According to the Colorado Division of Reclamation Mining and Safety (CDRMS), there are around 23,000 inactive and abandoned mines around Colorado. While this feature of the Centennial State’s landscape often goes unnoticed by backcountry travelers with the exception of long-decayed remnants of various shacks and structures, the tragic October death of Jennifer Nelson in southwest Colorado put the associated risks of this part of Colorado’s history on display.

Whether someone is exploring an abandoned mine site intentionally or happens to accidentally end up in one, entering into these structures and shafts can carry the risk of serious injury or worse, with the CDRMS warning about unstable soil, unsafe roofs and ladders, deadly gasses, poisonous snakes, and dangerous explosives that may be lurking. This is why the state has already closed around 14,000 of these abandoned mine openings, though many more still exist.

“Victims of mining accidents have encountered deadly odorless gases, fell down holes that opened under their weight, drowned in near-freezing pools of water at the bottom of shafts, and were buried in unpredictable cave-ins,” reads a CDRMS statement about the risk. “Many people are injured and killed every year while “just exploring” abandoned mines.”

A list of abandoned mine fatalities spanning the years of 1955 to 1999 that’s published on the CDRMS website provides a few examples of what can occur. Find a few accounts from that list below:

This first example provides a look at how ‘bad air’ can kill. Presumably, the two men in the case noted below weren’t aware of the bad air until it was too late given that they were found more than a mile into a mine. This may be an example of how toxic gasses and fumes can be odorless, adding to the risk.

“September 15, 1955 –Two men entered an old mine by digging through the tunnel from above. The mine atmosphere contained bad air (no oxygen). Both men were found dead approximately 6,200 feet from the portal 3 days later.”

This next example is also related to bad air, which in this case resulted in a significant and fatal fall. While bad air can kill, it can also limit motor skills, potentially making a fall more likely with the environment of an abandoned mine often featuring big drops and other hazards.

September 15, 1968 –A Fort Carson Soldier, who was exploring a mine, in the Cripple Creek area and was overcome by gases and fell 90 feet to his death. It was sealed by the state in 1987.

These next two examples shine light on an often-overlooked risk of winter travel. Accumulating and drifting snow can cover terrain hazards, including mine shafts that may be left behind in the backcountry.

April 5, 1970 –On an outing with friends, an individual fell to his death in a snow-covered shaft at the Glory Mine in Gilpin County.

December 7, 1986 –An 11-year old died when he fell into a mine shaft while skiing out of bounds on Aspen Mountain.

This next example highlights the risk associated with operating vehicles off-road in the backcountry. While established routes after generally safe and well-established, a fast-moving vehicle might not be able to correct course when a subtle mine shaft suddenly appears. Many mine shafts are overgrown and very difficult to see unless someone is right beside them. Also – while it’s unclear if it was a factor in the case detailed below, the weight of a vehicle may be more likely to break into a mine shaft that’s been covered opposed to the weight of a human or animal.

June 19, 1987 –Two 21-year old men were test driving a new 4-wheel drive vehicle in Gilpin County. One of the men was in the jeep when the jeep went into the Empress Mine shaft, fell, and the jeep became lodged 34 feet down the shaft. The vehicle had to be removed in order to continue rescue efforts. The man’s body was eventually found 350 feet below the surface.

These next two examples show a risk that comes with entering an abandoned mine that’s been unofficially reopened by a vandal. Many abandoned mines around the state have been sealed, but sometimes those seals aren’t effective – especially when something was sealed decades ago. If an attempt to seal a mine has failed, that shouldn’t be viewed as evidence that entry is safe or as a invitation to explore. In both of these scenarios, bad air is to blame for deaths. While someone else may have been able to enter through vandalized gates before, the people discussed in the stories below serve as evidence that everyone isn’t as lucky.

August 13, 1989–Three people aged 15, 16 and 17, entered the previously safeguarded Bookcliffs Mine in Mesa County and were in 300 feet from the entrance when they encountered a lethal concentration of CO2 and died. The 1/2″ x 2″ lock box hasp on the 1/4 inch thick steel door had been vandalized a few weeks to a few months earlier.

January 13, 1996 –A student from Mesa College in Grand Junction entered the Gearhart coal mine in the Bookcliffs area. The mine closure had been vandalized allowing entry. He died from lack of oxygen.

This last example of a fatality in an abandoned mine highlights an important lesson that can apply to a wide range of scenarios – if something starts to feel off, leave. Consider altitude sickness – if one starts to feel light-headed on a hike, turning around to seek lower elevation is the best option. ‘Bad air’ can put explorers in a similar scenario, with fatal effects often coming much quicker. In this example, two people left the mine when they started to feel faint, but the other person pushed on despite this sign of bad air and it cost him his life.

September 1999 –Suffocation death of a 49-year old Texas man in a mine tunnel near Lake City. Rescuers discovered the body 600 feet inside the entrance of the Chicago mine near Henson Creek. A companion and a child exploring the mine with the man left the tunnel when they felt faint. Authorities said the man died from lack of oxygen.

The CDRMS also provides a list of non-fatal accidents that have taken place in various mines. Most of those situations involve big falls followed by lengthy and highly-technical rescues. All of those situations aren’t related to people choosing to enter a mine, though, and that’s worth highlighting.

In several of those instances, people are merely in the vicinity of abandoned mining areas when the ground gives away or a slip sends them into a shaft. Meanwhile, in another situation, a 17-year-old fell 200 feet down Glory Hole Mine after a motorcycle accident. It’s also worth mentioning a trend seen in abandoned mine-related rescues that involves people entering mines while lacking the proper gear to climb out.

Long story short, the Gold Rush days of Colorado’s past resulted in the presence of a hazard that most outdoor recreation enthusiasts aren’t expecting to encounter. Being aware of this hazard is important for safety in Colorado’s backcountry terrain.

A few tips for safety in mining country include:

1. Avoid old mining structures that may be present. These structures are often decayed and pose various risks.
2. Avoid openings that may be found. Even a quick jaunt into an opening may trap you in the area or could expose you to bad air.
3. Avoid the area around these openings, as the ground around them may be unstable.
4. Follow all warnings posted in signage.
5. Stay on established trails and roads.
6. Travel with a buddy that’s able to get help if needed. Carrying a satellite-based communication device is recommended, as cell phone connection may not be available.
7. Remember that not all mine shafts appear to be human-created. Some can merely be a rocky opening in the ground. Exploring unknown spaces underground can pose extreme risk and should only be done by those who are trained and prepared with the right equipment to do so.

Find additional information on this topic from the CDRMS here.

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