Calistoga's hot springs bubbling with history, wonder
“The whole neighbourhood of Mount Saint Helena is full of sulphur and of boiling springs … and Calistoga itself seems to repose on a mere film above a boiling, subterranean lake.”
- Robert Louis Stevenson, “Silverado Squatters”
Gone are the steaming marshlands where, for generations, a series of small hot springs sent ethereal mists rising along the north end of the Napa Valley.
The land once known as the Springs Grounds today sits dry and partially developed with resorts and other uses in Calistoga. But beneath the surface, the scalding mineral water remains.
Calistogans have been tapping into the area’s geothermal aquifer for 150 years - filling spa pools with the heated fluids, bottling mineral waters for sale and in latter times drawing crowds to watch forceful geysers, one of which still regularly erupts from subterranean pressures.
The hot springs constitute both a natural wonder and a major piece of the town’s history. Without them, said Calistoga Mayor Chris Canning, “we wouldn’t be here.”
“Long before we had a wine industry, we had a spa industry,” said Canning, who doubles as executive director of the chamber of commerce.
Today the town of 5,200 is home to the largest hot springs resort area in the state, if not the nation. And town leaders point to new signs of economic progress, including the recent $23 million expansion of the Indian Springs Resort and the efforts underway to build two other luxury resorts in town.
The first attempt to commercialize the geothermal resource came when pioneer millionaire Samuel Brannan built an expansive 19th century resort at the Springs Grounds, which includes today’s Indian Springs Resort on Lincoln Avenue.
In 1862 Brannon held a gala opening for his destination, which included a hotel, cottages, steam rooms, mud baths, dance pavilion and racehorse track.
The developer later promoted the construction of a railroad from the Vallejo area that made it easier for his guests to travel to what was then a remote part of the state.
‘Calistoga of Sarafornia’
Brannan, whose early moneymaking ventures included selling high-priced goods to Gold Rush prospectors, reportedly had grasped Calistoga’s potential after visiting spa resorts in Europe and in Saratoga, N.Y. (Once when tipsy, he sought to say that he would replicate Saratoga in California, but instead he blurted that he would build the “Calistoga of Sarafornia.” Locals insist this slip of the tongue gave the town its name.)
The draw for visitors then was the same as it is today: the hot mineral waters and volcanic mud baths.
Native Americans are believed to have bathed in the surface springs for centuries, using the water and mud to relieve aches and pains.
The minerals in the water have “a natural calming element,” said Michael Lennon, general manager of the Calistoga Spa Hot Springs, a hotel and spa that includes four different hot pools fed by the underground aquifer.
“It will start to help you relax.”
Though scalding hot, the geothermal aquifer is classified by scientists as low to moderate temperature.
“We’re right at boiling which, compared to The Geysers, is pretty cool, believe it or not,” said Dean Enderlin, a geologist and fourth-generation Calistogan.
The surface temperature is typically near 212 degress Fahrenheit, but beneath the surface the water averages about 302 degrees.
The source that heats the water is believed to lie far beneath the surface from a magma chamber or chambers linked to past volcanic activity. A 1986 study for the state Energy Commission suggested that the intense heat boils water deep underground and sends it rising toward the surface via an earthquake fault zone that runs along the upper Napa Valley
Enderlin said the hot water becomes trapped beneath impermeable rocks but can rise when movement in the fault lines breaks the rocks.
Measure ground movements
The makeup of the underground system isn’t fully understood, said Shaul Hurwitz, a research hydrologists with the U.S. Geological Survey. What is known, he said, is that Calistoga lies less than 20 miles southeast of The Geysers, “which is probably the biggest geothermal field in the world.”
In 2009, Hurwitz joined professors and grad students from UC Berkeley for research at Calistoga’s Old Faithful Geyser of California. There they used sophisticated equipment to measure ground movement during eruptions.
“That was kind of a warm-up,” Hurwitz explained. The team went on to conduct similar experiments at Yellowstone National Park’s Old Faithful Geyser and in Chile as part of their research to better understand the activity of the nearly 1,000 natural geysers worldwide.