Sep. 5—SOUTH LAKE TAHOE — The embers are flying farther, the super-parched trees and underbrush igniting faster, the fires growing to unparalleled size at unprecedented speed. Worst of all, California's firefighting forces are stretched beyond their limit and continuously exhausted.
So the question, as climate change and drought have combined for the worst wildfire conditions in memory, is: How do you stop unstoppable fires?
The answer is as old as firefighting itself: adapt.
And that's exactly what the 4,662 firefighters battling the voracious Caldor Fire have been doing for the three weeks it's been laying waste to Sierra Nevada slopes on its march toward Lake Tahoe.
They're jumping farther ahead of the blaze, aggressively clearing space around homes in hamlets like Christmas Valley south of the lake well before the flames get there. For the first time in Northern California, they're using infrared-capable helicopters to drop water at night. And at ski resorts they're firing snow-making water cannons to wet the ground and buildings — a fairly new technique that's never been used to this extent before here.
Defense is the new offense in this firefight, and it seems to have lessened the scale of the disaster. By Saturday, the 3-week-old blaze had burned across 214,112 acres, destroying 920 homes and commercial structures, including most of the little town of Grizzly Flats in El Dorado County. Notably, there have been no fatalities.
"Our strategy has absolutely had to change under these conditions," Cal Fire Assistant Deputy Director Daniel Berlant said. "Just the fact that we keep talking about the new normal or that these conditions are unprecedented — we've been saying that for five years. The precedent is here.
"How we adapt to it must be in our strategy."
Maps and diagrams: See how firefighters are combating the Caldor Fire through wilderness, ski resorts and residential areas
By Saturday evening, the fire was 43% contained. The rest of the perimeter was a battle zone.
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Usually in a wildfire, the front line is the safest and most strategic place for firefighters to stop the spread, but only under the right conditions, said Cal Fire Assistant Chief Brian Newman, a fire behavior expert who is helping form strategies for fighting the Caldor Fire.
The conditions have been far from right in the Caldor Fire.
The fire's aggressive race through steep, rugged Sierra Nevada terrain often presented too much danger for crews to work right at the fire line. Flames were devouring drought-starved brush and trees — the driest in at least a decade — at unforeseen speed. Nearly every ember that landed on the ground immediately kicked up a new fire, shooting up into the tree canopy and taking hold even in meager plants growing in the crannies of granite faces.
"We definitely can't take a flaming front in a timber crown head-on," Newman said. "We have to adjust and go after the flanks, the edges."
So that's what they did, building firebreaks alongside the fire to limit its growth. They also cut breaks far ahead of where they might have in a less voracious fire.
Crews hit the ground aggressively in and around Christmas Valley, nearby Meyers and South Lake Tahoe to the north, chopping down overgrown bushes and grasses along the roadways, removing low-hanging tree limbs and cutting firebreaks in the forests surrounding housing clusters.
Those are tried-and-true tactics. The difference this time is how far afield they've had to anticipate the fire would travel and how much more quickly that would happen.
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That awful speed is being blamed largely on drought.
Of the past nine years, seven have been marked by drought. But the past two years were the worst in producing fire-ready fuel, said Craig Clements, director of the Wildfire Interdisciplinary Research Center at San Jose State University.
Not only are the forests overgrown from a lack of adequate thinning over decades, he said, but that packed overgrowth is drier than anyone could have feared years ago. Clements and his team have data on vegetation moisture content going back to 2010, and "what we're finding is fuel moistures are a month ahead of schedule of how fuels dry out for the season. We've seen 50% moisture content for about a month — and normally we see that in October."
The result: Embers that might have fizzled out on the moist forest floor are instead finding ready fuel — fuel that burns hotter and faster. That in turn creates more powerful energy and taller flames — sometimes as high as 150 feet, thrusting embers as high as 1,000 feet. At that height, they can catch stiff winds and take off; this season, embers have blown as far as 8 miles ahead of the fire's front line.
Before the 2017 Wine Country blazes ushered in a new era of mega-fires each year, a wildfire could be expected to hurl embers a mile or two ahead, said Scott Stephens, a professor of fire science at UC Berkeley.
"But 8 miles?" he said. "That's one for the record books."
So instead of anticipating spot fires lit by embers a couple of miles away, the Caldor crews have had to venture farther ahead. With dense smoke tamping down the flames, bulldozer crews spent days building firebreaks in the national forests east of Pioneer Trail, a major thoroughfare through South Lake Tahoe's eastern outskirts, a key area of defense for densely populated and commercial areas.
"The beauty of what they did on the Caldor Fire is they started looking at the terrain closer, farther ahead, so they could predict where the fire was going to run through — and they IDd the human structures we really had to worry about that are in the wake of the fire," said Doug Leisz, a retired U.S. Forest Service associate chief who helped oversee California firefighting efforts. "So they prepped those areas that were bound to get caught in the fire, removing fuels in towns like Meyers and the winter sports areas.
