LOWMAN, Idaho — Idaho Transportation Department (ITD) crews have finished cleaning up tons of rock, dirt and snow on Idaho Highway 21 between Lowman and Stanley one week after a record 6.5 magnitude earthquake last week.
The earthquake triggered several avalanches and landslides in Canyon Creek, an 11-mile corridor west of Stanley. Large boulders shook loose and dropped hundreds of feet to the highway, causing damage to the roadway. Aftershocks and the threat of additional landslides kept crews out of the area until Sunday, April 5.
“The earthquake was the second-largest on record in Idaho,” said Bill Nicholson, who leads the Avalanche Crew in Lowman. “I’ve been here thirteen years and never seen so much rock and earth hit the highway. Thankfully, we have a great partnership with USGS and the Geophysics Department at Boise State. They kept us updated on conditions, which helped us understand the situation and know when it was safe to get back in and start cleaning up.”
Maintenance crews from Lowman and Stanley attacked the clean-up from both sides. In just four days, they removed the debris and patched up the road before re-opening the highway to traffic.
“The community of Stanley sees Highway 21 as an important connection,” said Stanley shed foreman Brad Lynch. “It’s the most direct route to Boise and the Treasure Valley. During this pandemic, it was a concern having the route closed. I know my neighbors will breathe easier knowing we punched through and opened it up.”
In total, operators removed an estimated 2,000 cubic yards of debris from the highway. Several boulders were too large to be removed as-is. In such cases, crews used the “Boulder Buster” to break the boulders into a more manageable size.
“It was a great team effort,” said Brian Inwards, foreman for the Lowman shed. “The whole operation went incredibly well. Everyone pitched in and made it happen.”
ITD warns the traveling public on this corridor or other mountain highways of the increased risk of seasonal rockfall. Please drive with caution. Additional repairs to damaged guardrail will be completed this summer.