Things looked bleak for South Lake Tahoe as the Caldor Fire struck the esteemed resort community this week.
The fire was discovered over a granite ridge that officials had hoped the flames would not spread to the Tahoe Basin. Forecasters warned of gusty winds and bone-dry conditions that could push it further towards populated areas, raising fears of an urban conflagration. Tens of thousands of residents and visitors fled and blocked traffic on Highway 50.
But the threat appeared to have largely subsided on Saturday as authorities said fighting the 214,107-acre fire seemed like a corner. The fire is now 37% contained.
Crews took up positions in Christmas Valley and held fire south of Meyers in the northern Sierra Nevada. No buildings were on fire in South Lake Tahoe, and the crews were able to rescue houses in Christmas Valley and Meyers, too.
Firefighters had scratched containment lines around more than a third of the fire. They attributed a combination of aggressive firefighting tactics, improved weather conditions, and previous efforts to prepare the landscape for wildfire.
“If we had had the same weather and fire behavior for two more days, we would have had a real problem,” said Dominic Polito, a public information officer for the fire. “So there was a bit of Divine Mercy.”
“It no longer burns mile after mile in a single 12-hour period and that was only due to the change in weather,” he said.
Although it was too early to say South Lake Tahoe was completely out of the woods, authorities were cautiously optimistic, Capt said. Parker Wilbourn, another public information officer on the fire.
There are still some areas of concern where crews are working to make sure the flames don’t sweep over the containment lines, including the Christmas Valley and Kirkwood areas and parts of the Heavenly area, he said.
He ticked the factors that contributed to the improved forecast. Part of it was terrain: part of the north flank of the fire reached granite around Pyramid Peak in the Desolation Wilderness and drained it of the fuel to burn, he said. Some of it was luck as it always is.
Part of it is the weather: the winds are not quite as violent as originally forecast and have subsided in the middle of the week.
“A decrease in winds, a decrease in temperatures, and an increase in humidity have all played to our advantage over the past two to three days,” said Wilbourn. “We used this time to strengthen our containment lines and put the crews directly at the front for a firefight.”
Officials also noted the return of an inversion layer that is helping to keep the sun from heating up vegetation and the fire emitting a plume of heat and smoke, effectively stopping their activity: means the fire cannot breathe, “Polito said.
But ultimately, Wilbourn attributed three key factors that helped save South Lake Tahoe: extensive fire-fighting operations, the residents given defensible space around their homes, and previous forest management projects.
“They’ve been running a logging initiative for the past nine to ten years that really got rid of that fuel load,” he said, commending the US Forest Service for doing both the mandatory burns and vegetation thinning.
The Forest Service was working with the Sierra Nevada Conservancy on a project to burn 8,800 acres in Caples Creek drainage over 10 to 15 years from 2017 in wildfire after wind picked up and it burned at a higher intensity than intended which required the use of oppressive resources.
Like many western US forests, the watershed once benefited from frequent low-intensity fires caused by lightning strikes and indigenous burning practices, experts say. But after colonization and aggressive fire-fighting tactics reversed that cycle, with the imbalance exacerbated by drought and climate change, the forest there was filled with smaller trees and undergrowth, which, according to the Forest Service, increased drought stress for larger trees. These so-called ladder fuels can also carry fire into the cap so that it burns hotter and spreads faster.
By thinning the density of trees and reducing the number of smaller trees and vegetation, authorities had hoped to lessen the intensity of future forest fires that sweep the area.
The fire in Caldor was the first real test of the project and experts have been watching the result closely.
Wilbourn said it appears to have played a role in significantly slowing the spread of the fire in some areas and helping the crews catch it. He pointed on the perimeter map to a green pocket in the south finger of the fire that overlapped part of the prescribed burn, as well as other treatments he believed had been performed in the Kirkwood area.
“The reason for this is that you will see where some of this forest degradation has taken place,” he said.
Susie Kocher, forestry and natural resources consultant at the University of California Cooperative Extension, agreed.
“If you look at any of the fire maps, there’s a big gap between Kirkwood and Tahoe,” said Kocher, who was forced to evacuate her home in Meyers, California on Monday. “This is Caples.”
She said the Tahoe area has been more successful than many parts of the Sierra in attracting resources to such projects, partly because of its appeal.
The Tahoe Fire and Fuels Team, an inter-agency coalition formed after the devastating Angora fire in 2007, said it has done 65,000 acres of fuel reduction work in the Tahoe Basin over the past 13 years. The group also helps neighborhoods prepare for the fire.
In a recent community briefing, Rocky Oplinger, an operations manager, described how such work can help firefighters. When the fire was discovered over Meyers, it achieved fuel treatment that helped reduce the flame length from 50 to 15 feet, allowing firefighters to carry out a direct attack and protect homes, he said.
“In an environment like this, it takes both fuel cuts and active suppression to help the community and the forest survive,” said Kocher.
Nothing is known about the cause of the fire in Caldor, which broke out about six kilometers south of Grizzly Flats on August 14 and ultimately decimated the city. About 55,000 people had been forced out of their homes by Friday, but that number had decreased by Saturday as some were able to return, authorities said. The fire had destroyed 687 homes and 18 commercial properties, with damage assessments 75% complete, Wilbourn said.
Firefighters were able to save homes in Christmas Valley and Meyers using a combination of tactics that Polito said were fairly typical. First, the authorities used the weather and topography to estimate where the fire was likely to spread. The crews then went into these areas and prepared structures by removing piles of wood, lawn furniture, and brushes to give the embers less chance of settling.
When the fire hit, they were conducting what is called a “fire front chase,” Polito said.
“It is impossible to stop a big fire, but what we can do is position ourselves in vehicles and in so-called safety zones on the streets,” he said. “When the fire comes through and all the fuels start to ignite, we will follow him from behind and put out the various fuels that are near the buildings.”
They also lit backfires to clear the fuel between the communities and the fire, he said.
The firefighters were also helped by the fact that residents were evacuated quickly so crews could focus on rescuing homes rather than people, Polito said.
“Because the fire came so quickly, we couldn’t have saved all these houses if people had trampled on and blocked the streets,” he said.
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