Tree rings can tell a story. Wide bands signal a wet period, while narrow ones show a drought. Whole ecosystems can be encoded in trees. In Western Colorado, scientists are examining trees to find out more about the environment's story in an effort to protect the river they stand along.
On the banks of the Crystal River, a few miles south of the small town of Redstone, David Cooper surveyed a spruce tree with its roots exposed.
"OK, our first victim," Cooper said as he examined the roots and directed volunteers where to start digging.
Cooper has been a professor at Colorado State University for over thirty years, focusing on wetland and riparian ecology. For this study, he's been working with Dave Merritt of Functional River Ecology and Peter Brown of Rocky Mountain Tree Ring Research. The group is trying to get to the root of how this tree and the river are connected.
Using clippers, shovels and metal poles, volunteers like Sheehan Meagher helped unearth the tree completely.
"For me, it was kind of hard the first day because I was like, 'Oh, we're digging up these trees,'" Meagher said. "And I was like, 'I don't know how I feel about it. I'm a tree hugger.'"
Despite Meagher's initial hesitation, he's enjoyed getting to see science in action. And, he says it's for a good cause.
"I was like, 'Alright, where's the spruce that wants to give its life for science so that we can study this river and hopefully prevent this river from ever being dammed,'" he said.
The Crystal River is one of the few rivers in Colorado that doesn't have any major dams; large stretches of it are still pristine. As demand for water increases amidst a warming climate, policy makers often scan the landscape looking for new supplies. A free-flowing river like the Crystal can be an attractive option to supplement fast-growing communities.
Proposals to dam the Crystal and create a reservoir have cropped up over the years, most recently in the early 2010s. Those have been shelved due to cost concerns and local opposition, but locals say it's only a matter of time before someone else tries. They want to secure federal protections from Congress to protect the Crystal in perpetuity in the form of a "Wild and Scenic" designation.
This particular study was commissioned by the Wild and Scenic Subcommittee of the Crystal River Wild and Scenic and Other Alternatives Feasibility Steering Committee. The study is funded by grants that came from the Colorado Water Conservation Board's Wild and Scenic Fund, the Mighty Arrow Foundation, and Pitkin County Healthy Rivers, along with in-kind contributions from Wilderness Workshop and Western Resource Advocates.
At the heart of what Cooper, Brown and Merritt are trying to do with this study is establish the relationship between the trees and the Crystal's natural hydrologic rhythm, which wouldn't exist if it were dammed or diverted.
"For most of the work we've done over the last 30 or 40 years, we've shown that it's mostly big floods that disturb the ground and create habitat for establishment and allow these trees to get established," Cooper said.
Once the group got the tree out of the ground, they used a chainsaw to cut near the roots to get a cross-section. Brown and Cooper examined the cross-section.
"You can see the rings real well here," Cooper said, pointing with his finger. "Look how small they are. So that tree might be 25 or 30 years old."
But according to Cooper, these rings don't tell the full story. These trees have been cut by beavers. They've been knocked over and buried by rockslides in this narrow valley. The stem itself doesn't reflect the tree's true age. Cooper is looking for the very oldest part of the tree, called the pith. Once that is exposed, researchers can compare the cross section to the Crystal's water record. Cooper says they'll go year by year, and see whether each ring correlates with a wet or dry year.
"There's big floods and dry years and so if you're just within one or two years, you have really no idea what kind of flow regime was required to establish the plant," he explained. "So that's why we need to know the year. Not, not plus or minus one, the year. There's really no room for error."
In the same way that the river shaped the trees by spurring or constraining their growth, Cooper says these trees in turn shape the river, and make it what it is.
"You see that the trees grow around the rocks and then sediment accumulates above them," he said. "The roots of these plants hold this bar together. Without tree roots, this whole thing would be mobile. So the roots are building the floodplain and creating all of this habitat."
It could be awhile before a proposal to secure protections for the Crystal goes before any federal agency. But for locals like Sheehan Meagher, the time spent on this research is well worth it.
"Hopefully the research shows that these mass flooding events are critical to establishing this type of habitat," he said.
Any future dam would disrupt that, he said. Getting the science to back up that claim is worth taking a tree or two, he said.
"Please give your life to science, cottonwood," he said, laughing.
If there's the will and the funding, Cooper and his team will be back next year, documenting the story of the river and its trees, and building the case for its preservation.
This story was produced in partnership with The Water Desk at the University of Colorado Boulder Center for Environmental Journalism.
Copyright 2025 Rocky Mountain Community Radio. This story was shared via Rocky Mountain Community Radio, a network of public media stations in Colorado, Wyoming, Utah, and New Mexico, including KDNK.