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One year after the Bighorn Fire, what have we learned about its impact, and the potential for future infernos?

The Bighorn Fire wasn’t the largest wildfire that ever struck the steep, moody Santa Catalina Mountains rising up north of Tucson. Nor was it the deadliest, or most destructive. Nonetheless, the lightning-sparked, record drought- fueled blaze held the city’s attention in the summer of 2020 like few fires in recent memory.

That’s because the Bighorn burned for almost two months, roaring from rocky Pusch Ridge in the west, to the arid grasslands of Redington Pass in the east. Residents of the rustic town of Oracle watched the fire scorch up the back of the range, while those in the front-facing Catalina Foothills uneasily scanned the slopes as flames crept down toward expensive, custom-built homes.

Even those who lived far from the scene were reminded of the conflagration as soon as they stepped outside: As high winds stoked the flames in mid-June, heavy smoke was pushed down into the valley. Haze hung in the air for weeks, smudging the skies, and filling noses with the heavy, sickly sweet scent of burning trees.

By night, fire on the Catalinas dominated the news, as well as Tucson’s skyline. The mountain range began to glow an increasingly angry, infernal shade of orange, and on its darkened south face, hundreds of spot fires sparkled like bright gems against black velvet.

One didn’t want to see the seductive, destructive show, yet couldn’t look away.

“Every evening, I would climb up on my roof and look at this incredibly beautiful display of nature doing her normal and natural work,” says conservation advocate Randy Serraglio of Tucson’s Center for Biological Diversity. “But I know a lot of other people looked up … and saw an apocalyptic event.

“They were frightened by it and profoundly disturbed, and literally thought that their beautiful mountain range, in Tucson’s front yard, was going to be destroyed.”

The year 2020 was difficult for many reasons, not the least of which was Arizona’s continued lack of precipitation, record-breaking heat that reduced foliage to a tinder-dry state, and — not surprisingly — the size, length, strength and increased frequency of wildfires.

By year’s end, according to the Arizona Department of Forestry and Fire Management, more than 2,500 fires had burned through almost 1 million acres of state, federal and tribal lands in the Grand Canyon State. That accounted for more land than burned in the two previous years combined.

The vast majority of those blazes were human caused, including the year’s largest: the monstrous, vehicle-firecaused Bush Fire, which in three weeks consumed more than 192,000 acres of Phoenix-area Tonto National Forest. By contrast, the Bighorn Fire, which claimed some 120,000 acres in our smaller Coronado National Forest, was naturally caused — and burned more than twice as long.

“It moved low and slow, for the most part, but it just burned and burned and burned,” comments Mark Hart, public information officer for the Arizona Game and Fish Department, which provided support services during and after the fire. “And it looked awful, the spectacle of that fire burning out in full view of Tucson and Oro Valley.”

On the evening of June 5, 2020, an unseasonal, premonsoon lightning storm burst over the Tucson area, touching off several fires in surrounding mountains, including the most prominent: the rugged, deeply contoured Santa Catalina Mountain Range.

One ignited on Bighorn Mountain, near picturesque Pusch Ridge, where terrain is particularly steep and vegetation relatively sparse. Golder Ranch Fire Department, alerted by a 911 caller in Oro Valley, dispatched an engine company to keep an eye on the faint orange dot, but firefighters were unable to take further action. The fire was too high up, and in rugged terrain that could not be accessed at night.

“The next morning, there was smoke and fire up there,” remarks Steven Haas, manager of Catalina State Park near Pusch Ridge. “I remember getting the report, and thinking, ‘We’ve had fires on the mountains over the years, and they either burn themselves out, or don’t get too big.’”

But the blaze didn’t behave as expected. It was issued a formal incident name — the Bighorn Fire — and the state moved into extended-attack mode, sending out a Type 3 Incident Management Team to coordinate the response of local firefighting agencies and others. But the wildfire would continue to grow, fed by particularly high temperatures and near gale-force winds. By June 11, it threatened almost 1,000 homes in the wildland-urban interface — the uncomfortable transition point between open wilderness and built-up areas — and several parts of Oro Valley and the Catalina Foothills were put under evacuation alerts and orders.

Less than a week after the fire started, when Arizona requested help, FEMA issued a press release announcing that a National Wildfire Coordinating Group Type 1 Incident Management Team had assumed command of firefighting efforts. In it, the agency said that the Bighorn Fire “threatened such destruction as would constitute a major disaster.”

