Gateway West

The Gateway West project is jointly proposed by the company and Idaho Power to build and operate approximately 1,000 miles of new high-voltage transmission lines in Wyoming and Idaho. It is comprised of two major line segments. (Note: As a party to the project, Idaho Power has interest in specific segments between Populus and Hemingway, Gateway Segment E.)

Windstar to Populus, Segment D, will stretch approximately 488 miles starting at the Windstar substation near Glenrock, Wyoming, proceeding south to Medicine Bow and then spanning across southern Wyoming to the Populus substation near Downey, Idaho. This Segment D will include seven expanded or new substations and will enable access to existing and new generating resources, including wind, and will deliver electricity from these sources to customers.

On April 4, 2017, PacifiCorp issued its 2017 Integrated Resource Plan announcing plans to construct a portion of Segment D - Windstar to Populus. Independent of Idaho Power, PacifiCorp initiated state and local permitting and rights-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, sub segment D.2 – Aeolus to Bridger/Anticline.

Windstar to Populus, Segment D has been divided into three subsegments:

  • D.1 – Windstar to Aeolus: A single-circuit 230 kV line that will run approximately 75 miles between the existing Windstar substation in eastern Wyoming and the planned Aeolus substation near Medicine Bow, Wyoming.
  • D.2 – Aeolus to Bridger/AnticlineA single-circuit 500 kV line running approximately 140 miles from the planned Aeolus substation to a new annex substation (Anticline) near the existing Bridger substation in western Wyoming.
  • D.3 – Bridger/Anticline to Populus: A single-circuit 500 kV line running approximately 200 miles between the new annex substation (Anticline) and the recently constructed Populus substation in southeast Idaho.

Populus to Hemingway, Segment E, originates at the Populus substation near Downey, Idaho, and includes two 500 kV single-circuit transmission lines that run approximately 502 miles across Idaho to the Hemingway substation near Melba, Idaho. The Populus to Hemingway segment will include five expanded or new substations, and will enable access to existing and new generating resources, including wind, and will deliver electricity from these sources to our customers. 

Project timeline

  • Public Scoping – June 2008
  • Environmental Impact Statement – 2007 - 2013
  • Supplemental Environmental Impact Statement – 2014 - 2016
  • Public outreach – June 2008 through project completion
  • State and local permitting and obtaining rights-of-way – complete for Subsegment D.2 Aeolus to Bridger/Anticline
    • Certificate of Public Convenience and Necessity application for Subsegment D.2 submitted to the Wyoming Public Service Commission on June 30, 2017, and approved on April 12, 2018.
    • The Carbon County Board of County Commissioners approved the Conditional Use Permit for the D.2 segment and associated 230kV network upgrades September 4, 2018.
    • The Wyoming Industrial Siting Council approved the permit for the D.2 segment and associated 230kV network upgrades October 25, 2018.
    • Estimated line in service for customers – 2020 for D.2 subsegment, entire project by 2024 at the earliest.

Additional information about the project

Under the National Environmental Policy Act, the Bureau of Land Management (BLM) has completed the Environmental Impact Statement (EIS) for the Gateway West project. The BLM released its final EIS on April 26, 2013, followed by the Record of Decision on November 14, 2013, providing a rights-of-way grant for most of the project. The agency chose to defer its decision on the western-most portion of the project located in Idaho in order to perform additional review of the Morley Nelson Snake River Birds of Prey National Conservation Area. The BLM completed a supplemental environmental analysis for Segments 8 & 9 of the project which encompasses that area. On October 7, 2016, the BLM released its final supplemental EIS, followed by the Record of Decision on January 19, 2017. That Record of Decision was appealed to the Interior Board of Land Appeals. The Interior Board of Land Appeals remanded the January 19, 2017 Record of Decision back to Bureau of Land Management in April 2017. In May 2017, President Trump signed the Fiscal year 2017 Consolidated Appropriations Act into law which included Congressman Simpson’s agreement on Gateway West transmission line routing through the Morley Nelson Snake River Birds of Prey National Conservation Area. House Resolution 2104 directs the Secretary of Interior to grant a right of way on the Companies’ preferred routing (Alternative 1).

See below for additional information on public participation and project history, and visit the BLM website for more information.

Public participation

Public input is an important part of the transmission line development process and is welcomed at all stages. In addition to public, group and individual meetings, project materials and newsletters also have been sent to more than 11,000 landowners and other interested parties throughout this process and will continue through the end of the project with continued web page and newsletter updates.

For a comprehensive list of meetings, publications and other public outreach, can be found on our Gateway West website.

To contact Rocky Mountain Power about this transmission project, please call the major construction projects message line at 801-220-4221, or email Please be sure to include the project name – "Gateway West project" – in your inquiry.

Gateway West maps

Updated maps can be viewed below:

Further information also can be found at our Gateway West website

Next steps

The Record of Decision and rights-of-way grant contains many conditions and stipulations that must be met and accepted before the project segments can move to construction. The companies will continue the work necessary to meet these requirements. The companies will continue to meet regularly with the Bureau of Land Management to review progress.

There is more work to be done to obtain state and local permits, as well as obtaining rights-of-way for individual segments. The companies will continue evaluating the timing of next steps in the project to best meet our customer and system needs.

Project history

(Updated July 2019)