This story is part of our Quick Hits series. This series will bring you breaking news and short updates from throughout the state.
Almost 20% of the state was without power Thursday, but the cause still remains unclear.
Around 100,000 residents and businesses were impacted in central and northeastern Wyoming, as well as western South Dakota. The power outages started around 12:45 p.m. and most were resolved late Thursday evening.
The cause is still under investigation by multiple organizations.
The Western Area Power Administration (WAPA) is a federal agency that maintains a 15-state, high-voltage transmission network serving electricity utilities across the region, including in Wyoming.
“This outage was initiated outside of WAPA’s transmission system in central Wyoming, with the incident resulting in an abnormal voltage event that tripped multiple surrounding lines. This included some of WAPA’s transmission lines, which resulted in further power outages to utility communities across the region,” WAPA said in an emailed release.
Previously, WAPA shared an emailed statement Thursday evening saying, “We believe the outage, which began around 12:45 p.m. MST, was triggered by two tripped 500-kilovolt lines near Medicine Bow, Wyoming. This incident resulted in an abnormal voltage event that subsequently tripped a number of surrounding lines, including WAPA transmission, resulting in further power outages to communities across the area.”
Another major transmission line owner in the area is PacifiCorp, which is the parent company of Wyoming’s main utility Rocky Mountain Power (RMP). RMP did not respond to Wyoming Public Radio by press time.
A Thursday afternoon emailed press release from RMP said, “At 12:40 p.m. MT a widespread power outage occurred impacting more than 60,000 customers in Wyoming. The cause is currently under investigation. Our crews are working diligently to safely restore power as quickly as possible; however, due to the distance and complexity of the restoration process may take several hours.”
Utilities across the region have confirmed power is back on for most customers as of midday Friday, with some crews finishing up reconnecting other customers.
Also, the Dave Johnston Power Plant near Glenrock caught fire midday Thursday. While some were concerned it caused the power outages, emergency coordinators confirmed it did not, adding the fire could’ve been the result of outages.
Similarly, the Steamboat Gas Plant outside of Douglas was putting off black smoke because power to the plant was down. Both issues were deemed non-emergencies and resolved.
Update: 3:45 p.m. on Nov. 14
While a cause hasn't been assigned to the outage yet, some have wondered if it was connected to the Northern Lights that dazzled the night sky in the region over the last few days.
Earlier this week, the Space Weather Prediction Center of the National Oceanographic and Atmospheric Administration (NOAA) issued warnings about a severe geomagnetic storm that could cause power grid issues for states north of the 45th parallel.
That latitude marks Wyoming’s northern border with Montana.
“Possible widespread voltage control problems and some protective systems may mistakenly trip out key assets from the power grid. Induced pipeline currents intensify,” the alert from Nov. 11 said.
To be clear, utilities are still investigating what caused Thursday’s major outages.