Arrival of a Type 1 team opened a much bigger management toolbox, as commanders were able to order up additional regional and national resources, from specialized firefighting aircraft contracted with U.S. Forest Service for emergency use, to elite hotshot firefighters drawn from around the Western United States.

Local fire agencies continued to be part of the attack force. They included Northwest, Golder Ranch, Avra Valley and Picture Rocks fire districts, which provided engines, wildland firefighters, supportive structure protection for Foothills houses threatened by fire, and medical treatment services at the giant field camp housing firefighters at Catalina State Park. Also provided were water-tender trucks, charged with keeping the “dip tanks” erected in Foothills’ neighborhoods filled with water, so that firefighting helicopters could draw from them.

By the end of the massive firefighting campaign, when the Bighorn was finally brought under control on July 23 with additional assistance from cooling, long-awaited monsoon rains, it had cost more than $37 million to slay the fire-breathing monster on the mountain.

The Coronado National Forest, headquartered in Tucson, is a complex agency, overseeing a complex landscape. The U.S. Forest Service-managed land encompasses almost 1.8 million acres in southeastern Arizona and southwestern New Mexico. And although it doesn’t crack the Top 15 largest national forests in terms of size, it does manage multiple biologically diverse “sky island” mountain ranges, and thus, a greater variety of wildlife and plants than found in many other national forests.

In the Tucson region alone, those management areas include saguaro-studded deserts, dense oak woodlands, stream-fed canyons, and high-elevation, cold-weather forests of pine, fir and aspen, like those found on nearby Mount Lemmon, the highest point in the Catalina Mountains. (The hourlong drive up that one mountain takes visitors on a virtual trip from the Sonoran deserts of Mexico to the conifer forests of Canada.)

The entire Catalina Mountain range encompasses about 155,000 acres. And about three-fourths of that acreage was claimed by the Bighorn Fire.

Less than two weeks into the blaze, some 358,000 gallons of fire retardant — which was, as one news report noted, enough to fill more than 30 backyard swimming pools — were dropped on the Catalinas. That amount was nearly 50 percent more than was deposited onto all national forest wildfires in the entire state in all of 2016.

“On the Coronado and many places in the Southwest, we don’t have a fire ‘season’ anymore (because of ongoing heat and drought),” notes Coronado National Forest spokeswoman Heidi Schewel. “We have a fire year … and we need to be careful of fire every day.”

Much of the land burned by the Bighorn was touched by wildfire before — and recently, too.

In 2017, the grass- and brush-fed Burro Fire started in the foothills around Redington Pass and moved up the mountain, eventually engulfing more than 27,000 acres. And in 2002 and 2003, the notorious Bullock and Aspen fires collectively scorched about 115,000 acres, burning so hot in some areas that smoke plumes were visible from space, and old-growth forests were reduced to gray ash. The Aspen Fire was especially devastating, essentially burning to the ground most homes and businesses in the mountaintop hamlet of Summerhaven — a favorite day-trip destination for generations of Tucsonans seeking relief from desert heat.

“These ecosystems have now been exposed to multiple big events,” says Don Falk, a professor at the University of Arizona School of Natural Resources and the Environment. “And the question on everybody’s mind is, ‘What happens when a mountain range, an ecosystem, is touched by fire multiple times?’ This is becoming a very big deal because ‘reburns’ are becoming more and more common.”

Part of the reason for reburns can be directly traced to nearly a century of federal forest-management policy (what conservationists prefer to call “forest mismanagement”) that viewed fire on public lands —no matter how small or remote — as dangerous. Deemed the “10 a.m. policy,” the goal was to extinguish any and all fires by the following morning.

Unfortunately, that interrupted an ecosystem’s ability to regulate itself with periodic, naturally caused fires — as it had for millions of years — that cleared out deadwood and underbrush debris, removed old trees that starved younger ones of water and sunlight, and revitalized the soil by adding nutrients (in the form of dead vegetation) back to it.

It left many ecosystems, including those in the Catalinas, overcrowded with tangled, dry kindling littering the ground, and forests of spindly, unhealthy trees weakened by overcrowding and decades of battling each other for water and nutrients.

