Projects and Resource Planning

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Rosemont 138 kV

Project contingent on mine approval.

The Arizona Corporation Commission (ACC) voted unanimously in May 2012 to allow construction of a new transmission line to serve the proposed Rosemont Copper mine in the Santa Rita Mountains southeast of Tucson.


System Improvements

TEP has made plans for construction of a new 13-mile, 138-kilovolt (kV) transmission line that would link the proposed Toro Switchyard near Green Valley to the site of the proposed Rosemont Copper mine in the Santa Rita Mountains. Construction would begin only after the Rosemont Copper facility receives all necessary permits to develop and operate the mine. For information on the status of the Rosemont permitting process, please visit

More Information

Certificate of Environmental Compatibility (CEC) – PDF 1319 KB
Approved Line Route – PDF 541 KB

Project Archive


Transmission lines are necessary to allow energy to flow from power plants to major substations.

TEP is committed to strengthening the transmission system, which is the backbone of our electrical grid, and allows customers to power their homes and businesses.

Resource Planning

Safe, Reliable Power for the Future

Tucson Electric Power (TEP) is diversifying its portfolio of resources in response to new environmental regulations, emerging technology and changes in our customers’ energy needs.  To inform regulators, customers and other interested stakeholders about these and other changes, TEP and its sister company, UniSource Energy Services (UES), have developed Integrated Resource Plans (IRPs).   These IRPs present the detailed assumptions and analyses used to develop the companies’ strategies for serving customers’ long-term energy needs.

2017 IRP

TEP filed its 2017 IRP with the Arizona Corporation Commission on April 3, 2017. This IRP covers the period from 2017 through 2032.

TEP 2017 Integrated Resource Plan – PDF 10 MB

UES 2017 Integrated Resource Plan

2016 IRP

TEP and UES Supplement to 2016 Preliminary Integrated Resource Plans PDF 786 KB

TEP 2016 Preliminary Integrated Resource Plan – PDF 12 MB

TEP 2016 Preliminary Integrated Resource Plan Update (ACC Workshop) - PDF 12 MB

UES 2016 Preliminary Electric Integrated Resource Plan – PDF 8.15 MB

Harrison Substation

New substation for continued reliability

TEP is proposing to build a new 138-kilovolt (kV) substation at the northwest corner of North Harrison Road and East Speedway Boulevard that will help ensure continued reliability and satisfy customers' future energy needs.

Project Overview

Substation Information

The proposed Harrison Substation is a priority for TEP to ensure capacity and reliability to current and future residential and commercial customers on Tucson's east side. Three existing substations that serve the area are operating at or above capacity.

The proposed substation will connect to the existing 138-kV transmission line located along the south side of East Speedway Boulevard. The substation would improve electric reliability and reduce the frequency and duration of electrical service outages. The substation also would accommodate anticipated future growth in the area. The need for a substation in the area has been identified in long-term transmission plans filed with the Arizona Corporation Commission.

Fact Sheet and Map

If you have any questions regarding this project, please call (520) 884-3642.

Project Archive