The milk-hued hot springs of Shirahone have for a thousand years lured legions of stressed-out Japanese, who traversed mountain passes and paid small fortunes to wash away their troubles in the steaming thermal baths.

But in a scandal that has precipitated a nationwide crisis of confidence in Japan's beloved onsen, or hot spring resorts, a national magazine this summer reported that spa owners were secretly conning their customers. Shirahone village leaders came clean in July -- admitting they added artificial white dyes to baths after several springs had mysteriously begun losing their coveted natural cream color during the 1990s.

The deception created an uproar in Japan, where few things are more cherished in life than stripping down to your birthday suit for a group dip in scorching thermal baths. Government authorities, media outlets and citizen groups scoured the nation's treasured 22,000 hot springs for evidence of other cheats. Three months of investigations and at least one police raid later, officials have uncovered fraud at scores of onsen nationwide.

The deception seems bottomless: Some proprietors even clandestinely boiled tap water and passed it off as coming from Japan's natural springs. The tainted hot springs in at least 20 resort towns include several whose waters had been celebrated for centuries in epic poems, fables and woodblock prints.

Worse, the disclosures have stained one of the most precious and highly developed rituals of Japanese culture -- group bathing. The affronts have generated scathing newspaper editorials and dominated television news. Meanwhile, the mayor of Shirahone has been forced to resign in dishonor.

More than reputations are at stake. Some fear that the resulting loss of tourism revenue may cripple the rural economies of dozens of towns just as Japan is emerging from a 13-year economic slump.

Already, fuming Japanese are staying away from several of the resort villages involved, tourism officials and business owners reported.

"We have sinned," said Toru Tsuzuki, son of the former mayor of Shirahone and general manager of an onsen that took part in the ploy. "Perhaps it is not something a foreigner can fully understand, but we know how much the Japanese love hot springs and how much they feel betrayed by us."

For centuries, onsen have ranked among the most bemusing aspects of Japanese life for foreigners, whom the Japanese accuse of being unable to take the heat. Dave Barry, the famed humor columnist of the Miami Herald, once wrote after a skinny dip with a group of naked strangers in Japan that the water temperature preferred by the locals appeared somewhere in the neighborhood of "17,000 degrees Fahrenheit."

But in a hygiene-obsessed nation, where taxi drivers wear white gloves and teenage girls sometimes carry disinfectant to spray handrails in subway cars, such bathing is actually seen as the ultimate expression of cleanliness. Through the portals of onsen, friends and strangers join one another for escape from the pressures of daily life in one of the world's most competitive societies.

In Shirahone, for instance, men and women separate, shed their clothes, scrub their bodies raw with soap and rinse vigorously before immersing themselves in sulfured waters. Nationwide, innovative proprietors have created both outdoor and indoor bath themes, ranging from Hawaiian fantasies to the bullet trains.

Bathing is frequently viewed as an act of group bonding. Even at home, young families -- including at least one parent and small children -- bathe together, relaxing and sharing the news of the day while submerged in a steaming tub.

Onsen remain the highest expression of that bath culture, and such springs are said to be curative. Nihon Shoki -- or Chronicle of Japan, the nation's oldest official historical text -- describes a wounded snowy heron that miraculously recovers after bathing in spring water. Today, the Japanese insist that their springs, naturally heated by one of the most volcanically active geographies on Earth, can ease the pain of everything from arthritis to skin disease, as well as an especially bad day at the office.

"The Japanese people love to be clean, and our historic connection to thermal baths dates back more than 1,000 years," said Yoshiaki Yasuda, head of the Japan Hot Spring Society, an association of scholars who research hot springs. "The Japanese are also a high-stress people, and we find few things more relaxing than a hot bath. So there is almost nothing we love more than onsen -- which is why this deception has deeply hurt us."

Hot spring resorts escaped Japan's economic downturn, which began in 1991. The number of onsen increased 20 percent in a decade, evolving into the single biggest slice of Japan's huge domestic tourism industry, according to government statistics. Today, more Japanese towns rely on onsen-based tourism than on car factories for their financial livelihoods. Top government officials recently labeled onsen expansion as vital to boosting domestic consumption -- still a big concern as Japan's economy emerges from its slump.

Activist groups have set out to tighten Japan's hot springs laws and force thermal spas to post their ingredients, both natural and artificial. "This fraud has undermined the public trust, and the economic and emotional damage to the nation will take some time to overcome," said Tomino Hirano, head of an onsen watchdog group and a noted travel writer.

Nowhere is that more clear than in Shirahone, an ancient resort village about 120 miles northwest of Tokyo nestled dramatically amid the jutting cedar forests of the Japanese Alps.

The Shirahone public bath, which once lured 19,000 people a month, is now shuttered, awaiting further reviews by authorities after the Weekly Post magazine published photos of a city employee adding dyes to the water under the headline: "Shirahone spa was colored! Don't be fooled by the onsen boom!"

The milky color was a byproduct of natural minerals that had been in Shirahone's hot springs since time immemorial. No one is quite sure, however, why some of the springs began to lose their ancient color -- no scientific tests were conducted on the water to determine this. Some of the water sources did remain milky, while others went clear.

The shame of the scandal has cast a pall on all the townspeople, most of whom lowered their heads and spoke softly when asked about the situation. Privately, several business owners admitted that most of Shirahone knew about the secret white dyes, which began to become obvious almost a decade ago when several of the local water sources began spitting up clear water instead of the normal milky brew.

After their plot was exposed, embarrassed town officials withdrew advertising nationwide and destroyed thousands of pamphlets and posters promoting the doctored baths. At Ebisu-ya soba noodle shop, the owner, Toshio Saito, said he had furloughed one full-time waitress and a couple of part-time staffers because business was down. Inns, which typically charge $160 or more a night, are reporting cancellations and occupancy rates that have dropped by as much as 50 percent. They have also received letters and e-mails from furious clients, including many demanding refunds. "People had became so fond of that milky water -- it just cried out, 'I'm healthy! Come here and bathe!' " said Kazuyoshi Sato, a taxi driver. "It's such a shame it had to come to this."

The inns are trying to recover with an "honesty campaign," posting the ingredients of their baths and tapping mainly those remaining hot springs still producing the natural milky white water.

Tsuzuki, the son of the former mayor, hasn't given up yet.

"We know it will take some time, but we hope people will give us another chance," he said.

Special correspondents Akiko Yamamoto and Sachiko Sakamaki contributed to this report.

Toru Tsuzuki's spa for years added white dyes to some of its baths to simulate the milky color of Shirahone's natural springs. "We have sinned," he said.