The Vail to Tortolita (Vail-Tortolita) 230-kV transmission line rebuild is a joint project between WAPA and Tucson Electric Power (TEP) to upgrade WAPA’s existing infrastructure along an approximately 64-mile stretch in Arizona from just east of WAPA’s Nogales Substation, located in Pima County, to the Saguaro bypass (near Saguaro Substation), located in Pinal County. TEP is funding the project and WAPA is responsible for project management and construction.

The project will replace an existing single circuit 115-kV WAPA transmission line that is constructed of primarily wood H-frame structures with a double-circuit, 230-kV transmission line on mostly steel monopoles. WAPA will own one circuit and operate it at 115-kV. The circuit owned by WAPA will be installed beginning at the Saguaro bypass, include all structures between Rattlesnake to Tucson, and a portion of Tucson to Apache [ending in the vicinity of Nogales]. The circuit owned by TEP will be operated at 230-kV. It will be installed between TEP’s Vail and Tortolita substations, with a connection point at a new DeMoss-Petrie Substation (to be constructed by TEP) adjacent to WAPA’s Tucson Substation. With the exception of Nogales and Del Bac which will be bypassed, both circuits will be connected to each respective substation and switchyard along the route. Included substations and switchyards are Tortolita, Rattlesnake, Tucson, DeMoss-Petrie and Vail. The project will require the installation of approximately 380 steel monopole structures to replace H-frame wood pole structures.

The Vail-Tortolita Project was initially part of the larger Southline Transmission Line ​Project (Southline Project). The Environmental Impact Statement (EIS) process for the Southline Project began in April 2012. In 2021, TEP purchased development rights for the project’s western portion from Southline, LLC, resulting in the Vail-Tortolita Project. The original Southline Project assumed that Southline, LLC would rebuild and construct the project, however, the current plan for Vail-Tortolita is that WAPA will rebuild and construct the transmission line with TEP funding the endeavor. WAPA and the Bureau of Land Management (BLM) were joint lead agencies in preparing the Southline Project EIS. WAPA and the BLM issued the Final Environmental Impact Statement (EIS) [DOE/EIS–0474] on November 6, 2015. Each agency issued a Record of Decision (ROD) based on the Final EIS. WAPA issued its R​OD on April 5, 2016.


Due to project changes since the Final EIS and ROD were issued, WAPA is in the process of preparing a Supplemental Analysis (SA) [DOE/EIS-0474-SA-1] to evaluate the Final EIS [DOE/EIS-0474]. The SA will analyze the changes to the portion of the Southline Project that is now the Vail-Tortolita Project. The SA is expected to be available for public review by summer 2023.


For questions about the environmental review process please contact:

Natalie Ortega, Environmental Manager

Western Area Power Administration, DSW

Phone: (480) 341-0233


For technical questions regarding the project’s design and schedule, please contact:

Jake VanBinsbergen, Project Manager

CD&E on contract to Western Area Power Administration, DSW

Phone: (406) 633-5533




SUPPLEMENTAL ANALYSIS (expected summer 2023)




About WAPA: Western Area Power Administration annually markets and transmits more than 28,000 gigawatt-hours of clean, renewable power from 57 federal hydroelectric powerplants owned and operated by the Bureau of Reclamation, U.S. Army Corps of Engineers and International Boundary and Water Commission in 15 western and central states. It is part of the Department of Energy. For more information, visit​.

About TEP: Tucson Electric Power provides safe, reliable electric service to more than 438,000 customers in Southern Arizona. For more information, visit TEP and its parent company, UNS Energy, are subsidiaries of Fortis Inc. (TSX/NYSE: FTS), a well-diversified leader in the North American regulated electric and gas utility industry. For more information, visit

Last modified on October 17th, 2023