Project Information

Project Title

Ironwood 500 kV Transmission Line Project

Sector

Electricity Transmission

Electricity Transmission (all)

Project Location

Location Type: Coordinates

• Latitude *: 32.74569° (32° 44′ 45″ N)
  Longitude *: -114.49128° (114° 29′ 29″ W)
• Latitude *: 32.71791° (32° 43′ 5″ N)
  Longitude *: -115.71556° (115° 42′ 56″ W)

Project Sponsor Contact Information

• Company Name/Agency: Horizon West Transmission
  Project Sponsor: Horizon West Transmission
  Street Address 1 : 1 California Street
  Street Address 2 (Optional): Suite 1600
  City: San Francisco
  State: California
  Zip Code: 94111
  POC Name: Jaime Hoffman
  POC Title: President
  POC Phone: 805-403-2417
  POC Email Address: jaime.hoffman@nexteraenergy.com

Alternative Point Of Contact (Optional)

Yes 

• Company Name/Agency: Horizon West Transmission
  Project Sponsor: Horizon West Transmission
  Street Address 1: 1 California Street
  Street Address 2: Suite 1600
  City: San Fancisco
  State: California
  Zip Code: 94111
  POC Name: Fred Bauermeister
  POC Title: Senior Director
  POC Phone: 650-587-8075
  POC Email Address: fred.bauermeister@nexteraenergy.com

Project Purpose

The California Independent System Operator (CAISO) in its 2022-2023 Transmission Planning Process (TPP) identified a need to add a second 500 kilovolt (kV) circuit between California and Arizona to remedy several existing problems within the regional grid, as discussed in further detail below, and create additional electrical capacity to support further development in the local area. CAISO engaged in a competitive process under Federal Energy Regulatory Commission (FERC) Order No. 1000 and, after evaluating multiple proposals, selected Horizon West Transmission, LLC (Horizon West) to construct, own, operate, and maintain this new high-voltage transmission line. Following project award in April 2024, Horizon West has been actively engaging local communities, potentially affected stakeholders, and the federal and state regulatory agencies with jurisdiction over the project, which Horizon West calls the Ironwood 500 kV Transmission Line Project (Ironwood Project or Project), to identify the least-impactful route, design, and construction schedule that will achieve the project’s requirements while minimizing or avoiding impacts to residents and environmental resources.

As described in CAISO’s TPP, the intent of the Project is to:
• Add more than 3 gigawatts (GW) of available electric capacity to support large-scale industrial and commercial development
• Create a redundant electric source to Yuma County, Arizona to reduce overload risks and provide additional capacity for industrial development in the county
• Mitigate existing congestion constraints and overloads on existing transmission lines in southern California to allow greater power flow and enable access to lower-cost electricity supplies for ratepayers
• Expand the maximum import and export capability for power generated in California and other western states by creating a new interregional connection between the CAISO planning region and WestConnect planning region

Given the necessity for the Project to be constructed and operational in a timely manner to support the country’s energy goals, stabilize the regional electric grid, and provide the needed electric capacity for regional development (such as expanded geothermal energy production and lithium extraction development), Horizon West has developed an aggressive Project schedule that meets CAISO’s in-service requirements while affording ample time for state and federal regulatory review and consideration. Paramount to achieving this schedule and supporting America’s energy dominance is commitment from the lead state and federal agencies—namely, the California Public Utilities Commission (CPUC) and the Bureau of Land Management (BLM)—to commit the necessary personnel and resources for timely and effective review, analysis, and approval of the Project’s permit applications and supporting approvals. Because this Project supports the Administration’s Executive Order 14156 and is not tied in any way to renewable energy facilities, Horizon West is confident that with the support of BLM leadership we can achieve the Project’s construction start in 2029 and in-service date of 2030 to contribute to American energy dominance.

Project Description

The Ironwood 500 kV Transmission Line Project is a proposed approximately 86-mile, 500-kilovolt (kV) transmission line extending between Arizona Public Service Company's North Gila Substation near Yuma, Arizona, and San Diego Gas & Electric's Imperial Valley Substation near El Centro, California. The Project would increase regional transmission capacity, improve electric system reliability, and support delivery of energy resources identified through the California Independent System Operator's (CAISO) 2022–2023 Transmission Plan.

The proposed alignment traverses approximately 47.6 miles of Bureau of Land Management (BLM) land, 8.8 miles of Bureau of Reclamation land, approximately 0.7 miles of California state land, and approximately 29.2 miles of private land. The Project is located primarily within existing designated utility corridors, including BLM Section 368 Energy Corridors, and generally parallels the existing Southwest Powerlink 500-kV transmission line to minimize new disturbance.

