San Luis Transmission Project

Western proposes to construct, own, operate, and maintain a new 230-kilovolt transmission line about 62 miles in length between Western’s Tracy Substation and Western’s San Luis Substation and a new 70-kV transmission line about 5 miles in length between the San Luis and O’Neill Substations.  Western also will consider other transmission construction options including:

  • a new 500-kV transmission line about 62 miles in length operated at 230-kV between Western’s Tracy and San Luis Substations;
  • a new 500-kV transmission line operated at 500-kV about 62 miles in length between the Tracy Substation and Pacific Gas and Electric’s Los Banos Substation; and
  • a new 230-kV transmission line about 18 miles in length between San Luis Substation and Dos Amigos Substation. 

Additional components of the proposed project would include constructing:

  • new 230-kV breaker terminal bays at Western’s Tracy 230-kV Substation;
  • new 500-kV breaker terminal bays at the Tracy 500-kV Substation;
  • new 230-kV breaker terminal bays at Western’s San Luis 230-kV Substation;
  • new 500-kV breaker terminal bays at PG&E’s Los Banos Substation;
  • new 230-kV breaker terminal bays at Western’s Dos Amigos 230-kV Substation; and
  • new 230/70-kV transformer bank and interconnection facilities at San Luis Substation.

The proposed project also would include the following facilities and improvements:

  • Right-of-way easements for the transmission lines with a typical width of about 125 to 175 feet for 230-kV lines and 200 to 250 feet for the 500-kV line.
  • Tubular or lattice steel structures used to support the transmission lines.  For the 230-kV line, structures typically would be between 100 and 200 feet tall depending on site-specific conditions.  A few taller structures may be required in some locations to address engineering constraints. 
  • Access roads, including improvements to existing roads, new overland access, and new unpaved temporary roads to access the proposed project facilities and work areas during construction and operation phases.
  • Ancillary facilities, such as communications facilities (e.g. overhead fiber optic ground wires, regeneration facilities) for access control and protection.
Why this project is needed: Western’s transmission contract with PG&E, under which power is transmitted to the San Luis Unit, will end in Spring 2016. The San Luis Unit is a key component in delivering water to central valley agricultural companies and farmers. The transmission lines are intended to minimize expected power delivery cost increases for operating the San Luis Unit.