Project Location

Connecting southern Arizona and southern New Mexico, the project is designed to collect and transmit electricity, especially from renewable resources, while minimizing impacts to the environment and local communities.

The Southline Transmission Project is comprised of two sections:

  • The New Build Section would involve the construction of approximately 240 miles of new 345-kilovolt (kV) double-circuit electric transmission lines in New Mexico and Arizona, and would provide a capacity of up to 1,000 megawatts (MW). The New Build is defined by end points of the existing Afton Substation, south of Las Cruces, New Mexico, and the existing Apache Substation, south of Willcox, Arizona. This section includes an approximately 30-mile segment between Hwy 9 and I-10, which would enable potential access to the rich renewable resource areas of southern New Mexico, and a 5-mile loop between the existing Afton Substation and the existing Luna-Diablo 345-kV transmission line (a technical requirement of the project which serves to strengthen the existing system).

  • The Upgrade Section would consist of double-circuit 230-kV lines connecting the Apache Substation to the existing Saguaro and Tortolita Substations northwest of Tucson, Arizona. The Upgrade Section would rebuild approximately 120 miles of existing single-circuit 115-kV transmission lines, currently owned by the Western Area Power Administration (WAPA), providing up to 1,000 MW of transmission capacity between these substations. A new line segment approximately 2 miles in length will be required to interconnect with the existing Tucson Electric Power Vail Substation, located just north of the existing WAPA line.

The Project will interconnect with up to 14 existing substation locations and may include development of a new substation in Luna County, New Mexico.

Click here to access maps of the Southline Transmission Project.