Long-term Monitoring Shows Successful Restoration of Mining-Polluted Streams

Colorado State University Professor William Clements has spent the past 30 years analyzing how watersheds damaged by mining pollution would respond to remediation. He’s studied the most toxic of these waterways – Superfund sites as defined by the U.S. Environmental Protection Agency.

His research has focused primarily on the Arkansas River near Leadville, Colorado, where a long history of mining in the watershed began as far back as 1859. Clements, a scientist in CSU’s Department of Fish, Wildlife and Conservation Biology, said that the patterns of recovery that have occurred over time in Colorado and other states is a true conservation success story.

He joins a team of researchers to highlight these findings in a new paper that will be published in the June issue of Freshwater Science and is now available online. The streams highlighted in the study – including ones in California, Colorado, Idaho, and Montana – recovered from severe pollution damage from different metals within 10 to 15 years.

“So much of what we’ve presented to the public in the environmental realm has been gloom and doom,” said Clements. “It is good every now and then to have these success stories. We found that these systems can indeed turn around with a little bit of attention and time.”

The four mining-impacted watersheds in the study are among the few acid mine drainage sites where scientists have conducted extended studies to monitor the effectiveness of remediation efforts.

Over the past 31 years, Clements said the project in Colorado has involved over 100 CSU undergraduate and graduate students, and postdoctoral researchers. The research was a collaborative effort among CSU, Colorado Parks and Wildlife, and the Environmental Protection Agency.

Clements was an assistant professor at CSU when the project was launched in 1989. The research started with a very small grant from the EPA and led to a long-term study. It’s been a challenge to keep a 31-year study going, he said.

“Neighbors and colleagues and students volunteered to help out in the lean years with fieldwork,” he said. Did he imagine a transformation from a Superfund site to a Gold Medal trout stream, as designated by the Colorado Wildlife Commission?

“Absolutely not,” he said. “At the start, the study was designed to see what the effects of the mining pollution were. We studied aquatic insects in the upstream and downstream portions of the river and compared them to see what it would take to restore the river to its natural state. There was no way to see this remarkable transformation 30 years ago.”

Clements said these insects – including mayflies, stoneflies, and caddisflies – play important roles in the flow of energy in the river, contributing to the decomposition of leaves and recycling of nutrients.

What he and the other scientists observed can also be applied to other polluted watersheds. Clements currently has a similar Superfund research project in the Clear Creek watershed, near Blackhawk, Colorado. He is also optimistic about restoration efforts in the Animas River, which was polluted in 2015 following a wastewater spill caused by the Gold King Mine. Photos from the polluted river – which turned yellow – went viral and were featured in news coverage around the world.

“There are a large number of abandoned mines throughout the West, particularly in Colorado,” said Clements. “They are not always big Superfund sites, but there are lots of opportunities to take what we’ve learned about the historic effects of metals that began about 150 years ago and restore these waterways.”

The CSU team will continue to monitor the Arkansas River, observing which species – including aquatic insects and trout – exist upstream and downstream. Clements said how we define restoration success is partially a philosophical question, and the results might be viewed differently, depending upon the eyes of the beholder.

“There’s every indication that the Arkansas River may eventually get there, but it certainly hasn’t completely recovered,” he said. “Even though you eliminate original stressors that caused the shift, it may never go back to where it was hundreds of years ago. But the story here is really about this remarkable turnaround and how these systems in different states got to the same place is pretty thrilling.”

Clements said another benefit in Colorado related to the restoration efforts is that there is more public access to the Arkansas River, thanks to Colorado Parks and Wildlife and several federal agencies.

“There used to be a lot of private land up there,” he said. “Now there’s a great deal of river access and it’s put the Arkansas River on the map in terms of the tremendous fishery.”