“After decades of that, the forest was primed for those big fires in the early 2000s, the Bullock and Aspen,” Serraglio explains. “Part of the reason those fires got so out of hand and burned so violently was specifically because the Forest Service had spent many decades suppressing all fires as a general rule.”

In response, the Tucson-based Center for Biological Diversity has been working with the U.S. Forest Service to help blend existing wildfire prevention with the benefits of modern- day, intentionally set “prescribed burns” to return fire to the mountains’ cycle of life.

Last year, firefighters used some of the areas burned by the Bullock and Aspen fires as crucial fire breaks, which prevented the Bighorn from spreading farther and faster than it did. Because of that tactic, Falk estimates, less than one-fifth of the land burned by the Bighorn did so with high severity, which causes devastating crown fires that jump from tree to tree, taking virtually all vegetation in its fiery path. This can even change the biochemistry of the soil itself.

Serraglio says that, overall, the Bighorn burned in a “mosaic” pattern, which included medium-severity fires that typically consume ground vegetation, blacken lower tree limbs, and kill about 50 percent of trees; and low-severity fires that may do little more than burn through grasses, shrubs and vegetation that already has died.

Even now, in some Bighorn-burned areas, rebirth is already evident. Low-growing shrubs and tender grasses are sprouting, and colorful wildflowers will soon bloom in the darkened landscape. Young quaking-aspen saplings will rise up from subterranean root systems well-protected from fire, and will emerge onto a landscape devoid of large trees that would have otherwise blocked sunshine from ever reaching them.

“Of course, we know now that aspen isn’t just coming in,” Falk elaborates. “It was there all along, mostly living underground. It emerges after a fire, and takes its moment in the sun quite literally and becomes the dominant plant community.”

In some areas, he notes, those tall, slender-trunked aspen trees may dominate the landscape for as many as 100 years until slower-growing trees, like Douglas firs or other seed-generated conifers, can come in underneath, and eventually overtop them.

Ponderosa pines, blessed with fire-resistant bark, will likely rebound quickly, but it will be a very long time before lush alpine forests that were severely burned return to their former glory.

“The main thing to understand with these fire-adapted ecosystems, is that they may not recover on the same time frame that we would like to see them recover,” Falk emphasizes. “We’re impatient. We want to see everything happen right now.

“The problem with that is it’s not the way ecosystems work.”

By mid-June and into July, the Bighorn Fire was captivating the city with an everchanging tableau of nature’s might, as high winds and hot weather spread the flames across the embattled mountainscape.

During the day, great clouds of smoke leaked up from the bruise-purple peaks, staining otherwise unbroken skies of cornflower blue an exhausted, dirty gray. Fire cut into Romero Canyon near Catalina State Park, as well as popular hiking trails and recreational areas in Pima and Finger Rock canyons, prompting evacuations. Flames also penetrated Esperero Canyon, Cargodera Canyon, and the beloved upper Sabino Canyon as well.

Those who lived in the Catalina Foothills had a front-row (if uncomfortably close) view of the firefighting “air show”: waves of air tankers and helicopters bearing the distinctive, orange-and-white colors of wildland firefighting aircraft, all engaged in a carefully choreographed, aerial ballet aimed at controlling and directing a wildfire on the run. Hour after hour, and day after day, tandem-rotor Chinooks and a heavy-lift Sikorsky S-64 Skycrane ferried water to the fire, drawing from portable dip tanks or picturesque Rose Canyon Lake, where choppers hovered so low, the downward rotor wash roiled the otherwise placid water surface.

When the fire moved to terrain that permitted firefighters to work the fire line, nimble Bell 205s — the civilian version of the UH-1 “Huey” military transport chopper — briskly moved hand crews and supplies to and from the fireground.

Airplanes were in evidence, too — but gone were the hulking, propeller-driven war-birds seen at past wildfires here. Nearly 20 years ago, the Aspen and Bullock fires were worked by sturdy, turboprop Lockheed P-3 Orions and P-2V Neptunes. Both were anti-submarine patrol bombers flown by the U.S. Navy, and converted into firefighting service once the military no longer had any use for them.

The Bighorn, in contrast, was serviced by modern jet-engine “firebombers,” many of which previously served as civilian passenger aircraft, retrofitted to carry slurry.

