A toxic legacy

The Gold King Mine spill is a sobering reminder of the number of abandoned mines in Boulder County

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Courtesy of The Environmental Protection Agency/Wikimedia Commons

For decades after the first gold was found near Gold Hill in 1859, Boulder County endured a boom and bust cycle of mining as veins of minerals were discovered, mined and abandoned. The County is built, quite literally, on gold, silver, lead, tungsten and zinc, minerals that brought droves of settlers to the Front Range in the late 1800s and created a mining industry that still exists today.

While these abandoned mines may seem like endearing pieces of Western history, the early-August blowout at Gold King Mine near Silverton, Colorado — an EPA-triggered accident that turned the Animas River turmeric yellow — serves as a reminder of the toxic legacy mining has left behind in the West, including right here in Boulder County.

The Western mining legacy 

Of the more than 550,000 abandoned mines in the United States, Colorado is home to approximately 23,000 of those, according to the Colorado Geological Survey.

Boulder County sits on one of two mineral belts in Colorado. Known as the Colorado Mineral Belt (CMB), this strip of deposits extends some 250 miles north from the La Plata Mountains in the southwestern part of the state to Boulder County. It is the CMB that bore the lion’s share of the state’s silver and gold deposits.

The majority of Boulder’s mining industry was “hard rock” mining for minerals and precious metals such as gold, silver and tungsten. And while hard rock mining was lucrative, the process of exposing these metals created what has become one of the West’s most enduring environmental concerns — acid mine drainage.

Virginia Brannon, director of the Colorado Division of Reclamation, Mining and Safety, says that there are about 500 abandoned mining sites that create environmental issues statewide and about 220 of those affect waterways.

“The fact of the matter is that the vast majority of abandoned mine sites are actually just mine openings, and they are a public safety issue — and that’s most of what we have, especially in Boulder County,” Brannon says. “It’s not tailings piled up or soil that’s contaminated or waterways getting contaminated — it’s an old mine opening, and maybe people think it’s cool to go into those when in fact it’s extremely dangerous. Or people fall in — it’s happeend in the backcountry.”

Brannon says there are six abandoned mines in Boulder County with environmental, as opposed to public safety, issues; two have been remediated and have on-going treatment, while four have not been addressed.

“But none of them have direct flows going into waterways as is the case with Gold King,” Brannon says.

Even so, leaky mines have wreaked havoc on Western waterways.

“Mining in the western United States has contaminated stream reaches in the headwaters of more than 40 percent of the watersheds in the West,” the Environmental Protection Agency (EPA) writes on their website.

While mining may seem like an innocuous process, metals like gold, silver and copper are rich in sulfide minerals, which, when exposed to air and water, yield sulfuric acid. And if this doesn’t seem bad enough, the resulting sulfuric acid can further dissolve other harmful metal and metalloids, such as arsenic, from surrounding rock.

The resulting toxic byproducts can occur at any point in the mining process, from the underground tunnels where miners excavated rock, to waste rock piles, to open pits, leach pads and tailings. Earthworks conducted a literature review on acid mine drainage and found that “no hard rock surface mines exist today that can demonstrate that acid mine drainage can be stopped once it occurs on a large scale.”

Over time, acid mine drainage can make itself visibly known — it creates an obvious yellow-orange substance (sometimes known as “yellow boy”) when the pH of affected acidic water raises above 3, causing iron to leach out. (Remember high school chem — the natural pH of water is 7.)

The resulting precipitates can smother plant and animal life, as well as decrease the pH of the stream.

Colorado’s share of the burden 

The EPA’s website says that as of March 2012, the agency was spending $30,000 per day to treat contaminated mine drainage at the Summitville Mine in Colorado, “which will cost an estimated $170 million to clean up.”

Located in Rio Grande County, just 25 miles south of Del Norte, the Summitville Mine was first excavated around 1870, according to the EPA. However, the area was mined out by the mid-1880s. The site was reopened a number of times in attempts to extract more gold, but traditional mining techniques proved unsuccessful.

