Tri‐State Generation and Transmission Association (Tri‐State) proposed to rebuild the existing Montrose‐Nucla‐Cahone 115 kV transmission line to operate at 230kV. The rebuild was required to resolve maintenance issues, increase line capacity to meet growing demand, and improve transfer capabilities on the regional grid system. The transmission line is 80 miles long and is located across Dolores, Montrose, Ouray, and San Miguel Counties in Colorado. ERO prepared an Environmental Assessment (EA) in compliance with the National Environmental Policy Act (NEPA) and completed a visual assessment, biological surveys, and biological monitoring on behalf of Tri‐State. The Final EA was issued in September 2016 and the Finding of No Significant Impact was signed in February 2017. Much of the rebuilt transmission line is located on Bureau of Land Management (BLM) and U.S. Forest Service (USFS) lands. The transmission line rebuild includes a new 230kV substation near Nucla, a new alignment at the Dolores River Canyon crossing, and an increased right-of-way (ROW) width, from 100 to 150 feet, requiring an amendment to the existing BLM ROW grant. The BLM was the lead federal agency for the EA with the USFS participating as a cooperating agency. The EA addressed key environmental issues concerning threatened and endangered species, including Gunnison sage-grouse, cultural resources, tribal consultation, visual resources, rare plants, and land use to comply with the BLM and USFS Management Plans and applicable local, state, and federal regulations.