The crews of the planes worked tirelessly. An Avro RJ85, from the British Aerospace family of regional airliners, flew low along ridges, making precision discharges of brilliant red fire retardant in an effort to slow the advance of the flames. It was joined in the fight by an Erickson Aero Tanker — itself an MD-87 passenger airliner converted for tanker duty — and a meaty, wide-bodied DC-10 capable of disgorging more than 9,000 gallons of slurry in eight seconds, in a majestic, mile-long scarlet drop.

“Once the fire reaches a certain size, we can’t control it like we wish we could,” observes Jim Malusa, a plant ecologist at the University of Arizona School of Natural Resources and the Environment, who watched the aircraft movements with fascination from his midtown home. “But the Coronado (National Forest) and the teams they brought in did a fine job of directing it. This is what ultimately kept the fire under control in certain areas, and why it did not burn up the town of Oracle.”

To the uninitiated, the planes and choppers seemed to play starring roles in the nearly two-month-long firefighting campaign, but for those in the know, they actually had a high-flying support role for the often-unseen heroes: wildland firefighters working the terrain far below.

“This was a 100 percent full-suppression fire from the start,” emphasizes C.J. Woodard, Santa Catalina District ranger for the Coronado National Forest. “Everything lined up in terms of the abiotic factors at play in fires — weather, wind, temperature, burning conditions and burning period.

Everything was conducive to a rapid-growing wildfire. And if we had taken absolutely no action on this fire, there’s no telling how big it would have gotten, based on what Mother Nature wanted.”

At its height, almost 1,200 persons were assigned to work the Bighorn Fire — all headquartered at the Catalina State Park field camp. Among them were at least six, 20-person crews of highly trained U.S. Forest Service hotshots from western states ranging from Montana to New Mexico.

The yellow-clad hand crews worked 12-hour shifts in triple-digit heat, using chainsaws to fell trees, and hand tools to extinguish hot spots and dig an astounding 130 miles of fire line (more than driving distance between Tucson and Phoenix!) into the hard soil. After clearing the fire lines, and setting beneficial back burns to consume flammable vegetation that would have allowed the Bighorn to spread, they all piled into a brush truck or helicopter, and returned to base camp for a shower, hearty meal and good night’s sleep under the stars.

“Man, I have such respect for the Forest Service and all the people who fought that fire,” Haas says. “Those firefighters were out there in the hottest part of the year, with all that gear, that close to the fire, in such rugged terrain. It’s really an amazing operation.”

One day, the wind shifted, and fire began to move toward the park. Firefighters there swung into action, using sandy Sutherland Wash as a natural fire break, with the paved road running through Catalina State Park as a backup. (On the one-mile Birding Trail, visitors can still see the results of intentionally set backfires to keep the fire at bay.) “Burn scar” also appears in the park in the form of singed barrel cacti, fallen saguaros, and desiccated prickly pear — all desert plants not adapted to fire and heavily damaged by it. Fortunately, when the Bighorn Fire did enter, its spread was limited to just 30 percent of the 5,500-acre park.

Although many Tucsonans were surprised by the size, stamina and drama of the Bighorn Fire, many experts — especially those who work in the conservation and fire-science realms — have a decidedly more measured assessment. Yes, the fire was large, but not catastrophic, and overall, beneficial to the many species of plants and animals that live there.

“There certainly was an ecological cost from the Bighorn Fire, and we’re still evaluating that,” Falk admits. “Every mountain range is different, and no two of them are going to respond the same, but most of the area burned by the Bighorn Fire actually was good for the mountain.

“It’s just that we don’t hear about that because when the 10 o’clock news sends a crew up to study a big wildfire, the producer doesn’t expect the cameraman to come back with pictures of grass burning. They want to see big flames, and houses burning, and a giant catastrophe.”

Sometimes the benefits aren’t obvious, even when they’re right in front of us, Malusa says. Trees and other vegetation may have burned in Catalina State Park, but that also means that bighorn sheep in the area now have tender greenery to nibble on, rather than thorny prickly pear. They also are safer from predators like mountain lions, which were able to hide behind overgrown brush when stalking them.

“Fire can be a disaster when you lose your picnic area,” he quips, “but it’s probably pretty good for whatever else has moved in afterward.

“From an ecological perspective, the Bighorn really was more bark than bite,” he adds. “It was inevitable and essential. And with luck, we’ll come to accept that.”