BERNALILLO — A jury decided Wednesday that two utility companies hold most of the liability in one of the largest wildfires in New Mexico’s recorded history.

Jurors gave their verdict in Bernalillo following a weekslong trial that centered on whether Jemez Mountains Electric Cooperative and Tri-State Generation and Transmission Inc. did enough to prevent the Las Conchas Fire in 2011.

The blazed started when an aspen tree fell onto power lines that stretched through national forest land in the Jemez Mountains.

The fire raced across the southern edge of the mountain range, charring more than 240 square miles. It destroyed dozens of homes, threatened Los Alamos National Laboratory and blackened nearly two-thirds of Bandelier National Monument, along with areas held sacred by the tribes.

The threat of post-fire flooding continues to loom for the tribes and the monument.

Jemez Mountains Electric Cooperative operated and maintained the power lines. Tri-State Generation and Transmission Inc. provides the cooperative with electricity.

Jurors in Sandoval County District Court found the cooperative was 75 percent negligent for the wildfire, Tri-State 20 percent and the U.S. Forest Service 5 percent. Possible damage amounts will be determined at a later trial.

Tri-State spokesman Lee Boughey said the company was “disappointed with the negligence verdict” and will consider all of its legal options. He also said the company appreciated that jurors recognized that the Jemez Mountains Electric Cooperative and Tri-State operate independently.

Plaintiffs’ attorney Tom Tosdal said the Las Conchas Fire could have been averted had the cooperative responded to potential dangers by doing inspections and managing potentially hazardous vegetation along its power lines.

But cooperative attorney Al Green dismissed claims that it ignored industry standards. He said the utility had a tree-trimming program at the time of the fire that was much like those adopted by rural co-ops across the country. Green also said it wasn’t unusual for a downed tree to start a fire.

Jurors weighed whether the defendants should be held liable for not removing the tree, which was on private land, or taking action to prevent it from falling onto the power line.

Cochiti and Jemez pueblos are among the more than 300 plaintiffs in the case, which consolidates several lawsuits filed in the wake of the fire. The plaintiffs include property owners, businesses and insurance companies.