About the Ironwood Transmission Line

The Ironwood Transmission Line is a proposed approximately 87-mile, 500-kilovolt transmission line that would increase reliability to the energy grid, helping to keep the lights on and prevent power failures. In addition to increasing reliability, this project helps meet state energy goals. If we’re going to accomplish that, we need lines like these to connect power supply to the region’s communities. 

Horizon West Transmission was recently selected by the California Independent System Operator (CAISO) to build and maintain the power line. The proposed Ironwood Transmission Line project is part of a portfolio of electric transmission projects that the CAISO has identified as necessary to meet the future needs of the region’s electric grid. The project would span a portion of Yuma County, Arizona, and Imperial County, California and help provide critical reinforcement of the electric grid in Arizona and Southern California by providing over 3,000 megawatts of power that can be transferred from the electrical grid. This will enable the delivery of low-cost energy to communities throughout the region. 

Transmission lines running across vast dry lands

Why It's Important

The region’s electricity demands require a dependable pathway for energy. The energy grid is under increasing stress due to growing energy needs and natural disasters. This project will boost reliability and resiliency while benefiting our agriculture, industry and residents.

Project Details

Below are some of the many features of the Ironwood Transmission Line project:

  • The project will help maintain reliability of the regional electric grid to meet future energy demands and help reach state energy goals.
  • The Ironwood Transmission Line would reinforce the electric grid by providing access to more than 3,000 megawatts of power, enough to serve more than 2 million homes.
  • The project is expected to be in service by 2030. The detailed project schedule and the anticipated in-service date are subject to change and may be influenced by the timeline for obtaining necessary regulatory approvals.

Community Benefits

The Ironwood Transmission Line project will provide access to reliable energy to members of the community. This project also will generate significant benefits for the communities that host them.

Construction worker using equipment while wearing a blue hard hat and yellow construction vest

Employment opportunities

The project will create employment opportunities, including jobs to construct the project. That means more in-demand jobs benefitting our construction and industrial industries.

Construction worker and business man shakings hands

Economic growth

The transmission line would enable further development of Imperial and Yuma County’s extensive energy industries. It would help power an energy economy, spurring economic opportunities and benefits for local communities.

FREQUENTLY ASKED QUESTIONS

Learn more about the Ironwood Transmisson Line

The electric transmission system, commonly known as the grid, moves electricity across high-voltage lines from various power sources to the communities where it can be used. The proposed project is critical to improving the efficiency and reliability of the electric grid.

Who is Horizon West Transmission?

Horizon West Transmission, LLC (Horizon West), is a subsidiary of NextEra Energy Transmission, a leading competitive transmission company that develops, finances, constructs, operates and maintains transmission assets across North America. 

NextEra Energy Transmission subsidiaries own and operate high-voltage transmission assets in 10 states and Canada. The company’s investments are critical to improving the efficiency and reliability of the electric grid.  

 

What is the Ironwood Transmission Line project?

The proposed Ironwood Transmission Line project is an approximately 87-mile, 500-kV transmission line that would primarily span southern Imperial County, California, connecting the existing North Gila substation in Yuma County, Arizona, and the Imperial Valley substation in Imperial County. 

The critical east-west corridor would serve southern California’s and southwestern Arizona’s population centers, unlocking access to vast resources in Arizona and California’s Imperial Valley region.

 

What is the purpose of the Ironwood transmission line?

In May 2023, CAISO identified a portfolio of transmission projects in its 2022-2023 Transmission Plan that are needed to meet growing energy demand.

CAISO is the non-profit, independent system operator responsible for maintaining the reliability of the electric grid, planning for new transmission lines and operating the wholesale energy market in California and a small portion of Nevada. A new approximately 87-mile, 500-kV transmission line was included in the CAISO’s 2022-2023 Transmission Plan.  

Overall, the proposed transmission line will help maintain the reliability of the electric grid and help meet state energy goals by providing access to multiple energy resources.   

 

What is your role in this project? 

The CAISO selected Horizon West Transmission as the project sponsor for the Ironwood transmission line.  

Horizon West is now developing a detailed environmental assessment to evaluate proposed routes, which will be shaped by input from stakeholders, environmental groups, local governments, Tribal Nations and other interested parties.

 

Who will receive the power?

The Ironwood power line will help provide critical reinforcement of the electric grid in southern California and southwestern Arizona and provide over 3,000 megawatts of transfer capacity, enabling the delivery of energy to population centers in the region.

 

How will local communities benefit from the Ironwood project?

The project is expected to provide numerous benefits to the local community, including:

  • Providing increased access to low-cost, reliable energy to California and Arizona
  • Improving the reliability of the regional electric grid
  • Spurring investment in local economies during construction
  • Limiting impacts to local landowners by using existing transmission corridors and federal land where possible
  • Enabling further development of Imperial County’s resources industry
  • Providing state and local tax revenues of more than $128 million over the life of the Ironwood project that can be used to help fund schools, parks and roads

 

Where will the project be located?

The proposed transmission line will be located in southern California and southwestern Arizona. 

A detailed environmental assessment is being conducted to evaluate proposed routes, which will be shaped by input from stakeholders, environmental groups, local governments, Tribal Nations and other interested parties.

After an independent analysis and public input, the California Public Utilities Commission, Arizona Corporation Commission and federal siting authorities will issue the final determination on the transmission line route.  

 

What is the expected schedule?

The Ironwood Transmission Line is anticipated to be in service by 2030. The project schedule is subject to change based on regulatory approvals.

Estimated project schedule: The Ironwood Transmission Line is anticipated to be in service by 2030.

 

*The project schedule is subject to change.

The process to build transmission lines in California provides multiple opportunities for public participation. To start, Horizon West Transmission, a regulated public utility in California, conducts engineering and technical studies. Horizon West then solicits input from local communities and develops the project plan and preferred and alternative routes. When ready, Horizon West Transmission must obtain a Certificate of Public Convenience and Necessity (CPCN) from the California Public Utilities Commission (CPUC), which is a public process. The CPUC, which oversees California public utilities, issues a permit based on an environmental review, project need and cost. The Bureau of Land Management and Arizona Corporation Commission have separate but similar review processes. For additional details, please email us at horizonwest@nee.com.

The process to build transmission lines in Arizona provides multiple opportunities for public participation. To start, Horizon West Transmission, a regulated public utility, conducts engineering and technical studies while coordinating with key stakeholders, including Tribal Nations, and federal, state and local agencies to identify the least impactful routing and siting options. Horizon West solicits input from local communities and develops preferred and alternative routes. Horizon West submits an application to the Arizona Corporation Commission (ACC) for a Certificate of Environmental Compatibility (CEC). The ACC’s Power Plant and Transmission Line Siting Committee evaluates the project, hosts a public hearing and issues a recommendation on the CEC. The ACC considers the recommendation during a public meeting, votes and issues a decision.  Horizon West anticipates filing its CEC application to begin the state permitting process in 2026. For additional details, please email us at horizonwest@nee.com.

Have questions?

For project inquiries, please email us at horizonwest@nee.com.