Geospatial analyses have been completed using Geographic Information Systems (GIS), aerial imagery, agency databases, desktop studies, and field reconnaissance to identify environmental, cultural, and land use constraints. The Project area includes or is adjacent to sensitive resources including Areas of Critical Environmental Concern (ACECs), National Conservation Lands, the Imperial Sand Dunes Recreation Area, Heber Dunes State Vehicular Recreation Area, Mittry Lake Wildlife Area, the Colorado River corridor, wetlands and jurisdictional waters, desert dune systems, special-status species habitat, agricultural lands, visual resource management areas, and known cultural and historic resources. Cultural resource investigations have identified prehistoric and historic archaeological resources, historic properties, and areas with archaeological sensitivity. Consultation under Section 106 of the National Historic Preservation Act and Tribal engagement are ongoing. Environmental resource surveys and technical studies are being completed to support the National Environmental Policy Act (NEPA) review and will inform final project design, avoidance measures, and mitigation commitments.

Technical and Financial Ability

The Project will benefit from the extensive, enterprise-wide financial resources of its ultimate parent company, NextEra Energy, Inc. (NextEra Energy). Horizon West is wholly owned by NextEra Energy Transmission, a wholly subsidiary of NextEra Energy Inc., one of the largest power and utility holding companies in North America. NextEra Energy Transmission is a leading competitive electric transmission company operating approximately 3,100 circuit miles of transmission lines across 18 states and Canada, representing $8 billion in investments. NextEra Energy Transmission develops, finances, constructs, operates and maintains transmission lines and substations across North America, with a demonstrated specialization in executing large, complex transmission projects. Horizon West has an established track record in California, having been selected by CAISO to develop the Suncrest 230 kV Dynamic Reactive Power Support facility, placed into service in February 2020, and the Estrella Substation, currently under development to improve reliability in the Paso Robles area. As a regulated utility in California working in coordination with CAISO and the CPUC, Horizon West has the technical expertise, organizational infrastructure, and financial backing to successfully deliver the Ironwood Transmission Line.

Summary of Financing, Reviews and Authorizations

Ironwood 500 kV Transmission Line Project will require Federal and State environmental review and authorizations prior to construction. The Project will require a ROW Grant from the BLM and approvals from BOR, USACE, USFWS and potentially the Bureau of Indian Affairs, Department of War and/or Department of Homeland Security depending on the final route determined by the California Public Utilities Commission (CPUC) and BLM. In March 2025, an SF-299 Application and a Plan of Development were submitted to the BLM. BLM will serve as the lead Federal agency for environmental review under the National Environmental Policy Act (NEPA). BLM has yet to publish a Notice of Intent (NOI) formally initiating the NEPA review process.

At the CA State level, a Proponent's Environmental Assessment (PEA) was submitted to the CPUC in September 2025. CPUC will serve as the lead agency for environmental review under the California Environmental Quality Act (CEQA). The PEA was deemed complete in March 2026, and CPUC published a Notice of Preparation (NOP) for the Environmental Impact Report on August 7, 2026, initiating a 45-day public scoping period.

In Arizona, the Project will require a Certificate of Environmental Compatibility (CEC) from the Arizona Corporation Commission (ACC). An application to kick off the ACC process is currently being prepared. A hearing to review the Project and consider approval or denial of the CEC is anticipated to occur in late 2027, following availability of the Draft Environmental Impact Statement (EIS) prepared through the NEPA process and the Draft Environmental Impact Report (EIR) prepared through the CEQA process.

The Project will require completion of the applicable NEPA and CEQA environmental review processes and receipt of Federal, State, and local permits and authorizations prior to construction. Construction is currently scheduled to begin in June 2029, with the Project anticipated to be placed in service in December 2030.

No Federal financing is required for the Project.

Project Assessment

The Ironwood 500 kV Transmission Line Project meets the definition of a "covered project" under 42 U.S.C. § 4370m(6)(A) of the Fixing America's Surface Transportation (FAST) Act. The Project is a major infrastructure project within the energy sector (i.e., electric transmission) that requires authorization and environmental review by multiple Federal agencies and is subject to the National Environmental Policy Act (NEPA). The federal agencies with jurisdiction over the project include the BLM (Yuma Field Office and El Centro Field Office), the Bureau of Reclamation, the US Army Corps of Engineers, the USFWS and potentially the Bureau of Indian Affairs. The California Independent System Operator (CAISO), who determined the Project’s need as part of its annual Transmission Planning Process, anticipates the Project’s total cost to be approximately $340 million. Given the CAISO’s determination of need, identification of a near-term deadline by which the transmission line is needed to be operational, and the continuing challenges associated with progressing the schedule at the Federal level at a rate needed to meet the CAISO’s timeline, the Project would benefit from enhanced oversight and coordination.

Project Resources

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Form Submitter Contact Information

• Name: Jennifer Field
  Title: Director, Environmental Services
  Work Phone: 561-758-7277
  Email Address: jennifer.field@nexteraenergy.com

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