Spanish Fork to Mercer transmission project

Project overview

The project will be a new 45-mile-long 345-kilovolt transmission line from the existing Spanish Fork substation in Mapleton, Utah, to the existing Mercer substation in Eagle Mountain, Utah. The new transmission line will provide additional capacity to help in serving load growth in Utah while increasing overall system reliability. This line will also deliver electricity generated from energy resources, including renewables and thermal resources (wind, gas and coal), while adding the benefits of increased reliability and capacity.

About the project

The purpose and need for the Spanish Fork to Mercer 345 kV line is to ensure the transmission system is reliable. With the increase in energy use across PacifiCorp's service area and the increase in solar power development in southern Utah, a new line is needed to transport this cost-effective resource to population centers across PacifiCorp's service area. The Spanish Fork to Mercer line is the most economical way to meet the reliability requirements and transmit solar energy from Southern Utah to homes and businesses. Without a new line, if the existing double-circuit 345 kV lines connecting Utah and Salt Lake counties experienced an outage, the existing 138 kV system in Utah Valley would not meet reliability planning standards. To fix this, PacifiCorp is building a new 345 kV line to allow cost-effective solar power to serve population centers. The installation and energization of the Spanish Fork to Mercer line will enable an additional 2,950 megawatts of renewable energy to connect to the grid.

345 kV Typical Single-Circuit Monopole 

(image of typical structure – not actual)


  • Voltage: 345 kV
  • Type of structure: Steel monopole
  • End points: Spanish Fork Substation and Mercer Substation (Eagle Mountain area)
  • Length: Approximately 45 miles
  • Height of monopoles: 90-135 feet
  • Span between monopoles: 600-800 feet
  • Right-of-way width: 125 feet

Project map

The project is currently in the planning and design phase. PacifiCorp is conducting a routing study to identify a suitable route for the new transmission line and is integrating public outreach and engagement activities as part of the route study process. Several potential routes were identified for this project taking into consideration impact on existing land uses, biological and environmental factors, known resource constraints and feasibility. Considering these factors, certain route options have been eliminated from further consideration. The project map indicates the preliminary preferred route (bold black line) and alternate routes (dashed black lines) that are being studied. 

Spanish Fork to Mercer Project Map

Project timeline

The affected entities in the Spanish Fork to Mercer 345kV Project include the cities of Eagle Mountain, Genola, Mapleton, Spanish Fork and Salem, Utah County, South Utah Valley Electric Service District, Utah Municipal Power Agency, Utah Associated Municipal Power Systems, Southern Utah Valley Power Systems, Utah Department of Transportation, Bureau of Reclamation, Bureau of Land Management, Utah Department of Natural Resources, and Utah School and Institutional Trust Lands Authority, with an estimated timeline for the project as follows:

Design & engineering:
February 2023 - April 2024
Local/state permitting:
April 2024 - March 2025
Project surveying:
April 2024 - April 2025
Bureau of Land Management Notice to Proceed:
Expected August 2025
Rights of Entry/Rights of Way acquisition:
August 2024 - January 2025
April 2026 - October 2027
In-service: November 2027  

After providing a project introduction to local jurisdictions, PacifiCorp will voluntarily host Public Open House meetings in various locations in efforts to gather information and feedback from the public, answer questions and invite discussion. Throughout the permitting process it is anticipated that local jurisdictions along the project route may require additional public workshops, outreach, and engagement.  Information about all open house meetings and engagement opportunities will be noticed and can also be found on this page. 

Public outreach

PacifiCorp recently held four (4) public open house meetings with the intent to inform the communities in the project area about the Spanish Fork to Mercer Transmission Project and encourage questions and comments. Open house meetings have been hosted in Goshen, Salem and Spanish Fork on June 18, 19, and 20, 2024. Additionally, we held a virtual open house on June 25, and an open house meeting in Genola on July 15.  

The in-person meetings included large map books for viewing, GIS stations that offered the ability to zoom in to individual properties, and project staff to answer questions.  A video of the virtual meeting and Q&A session will be made available on our website in the near future. The following information that was provided at these meetings.

Spanish Fork to Mercer Project Overview

Spanish Fork to Mercer Project Map & Viewpoint

Spanish Fork to Mercer Map Book

More information

Requests for additional information on the Spanish Fork to Mercer Project may be directed to

Please include your request, along with your contact information and preferred contact method.  

Updated June 28, 2024