Restoration of iron fen on Mt. Emmons appears to be successful

Unique 8,000-year-old wetland is making a comeback

By Cayla Vidmar

The restoration of a unique wetland on Mt. Emmons is wrapping up this summer season. This special wetland—specifically called an iron fen—was designated in 1999 as a Natural Area by the state of Colorado because of the unusual chemical makeup of the water and soils that provide an ideal ecosystem for rare carnivorous plants and unusual dragonflies. The iron fen has likely been around for about 8,000 years, according to fen expert and senior research scientist and professor at Colorado State University Dr. David Cooper.

According to a report compiled for the Coal Creek Watershed Coalition by Dr. Cooper, “Where perennial ground water discharges to saturate wetlands all year, dead plant leaves, stems and roots only partially decompose and accumulate to form peat soils, and these ecosystems are fens.”

What makes the Mt. Emmons fen unique is that it contains a pyrite-rich bedrock and talus, characteristic of only a few fens in the region. When the pyrite oxidizes it produces sulfuric acid, “which, when dissolved in water, forms a strong acid that can leach ions from the rock, including iron,” Cooper states.

According to Colorado Parks and Wildlife, “Mount Emmons and a few other iron fens in the southern Rocky Mountains … are rich in mineral ions (especially iron and sulfur) but have a very low pH, which results in an unusual flora,” including small orchids and one of only four populations of roundleaf sundew in Colorado. Roundleaf sundew is a carnivorous plant that lures insects into a sticky trap, then digests its meal with enzymes before unfurling its trap once again.

The Grand Mesa, Uncompahgre, and Gunnison National Forests District (GMUG), along with the Army Corps of Engineers and Coal Creek Watershed Coalition, are working to restore the iron fen to pre–wagon road days, which runs parallel with Kebler Pass. The iron fen is located to the north of Kebler Pass Road on Mt. Emmons, and spans 15.1 acres across a sloping hillside.

In 2004 the Colorado National Heritage program conducted a “Survey of Critical Wetlands and Riparian Areas in Gunnison County,” which concluded that historic mining operations had dried up nearly a third of the original fen, but the remaining area was functioning well.

The dewatering of the fen is mostly being caused by water being diverted into a historic ditch away from the old wagon road. According to Ashley Hom, a hydrologist for the GMUG Forest Service, “Without that ditch the water would destabilize the hillside,” which poses a risk for Kebler Pass Road.

In 2015 a storm on Kebler Pass dumped rain on top of snow, causing “substantial surface flow” across the fen, down the hillside and onto the road, which prompted emergency action by the National Forest personnel to widen the ditch between Kebler Pass Road and the fen, according to the Mt. Emmons restoration and mitigation plan.

While the ditch helped stabilize the hillside by diverting water out of the ground, it also resulted in significant dewatering of the iron fen. This issue is what prompted the restoration project through the GMUG Ranger District, which began in fall 2016.

“The goal of this project is to restore the surface and groundwater hydrology, along with the native vegetation, on the portion of the Mt. Emmons iron fen that was impaired by the emergency action that extended portions of the historic ditch… and included construction of a rockery wall, spillway, culverts, and rip-rap on Kebler Pass Road to protect the road yet allow for natural surface and sub-surface water flow from the fen,” according to the restoration and mitigation plan.

There is still some work to be done, states Hom, including more ditch work, planting, feeding and monitoring in the area, which will resume this summer.

Eight monitoring wells have been placed in the fen, four above the ditch and four below the ditch, and hydrologists will monitor the ground water levels in the wells, and the restoration “will be considered successful if [the wells] below the ditch show the water table depth there to be decreasing or rising closer to the surface,” according to the restoration and mitigation plan.

The plan states that “restoring the presence of a shallow water table within the area should provide for fen-like hydrology,” which will, in turn, restore historic vegetation to the iron fen below the ditch.

“Overall the rehabilitation of the drainage ditch within the Mt. Emmons iron fen appears to be successful. Ground water levels have already risen to within 30 centimeters of the surface and water table levels below the ditch are within at least 15 centimeters of those above the ditch,” according to the GMUG watershed team.

There have been many agencies involved in the restoration of this unique swath of wetland, including the Army Corps of Engineers, which permitted the project, and the Coal Creek Watershed Coalition that allocated $45,000 for phases 1 and 2 of the restoration and mitigation project.

You can follow progress of the project and direct questions to Ashley Hom at the Gunnison Ranger District, (970) 642-4406 or ashleyhom@fs.fed.su.