Out on the far-east edge of Contra Costa County, a sprawling icon of national history could soon rot away into oblivion unless an East Bay developer is able to pull off his $150 million dream of restoration.

It's called the Byron Hot Springs Hotel.

A century ago, it was one of California's premier playlands of the rich and famous, a spa resort set amid 57 natural hot springs that bubbled at more than 100 degrees. It had tennis courts, one of the first golf courses to be built on the West Coast, and a five-star hotel designed by the architects of San Francisco's Fairmont and Cliff House.

Its luxury rooms drew glitterati ranging from actors Clark Gable and Mae West to author Jack London and baseball slugger Joe DiMaggio.

Decades later, during World War II, the U.S. Army used the resort as a top-secret interrogation center for prisoners of war - one of only two such interrogation centers in the nation, the other being in Virginia. In a novel experiment, guards let the mostly Japanese inmates soak in the spas and party in the swank rooms - and then clandestinely recorded their relaxed conversations, gleaning what Army researchers now say were important tips about enemy operations in the Pacific.

After the war, the resort slipped into decline as other areas of the Bay Area boomed and drew tourists away. It had moments of resurgence, such as a stretch as a religious retreat in the 1950s and a 1970s visit from renegade author and Merry Prankster Ken Kesey, but by the 1980s it was shuttered for good.

Today, if you stand on a hill overlooking the old resort on the edge of the tiny town of Byron, you can still tell this was once a special place. The magnificent, and intact, shell of the brick-walled hotel sits serenely amid more than 300 palm and olive trees, placid grasslands spread around it for 161 acres - and if you squint, it looks as if it's ready for business.

Saving structures

East Bay Associates developer David Fowler says he would like to make that squinting impression come to life. It won't be easy.

The remaining buildings need gutting and restoring, the walls that are left are splattered with graffiti, and several historic structures have been burned in recent years by partiers who left empty beer cans among the ashes. A few more years of intense vandalism, combined with the ravages of time and weather, and it may be too late to do anything in quite the same way, Fowler said.

But like a proud papa who can see no wrong in his child, Fowler professes nothing but optimism.

"Just look at this place," he said, standing in front of the hotel one recent morning, spreading his arms to take in the building, the nearby spring wells, and a grove of towering palms. "It has history, beauty and romance. If I do a primo job, people will come."

Fowler is about to submit building plans to Contra Costa County planners, and if approved, he intends to begin work on his project early next year. He says he has loans and potential investors lined up, and by 2011 he expects to have pumped $150 million into making Byron Hot Springs a premier tourist destination.

Historic resource

His plan is to rehab the existing brick hotel (a stately Victorian wonder styled after the Fairmont), open up several of the hot springs for soaking, install a high-end restaurant, and - perhaps most ambitious of all - reconstruct a version of a second hotel that burned down in 1912. That hotel, a twin-towered Moorish castle of sorts, and the mini-Fairmont were both designed by the famous Reid brothers, James and Merritt, and the architecture alone helped earn Byron Hot Springs a place years ago on the state historic resources list.

Fowler, who builds custom homes, bought the resort property in 1989 for $1.5 million, and has been lining up plans and investors ever since. He submitted an early version of his plan last spring to the county, and was told to come back with more detail.

This time he thinks he has it nailed. County planners would be happy if he does.

"The county plan does encourage restoration of the historic use of that hotel," said Robert Drake, principal county planner. "And there's no question - there's some real history there. We just need to make sure that some of the basic public health, safety, welfare and building issues are addressed before such a project can go through."

For Contra Costa County historian Carol Jensen, author of "Byron Hot Springs," seeing the resort come back to life would be "absolutely amazing."

"Look, back when it was a luxury resort, people came from all over the nation to stay there," she said. "It was called the 'Carlsbad of America,' (a riff on the centuries-old spa in the Czech Republic). There was just nothing like it in all the West."

Just as important as the playland aspect, though, is the resort's place in military history.

From 1943 to 1945, more than 3,500 high-ranking Japanese POWs were sent there, along with hundreds of German and Italians. The resort had already begun to fade by the start of World War II, so the owner at the time, Mae Mead, was only too happy to lease it to the Army.

Interrogation center

The Army, according to Maj. Alex Corbin, who conducted a history study of the camp earlier this year, had decided it would try kindness instead of harshness to get information from the prisoners. Byron fit the bill perfectly, Corbin wrote.

The Army dubbed the prison Camp Tracy, and kept its true nature hidden from the community. Guards installed secret microphones all over the resort, and by listening they managed to glean valuable information about Japanese biological weapons, the location of ships and munitions plants, and code names for some Japanese Army units.

"Nobody even knew what was going on there until years later," said Jensen. "But it's an incredibly important part of history."

The National Park Service last year began compiling an oral history on Camp Tracy and Fort Hunt in Virginia, the only other World War II interrogation center in the United States. And on Nov. 16, a Japanese documentary made last year about the center, "Camp Tracy," will make its American premier with a showing at the Delta Theater in nearby Brentwood.

Fowler hopes the surge in historical interest will help his cause. And if he rebuilds, he plans to install a little museum of sorts honoring the resort's past.

"This place is the big daddy of historical restorations," he said. "By the time I'm done, it should feel when you come here like you are going all the way back to 1900."