ITD responds to 6.5 magnitude earthquake

two landslides fell across idaho highway 21

ITD maintenance and bridge personnel are cleaning up debris and inspecting infrastructure after a 6.5 magnitude earthquake shook the Idaho Central Mountains Tuesday night.

Several mountain highways saw rockfall on the roadway following the quake. That includes Idaho Highway 75 (ID-75) near Stanley, ID-21 north and south of Lowman, ID-55 between Horseshoe Bend and Cascade, and ID-52 east of Emmett. Maintenance crews were immediately deployed to clear these hazards from the roadway and ensure the road was safe for travel.

Aftershocks continue to rock the region, causing additional rockfall. Crews are patrolling these high-risk areas to actively clean rocks from the highway. ITD urges the traveling public to use caution when driving in these areas.


After the earthquake, maintenance crews scanned bridge structures for damage. At this time, there has been no damage of concern noted and the highways remain open. As is always the case, if any issue is spotted, ITD will immediately close a bridge.

ITD’s Bridge Department is conducting more-detailed analysis of the situation. They are conducting additional analysis of structures closer to the earthquake’s epicenter. Over the next several weeks, inspections will be conducted on priority structures to determine whether damage has been done and repairs are needed.


A storm system dumped 27” of snow in the Canyon Creek section of Idaho Highway 21, from Grandjean to Banner Summit. This increased the risk of avalanches and ITD closed the highway at 2:00 p.m. Tuesday, several hours before the earthquake.

The earthquake did cause several slides to fall onto the highway in this section. Crews entered the area to begin clean-up Tuesday night and quickly found the landslides were extensive. The crew contacted U.S. Geological Survey, which informed them of aftershocks and the risk of additional landslides. The crew withdrew and will remain out of the canyon until USGS has determined the risk of aftershocks is reduced.

At this time, the number and extent of landslides on this section are unknown. There is no timeframe when crews can re-enter the Canyon and begin clearing the road. Additional repairs to the roadway may be required as well. The Department is advising it may be many days before this section of ID-21 re-opens. Idaho Highway 75 and U.S. 93 remain open to access Stanley.


Per Governor Brad Little’s Stay-Home Order, the ongoing maintenance and operation of roads are essential services and will continue during the COVID-19 pandemic. ITD crews will continue to respond to rockfall and other hazards created by the record earthquake. Additional essential services, such as plowing snow, pothole repair, and striping will also continue. The Department is committed to safely executing its Mission: “Your Safety. Your Mobility. Your Economic Opportunity.”