Ten West Link Transmission Line Project is an under construction 125mile (201km)-long, single-circuit, series compensated, 500kV transmission line in the US.

The power line is being built to improve transmission system efficiency between Arizona and California. It will also facilitate the development of new energy storage resources in the two states and help them to reduce their carbon footprint.

In 2015, independent non-profit electricity grid operator California Independent System Operator Corporation (CAISO) selected Delaney Colorado River Transmission (DCRT), a joint venture led by affiliates of Lotus Infrastructure Partners, to develop the project.

The transmission line received Fixing America’s Surface Transportation Act (FAST-41) coverage in 2016 and the Final Environmental Impact Statement (EIS) was published by the Bureau of Land Management (BLM) in September 2019.

The construction of the line was approved by the US Department of the Interior in July 2022.

Construction activities commenced in late-2022, followed by a ground-breaking ceremony in January 2023.

Ten West is expected to start operations by 2024. The transmission link project will be operated by CAISO.

Once complete, the project will strengthen the western electric grid and deliver more than 3GW of renewable energy resources to consumers throughout California and the Desert Southwest.

Ten West Link Route details

The EIS analysed the Applicant Proposed Action and four Action Alternative routes for the project. The Record of Decision (ROD) approved the Agency Preferred Alternative (Alternative 2: BLM Utility Corridor Route).

The decision authorised a 200ft wide, 50-year right-of-way (ROW) grant to DCRT to construct, operate, and maintain the 500kV alternating current (AC) overhead transmission line.

The Ten West Link Transmission Line will stretch approximately 125 miles connecting Arizona Public Service Company (APS) Delaney substation near Tonopah, Arizona, and Southern California Edison (SCE) Colorado River substation near Blythe, California.

Around 103.5 miles of the line will be in Arizona and 21.5 miles in California.

Majority of the route will traverse through federal land, including lands managed by the BLM, Bureau of Reclamation, the US Army and Yuma Proving Ground (YPG).

The selected route will focus on utilising BLM utility corridors and minimise impact on biological, cultural, recreational, and other resources as well as avoid avoiding the Kofa National Wildlife Refuge (NWR).

Ten West Link Infrastructure details

Ten West Link will be designed to transmit 3,200MW of electricity as well as offer connection capability for new energy projects in the region.

The project infrastructure will include a 500-kV transmission line, transmission supporting structures, conductors, overhead ground wire, and a new series compensation system substation (SCS).

The SCS and an overhead 12kV electric distribution line will be located in the middle of the route to service the SCS.

The support structures are expected to be made of steel lattices of various configurations- such as self-supporting lattice, H-frame lattice, and guyed V.

The height of the structures would vary between 72ft and 195ft, based on the span length required and topography.

The distance between the two structures will range between 400ft and 2,300ft.

Wire cables, or conductors, strung between transmission line structures will transmit the electricity. The minimum conductor height above ground would be 36.25ft and 51.25ft for the Colorado River crossing.

The project will use insulators to suspend the conductors from each structure to prevent the flow of electrical current to the ground or another conductor.

Two overhead ground wires would be installed on top of the structures to protect the conductors from lightning strikes.


In October 2022, DCRT closed on a non-recourse project financing for Ten West Link.

The construction financing for the project was led by MUFG Bank, Société Générale and ING Capital.

MUFG and SocGen acted as the administrative agent for the debt facility and as the documentation agent, respectively.

The project is expected to entail an investment of $400m.

Contractors Involved

EC Source, a MasTec company, secured the engineering, procurement, and construction (EPC) contract for the transmission line.

Environmental Science Associates, a US-based environmental consulting firm, was engaged to deliver archaeological monitoring services for the project, while Energy Environmental Group offered environmental services.

Power Engineers was contracted to provide cultural resources services for the project.

EC Source contracted Midal Cables, a leading manufacturer of aluminium overhead conductors, for transmission line conductors required for the project.