Grizzly Flat residents Kathy Gallagher and Paul Johnson were riding their quads in a south county area razed by the Caldor Fire last week when they spotted what looked like a smoldering campfire.

Off Leoni Road between Leoni Meadows and Grizzly Flat, it wasn’t in an area where the two thought someone would be likely to set up camp — inside the burn scar and up a steep hill. Stephanie Bishop, public information officer with California Interagency Incident Management Team 4, confirmed the smoke was rising from a snag that held the Caldor Fire’s heat over winter.

Johnson called the smoldering snag in to authorities, who dispatched a crew of Forest Service firefighters to hike in and eliminate the hot spot. When fire crews arrived May 30 a small section of the burning snag had fallen on the ground with fire in the remaining standing snag and in the log on the ground. Fire personnel estimated the snag was about 30 feet tall and 3 feet in diameter.

At about 4,000 feet elevation that part of El Dorado County was covered by snow in the months following Caldor’s containment, but that isn’t always enough to fully douse embers that can smolder underground.

“This blows my mind that it has been months, with a lot of snow, and this (fire) was still able to keep going,” Gallagher said.

Overwintering fires, known as “zombie fires,” are seen around the globe and are not a new phenomenon. Reports of such blazes have come out of Alaska, Canada and the Arctic, and the recently-ranked largest fire in New Mexico history, the Calf Canyon Fire, was found last week to have been caused by a prescribed burn that reignited following at least three winter weather events.

In the Eldorado National Forest, such smoldering held through winter has been seen in the past in areas burned by the Cleveland (1992), King (2014) and Fork fires (2020), according to officials, who noted that on a burn scar as large as the 220,000-plus acre Caldor Fire, hot spots are expected to pop up.

On the Caldor Fire footprint reports of smoke have also come out of the Mormon Emigrant Road and Bonnetti Road areas.

With little left to burn on the burn scar, these zombie fires likely won’t resurrect the full fury of Caldor’s flames but firefighters extinguish and patrol each incident. New technology is also at work to help determine if these hot spots have the potential to spark a new forest fire.

“We are using new technologies to examine areas on the fire that tell us if an area has had high intense burning conditions or if an area didn’t burn with high intensities,” Bishop said. “This gives us an idea if there is a greater potential for fire spread via surface fuels on the ground.”

Forest officials ask anyone who comes across smoke on the burn scar to call 911.