March 17, 2026
May 13, 2026
Prior To Major Event
1. Did the distributor have any prior warning that the Major Event would occur?
Yes.
Please Provide Additional Comments:
In the early afternoon of Saturday, March 14, a forecast predicted strong wind gusts and freezing rain for the late morning of Tuesday, March 17. The on-call management team was immediately notified and maintained a close watch on the weather patterns throughout the remainder of the weekend. At 1:30 p.m. on Monday, March 16, the team convened to evaluate the updated forecast and finalize resourcing decisions ahead of the forecasted weather event. During this meeting, it was noted that while the potential for high winds and light mixed precipitation remained, the projected timing of the peak gusts had shifted to earlier Tuesday morning around 8 a.m.
2. If the distributor did have prior warning, did the distributor arrange to have extra employees on duty or on standby prior to the Major Event beginning?
Yes.
If yes, please provide a brief description of the arrangements, or explain why extra employees were not arranged:
Based on the forecasted timing of the weather event, Hydro Ottawa determined that additional staffing arrangements were unnecessary prior to the onset of the storm. Because the high winds were projected to arrive at approximately 8 a.m., the on-call management team concluded that the event would coincide with the start of the regular business day when all regular staff would already be on-site and available for immediate deployment. Furthermore, by opting not to activate extra resources prematurely, the utility preserved the available on-call staff, ensuring that personnel would not reach their hourly limits should the event persist into the evening and require extended response efforts.
3. If the distributor did have prior warning, did the distributor issue any alert to the public warning of possible outages resulting from the pending Major Event?
No.
4. Did the distributor train its staff on the response plans to prepare for this type of Major Event?
Yes.
DURING THE MAJOR EVENT
1. Please identify the main contributing cause of the major event as per the table in section 2.1.4.2.5 of the electricity reporting and recording keeping requirements
- Loss of supply
- Lightning
- Adverse weather - Wind
- Adverse weather - Snow
- Adverse weather - Freezing rain/ice storm
- Adverse environment - Fire
- Adverse environment - Flooding
- Others
Please provide a brief description of the event. If the event was caused by weather conditions, please specify the type of weather involved – such as high winds, freezing rain, tornadoes, ice
storms, blizzards, heavy rainfall, flooding, or lightning storms.
The combination of flash-freeze conditions and high winds on March 17, 2026 resulted in widespread system outages. These environmental factors caused instances where overhead conductors made contact with each other and instances of downed wires across the service area.
2. Was the IEEE Standard 1366 used to derive the threshold for the Major Event?
Yes, used IEEE Standard 1366
3. When did the Major Event begin?
March 17th, 2026
Time: (2:57 a.m.)
4. If the Major Event was not caused by adverse weather, did the distributor issue any information about this Major Event, such as estimated times of restoration, to the public during the Major Event?
N/A
If yes, please provide a brief description of the information. If no, please explain:
N/A
5. How many customers were interrupted during the Major Event?
62,531 customers were interrupted during the Major Event.
What percentage of the distributor's total customer base did the interrupted customers represent?
16.50%
Please provide any additional comments relevant to question #5:
N/A
6. How many hours did it take to restore 90% of the customers who were interrupted?
13.9
7. How many customers experienced service interruptions lasting less than 24 hours?
62,531
8. How many customers experienced service interruptions lasting between 24 and 48 hours?
0
9. How many customers experienced service interruptions lasting between 48 and 96 hours?
0
10.How many customers experienced service interruptions lasting between 96 and 168 hours?
0
11.How many customers experienced service interruptions lasting over 168 hours?
0
12. Were there any outages associated with loss of supply during the outage?
Yes.
If yes, please report on the duration and frequency of the loss of supply outages:
There were two outages due to Loss of Supply. The initial outage occurred for a duration of 4 hours and 36 minutes (6:15 a.m. to 10:51 a.m.) and affected 2,063 customers. This was followed by a secondary event with a duration of 2 minutes (9:38 a.m. to 9:40 a.m.), which affected 12,963 customers.
13. In responding to the Major Event, did the distributor utilize assistance through a third party mutual assistance agreement with other utilities?
No.
If yes, please provide the name of the utilities that provided the assistance:
N/A
14. Did the distributor run out of any needed equipment or materials during the Major Event?
No.
If so, please describe the shortages:
N/A
15.Provide the following characteristics of the Major Event:
i. Total number of feeders interrupted during the course of the event
53
ii. The maximum number of customers that were concurrently without power at any point during the event.
28,080
16. What is the total number of damage assessments performed by the distributor during the course of the event?
32
17.What percentage of damage assessments were completed:
i. Within 4 hours after the interruption began
63%
ii. Within 8 hours after the interruption began
34%
iii. Within 12 hours after the interruption began
3%
iv. Over 12 hours after the interruption began
0%
18. What communication methods were used to inform customers during the Major Event? Select all that apply:
- Distributor's website
- Social media
- Text message
- Telephone line
- Radio broadcast
- Others
If Other was selected please specify
Banner and message on the distributor's outage map
19. During the Major Event, did any of the communication methods used become unavailable? If so, identify which one(s).
No.
20. Provide SAIDI and SAIFI values for this Major Event.
SAIDI: 0.281
SAIFI: 0.165
AFTER THE MAJOR EVENT
1. What actions, if any, are being taken to be prepared for or mitigate such major events in the future (i.e. staff training, process improvements, system upgrades)?
- No further action is required at this time
- Additional staff training
- Process improvements
- System upgrades
- Others
Additional Comments:
To mitigate the impact of future major events, Hydro Ottawa has identified several technical and process improvements. The company continues to prioritize the replacement of older porcelain insulators, which were identified as a recurring point of failure during the storm. Additionally, spacers will continue to be installed in areas known for "slapping conductors" to prevent intermittent faults.
These technical efforts are paired with operational enhancements, including the expansion of the RACI chart to clarify daytime Incident Command roles, the formalization of an alternates list for critical roles during vacation periods, and the implementation of tabletop exercises to refine leadership ramp-up procedures.