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Environmental Review -- NEPA
Transmission Infrastructure Program

Southline Transmission Project

A map of Arizona and New Mexico showing potential line upgrades.The Southline Transmission Project  is a proposed transmission line designed to collect and transmit electricity across southern New Mexico and southern Arizona. The project will consist of two segments: 

  • A new 240-mile, 345-kilovolt double-circuit transmission line between the existing substations at Afton, New Mexico, and Apache, Arizona.
  • Upgrade of about 120 miles of Western's existing transmission lines between the Apache and Saguaro substations in Arizona from a 115-kV line to a 230-kV double-circuit line. This upgrade would provide about 1,000 megawatts of capacity.

Western has two public involvement efforts underway for this project:

  1. Transmission customer invovlement
  2. Environmental review process

Transmission customer involvement

Western is evaluating to what extent it will participate in the ownership of proposed project, and is currently seeking input from transmission customers to define if and how Western participates in this project.

Project comments: Transmission customers can send comments or feedback about this project to:


Environmental review process

Western is a joint lead agency with the Bureau of Land Management in preparing the environmental impact statement , or EIS, for the project.

Project documents:

Environmental review process comments: See the BLM Southline web page for how to provide comments.

Project-related sites:

For up-to-date information about the project, visit: