MIDDLETOWN, Lake County — The shock came a year ago.

A YouTube video playing in a Santa Rosa motel room flashed what the small group of guests, chased from their homes last Sept. 12 by the historic Valley Fire, never imagined they’d see: The beloved retreat they ran in the hills of Lake County had been reduced to piles of rubble and ash.

The managers of Harbin Hot Springs, who helped shape the decades-old mantras of tolerance and self-expression that lured droves of spiritual seekers to their clothing-optional getaway, lost not only their livelihoods but also a community — one that included 55 residents, 240 employees and tens of thousands of annual visitors.

The circle extended to Middletown locals who, in addition to taking part in dance classes, healing workshops and meditation, counted on out-of-town traffic to support their own businesses.

“The mother ship was destroyed,” said Sajjad Mahmud, senior vice president of Harbin and a 30-year resident. “We had so many people coming from so many places. There’s been a great sense of dislocation.”

But amid the charred remains of cabins, massage studios and a wooden temple, the center’s signature springs continued to flow. The water in the pools, the managers said, gave them hope for the future.

Now Harbin, like the rest of the region, is trying to move beyond a fire that, across the region, killed four people while leveling nearly 1,300 homes and 66 businesses.

On the anniversary of California’s third-most-destructive wildfire, the heads of Harbin Hot Springs are among hundreds of Lake County residents working to rebuild. Few, though, are being watched as closely.

Harbin’s comeback from the Valley Fire — and the momentum it may provide a broader, regional recovery — hinges on a multiyear plan being hatched at a small house in Middletown, the group’s temporary base of operations.

Their undertaking involves clearing out wide swaths of dead trees on the mountain property, reclaiming the area’s natural hot springs, and surrounding the soaking pools with a mini-village of rebuilt lodging along with a restaurant, theater and conference center.

The effort, which could cost as much as $60 million, is complicated by estimates that Harbin’s insurance payout will cover only a fraction of the bill.

“Harbin was put together over 40 years,” Mahmud said, appearing unfazed by the obstacles. “If you start thinking too far ahead, it’s overwhelming. I think what we’re doing, as they say in the cliche, is taking one day at a time.”

On the scorched hillsides where the rustic resort once stood, the sound of heavy machinery echoed on a recent morning. All of the burned structures were gone, and the frames and foundations of new decks and refurbished pools were emerging, alongside shoots of newborn oak and bay trees.

Harbin’s managers say they’d like to partially open by the end of the year, but acknowledge that’s a best-case scenario.

“The immensity of the destruction was overwhelming,” said Will Erme, one of the retreat’s managing directors and former residents, as he walked past a metal dragon gate that survived the fire. “I knew we would start rebuilding, but we didn’t know how or when.

“There was this period of not knowing,” he said. “There are still many periods of not knowing.”

The Valley Fire, which burned quickly from the mountain community of Cobb to Middletown 10 miles away, destroyed all but a handful of the dozens of historic buildings at Harbin. Many dated to the early 1900s, a time when the site operated as a high-end resort with Turkish baths and a dance pavilion before it was acquired by the Heart Consciousness Church and its new-age practitioners in the 1970s.

Among the small staff that has returned since the fire is a security team that works out of a trailer, keeping nefarious or merely curious interlopers off the property. On some days, dozens of onetime visitors drive up the dead-end road in the isolated canyon to check on progress.

“They just want to know that we’re coming back soon,” said Nikki Palmer, who was manning the entrance. “One woman recently told me that God sent her. I just got her a chair and let her sit by the sign. She did some yoga and said some prayers. Most people just need a few minutes.”

The initial work at Harbin is focusing on the the site’s spring-fed pools, the centerpiece of the retreat and a product of Lake County’s unique geothermal activity. Geysers, warm creeks and a 4,000-foot volcano, Mount Konocti, loom nearby.

Harbin managers say that if all goes well, six rebuilt pools — and two new ones — will open to the public on New Year’s Eve. Few buildings will be in place by then, but guests will be able to soak in the mineral water, eat at food trucks and camp. Watsu, a type of aquatic massage that started at Harbin, and other bodywork are expected to resume.

Construction consultant and Lake County resident Shah Allard, who was inspecting new walls around a hot tub, said the pool complex will in many ways be better than it was.

New pipes that tap the area’s seven underground springs and a more modern pump house will boost water flow by 10 percent and better control temperatures. The hottest pool will sizzle at a steady 112 degrees.

“It’s very high-tech,” Allard said, standing between hot and cold tubs where people once enjoyed the rush of plunging in one, then the other. “I don’t think I’ve seen this anywhere in the world.”

The long-term plans for Harbin are less certain. The managers have drawn up a lengthy to-do list, which includes building a dozen guest cottages and a small market next year, but the timeline beyond that is fuzzy, in part because of finances.

An insurance payout between $10 million and $12 million is expected, well short of the estimated planning and construction costs for the new Harbin. The resort had limited coverage.

Members of the management team, however, hope to come up with enough money through savings, visitor fees, grants and a fundraising drive to pay for the work as they go along.

A few hundred thousand dollars in donations have already come in, but the money went to displaced residents and employees, many of whom are now staying in communal houses that Harbin owns in and around Middletown.

Heather Rogers, a magician in El Cerrito and a longtime Harbin devotee who has been following the retreat’s headway on Facebook, said she’s ready to “come home.”

The resort was one of the few places where she could truly unwind, and she liked to stay, for $60 a night, in the “mermaid room,” with its funky collection of mythic statues.

Her relaxation was aided by the center’s policy barring cell phones, cameras, drugs and alcohol. Those who wanted no disruptions, as Rogers sometimes did, could wear “silence beads.”

“People talk about it being a scene, and it’s true there’s naked people cuddling all over ... but Harbin has this magical power, and it’s the only place on Earth I’ve found it,” she said. “It was like a Disneyland for people who need to shut down and are a little new-agey.”

Interest in the rebuild goes far beyond the guests.

Bringing money and jobs into the county, which was struggling economically even before the Valley Fire, is critical for financing the pipeline of projects planned for burned areas, said Lake County Community Development Director Bob Massarelli.

“Harbin Hot Springs, with the tourist tax and the revenue it generates, is really important,” he said.

Of the homes and businesses destroyed by the 76,000-acre fire, only about 125 have been rebuilt or permitted. Two other wildfires in the county last year, and this year’s Clayton Fire in Lower Lake, left a couple hundred more homes in ruin.

Harbin Managing Director Eric Richardson says that if there’s a silver lining for the resort, it’s the unique chance to move forward with a “tabula rasa” — a clean slate.

The reconstruction will result in a modern and environmentally friendly campus, he said, that has more light and a greater sense of openness, while still retaining its earthy, artsy charm.

“Keep the quirk,” is one of the credos that the managers often cite.

“Harbin had this great synergy when it was operating. It was this healthy but very relaxed buzz,” Richardson said. “I look forward to when that experience is fully alive again, and I believe it will be that much richer.”

Kurtis Alexander is a San Francisco Chronicle staff writer. Email: kalexander@sfchronicle.com Twitter: @kurtisalexander