In front of thousands of Facebook Live viewers on Tuesday evening, Jeff Marsolais, forest supervisor for the Eldorado National Forest, put it straight: “This fire has simply outpaced us.”
He spoke of the Caldor Fire, which has singed nearly 144,000 acres since its Aug. 16 ignition and is moving in a northeasterly direction toward the Tahoe Basin. Resulting smoky conditions have made national headlines and the fire rages on, particularly along its northeast boundary. As of the publishing of this news piece, the fire is 12% contained while fuel conditions and rugged terrain remain a significant challenge for firefighters.
Yet an end to the wildfire’s reign is in sight — tentatively. The Caldor Fire, whose cause remains unknown, is expected to be fully contained by Sept. 8, just under two weeks out.
Several factors go into determining an estimated date of wildfire containment, and the will-they-won’t-they of meeting the current deadline is made all the more pressing by Caldor’s recent designation as the number one prioritized fire in the entire U.S. due to values of the resources at risk in its path (read: the entire Tahoe Basin).
But really, the date is just a filler.
“We have to put in a date even if we are not sure of when that date will be,” explained Dana Walsh, one of the public information officers (PIOs) assigned to the Caldor Fire. “They put in a first point date where they have some potential expectation, but that date will be continuously reevaluated as we get closer.”
Terrain, fuel type, fuel moisture, and weather are major factors considered in the determination of a hopeful containment date, and a panel of experts monitor the situation — weather, forestry, and firefighting pros work together on the incident command team for each wildfire.
Complete containment is when a fire is fully surrounded and fire crews are confident the flames won’t pass the established perimeter. That line of defense can be personnel or natural obstacles (bodies of water, rock outcroppings, roads). The percentages associated with containment show how much of the fire’s perimeter is considered established.
“[Containment] doesn’t mean there’s no heat left,” explained Nicholas Prange, a PIO assisting with the Dixie Fire, north of Tahoe. “There could still be some smoldering stumps or roots or some heat in that area, but it’s not going to go beyond that.”
Spanning more than 750,000 acres across Butte, Lassen, Plumas, Shasta, and Tehama counties, and the single largest fire in California state history, the Dixie Fire is 46% contained … with no completed containment date in sight.
Prange says there are too many variables at play to pin down an end date, and Walsh confirmed this. “Because of the conditions of the Dixie Fire,” she said, “it makes sense that they finally moved it to ‘uncertain.’”
Hot spots could linger for months after a fire is 100% contained. In the Caldor Fire’s case, Walsh said hot spots will be burning for multiple months, likely until wintertime precipitation.
