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Boulder Creek is seen on Monday, August 23, 2021, in Boulder. The 31.4-mile-long creek stretches from the Rocky Mountains to east of Boulder. (Olivia Sun, The Colorado Sun)

State water quality officials have issued a cease and desist order and threatened substantial fines against owners of the Caribou gold mine above Nederland because of heavy metals leaking into drinking water sources, hammering Grand Island Resources over repeated violations. 

The dripping heavy metals are not a current threat to Middle Boulder Creek, Barker Reservoir or the parts of Boulder County downstream, state officials said. But they ordered the owners to build a new containment and cleanup system, and threatened to impose fines of up to $54,833 per day for each of multiple violations for the toxic metals and for failing to report test results.    

“A notice of violation is one of the most serious actions we take, and I think this shows that we really are committed to protecting the resource up there,” said Kelly Morgan, an environmental protection specialist for water quality in the Colorado Department of Public Health and Environment. “This is a big deal to us.” 

In a statement from a Nederland address, Grand Island Resources acknowledged the violations, and said that it had been moving since before the state’s notice to solve the problems and “replace the last 50 years of antiquated and obsolete water purification methods and treatments.” 

“We are working hand in hand with federal, state and local agencies. . .  to make all the necessary investments and capital improvements that were not made by previous operators of the Cross and Caribou Mines,” the statement said. The company said it has hired a top engineering team to design new water capture and treatment facilities as ordered by the state. 

Nederland wants the Boulder County Commissioners to help monitor the situation, and is keeping careful track of water supplies fed by Coon Track Creek, where the mine discharges water, and downstream waters, town trustee Alan Apt said. Nederland over the summer passed a “natural rights of rivers” resolution for exactly this reason: protecting western Boulder County’s natural resources for the public, he noted. 

“And then the next thing you know, here comes a water quality violation,” Apt said. “I don’t know if they’ve been dumping enough pollutants to make it all the way down here, but we don’t want any precedent set that says any level of pollution is permissible or OK.”

The once-thriving mine is near popular backcountry attractions a few miles northwest and northeast of Nederland, including Eldora ski area, to the Rainbow Lakes and Fourth of July trailheads, to the Caribou Ranch Open Space playgrounds. The area is especially popular for hiking and backcountry skiing, said Apt, who has written a backcountry skiing guidebook. 

Apt said Grand Island wants to increase the amount of ore it mines at Cross and Caribou and hopes to build an ore crushing and processing plant at the site. “If you’ve already polluting at a small amount, I wonder what it’s going to be like at higher volumes,” he said.

The company’s attorney Ed Byrne said Boulder County approved an ore processing facility in 2008 and Grand Island still plans to build it, which would save dozens of truck trips a day.

The company said in a statement that it has already made “substantial” investments to show that the historic mines “can be operated in a manner that is environmentally responsible and economically resilient.”

This includes “a new $150,000 water treatment system installed last week,” Byrne said in response to emailed questions.

The new equipment, Apt said, “indicates to me they knew it was inadequate. And in spite of that, they were operating and polluting.”

In terms of how high the eventual fines might be, Byrne said, “there was no chemical spill or release of ore processing water. The higher fine levels are typically reserved for damaging or reckless releases, not rare exceedances of stringent numerical aquatic life standards.”

Nederland Cross and Caribou Mine contamination state violations
The Cross and Caribou Mine is leaking heavy metal contaminants into Coon Track Creek, which feeds into tributaries of Barker Reservoir, the state says. The area includes a number of popular Nederland recreation sites, from Eldora and Rainbow Lakes to Caribou Ranch Open Space. (Google Maps screenshot)

When mining breaks open mountains, naturally present heavy metals like lead, copper, cadmium and zinc are leached out in reaction to air and water. Cross and Caribou had two older lined ponds where water leaking from the mines was treated with lime to reduce acidity and turn the heavy metals into solids that can be filtered out. The state water quality permit allowed a discharge pipeline from the second pond into Coon Track Creek. Mine owners are supposed to test discharge water themselves for the regulated heavy metals, and report results periodically to the state. 

Fish and other stream wildlife are far more susceptible to small levels of heavy metals than humans, Morgan said, and water quality regulations are set up to protect natural habitat in streams like Coon Track Creek and downstream waters, which eventually merge into Boulder Creek. 

The state’s cease and desist order says mine owners failed to make some required pollutant reports in March and April of this year. When the state looked deeper, it found pollutant violations in those months but also many more alleged violations before and after, spanning a period of December 2020 through August 2021. 

In April, for example, Cross/Caribou self-reported copper traces of 50 micrograms per liter of water, when the state standard is a daily maximum of 20. In January, the mine reported lead of 10 micrograms per liter, when the state 30-day average limit was 3.8. The state’s order charges the mine with violating the Colorado Water Quality Control Act. The notice of violations and cease and desist order in early November say the state is continuing to investigate and may have “additional enforcement actions.” 

“Any violation of a discharge permit is cause for concern, and whenever there’s a pattern of violations that indicates to us that we need to do a little bit more investigation into the problem, that’s where we are at in the process now,” CDPHE’s Morgan said. 

Grand Island Resources must also answer to the state’s Division of Reclamation, Mining and Safety, and will be subject to a hearing in front of the division’s board in mid-December. The company was trying to make improvements in recent months, Morgan said, but the state hasn’t found them effective. 

“Grand Island Resources piloted a treatment system over the summer that was unsuccessful. They are proposing to pilot another treatment system this winter,” Morgan said. 

The violations related to failing to report tainted water were not intentional, Byrne, the company’s attorney, said. Some were “a misinterpretation on our part of the state reporting protocols,” he said, and others were related to weather delaying timely deliveries to a lab in Montana. 

State regulators and local officials look uphill at leaking mines and keep in mind past blowouts that have tainted entire watersheds in Colorado. In August 2015, millions of gallons of tainted water blew out of containment at the Gold King mine above Silverton, turning the Animas River into a toxic, orange ribbon flowing through Durango and across the Southern Ute and Navajo nations, in one of Colorado’s worst environmental disasters in recent years. 

The Gold King blowout, triggered by EPA contractors exploring a cleanup of what would later become part of a Superfund site, killed off wildlife in parts of three states and damaged agriculture

Environmental groups said the Nederland situation and other mine leaks prove their point in pushing for  “natural river rights” resolutions by Colorado towns. 

“Heavy metals pollution from mines is a problem all over Colorado,” said Gary Wockner of the water protection advocacy group Save the Colorado. “Any ongoing use, or expansion, of this mine must comply with the letter of the law to protect the watershed for residents in Caribou Valley and Nederland as well as stream health and drinking water all the way to Boulder downstream.”

Michael Booth is The Sun’s environment writer, and co-author of The Sun’s weekly climate and health newsletter The Temperature. He and John Ingold host the weekly Sun-Up podcast on The Temperature topics every Thursday. He is co-author with...