Aspen is preparing an EIR/EIS for the Transmission Agency of Northern California (TANC) and Western Area Power Administration (Western), which is proposing to provide approximately 600 miles of new 500-kV and 230 kV transmission lines and associated facilities to the California electric system. The TANC Transmission Project (TTP) will provide new access to renewable energy resources in northern California, northwestern Nevada, and the Pacific Northwest; enhance the California-Oregon Intertie; reduce existing congestion and system losses; increase the load-carrying capability and reliability of northern California's transmission system; improve the reliability of Western's existing Balancing Authority Area; and relieve existing electrical transmission system constraints in northern California.

The proposed TTP consists of five segments of transmission line corridors that extend from northeastern California through the Central Valley and split westward to the San Francisco Bay area and eastward to the Sierra Foothills. The proposed corridors have been identified to avoid, to the extent possible, residential and known environmentally-sensitive areas, and take advantage of accessible competitive renewable energy zones, as recommended by the State of California's Renewable Energy Transmission Initiative.

The EIR/EIS discusses the potential environmental effects of the proposed TTP, and provides mitigation measures that could minimize any potential significant adverse effects. It also discusses the potentially significant environmental impacts of the alternatives to the transmission line routes and the proposed mitigation to reduce those impacts.

On February 27, 2009 TANC and Western issued a Notice of Preparation for the EIR for the project. The Draft EIR/EIS is expected to be published in late 2009.