Fourmile Creek Channel and Habitat Restoration

Location: Boulder County, Colorado

As part of Fourmile Creek Watershed Master Plan, Michael Baker International identified a Mine Tailings pile immediately adjacent to Fourmile Creek that had been exposed during the 2013 flood. Michael Baker informed Boulder County and the Environmental Protection Agency (EPA) about the Tailings pile and participated in meetings to discuss the immediate need to remove the Tailings. The Tailings pile was located in an extremely constrained reach of Fourmile Creek and was tested to have high levels of arsenic. The channel had little hydraulic capacity and limited habitat features in the reach. The post-flood location of the Creek threatened to further erode the Tailings pile and the adjacent Fourmile Canyon Road. Under the direction of Boulder County, Michael Baker worked with the EPA during the Mine Tailings removal to identify an ideal post-removal channel location, pattern (planform), and channel dimension (cross section) that included a bankfull channel with connected floodplain bench. Michael Baker also worked in the field with the EPA’s contractor to direct them on placement of in-stream and riparian habitat features and channel grade control features in the reach utilizing on-site natural materials. Michael Baker, Boulder County, and the EPA worked in concert in an emergency nature to remove the Tailings pile and restore approximately 1,000 feet of Fourmile Creek. The project resulted in a site that increased in-stream and riparian habitat potential, eliminated a point source of pollution, restored floodplain connectivity, significantly increased hydraulic capacity, protected Fourmile Canyon Drive, restored a historic cultural resource (the Switzerland Trail), improved site lines for roadway safety, and created a water supply location for the Fire District. The project transformed one of the highest risk locations in Fourmile Canyon into one of the most resilient locations.

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