Rio Rico-Harshaw 138kV Transmission Line Project

UniSource Seeks Approval for Transmission Line Route

The Arizona Power Plant and Transmission Line Siting Committee will review UniSource’s application for a Certificate of Environmental Compatibility (CEC) at a public hearing beginning Monday April 17, 2023, at 1 p.m. at the Quality Hotel Americana Nogales, located at 639 N. Grand Ave, Nogales, AZ 85621.

Public comment will be taken in a special evening session on April 17, 2023, beginning at 5:30 p.m., via telephone, Zoom, or in person.

Details on how to participate via telephone and Zoom will be posted here at before the hearing begins.

Comment Deadline
Public comments received after Feb. 7, 2023 were not included in UNSE’s CEC application, filed with the ACC on March 3, 2023. We encourage public involvement in this process and continue to accept and review comments. Comments can also be provided during the CEC hearing as described above.

UniSource Energy Services is developing plans for the new Rio Rico to Harshaw 138 Kilovolt (kV) Transmission Line Project.

The Rio Rico to Harshaw Line will involve the construction of an approximately 20-30 mile, single-circuit 138 kV transmission line mounted on steel monopole structures. The project will interconnect UniSource’s existing 138 kV transmission system to the proposed Harshaw Substation through a Proposed 138 kV switchyard in Rio Rico.

The line will serve the Hermosa Project, a mine exploration project in Santa Cruz County owned by Arizona Minerals Inc. (AMI), a subsidiary of South32, while improving service reliability for residential and other electric customers in the vicinity, including the Flux Canyon, San Rafael Valley, Washington Camp and Lochiel areas. UNSE’s existing 13.2-kV distribution line does not have sufficient capacity to support current and future energy needs in these areas while also satisfying the Hermosa Project’s anticipated energy requirements.

Project Details

UniSource Energy Services: Additional documents

Additional documents

Additional information