Black Mountain Expansion Project
UniSource is working to establish greater energy independence and security for customers to reduce our reliance on the regional energy market, where resources are increasingly scarce.
New generating resources will support projected growth and economic development in Kingman, Lake Havasu and throughout UniSource's Mohave County service territory. To satisfy growing customer energy needs, UniSource is exploring a possible expansion of facilities at the Black Mountain Expansion Project located about 15 miles southwest of Kingman. If the station is expanded, it will require a new 230 kilovolt (kV) generation tie transmission line connected at the Griffith Substation which is owned and operated by Western Area Power Administration.
UniSource is in the due diligence phase of this process, collecting and analyzing information before making a final decision to move forward.
Need
UniSource buys much of its power from other providers on the regional energy market. Reliable energy is becoming increasingly unavailable in the desert Southwest, particularly during extreme summer heat. From 2015 to 2021, customers’ peak energy demands increased by 16 percent and we expect strong demand for energy to continue over the next five years.
To preserve the reliability and affordability of our service in the face of growing demand and significantly reduced resource availability on the southwestern regional grid, we must invest in additional resources. UniSource’s 2023 Integrated Resource Plan (IRP) calls for additional renewable, storage and natural gas generating resources by 2038.
Benefits
By expanding local generating capacity, UniSource reduces the need to buy power from the market. Additional capacity will support economic growth and job creation in the Mohave County area. A new, local generating resource will help meet expanding energy needs.
Local generating resources will provide grid stability throughout the Mohave County area. Natural gas-fired turbines, similar to those already in use at Black Mountain Generating Station, can adjust output quickly to meet changing customer energy needs. New natural gas-fired units can provide affordable, around-the-clock reliability for customers today and in the future, reducing costs associated with purchasing energy and transmission across facilities owned by other companies.
Project Description
UniSource is considering the addition of four 50 megawatt (MW) natural gas-fired turbines equipped with state-of-the-art emission controls at Black Mountain. These systems use substantially less water than a conventional steam turbine or a combined cycle plant, minimizing aquifer withdrawals.
Currently, the company is in the due diligence phase, collecting and analyzing information, and identifying air permit and plant and line siting requirements before making a final decision to move forward. UniSource will weigh this option against others submitted in response to an anticipated all-source request for proposals later this year.
A new 230 kilovolt (kV) generation tie transmission line would be needed to connect additional energy resources to the regional grid.
UniSource would construct the new transmission line between the Black Mountain Generating Station and the Griffith Substation, located about 3 miles northeast of the station.
The Griffith Substation is owned and operated by Western Area Power Administration.
The Arizona Corporation Commission voted on May 8, 2025 to approve the Certificate Environmental Compatibility.
In March 2025, the Arizona Power Plant and Transmission Line Siting Committee voted unanimously to approve a Certificate of Environmental Compatibility (CEC) for the Black Mountain 230-kilovolt Generation Tie line.
- Certificate of Environmental Compatibility — granted March 31, 2025
Line Siting Hearing
- Day 1 Transcript — March 24, 2025
- Day 2 Transcript — March 25, 2025
Prehearing Conferences
- Transcript — Jan. 29, 2025
- Transcript — March 19, 2025
Certificate of Environmental Compatibility Application
- Application — Filed Dec. 20, 2024
- Public Notice of Hearing
Prefiling Conference — Dec. 11 , 2024
Virtual Project Tour
In June 2024, the Arizona Corporation Commission voted at an open meeting to approve UniSource’s request for a disclaimer of jurisdiction.
Under Arizona law, individual generating units under 100 megawatts (MW) do not require a certificate of environmental compatibility (CEC). The two existing 45-MW natural gas units at Black Mountain were constructed without a CEC because the capacity of each is below the 100 MW threshold. As such, UniSource asked the Arizona Power Plant and Transmission Line Siting Committee to disclaim jurisdiction over the potential expansion.
Hearing - April 24–25, 2024
- Transcript — Day 1
- Transcript — Day 2
- Order Denying Application for Disclaimer of Jurisdiction — Issued May 2, 2024
Prehearing Conference – April 16, 2024
Procedural Conference – April 8, 2024
Prefiling Conference – Feb. 28, 2024
Application for a Disclaimer of Jurisdiction, or, in the Alternative, a Certificate of Environmental Compatibility
Public and agency input has been an important component of the planning process for the Black Mountain Expansion Project. UniSource has requested public input through open houses, virtual presentations, newsletters, and other forms of communication.
As the project continues through due diligence, permitting, right-of-way acquisition, and construction, residents and other stakeholders are always welcome to share their input by contacting us at:
- UniSource Energy Services
ATTN: Black Mountain
PO Box 711
Mail Stop CB200
Tucson, AZ 85702 - Sending an email to blackmountain@uesaz.com
- Calling 928-681-6500 and leaving a voicemail message.
As required by Arizona law, UniSource obtained a Certificate of Environmental Compatibility (CEC) from the Arizona Corporation Commission (ACC) before constructing the transmission line.
UniSource filed a CEC application in December 2024 with the Arizona Power Plant and Transmission Line Siting Committee (Line Siting Committee). In March 2024, the Line Siting Committee voted unanimously to grant UNSE’s application for a Certificate of Environmental Compatibility (CEC) for the Black Mountain 230 kV Generation Tie Line. The Arizona Corporation Commission reviewed and approved the CEC in May 2025.
UniSource requested, and was granted, a Disclaimer of Jurisdiction from the Arizona Corporation Commission for the expansion of the Black Mountain Generating Station.
January 2025
October 2024
- Project Newsletter No. 2
- Open House Posters – October 2024
- Agency Briefing No. 2 – Presentation
- Visual Simulations — Draft Route Alternatives
- Comments
September 2024
August 2024