The warm waters of Takhini hot springs have been soothing Yukoners for at least a century. They are the largest developed hot springs in the territory, but no one knows for sure why hot water happens to bubble out of this particular spot in the earth.

"Takhini is in a geologically interesting area," says Tim Sadlier-Brown, a Vancouver geologist who has studied hot springs throughout western North America. "These sorts of springs are the result of some fortuitous plumbing."

He points out that not so long ago -- in geologic terms -- the area south of the springs was a center for volcanic activity. Some of the Yukon's youngest volcanic rocks can be seen in Miles Canyon on the Yukon River where the basalt rocks are about 6 million years old.

Sadlier-Brown once looked for geothermal sources around Alligator Lake south of Whitehorse, where the lava is only about 3.2 million years old. He says that it is hard to know whether the young volcanoes around this area are still generating heat under the earth's surface.

"There are types of volcanoes in which the magma originates way down deep, and for obscure reasons they discharge at the surface, deposit lava and cool down, never to be heard from again. This is typical of some basaltic volcanoes," he says.

But other volcanoes are active for a long period of time and have magma chambers located higher up in the cinder cone. When groundwater approaches these chambers, you might get steam. Volcanoes such as Mount St. Helens and Mount Baker in the state of Washington are of this type.

"The odd thing is that the Takhini hot springs are not that far away from these old volcanoes. One possibility is that some magma never made it to the surface and has warmed up an area there," he says.

If the nearby volcanoes are not supplying the heat, the earth's natural gradient is most likely doing the job. Many of western Canada's major hot springs are formed by groundwater circulating down through faults in the earth.

The water is heated up about 25°C for every kilometer that it descends towards the Earth's molten core. After it is heated, the water becomes more buoyant and works its way back to the earth's surface.

To qualify as a hot springs, the water temperature at the source must be at least 32°C. At the Liard hot springs, water emerges from the main spring at a scalding 53°C. The water at the Banff hot springs emerges from the ground at about 47°C, the same temperature as the Takhini springs.

At both Liard and Banff, cooler water is diverted into the pools to lower the temperatures to a more comfortable 40°C. In the Takhini pool, located about 30 metres from the source, the water temperature is about 38°C.

Many hot springs are highly mineralized because as the water heats and circulates underground, it actually dissolves surrounding rocks, releasing the minerals. Sulfur springs, in particular, are touted for their therapeutic properties. The water at Takhini is highest in calcium and sulphate.

Pumping out about 87 gallons of water per minute, the Takhini springs have a modest flow rate compared to the main spring at Banff, with 454 gallons per minute. The complex of springs at Liard, Canada's second largest thermal spring system, pumps out more than 2,000 gallons per minute.

But the Takhini springs are large enough to have untapped potential as a source of geothermal energy. Now hot water from the springs heats the pool and the adjacent buildings. The new owners of the resort plan to replace this pool with a more natural-looking one, but they also want to use this energy source for more than recreation.

One of their ideas has worked successfully in the past. During the building of the Alaska Highway, greenhouses built at the springs were heated with hot water, and tt's reported that the crops grown there flourished. Many of the new owners also plan to build their homes in the area, and will be investigating whether geothermal energy can be used to heat them.

Canada has never really tapped its deposits of geothermal energy. Sadlier-Brown worked on a major geothermal project for BC Hydro during the 1970s, but says that interest in this energy source cooled down after the oil crisis ended.

Iceland heats about 85 percent of its buildings with geothermal energy, and California produces 5 percent of its electricity with heat from the earth. In the western United States, geothermal energy is used to heat a few commercial greenhouses, as well as homes in Nevada.

The exact heat source of the Takhini hot springs might never be known. But the new owners are focusing more on what is available once the water emerges from the ground. In a cold northern climate, a clean renewable source of energy is not something to be taken for granted.