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In CUriosity, experts across the 91��ý campus answer questions about humans, our planet and the universe beyond.

Shemin Ge, professor in the Department of Geological Sciences, shares how a source of clean energy known as geothermal power could pose unexpected risks to Colorado's iconic hot springs.

Shemin Ge remembers a winter drive she took around Steamboat Springs, Colorado. Ice had formed over the trees, and a blanket of snow lay over the landscape.

Then Ge saw something surprising in the middle of all that white.

“[There was] snow everywhere, all the way to the rim of the hot springs. There you have steamy things coming out,” said Ge, professor in the Department of Geological Sciences at 91��ý. “What a beautiful, nice thing to see.”

Ge is a hydrogeologist, a scientist who studies the interactions between water and rock around the planet. In Colorado, she has plenty to explore.

The that the state is home to at least 93 “thermal areas”—places where hot water from underground bubbles up to the surface, forming pools and streams.

Hot springs play an important role in the cultures of many of the West’s Native American groups. They’re also a big draw for locals and tourists alike who enjoy long, leisurely dips with a mountain view.

Why are these relaxing features so common in Colorado?

Like so many things in the West, the answer comes down to the Rocky Mountains. Tens of millions of years ago, collisions between the planet’s tectonic plates caused the ground under the American West to buckle, building the mountains we know today.

That same uplift created a network of cracks and channels in the hard, rocky crust below the region—perfect pathways for toasty water to flow to the surface.

“Earth’s crust is thinner [in the West] compared to the eastern part of the country,” Ge said. “When the crust is thinner, it’s easier for the deep, hot mantle to come up closer to the surface.”

Ge’s own research has explored a modern human activity that could influence these ancient features.

In recent years, energy companies and other entities have begun investigating a potentially abundant source of sustainable power: geothermal energy.

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Geothermal energy can come in many forms, but, in general, people dig deep wells to pump up hot water from underground. Once at the surface, that water can be used to heat floors or sidewalks, or even power turbines and generate electricity.

But when people pump hot water up, they usually replace that liquid with cooler water from the surface. This could, in theory, cool some hot springs down.

In a , Roseanna Neupauer, a professor in the Department of Civil, Environmental, and Architectural Engineering at 91��ý, and Ge explored this idea. The team used computer simulations, or models, to recreate the geological conditions under Colorado’s surface. In particular, the group tested what might happen if people installed a well near Mount Princeton, a hub of geothermal activity near Buena Vista, Colorado.

The possible impacts of that hypothetical well depended on how close it came to hot springs. If the well sat about 650 feet east of a spring, it might lead to cooling, and temperatures could dip by as much as 27 degrees Fahrenheit over the long run.

Ge said that scientists still have a lot of research to do before they can say for sure whether geothermal energy poses risks to Colorado’s hot springs.

But, she added, it’s important to ask the question. Nothing makes a frigid winter day better than a long, relaxing dip in one of Colorado’s many hot springs.

“Geothermal energy is a sustainable, renewable source of energy, and I would love to see it used more,” Ge said. “But we don’t want to cause a negative impact for the people who live nearby.”