San Francisco Chronicle - (Sunday)
Strategies adapt for Caldor battle
3 new tactics: Crews clear fuel far ahead, use night-flight copters, snow cannons
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.”
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-andtrue 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
As the Caldor Fire has grown to more than 200,000 acres, it has destroyed homes in forested communities such as Grizzly Flats, charred forest lands, encroached on high-profile ski resorts and threatened South Lake Tahoe, a vibrant lake basin city. Each of these scenarios presents unique challenges for firefighters, who employ different strategies based on terrain, weather and threats to property or lives.
Here’s a look at how they’ve battled the fierce blaze in three different situations over the past three weeks:
Limited by the rugged mountain terrain, firefighters were left mainly to watch, monitor and direct the windblown flames as they consumed acres of dry timber that had mostly avoided wildfires in recent decades.
Early efforts to slow the spread of the blaze included firefighting aircraft dropping water and retardant on the flames, including the first nighttime drops in Northern California history. But fires aren’t extinguished from the air. Fires are put out by firefighting on the ground.
In the wilderness, fire crews couldn’t combat the fast-moving flames headon, instead going in after the fire front moved through to try to save homes and cabins. Crews also focused on building and strengthening containment lines ahead of the fire front. Rivers, ridges and roads were key points to slow its spread.
The goal was to steer the fire away from structures in hopes that it would burn out before destroying towns and lives. As the fire turned toward Christmas Valley, firefighters did defensive work, clearing brush near homes and putting out spot fires to protect the community.
The uncontrollable flames climbed their way toward Sierra-at-Tahoe, destroying structures along the way. With Kirkwood and Heavenly also in the path of the blaze, firefighters changed tactics in an effort to save the popular ski resorts.
They used heavy equipment and hand tools to cut defensible space around structures and taped up air vents to block embers. The resorts’ water hydrants, which are normally used to make snow, were repositioned to douse buildings with water and saturate the ground. Air drops continued while workers scraped the landscape of dry materials, chainsawing away branches and drenching building exteriors with fire-retardant gel. Some cabins outside Sierra-at-Tahoe were lost and some maintenance buildings were burned, but the lifts and resort survived as the fire moved past the area.
To protect the valley, contingency lines were drawn around the Kirkwood peaks, where some firefighters were stationed alongside to watch for flying embers. The preventative measures performed there had kept the fire from reaching the resort as of Sept. 3.
Wildland, forest areas
Ski resort areas