Aspen Journalism: Rare earth elements found in Lincoln Creek raise new questions 

Recent sampling shows that a high-alpine tributary of the Roaring Fork River, in addition to having high concentrations of certain metals, also contains rare earth elements. But what that means for human and aquatic health is unclear.

Scientists from the University of Colorado Boulder presented the preliminary results from water-quality sampling on Lincoln Creek over last summer at a public meeting hosted by the Roaring Fork Conservancy at the Basalt Regional Library on Thursday. 

Occupying a lesser-known corner of the periodic table, rare earth elements (which, despite their name, are commonly occurring in Earth’s crust) are a set of 17 heavy metals that are used in making products such as cellphones, fiber-optic cables, and computer monitors. With names such as yttrium, lanthanum, and neodymium, they often turn up at sites in Colorado where there is acid rock drainage, such as upper Lincoln Creek.

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“You get a phone’s worth of neodymium coming down the mineralized tributary about every 5½ minutes,” said Adam Odorisio, a graduate student and researcher at CU’s environmental engineering department. “This translates to 96,000 phones per year. And what I think is the most striking fact in this is that this is for one tributary. You multiply this across hundreds of acid mine sites in Colorado and potentially thousands across the Western U.S., and it’s very exciting for resource extraction.” 

CU scientists are also monitoring other high alpine acid rock and mine drainage sites in Colorado, including the Snake River. Odorisio said the concentrations of rare earth elements in a mineralized tributary that feeds Lincoln Creek was in the middle of the pack when compared to other sites around the state.

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In addition to the potential for mining rare earth metals, scientists are eager to learn more about their impacts to human health and aquatic environments. There are no state or federal water quality standards for rare earth elements. Lincoln Creek is a source of drinking water for Front Range cities, including Colorado Springs. 

“This is just wide open as an unknown area,” said Diane McKnight, a professor at CU’s Institute of Arctic and Alpine Research. “It’s not clear that it’s something to worry about here. The water from (Lincoln Creek) that goes into the Twin Lakes system is highly diluted.” 

Over nine days from June through October, the CU team collected 79 water samples from eight sites, took sediment core samples from the Grizzly Reservoir lakebed, and collected rock scrapings and bugs from the waterway. Early results also confirmed what the Environmental Protection Agency found in previous water-quality tests: The water is highly acidic, and concentrations of metals including zinc, copper, and aluminum exceed standards for aquatic life. Scientists found that a groundwater source could also be adding metals to Lincoln Creek. They are still analyzing the data and plan to present more results at a spring meeting.

“For the greater scientific community, the fate of rare earth elements in aquatic systems is not well understood,” Odorisio said. “We are hoping to change that.”

The results may be of use to the Lincoln Creek workgroup, an ad hoc group — composed of officials from Pitkin County, Colorado Parks and Wildlife, the U.S. Forest Service, Colorado Department of Public Health and Environment, Independence Pass Foundation, Roaring Fork Conservancy, and others — that is trying to understand how contaminants are impacting Lincoln Creek and the Roaring Fork River. The group has hired consultants LRE Water to compile water-quality data collected by several different agencies last summer and propose options to clean up the waterways. 

“The rare earth metals is a group we haven’t really thought through,” said Kurt Dahl, Pitkin County’s environmental health manager. “That’s one of the things that we are talking through with the contractor, LRE Water.” 

The water quality of Lincoln Creek has been under increased scrutiny in recent years as fish kills and discoloration of the water downstream of Grizzly Reservoir have become more frequent. In July, reservoir owner and operator Twin Lakes Reservoir & Canal Co. drained the reservoir for a planned dam-rehabilitation project, releasing an orange slug of sediment-laden water from the bottom of the reservoir downstream. Testing showed that the water had high levels of iron and aluminum, but not copper, which is toxic to fish.

An EPA report in 2023 determined that a “mineralized tributary,” which feeds into Lincoln Creek above the reservoir near the ghost town of Ruby, is the main source of the high concentrations of metals downstream. 

The process that causes metals leaching into streams can be both naturally occurring and caused by mining activities. In both cases, sulfide minerals in rock come into contact with oxygen and water, producing sulfuric acid. The acid can then leach the metals out of the rock and into a stream, a process known as acid rock drainage. The contamination from acid rock drainage seems to be increasing at other locations around Colorado and may be exacerbated by climate change as temperatures rise. 

The recent water-quality-testing effort on Lincoln Creek is probably just the beginning of a long-term data-collection and monitoring program, Dahl said. 

“I think there’s still a lot of energy around this,” Dahl said. “People are really invested in this, and it’s going to take a couple of years to get it characterized.”

Aspen Journalism, which is solely responsible for its editorial content, is supported by a grant from the Pitkin County Healthy Community Fund.

This story is provided by Aspen Journalism, a nonprofit, investigative news organization covering water, environment, social justice, and more. Visit aspenjournalism.org.