California has cited a backcountry adventure company for failing to protect employees and violating safety regulations after one of the deadliest avalanches in the state’s history buried 13 skiers, killing six clients and three guides.

The state’s workplace safety agency this week reported that it had found “serious” and “willful” violation by the company, Blackbird Mountain Guides, and proposed fines totaling $151,300. It is the first time the company has faced discipline for the disaster.

In February, 15 skiers on a trip run by the company left the safety of a mountain hut at Frog Lake near Truckee, Calif., during a historic storm. They ventured into the blizzard despite clear warnings from the state avalanche forecaster that danger was high, including “a recommendation not to travel in, near, or below avalanche terrain.”

The California Division of Occupational Safety and Health, known as Cal/OSHA, cited Blackbird for a total of seven violations, among them: failing to provide the right risk assessment training for employees; failing to properly identify risks; and failing to protect employees from the “imminent hazard” of traveling through avalanche terrain.

Because the agency focuses on workplace safety, the findings apply only to the guides, not the clients.

The ski group was slogging through feet of fresh powder in a forest beneath a steep mountainside when the avalanche hit, burying some people as deep as 10 feet. It is not clear what triggered the slide. Nine skiers suffocated.

In the penalty notification, which was first reported by CapRadio, the agency cited Blackbird for failing to assess whether guides needed more safety equipment. Those include special backpacks equipped with airbags to help keep people above the snow and emergency breathing devices known as Avalungs that could have helped them survive longer once buried.

Blackbird Mountain Guides said in a statement that it had filed a formal appeal and had been in compliance with all regulations and mountain-guide safety practices.

“Mountain guiding takes place in dynamic wilderness environments where conditions change minute to minute — it’s not a controlled setting such as construction sites,” the statement said. “We welcome the opportunity to work with Cal/OSHA to contextualize the unique realities of operating in backcountry environments.”

The statement noted that all three guides who died — Andrew Alissandratos, Nicole Choo and Michael Henry — were certified by the American Mountain Guides Association.

The company also faces two criminal inquiries: one by Cal/OSHA’s Bureau of Investigations, which remains open, and one by the Nevada County Sheriff’s Office, which was recently forwarded to the county’s district attorney. No criminal charges have been announced.

Blackbird said it continued to cooperate with all investigations and “remains committed to working with every agency reviewing this tragedy to further the understanding of what occurred.”

An independent report commissioned by Blackbird and released this month attributed no direct blame to the company. It said that the company had followed established risk-management practices “including terrain and route selection, continued assessment of weather and snowpack conditions, and careful management of exposure.”

It added: “Guiding under elevated avalanche hazard is a recognized and accepted professional practice when these methods are applied.”

Blackbird was founded in 2020 and its guides have led hundreds of winter trips in the region without fatal accidents. It regularly took clients to the huts at Frog Lake, even in storms, and had established routes that skirted the most dangerous terrain when avalanche risk was elevated.

The group had veered slightly off one of those routes when it was hit, according to location data from that day.

Before the accident, two guided trips had been combined into one, and 15 skiers were clustered under a steep slope when an avalanche buried 13 of them in snow as deep as 10 feet. Cal/OSHA cited the company for failing to consider the risks of combining two groups.

The slide left only one guide and one client above the snow, which meant there were not enough rescuers to uncover all of the others before air ran out.

As the storm was still raging, the owner of Blackbird and one of its senior employees headed to the accident site to attempt a rescue, despite warnings that avalanche danger was too high.

Cal/OSHA also cited the company for that decision, saying it had allowed an employee to bypass a command post and enter the avalanche zone against the recommendation of local law enforcement.