | 7h | 1,071 | 1,927 |
| 7 | May 23, 2021 09:30 | May 23, 2021 12:00 | 2h 30m | 1,059 | 2,350 |
| 8 | November 29, 2021 17:00 | November 29, 2021 23:15 | 6h 15m | 870 | 405 |
| 9 | June 29, 2021 23:45 | June 30, 2021 03:15 | 3h 30m | 781 | 1,628 |
| 10 | June 7, 2021 19:00 | June 8, 2021 01:15 | 6h 15m | 744 | 362 |
Outage episodes by size in 2021: 44 reached 100+ customers, 7 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 Williamson 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 |
|---|---|---|---|---|---|
| Ameren Illinois Company | 2021 | 3.2 hrs | 1.11 | 2.0 hrs | 0.88 |
| Southeastern IL Elec Coop, Inc | 2021 | 2.2 hrs | 1.32 | 2.0 hrs | 1.25 |
| Ameren | - | - | - | - | - |
| Egyptian Electric Coop Assn | - | - | - | - | - |
| Southern Illinois Elec Coop | - | - | - | - | - |
About this data
- Outage figures come from DOE/ORNL EAGLE-I, which records customers out by county every 15 minutes. EAGLE-I tracked about 98% of Illinois's customers in 2021; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 35,624 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. Williamson County has data for 2015–2025.
Cite this report
MassOutage (massoutage.com), Williamson County, IL 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/illinois/williamson-county