UniSource Energy Corporation (UniSource Energy) is a holding company that conducts its operations through its subsidiaries. UniSource Energy owns Tucson Electric Power Company (TEP), UniSource Energy Services, Inc. (UES), Millennium Energy Holdings, Inc. (Millennium) and UniSource Energy Development Company (UED). The Company conducts its business through three segments: TEP, UNS Gas and UNS Electric. TEP is an electric utility that provides electric service to the community of Tucson, Arizona. UES, through its two operating subsidiaries, UNS Gas, Inc. (UNS Gas) and UNS Electric, Inc. (UNS Electric), provides gas and electric service to 30 communities in Northern and Southern Arizona. UED developed and owns the Black Mountain Generating Station (BMGS), a natural gas-fired combustion turbine in Northern Arizona that, through a power sales agreement provides energy to UNS Electric.