A cottonwood tree that collapsed onto a 115-kilovolt transmission line in the Crystal River Valley resulted in an “unusual” power outage on Monday that affected more than 21,000 people, Holy Cross Energy CEO Bryan Hannegan revealed that evening.
Crews responded to the outage at the midvalley substation — which supplies power to Aspen, Snowmass, Basalt and parts of Carbondale and Glenwood Springs — around 9:30 a.m. Monday. Power returned to the valley communities by 12:30 p.m.
Aside from the outage’s reach, which impacted roughly one-third of Holy Cross Roaring Fork Valley customers, the lack of power was especially felt on Monday after temperatures plummeted and snow fell through Sunday night.
Noting that it wasn’t exactly the “best, warmest” day to lose power — however on-brand for 2020 — Hannegan said, “With the first major snow, we usually do have some impacts to our system, but this one was different.
“This one was a new one for me,” he continued.
The cottonwood tree, which hadn’t even been officially identified as the culprit until an engineer alerted Hannegan to the update Monday evening, fell onto a transmission line that connects Xcel Energy’s substation outside Carbondale to Holy Cross’ substation in Basalt, where the breaker fault occurred. The transmission bus along which the breakers failed is the primary intersection between Xcel’s statewide and regional power network and Holy Cross’ local power network — which is essentially a loop off the substation upvalley to Aspen and back, Hannegan explained.
“We really have one way in and one way out in this portion of our service territory,” he said. “And when that’s blocked, we need another option.”
“This was an unusual outage. It’s not one that many of us have seen in our career. It’s one of the reasons why we want to take the time to understand what happened and how to mitigate against that happening again in the future. It was a large outage, and so it’s consequential,” Hannegan continued. “I think it speaks to the need to continue to engage our communities, as we have been since the Lake Christine Fire, on how to provide multiple options of resilient power supply in this area.”
While engineers from Holy Cross and Xcel energy companies are still investigating the incident, Hannegan believes Sunday’s snowfall is likely a factor. Monday morning saw more than six inches of fresh outside.
“More than likely, although we don’t know — we haven’t taken a look at the darn tree — but I suspect there was some snow loading on that tree that pushed it over into the line, and there you go,” Hannegan said at 5:30 p.m. Monday, moments after learning of the fallen tree. “We’ll continue to do more investigatory work.”