As one heads north on Colorado 91 over Fremont Pass, just past Climax Mine, a flat and barren expanse is seen to the west of the highway. Once an active tailings-storage facility, signs of life are now emerging above the reclaimed field’s hardened dirt.

Climax is in the process of transforming the westernmost corner of the Robinson Tailings Storage Facility, also known as Lake Irwin, into a wetland. The site will offset wetland habitat lost in Climax’s McNulty Gulch expansion project, an enlargement of the mine’s overburden stockpile facility visible just across the highway to the east.

McNulty Gulch is home to several wetland habitats, including seeps, springs and plant families like sedges, willows and rushes that will all be disturbed in the coming years as the mine expands.

Climax will soon need additional storage space for unmineralized overburden material, and was required to apply for a U.S. Army Corps of Engineers Section 404 permit before enlarging the stockpile’s footprint. The permit, which was conditionally approved, requires Climax to replicate McNulty Gulch’s wetlands at a two-to-one replacement ratio.

Since 2017, Climax has worked to bring nine acres of wetland to life at Lake Irwin. This is the first phase of the 36-acre project.

Before planting could occur, the site needed grading and an engineered water-delivery system.

The acreage was excavated to remove historic tailings, which were transported north to the Mayflower Tailings Storage Facility. The area was then graded for drainage and covered with topsoil where needed. A network of culverts was also engineered to catch and direct the snowmelt that flows down Sheep Mountain each spring, runoff that has flooded the site in past years.

In 2018 and 2019, Climax focused on planting.

Cuttings were collected from willows already accustomed to extreme temperatures and strong winds at McNulty Gulch and the headwaters of the Arkansas River, and planted at Lake Irwin. After growing from seed at AlpineEco Nursery in Buena Vista, herbaceous plants like beaked sedge, tufted hairgrass and mountain rush were also transplanted on the site.

To date, over 40,000 herbaceous plants and willows have been planted at Lake Irwin. Thousands more plants will be added to the wetland in the coming years as phase two (18 acres) and phase three (nine acres) of the project unfold. The project’s phases will be monitored by the Army Corps of Engineers.

In 2014, Climax completed a similar mitigation project after disrupting a wetland during the construction of the mine’s new water treatment plant. The constructed wetland is now a healthy riparian habitat, a small fenced-in plot brimming with tall green grasses between the water plant and Tenmile Creek.

Climax currently holds a silver tier certification from the Wildlife Habitat Council for site-wide biodiversity and conservation initiatives.

“Ideally, we’d like Lake Irwin to look like this in five years,” Climax’s Chief Environmental Scientist Diana Kelts said of the wetland near the water plant. “But on a larger scale.”

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