Tracking Transmission Projects

To monitor the timely development of transmission projects, the California Public Utilities Commission (CPUC) tracks planned projects through the Transmission Project Review (TPR) process that includes projects approved through the California ISO’s annual Transmission Planning Process and repair and replacement projects initiated by utilities. The TPR process provides detailed, public bi-annual reporting by investor-owned utilities on active transmission projects in development. The reports provide detailed information about the type of transmission project, approval and development status, among other information. The TPR process requires each of the three large investor-owned utilities (Pacific Gas and Electric Company, Southern California Edison Company, and San Diego Gas & Electric Company) convene bi-annual public meetings where stakeholders can ask questions and receive clarification on the reports. The TPR data is used to monitor transmission project progress and costs, among other purposes.

The latest data shows the following break down for total transmission projects:

 Of 503 total transmission projects, 113 were TPP-Approved, 390 were owner initiated.

The Transmission Development Forum is a biannual public forum between California ISO, CPUC and utilities to provide status updates on approved transmission projects that affect clean energy projects seeking interconnection to the transmission system. Materials from the January 2024 forum are available on the California ISO's website.

The Tracking Energy Development (TED) Task Force is a joint staff effort of the CPUC, California Energy Commission (CEC), and Governor's Office of Business and Economic Development (GO-Biz) to track new energy projects under development. The TED Task Force coordinates action to understand and address barriers impacting energy development throughout the State. While not focused on transmission, the TED Task Force tracks new energy projects in interconnection queues, which may be impacted by delays to transmission expansion projects.

Transmission Project Approval

The CPUC is the lead agency in approving the construction of transmission facilities in the California ISO balancing area. The majority of transmission projects approved through the California ISO’s Transmission Planning Process (TPP) and those initiated by utilities do not require CPUC certification or permits. These projects are exempt from needing CPUC approval. The transmission owner determines if their projects are exempt or require CPUC approval. Projects still under determination are noted as to be determined (TBD).

Those determined to require CPUC approval proceed in one of two ways:

  • Advice Letter – Notice of Construction: This streamlined administrative process allows the transmission owner to file an action request noticing the start of construction.
  • Certificate of Public Convenience and Necessity (CPCN) or Permit to Construct (PTC): These are required for projects that require California Energy Quality Act (CEQA) review by CPUC. Only a small percentage of transmission projects require CEQA review or other environmental studies or assessments. These proceedings are public, providing opportunities for community engagement that can impact the timeline to certify or permit construction. Visit CPUC's current projects for more information about CPUC’s environmental review process and the status of specific transmission projects under CPUC review or monitoring during construction.

Here's how current transmission projects break down by approval method:

A breakdown of the approval processes for the 113 TPP-approved projects and the 390 owner initiated projects.

The TPR Data Fact Sheet contains additional data and analysis.

The CPUC’s General Order (GO) 131-D provides guidance to utilities and private developers on the need to inform the CPUC of their intent to construct a transmission project or go through a formal approval process prior to construction. The general order outlines rules for permitting and construction of electrical transmission lines, power lines, substations, and generation facilities. Public engagement by stakeholders, including communities, is part of the approval process.

The CPUC is updating GO 131-D to implement Senate Bill 529 (Hertzberg, 2022) and to further streamline and clarify the regulatory approval process for electrical transmission infrastructure. Information about the CPUC’s Rulemaking (R.23-05-018) is available on the General Order 131-D Update webpage.

Transmission Project Construction

Following approval by California ISO and CPUC, the transmission project owner must satisfy any conditions of that approval, such as revegetation, wildfire/safety requirements, traffic plans and air quality compliance.

When the project owner receives approval, construction may commence. The project owner must finalize engineering, procure equipment, and secure its workforce for the construction project. While smaller scale projects may be completed within 18 months, larger and more complex projects often take years to complete.


Siting, Transmission, and Environmental Protection Division