Grid United and Black Forest Partners are co-developing Southline Transmission Project (“Southline”), an approximately 280-mile, double-circuit, high-voltage transmission line and associated substation facilities.
Southline will ultimately connect the electrical transmission systems of the El Paso and Tucson areas in two phases, running from Grant County, NM, to Pima County, AZ, then Grant County, NM, to Dona Ana County, NM. This includes a new transmission line between the Afton substation west of Las Cruces, New Mexico, and the Apache substation in Willcox, Arizona, as well as the upgrade of a Western Area Power Administration transmission line between the Apache substation and Vail substation east of Tucson, Arizona. The design provides the capability to transport power bidirectionally and will enable electricity generated in the Desert Southwest to reach key markets while improving the grid reliability of the region.
Southline has been reviewed under the National Environmental Policy Act and has received federal and state permits.
New tax revenue for local governments, communities, and schools: $100 million+
Sponsorships and Donations for local communities: $4 million+
Construction Jobs: 800+
Indirect and induced economic benefits across New Mexico and Arizona: $1 billion+
Enhanced grid reliability and resiliency in the Desert Southwest ➔ a power system that is less vulnerable to price volatility and extreme weather events
Improved interregional transmission ➔ development of new energy generation projects in New Mexico driving hundred of millions in new investment
Routing along existing infrastructure and upgrading existing transmission lines where feasible ➔ minimal impacts to land and resources
Southline successfully completed an in-depth, multi-year federal and state regulatory process through which major state and federal permits have been obtained. Southline is in the final stages of development, which includes completing detailed engineering, performing pre-construction environmental surveys, and finalizing commercial arrangements.
Southline’s Final Environmental Impact Statement was published in October 2015. The Bureau of Land Management and Western Area Power Administration Records of Decision (RODs) were published in April 2016. The Arizona and New Mexico state siting processes were completed in February 2017 and August 2017, respectively.
Southline expects to begin construction in early 2026. The first phase could be operational by 2028, with the full project online by 2029.
Building America's Next-Generation Infrastructure to Power Our Future.
Black Forest Partners and Grid United are co-developing Southline Transmission Project.
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