The site wasn’t lucrative again until the mid-1980s, when a new company — the Summitville Consolidated Mining Company, Inc. — bought the area and used new techniques to extract gold by treating the ore with a sodium cyanide solution, which pulled gold out of the ore. The valuable metal was extracted from the resulting solution using activated carbon in a large pool known as a heap leach pad.

The EPA claims that a leak was almost immediately detected in the liner of the mine’s heap leach pad.

The state government issued the Summitville Consolidated Mining Company a cease-and-desist order in 1991 after high levels of heavy metals were found in surrounding waters, presumably due to the damaged pad liner in the heap leach pad. The mining company filed for bankruptcy in 1992 and the EPA assumed cleanup of the site, but it would be another three years before the site was placed on the National Priorities List of Superfund sites.

At the time they took over the Summitville Mine cleanup, the EPA estimated that 3,000 gallons of contaminated water were leaking from the site every minute. Troublesome contaminants included copper, cadmium, manganese, zinc, lead, nickel, aluminum and iron, which leaked into tributaries of the Alamosa River and eventually into the river itself. The contamination ultimately wiped out all life across a 17-mile stretch of the Alamosa River.

This year marks the fourth five-year review of the Summitville Mine site.

Troubling as it is, the Summitville Mine is only one such story of mining contamination in the state. Many of the state’s abandoned mines leak at consistent low levels throughout the year. Some release toxic wastes during the spring melt. Still others release large quantities of contamination in one fell swoop — in the early 1980s, a spill occurred at the California Gulch Superfund site near Leadville, Colorado, killing off aquatic life on the headwaters of the Arkansas River. In 2009, thousands of gallons of Tang-colored mining waste flowed into a 400-mile watershed at the North Fork of Clear Creek, again killing life along part of the river.

With 23,000 abandoned mines, limited funding for cleanups and mining sites located across public and private lands, the possibilities for disaster are daunting.

Trouble at home 

With Boulder’s rich history of mining, the county has shouldered its share of mining’s toxic legacy.

Just a mile and a half south of Ward in Boulder County sits the Captain Jack Mill site at the headwaters of the Upper Left Hand Creek. The site includes a number of mines, the Big Five discharging tunnel, a waste rock pile and a settling pond.

To fully understand the problem at Captain Jack, you have to first understand the flow of water near the site: Left Hand Creek is fed by James Creek, which in turn is fed by Little James Creek.

Little James Creek is currently devoid of life, but full of arsenic, beryllium, copper, iron, lead, manganese and zinc — all mining products. Yet by the time the Little James meets James Creek, just a mile downstream, most of the metals have settled and aquatic life resides. Even further down, where James Creek meets Left Hand Creek, the water is even cleaner — but not before Left Hand Creek gets a dose of polluted runoff from abandoned mines at the Captain Jack site.

All of this is old news: complaints about the quality of water on Upper Left Hand Creek have accumulated since the first days of mining, but the federal government didn’t got involved at the Captain Jack site until September 1986, when the Mine Safety Health Administration (MSHA) found the owners of the site improperly storing chemicals at the mill buildings. The EPA sent an emergency response team to the site. They recovered and removed barrels of chemicals, and then the EPA began testing Left Hand Creek.

But it wasn’t until 1992 that the Colorado Mined Land Reclamation Division received reports that mill operators were dumping waste directly into Left Hand Creek. The EPA was alerted soon after when a Boulder County Health Department official noticed a milky substance in the water. Subsequent water samples reveled high levels of zinc, cadmium, copper and lead.

The Left Hand Water District temporarily shut down its intake value while the EPA cleaned up, and the Captain Jack Mill was soon shut down permanently. In 2003 the EPA decided that the risk was too large not to place the mill site on the National Priorities List as a Superfund.

And while all eyes are on abandoned mines in the wake of the accident at Gold King Mine, Brannon from the Colorado Division of Reclamation, Mining and Safety asks people to remember that it was only in 1977 that the federal and state governments created laws to regulate soft and hard rock mining practices.

“People tend to think there’s always a responsible party or there most be some kind of financial assurance or someone we can go after,” Brannon says. “And in these old mines where mining happened before we had laws to restrict their activities, we don’t usually have anyone to go after.”