October 21, 2025
PHOENIX – Western Resource Advocates today celebrated a ruling by the Maricopa County Superior Court that found the Arizona Corporation Commission exceeded its authority in overturning a decision by the state’s Power Plant and Transmission Line Siting Committee requiring UniSource Electric to first obtain a certificate of environmental compatibility before it can build a 200-megawatt methane gas plant expansion.
WRA applauds the Court’s decision. This ruling benefits all Arizonans by ensuring their voices will be heard when projects like a gas plant expansion will impact them.
In March 2024, UniSource filed a request with the state’s Power Plant and Transmission Line Siting Committee asking for a legal determination that its proposed Black Mountain Expansion Project near Kingman in Mohave County did not require a certificate of environmental compatibility.
Under Arizona statute, certificates of environmental compatibility are required for new facilities that are 100 megawatts or larger. UniSource argued that its project – which includes four new 50 megawatt gas turbines that operate together as a 200 megawatt facility – is four different new plants, each of which is below the threshold for a certificate of environmental compatibility.
The Line Siting Committee’s certificate of environmental compatibility process enables communities, including those already disadvantaged and burdened by existing energy projects, to have a voice in the construction of new facilities. The Line Siting Committee rejected UniSource’s extreme legal argument on May 2, 2024, in a 9-2 vote.
However, with a 4-1 vote June 11, the Arizona Corporation Commission overturned the Line Siting Committee’s decision.
WRA filed a legal challenge to the ruling Aug. 29, 2024, requesting the Court overturn the Commission’s decision. In the complaint, WRA argued that under Arizona statute, the Commission is not authorized to review decisions made by the state’s Line Siting Committee concerning whether a major energy project needs environmental review. The Sierra Club and the Arizona Attorney General also filed suit. Today, Superior Court Judge Dewain D. Fox agreed with WRA, and stated the Court will issue an order sending this matter back to the Committee. The Line Siting Committee’s decision requiring a certificate of environmental compatibility now stands, and UniSource must file an application requesting a certificate from the Committee, allowing local communities a voice in the Black Mountain expansion.
The Line Siting Committee has decades of expertise in carefully reviewing applications like the Black Mountain expansion. Moving forward, the Commission should rely on that expertise for similar applications.
Media Contact:
James Quirk, 908-902-3177, james.quirk@westernresources.org
