A few minutes after 12:30 a.m. on July 6, Polson resident John Freemole was sleeping when things suddenly began to move about.
“There was shaking... the house shook,” he said, adding he realized it was an earthquake.
After checking his house and determining there was no structural damage, Freemole said he “went back to bed.”
According to the United States Geological Survey website, a magnitude 5.8 earthquake shook Montana, with an epicenter northwest of Helena.
A request for further comment from the U.S. Geological Survey was not immediately returned.
Following the earthquake, the Selis Ksanka Qlispe Project underwent an evaluation to ensure its safety, according to a press release dated July 7.
Energy Keepers, Inc., the tribally owned corporation of the Confedarated Salish and Kootenai Tribes that managed the acquisition of the dam, stated that protocol in place by the Federal Energy Regulatory Commission called the Dam Safety and Surveillance Monitoring Plan was followed.
Following the earthquake, FERC asked officials “to inspect the dam for any damage,” a representative of the commission stated by email Tuesday morning.
A DSSMP is “a rigorously designed engineering monitoring system that collects” information used to determine changes that occur over time or by “a significant event” such as an earthquake, the press release explained.
The plan, as EKI Chief Executive Officer Brian Lipscomb clarified, is designed to monitor “multiple safety aspects” of the dam.
There are “extensive” weekly inspections of the dam, and when events such as an earthquake occur, another inspection is “immediately conducted.”
Data was reviewed by EKI’s Chief Dam Safety Engineer Matthew Pruchnik, the press release stated.
FERC confirmed “no damage was found and we do not have any concerns.”
Freemole, a Polson resident of 36 years, recalled that the last memorable earthquake on July 26, 2005, wasn’t as strong as last week’s shake.
“I don’t know that (the previous earthquake) was as bad, but you could feel it,” Freemole said, adding that there have been “several earthquakes” in the 12 years leading up to last week’s event.
The 2005 earthquake rumbled the state with a magnitude of 5.6, the U.S. Geological Survey reported.