2025-2026 Transmission Planning Process: Errata issued to Board-approved Transmission Plan

The California ISO (ISO) has issued an errata to the Board-approved 2025-2026 Transmission Plan to correct and clarify the table of deliverability reservations associated with geothermal resources. The errata can be found on the 2025-2026 Transmission planning process webpage.

The errata updates Table 1-1: Deliverable Resources and Resource Locations in the Board-approved 2025-2026 Transmission Plan to explicitly reflect all geothermal deliverability reservations that were intended for inclusion and that are consistent with the resource assumptions contained in the California Public Utilities Commission's (CPUC) planning portfolio used in the development of the transmission plan. While the transmission plan identified the ISO's intent to reserve deliverability for all geothermal resources included in the portfolio, the approved table did not explicitly specify the full amount of geothermal reservations.

The updated reservations will be incorporated into Cluster 16 interconnection request window materials to ensure consistency between the Board-approved Transmission Plan, the CPUC portfolio assumptions, and the deliverability reservations available to eligible geothermal resources.

The ISO will present the errata to the ISO Board of Governors at its Aug. 2026 meeting.

Please contact Yelena Kopylov-Alford at ykopylovalford@caiso.com or ISOstakeholderaffairs@caiso.com with any questions.