For almost 150 years, visitors have ventured to central Colorado to soak in pools at Mount Princeton Hot Springs Resort, a major tourist attraction benefiting from mineral-rich water heated deep underground.
With temperatures surpassing 180 degrees Fahrenheit, the resort holds some of the hottest water out of Colorado’s roughly 400 known hot springs. All rely on geothermal energy, a resource the state could harness as a climate-friendly alternative to fossil fuels currently used to generate electricity and heat buildings.
It’s a possibility Gov. Jared Polis has put it at the center of his climate strategy. In 2022, the governor launched the “Heat Beneath Our Feet Initiative” to find ways to help the young industry establish a foothold in Colorado and other Western states. His administration has also set up incentive programs and updated rules to support proposed geothermal projects.
The push, however, has caught the attention of Colorado's hot springs industry. In late February, Thomas Warren, the general manager of Mount Princeton Hot Springs Resorts, joined other hot springs owners and operators to demand changes to HB25-1165, a bill supported by the governor’s administration to streamline regulations covering underground carbon sequestration and geothermal energy development.
Warren asked lawmakers to add clear legal protections for hot springs. Without the changes, he warned a geothermal energy boom could damage resorts across Colorado, cutting off a vital economic engine for rural communities.
Even though the sponsors incorporated some of his ideas as amendments, Warren still isn’t fully at ease.
“There’s so much pressure for green energy right now,” Warren told CPR News. “We understand why it has to happen, but I worry sometimes that decisions are made hastily in order to meet climate goals. The last thing we need is to disrupt an entire hydrology that's been operating for eons.”
The “magic” science behind hot springs
One reason for concern is the mysterious origins of the state’s famous soaking pools.
The principles behind the natural marvels are simple enough. As snowmelt and rainwater seep into the ground, the earth’s interior heats the water until it rises back through tilting cracks and fissures. That underground plumbing system opened due to the same tectonic forces responsible for building the Rocky Mountains.
What’s less clear is the extent and shape of those networks. Even though hot springs operators rely on geothermal heat, they often can't explain how it arrives at their resorts or other natural soaking locations on public lands.
“The science of what makes a geothermal hot spring happen is not well understood,” Steve Beckley, the owner of Iron Mountain Hot Springs in Glenwood Springs, said during the bill’s initial legislative hearing. “It's somewhat like magic.”
Some resort operators now want more clarity on the process before geothermal energy projects start drilling across Colorado. Warren has been keeping a careful eye on a proposal to build Colorado’s first geothermal power plant less than two miles from Mt. Princeton Hot Springs Resort.
If the plan proceeds, the operation would generate electricity by tapping a geothermal reservoir that backers suspect lies thousands of feet below the location. Mt. Princeton Geothermal, the company behind the proposal, claims the underground system is more than large enough to power thousands of homes and feed nearby hot springs.
Warren isn’t so sure. Last year, the resort hired a third-party engineer to model the power plant’s potential impact. He said their work found the project could cool and diminish hot springs at the resort. “That is what has made us very, very cautious on how this should proceed,” Warren said.
Similar fears have held up geothermal energy development in Japan. In New Zealand, geysers and hot springs enjoyed by local indigenous groups for centuries declined following the construction of geothermal heating systems in Rotorua City in the 1970s and 1980s. Those features have partially recovered after a preservation project plugged boreholes starting in 1986.
A shifting legal landscape
State lawmakers claim they’re determined to prevent similar issues from bubbling up in Colorado.
“I cannot overstate this enough: we must protect our hot springs resources,” Rep. Matt Soper, a Republican co-sponsor, said during a legislative hearing in February. “We will work something out to ensure that we're protecting our hot springs and we're not overregulating geothermal development.”
The commitment comes almost two years after Gov. Polis signed SB23-285, an earlier geothermal reform bill. Prior to the legislation, the Colorado Division of Water Resources had exclusive authority over projects to tap underground heat. The arrangement made sense since the same agency oversees drinking well construction, which closely resembles projects to drill shallow boreholes to tap geothermal energy for buildings or greenhouses, according to a state legal analysis published last year.
But modern geothermal projects often drill far deeper to access higher temperatures. Startups are also experimenting with “enhanced geothermal systems,” which use techniques similar to hydraulic fracturing to access heat locked inside dry rock formations rather than geothermal aquifers.
To recognize those differences, the law gave authority over “deep” geothermal development to the Energy and Carbon Management Commission, which oversees Colorado's oil and gas industry. The regulatory body now issues permits for geothermal projects planning to drill deeper than 2,500 feet.
It appears, however, the same legislation deleted a key provision protecting hot springs operators. The 2024 legal analysis claims the mistake occurred “due to formatting and numbering” and no regulatory agency wanted it “removed from statute.”
A recent amendment adopted by lawmakers last week attempts to address the issue. The current version of the legislation now requires backers of a proposed deep geothermal project to notify hot springs operators within a quarter mile of a proposed drilling site. It also mandates regulators consider any potential risks to existing hot springs and set up a system to recognize historic hot springs under state law.
Warren appreciates the change but wishes lawmakers had gone further. In his view, the state should protect geothermal energy along the same lines as water rights. That means if a future development damages his company’s hot springs, it should have the legal authority to demand the operation immediately stop extracting energy. “This definitely does not give us that level of protection,” Warren said.
The Colorado House voted to approve the bill earlier this month. The legislation now awaits an initial hearing in the Senate Transportation and Energy Committee.
