FRESNO — Yosemite National Park officials were overconfident that they could manage a controlled burn last summer that whipped into an explosive wildfire and forced dozens of evacuations, the National Park Service said in a report issued Friday.
The prescribed burn in August near the mountain town of Foresta, on the park's western edge, was intended to eliminate tinder-dry vegetation that could cause a wildfire.
But the 90-acre burn jumped fire lines and ended up blackening more than 11.3 square miles, fed by the dry grass and dead trees the burn was supposed to safely devour.
"The hubris of success" affected the team's mental state, contributing to the problem, the park service said.
In response, the agency plans to review and clarify national guidelines outlining the factors that crews should consider when rating the relative complexity of each controlled burn.
Yosemite Superintendent Dave Uberuaga has ordered a revision of the park's policies for tracking fuel danger, moisture, fire behavior and weather, and will ensure that local crews consult with regional fire staff before ordering high-risk controlled burns.
"We had a sense of pride that we had been successful in managing a lot of fires with good resource results, and that may have made this little 90-acre fire look a lot more manageable than it was," Uberuaga said.
"It's one of those things where we'll look back, and it will cause us to pause a lot more the next time."
The park's look back comes after criticism from local residents, who said fire crews underestimated the danger posed by dozens of burned-out tree husks in the area, remnants of a 1990 blaze that closed Yosemite for the first time in its history.
Last summer's fire forced the evacuation of dozens of Foresta homes, a handful of campgrounds and prompted authorities to close off several roads through the park.
Park service officials said winds and air quality in the area initially met the criteria for a prescribed burn.