At a Glance

Stability, resilience, ecology, and public safety are restored to a flood-damaged canyon in Colorado’s Front Range.

Project Description

In the fall of 2013, a severe storm dumped 10-20 inches of rain along Colorado’s northern Front Range, causing severe flooding in the foothills, and wiping out Lefthand Canyon Road, the main road leading in and out of the mountains northwest of Boulder. The road follows the path of Lefthand Creek, a stream which begins on Niwot Mountain, runs through a canyon, and flows onto the plains, where it joins St. Vrain Creek and ultimately the South Platte River. During the storm, Lefthand Creek suffered extreme erosion, deposition, and habitat degradation.

Working with AECOM, Biohabitats helped the Central Federal Lands Highway Division of the U. S. Department of Transportation enhance the resilience of both the road and creek. While AECOM led the effort to relocate the roadway further from the creek, Biohabitats developed a design to restore stability and habitat to nearly 2.5 miles of the creek and its floodplain. Biohabitats began by conducting an assessment of the entire project reach and prioritizing restoration reaches. Despite the challenges of working in a canyon with limited floodplain area and an adjacent roadway, Biohabitats recognized many opportunities to increase the floodplain and incorporate aquatic habitat features, such as riffles, pools, and woody debris, which had been removed by the flood. Biohabitats produced 30% construction plans and worked closely with the grading contractor to make adjustments to the channel design during construction.

Details

Bioregion

Southern Rocky Mountain

Physiographic Province

Southern Rocky Mountains

Watershed

South Platte River

Expertise Areas

Design & Build, Ecological Restoration, Water

Owner

U.S. Department of Transportation, Federal Highway Administration

Location

Boulder County, Colorado, flood, Left Hand Creek, United States

Project Team
  • AECOM
  • Anderson Consulting Engineers