"They did a tremendous job of preparing those areas, and they weren't hit as hard as a result. I was thrilled to see how well they did that. They had to," he added.
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This fire's unusual speed and reach also mean Cal Fire pulled the trigger quicker on evacuations.
Just a few years ago, emergency officials tried to avoid disrupting lives by not evacuating areas that weren't under immediate threat. But the deadly Wine Country fires revealed the dire consequences that could occur when authorities fail to get people out of the way.
With that in mind, South Lake Tahoe officials on Monday ordered people in the entire city and surrounding areas to leave as the fire plowed over Echo Summit and began threatening communities on the city's outskirts. The famed tourist destination, home to roughly 22,000 people, emptied out by early afternoon.
"They're evacuating people earlier, which is great. ... It makes it easier to fight the fire," Stephens said. "So in places like Meyers, since there were no people there, it's given more space for the resources to get in there and move freely, and that has made them more effective."
Some of those early evacuations were adjustments everyone had hoped to avoid.
Even as the Caldor Fire raged toward Lake Tahoe, no one — not city leaders, fire officials or local foresters — expected it to burn across Echo Summit into the Tahoe Basin. The summit is a hulking granite crest that divides the western slopes from the rugged Eastern Sierra ridges. Fire typically wouldn't thrive in that rocky terrain, so it's seen as a firewall.
But gusting winds and intense flames flung embers across the granite anyway, and fire took hold in the sparse plants on that rock face. Then it shot embers across Christmas Valley to the east, with flames burning down both sides of the valley hamlet. That's when preparation paid off.
Crews had cut firebreaks along the hillsides above Christmas Valley and key ridge lines, and they broadened fuel breaks along roads, strategies that "allowed that fire to come down with much less intensity," Newman said.
Engine crews swarmed the national forest abutting the community and in backyards, clearing lower tree limbs, cutting down underbrush, moving propane tanks away from buildings, and arranging hoses to prepare to save homes. Property loss in the valley was minimal.
Building firebreaks beyond firebreaks, assuming the fire will burn past those lines — this is the new normal, firefighters said.
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The conditions necessitated two other weapons in the Caldor battle: snow cannons at ski resorts and night-vision helicopters able to attack in the dark.
The copter plan was hatched when, three days after it started on Aug. 14, the Caldor raced into Grizzly Flats, sending residents fleeing and flattening much of the town.
Fire officials in Southern California offered to send night-flight helicopters to help, said Kyle Tolosano, regional aviation safety manager with the U.S. Forest Service working the Caldor Fire. Equipped with infrared technology, the copters have been used in Southern California since 2012 — but never up here.
The aircraft arrived Aug. 18 and joined the battle near Pollock Pines in El Dorado County, pulling water from Jenkinson Lake and dropping it along the Highway 50 corridor.
Water and fire retardant can provide crucial support for fire crews, but these blazes aren't extinguished from the air. Fires are put out by people on the ground with hoses and tools like Pulaski axes and double-ended McLeod rakehoes.
With that in mind, the copters' mission was to use water and fire retardant to slow the fire's spread and give firefighters below space to protect structures and build firebreaks, Tolosano said. This was crucial for speed, but also because the hotter, drier weather has been giving firefighters less of the break they usually get at night, when flames traditionally slow in lower temperatures.
It was a landmark moment. "That's the first time we've ever done that in Northern California," Tolosano said.
Berlant said Cal Fire had already acquired night-flight-capable helicopters in anticipation of the worsening fire seasons — but its crews in Northern California were still training and not yet mission-ready.
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Ski resort snow blowers have been another weapon added to the arsenal. And so far, it seems to be working.
The Sierra-at-Tahoe resort used them to blast water at its structures as the Caldor closed in on Aug. 29. Combined with vigorous work by the staff and a private firefighting crew to increase defensive space, the technique warded off catastrophe. The resort lost one maintenance shop, but the chairlifts, towers and buildings appear to have escaped unscathed, managers told The Chronicle.
The biggest use of the cannon-shaped snowblowers unfolded at Heavenly above South Lake Tahoe.
"They're going full bore," continuously wetting down buildings and land, not only protecting the property but creating a bit of a firebreak, said Michael Reitzell, president of the California Ski Industry Association. And with wells and two large reservoirs to pull from, there was no danger the resort would run out of water, he said.
The snow guns had been "used for small spot fires before, but this is the first time they've been used like this," Reitzell said. "It's pretty unprecedented."
Kerry Green, an emergency management specialist with the U.S. Forest Service assigned to the Caldor Fire, said the overarching strategy lesson of the past month — and this awful season in general — is to assume wildfires will defy expectations.
From now on, they will be more extreme, more erratic.
Expect this, she said: "A bigger, badder fire."
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