A 54-year-old hiker’s fatal fall into an abandoned mine shaft near Ouray last month highlights a broader danger left behind by Colorado’s rich mining history: more than 23,000 inactive mining sites, many still unmarked, unsecured or unknown to the state.
Colorado has closed about 14,000 abandoned mine openings since 1980, but officials say thousands more remain. Erosion, vegetation and shifting terrain obscure decades-old mine features, making them hard to track and harder for hikers to spot before it’s too late.
“Obviously that leaves a lot more than we think are out there. Some we know about, some we certainly do not just because in these historic mining areas, time changes things as well,” said Jeff Graves, program manager for Colorado’s Inactive Mining Reclamation Program.
“A feature may not be visible at the surface because it was covered in timber and over time that timber rots and suddenly now there’s a new feature or the ground collapses and something exposes its surface,” he said.
The state was unaware of the 8-foot-wide mine shaft near Spirit Gulch in the Uncompahgre National Forest before Jennifer Nelson, of Ridgway, fell to her death while hiking with dogs Oct. 20, Graves said.
After she was reported missing Monday evening, rescuers found her body the following morning in a deep, water-filled pit about 50 feet off the mining road, the Ouray Plaindealer reported. The dogs stayed nearby, watching volunteers, according to the newspaper.
Historically, more rescues have been along the Front Range, which Graves attributes to the higher population near historic mining sites, but the state doesn’t keep records of mine-related accidents or fatalities.
Nelson, who served on Ridgway’s planning commission, was hiking in an area above the historic Idarado Houses, a popular summer hiking spot with wildflower basins and Red Mountain views. It is accessed via an old gated mining road and has ruins of the Barstow and Greyhound mines.
There was no visible cue, like a rock pile, that there was a shaft nearby, Graves said.
Mine shafts, which are vertical openings, are the No. 1 cause of death and injury in abandoned mines, according to the state. Debris, rotten timber and false floors can hide vertical openings.
Other horizontal mining features, like tunnels, can often have unstable roofs or low oxygen levels, Graves said.
Victims of mining accidents have fallen through hidden holes, drowned in near-freezing water, been buried in cave-ins or encountered deadly gases.
“The horizontal ones I think become more enticing for folks because it doesn’t appear like there’s a hazard,” he said. “But those hazards are sometimes difficult to visualize or even see.”
Nelson’s cause of death is still being investigated by the county coroner’s office, Ouray County Sheriff’s Office and Colorado Bureau of Investigation.
Colorado’s Division of Reclamation, Mining and Safety has two lists of incidents dating to the 1950s on rescues and fatalities in abandoned mining sites, compiled from state records and search and rescue organizations.
One outdated list, on the DRMS website, estimates 18 people have died inside abandoned mine openings in Colorado since 1955.
“That number on the website is likely, I can assure you, an undercount,” he said. “The last time it was updated was probably 15 years ago.”
After Nelson’s death, the state put construction fencing around the site, but the abandoned shaft will not be closed until next year.
Snow will hinder efforts to secure the shaft and conduct endangered species evaluations or assess environmental impacts, Graves said. If the shaft is a home to bats, for example, staff might consider installing a steel grate to allow them to enter and exit rather than filling the hole with rock.
Securing an opening costs, on average, about $5,000, but depends on the type of closure, size and area of the mine feature, Graves said.
The to-do list is long for the team of 20 assigned to secure dangerous mine openings across Colorado.
“Usually our working inventory is one to two years’ worth of projects and so that may be as many as 400 mine features,” he said. “It’s a lot to do.”
The abandoned mining shaft that Nelson fell into was on public land, but the fear of being held liable for a hiker falling into dangerous structures has led private landowners to forbid public access, including on popular fourteeners.
Owners of the Trinchera Blanca Ranch restricted public access to fourteener Mount Lindsey in the Sangre de Cristo Range in 2021, citing a federal-court decision that potentially exposed landowners to lawsuits from hikers and other recreational visitors, but reopened the mountain in March.
Adjustments to the legislation, the Colorado Recreational Use Statute, layered with the waiver that hikers must sign before attempting to hike the mountain, brought “a level of comfort with opening the peak,” a spokesperson for the ranch, which is owned by billionaire conservationist Louis Bacon, previously told The Sun.
Under the law, hikers are allowed to sue if an injured person could prove that the landowner displayed “willful or malicious failure to guard against a known dangerous condition.”
Another owner of mining land spanning three fourteeners in the Mosquito Range above Alma restricted public access in previous years, citing similar concerns that hikers injured in the old mining structures on the peaks could sue him. John Reiber sold off 289 acres atop Mount Democrat in 2023 to The Conservation Fund, which later transferred the land to the U.S. Forest Service, resolving access issues on the popular Decalibron Trail.
The deal did not include Reiber’s property across Mount Lincoln, though, and he still requires that all hikers scan QR codes and sign liability waivers promising not to sue him if they are injured on his property.
A dedicated team of rescuers, the Colorado Front Range Mine Rescue, trains year-round to assist small mines in case something goes wrong with their miners underground, but is also available for emergencies involving the public near abandoned mines, president David Hunsicker said.
“We’ve been called out maybe three times in 15 years,” Hunsicker said. “It’s a little more rare than you think.”
The state uses historical inventories, through the Bureau of Land Management and U.S. Forest Service, and private landowners, to identify old mining sites. On average, the public informs state officials of about 10 abandoned mining sites a year, Graves said.
If you see an inactive mining feature, call the state at 303-866-3567, or email them at drms_info@state.co.us, with the location and GPS coordinates if possible, and a map showing how to access the area.
