The existing transmission grid across the West is aging and increasingly operating at its full capacity during peak periods of customer electric use. Idaho Power and Rocky Mountain Power (the companies) have jointly proposed the Gateway West Transmission Line Project to enhance reliability and deliver electricity from existing and new generating resources, including renewables such as wind.

The project would build and operate approximately 1,000 miles of new high-voltage transmission lines between the Windstar Substation near Glenrock, Wyoming and the Hemingway Substation near Melba, Idaho. The project would include approximately 150 miles of 230 kilovolt (kV) lines in Wyoming and approximately 850 miles of 500 kV lines in Wyoming and Idaho.

The Bureau of Land Management (BLM) was the lead federal agency that conducted the environmental review and analysis as part of the National Environmental Policy Act (NEPA) process.

Recent project milestones
  • The BLM released its Record of Decision (ROD) on November 14, 2013, for segments 1 through 7 (Windstar to Populus, Populus to Midpoint and Populus to Cedar Hill) and segment 10 (Midpoint to Cedar Hill) of the project. It identifies the BLM authorized route on public land.
  • The BLM postponed a decision on segments 8 (Midpoint to Hemingway) and 9 (Cedar Hill to Hemingway) to resolve routing in this area. The companies submitted a revised application for segments 8 and 9 in August 2014. The BLM determined that new information included in this application would require additional analysis to supplement the analysis in the 2013 final EIS for the original, 10-segment project.
  • A draft supplemental EIS for segments 8 and 9 was released March 11, 2016, and the final supplemental EIS was published on October 7, 2016.
  • The BLM released its ROD for segments 8 and 9 on January 19, 2017.
  • The Interior Board of Land Appeals (IBLA) remanded the January ROD back to the BLM Idaho State Office for reconsideration of the route alternatives on April 17, 2017.
  • President Trump signed the Fiscal Year 2017 Consolidated Appropriations Act into law on May 5, 2017, which included provisions from House Resolution 2104 to route the Gateway West transmission line through the Morley Nelson Snake River Birds of Prey National Conservation Area (NCA).
  • The BLM published a draft EA for segments 8 and 9 on November 3, 2017. The BLM is accepting comments on the draft EA through December 4, 2017.
  • The BLM published the final EA for segments 8 and 9 on January 5, 2018.
  • The BLM released the Decision Record for segments 8 and 9 on April 18, 2018.
What's Ahead?

In its 2017 Integrated Resource Plan, PacifiCorp announced plans to construct a portion of the Gateway West Transmission Line in Wyoming. PacifiCorp will initiate state and local permitting and right of way acquisition for 140 miles of 500 kV transmission line between the planned Aeolus substation near Medicine Bow, Wyoming and the Jim Bridger power plant near Point of Rocks, Wyoming. Visit PacifiCorp’s Energy Gateway website for more information.

There is more work to be done to obtain state and local permits, as well as obtaining rights-of-way for the entire length of the project. Rocky Mountain Power and Idaho Power will continue evaluating the timing of next steps in the project to best meet our customer and system needs.