Click the link to read the article on the Aspen Journalism website (Heather Sackett):

August 15, 2025

High above Aspen at 11,400 feet, past the ghost town of Ruby, at the end of a rough dirt road surrounded by willows and ramshackle cabins, Lincoln Creek runs clean and clear.

The mountain stream is barely more than a trickle at its headwaters, but it still supports fish that dart and hide in the cool shadows. But just a few hundred yards downstream, the creek begins to turn foul. 

First by what appears to be a small tributary or groundwater that flows into the creek and leaves a white residue on the rocks, an indication of aluminum. Then comes the runoff from the abandoned Ruby Mine, which leaves a hardened orange crust on the ground where it joins the creek. Just downstream of the mine is the site where experts say the majority of the aluminum, copper, zinc and iron contamination is entering Lincoln Creek: the “mineralized tributary.”

Although it’s hard to pinpoint the exact source — the entire mountainside above the creek on the east side is stained orange, suggesting the widespread presence of metals — a group of scientists, government officials and local nonprofits are ramping up efforts to better understand the workings of the Lincoln Creek watershed and what can be done to improve its water quality. 

On Wednesday [August 13, 2025], a team from the Roaring Fork Conservancy and Pitkin County spent the day collecting water quality samples from Lincoln Creek, the Ruby Mine discharge, the mineralized tributary and points downstream. It was the third time this summer scientists have collected water samples from the creek, and it is part of an overall effort with Colorado Parks and Wildlife and University of Colorado Boulder to test and monitor the area. 

“I think one of our big goals is really to continue to fill in the data,” said Chad Rudow, water quality program manager with the Roaring Fork Conservancy. “As I like to tell people, science takes time. To even apply statistical analysis to it, you need to have a fair bit of data.”

Local residents, government agencies and environmental groups have long been concerned about Lincoln Creek, which, according to a report from the Environmental Protection Agency, is toxic to aquatic life. The tributary of the Roaring Fork River has been under increased scrutiny in recent years as fish kills and discoloration of the water downstream of Grizzly Reservoir have become more frequent. 

“We’re worried about the aquatic health of the river,” said Bryan Daugherty, environmental health specialist with Pitkin County. “There certainly could be human impacts if it got really bad, but at this point it’s really the aquatic life that we’re concerned with.”

Since early 2024, the ad hoc Lincoln Creek Workgroup has been meeting to figure out what to do about the contaminated creek. Bolstered by a state grant of $100,000, the group is increasing water quality testing. The team of scientists has grown the number of testing sites this year from seven to 14 and are focusing current efforts on what’s happening above Grizzly Reservoir. 

Pitkin County Healthy Rivers, whose mission is to maintain and improve water quality and quantity in the Roaring Fork River basin, is playing a crucial role by securing grant money and working with consultant LRE Water on phase II of the data collection and modeling project, which will cost $207,000. Colorado Parks and Wildlife staff have also set up conductivity loggers, which measure how well water conducts electricity, and trail cameras to take photos of Lincoln Creek. 

“It’s definitely a team effort with a lot of different groups playing an important role in adding different pieces to the overall puzzle,” Rudow said. 

Highly acidic concentrations

The process of 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, which is happening in other mountainous regions of Colorado and around the West.

The metals concentrations from acid rock drainage seems to be increasing in recent years and may be exacerbated by climate change as temperatures rise. But because the vast majority — 98.5% of the copper, according to the EPA report — of the contamination is from natural sources and not related to the Ruby Mine, the EPA is not authorized to clean it up. That leaves local and state agencies, and nonprofit organizations to fill the gap.

Wednesday’s testing revealed a pH of 7.29 on the upper reaches of Lincoln Creek (7 is considered neutral); 6.4 below the Ruby Mine and 3.2 below the confluence of the mineralized tributary. The pH scale is logarithmic, meaning a decrease of one whole number equals a 10-fold increase in acidity. 

“The highly acidic concentrations that we’re seeing up here is part of the process that’s speeding up mobilizing the metals from the rock into the stream system,” Rudow said.

Scientists also collected data about dissolved oxygen, water temperature and salinity. The water samples are then shipped to a lab in Fort Collins, which tests for metals concentrations.

Rudow and others also used Wednesday’s trip to the high alpine as a chance to scout spots for an upcoming synoptic survey. At the request of LRE, scientists will pick a day this fall to take water quality samples and flow measurements at points along the entire length of the creek to better understand the sources of contamination. But only year-round tributaries — not seasonal snow-fed seeps — will be included.

“We’re pushing that into September because what we really want to focus on for that project is those year-round streams that are coming into Lincoln Creek,” Rudow said. “(LRE) is going to take all of this data and ultimately build a model to show what’s going on in the creek and how these different inputs are influencing the creek.”

Water quality sampling in 2024 focused on Grizzly Reservoir and points downstream to better understand the impacts of a dam repair project. Last summer the reservoir was drained for work on the dam, and a slug of sediment-laden, orange-colored water was released downstream, alarming Aspen residents. 

Both sides of the divide

The water quality issues on Lincoln Creek bind together water users on both sides of the Continental Divide. Lincoln Creek feeds into the Twin Lakes Reservoir and Canal Company’s transmountain diversion system, in which Grizzly Reservoir is used as a collection pond before sending water through the Twin Lakes Tunnel to the Front Range, where it is used primarily in cities, including for drinking water. Colorado Springs Utilities owns about 55% of the water in the Twin Lakes system, while about 35% goes to the Pueblo area. 

Twin Lakes President Alan Ward, who also works as a water resources manager for Pueblo Water, is a member of the Lincoln Creek workgroup. Each organization contributed $5,000 toward the LRE Phase II work. 

Ward said next summer Grizzly Reservoir will be drained again so Twin Lakes can work on the damaged outlet works that release water downstream to Lincoln Creek. To avoid another sediment release, the company will create a small basin with cofferdams where the last 10-12 acre-feet at the bottom of the reservoir can settle out before sending it downstream or through the Twin Lakes Tunnel.

Ward said impacts to drinking water aren’t much of a concern for the east side of the divide because the water from Lincoln Creek is diluted by the 141,000-acre-foot Twin Lakes Reservoir, which stores water from multiple sources. 

“I think for us the concerns are more on Lincoln Creek itself because Grizzly Reservoir is right in the middle of it,” Ward said. “We just want to stay really engaged on this to figure out the water quality issues and how they impact Grizzly Reservoir itself and if there are ways to mitigate the problem.”