Restoring Lion Creek

TU and project partners removed tailings materials that averaged 3 feet in depth and buried the streambank along Lion Creek, a tributary to Clear Creek in Colorado.  

By Lauren Duncan

In late November 2016, Trout Unlimited’s Abandoned Mine Lands (AML) team wrapped up a successful restoration project at Lion Creek, above the town of Empire, Colorado. TU’s AML team, comprised of Jason Willis, Deb Phenicie and Lauren Duncan, worked with Frontier Environmental Services Inc. to address impacts from historic mining in the Lion Creek area.

The Lion Creek area was once home to the Empire Mining District, also known as the Upper Union District. Ore was discovered in the district in 1862 on the southeast slopes of Silver Mountain, north of Empire. Mining continued in the area until about 1950. The most notable mine in the district was the Minnesota Mine. The Minnesota, located upslope of Lion Creek, produced gold and silver and, in 1942, was the largest producer of gold in Clear Creek County, milling over 10,000 tons of ore per year.

Since closure, the Minnesota Mine has significantly contributed to sedimentation and metal loading in Lion Creek. The EPA undertook remediation of the Minnesota Mine in 1996 to decrease the adverse environmental impacts of the mine through consolidation and capping of waste rock and tailings (processed ore).

Large amounts of leftover tailings remained in the Lion Creek drainage, however, after remediation of the Minnesota Mine was complete. The weathering of these tailings causes acid rock drainage, degrades water quality, causes erosion into surface waters, and provides a direct exposure pathway to humans and animals. TU stepped in to perform restoration at Lion Creek to address these environmental impacts, protect several residential drinking water wells downstream of Lion Creek, and safeguard the downstream trout fisheries of the West Fork of Clear Creek and the mainstem of Clear Creek.

In partnership with the National Forest Foundation and the U.S. Forest Service, Trout Unlimited and Frontier Environmental worked together to perform successful restoration at Lion Creek. Project work included excavating 600 cubic yards of tailings, disposing of those tailings in a secure repository, placing clean fill at the streamside tailings area, grading and terracing 150 feet of “rough” floodplain, replanting the site and establishing native riparian vegetation.

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Natural toe stabilization, sedge mats and wetland plants installed at the water line at Lion Creek.

Trout Unlimited’s work at Lion Creek is expected to improve watershed health, which will benefit local landowners, recreationalists, and downstream fish habitat and water users. Land in the immediate vicinity of the project area will be drastically improved due to removal and relocation of mine tailings, floodplain restoration and re-vegetation along Lion Creek. These improvements on the land are expected to have a positive effect on the water quality in the project area, especially during periods of high flow and rainfall events. The resulting enhancements to soil and water quality will have a combined synergistic effect on the populations of macroinvertebrates and fish in downstream receiving waters of West Fork of Clear Creek and the mainstem of Clear Creek. Wildlife populations will also benefit directly from improvements to soil and water quality because heavy metal and acid-generating exposure pathways will be reduced.

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Looking downstream from the top of the Lion Creek project showing before (top), during (middle), and after (bottom) conditions at Lion Creek. 

This project isanother example of the effective partnership between Trout Unlimited, mining industry leaders (Freeport-McMoRan and Newmont), the Clear Creek Watershed Foundation, private landowners and the U.S. Forest Service. Together, we were able to complete a successful project that will improve the water and environmental quality at Lion Creek. We are excited to see positive results in years to come and look forward to exploring future work in the Lion Creek area.

Lauren Duncan is an abandoned mine restoration project manager for Trout Unlimited.