Project overview
The Golden Pacific Powerlink is a proposed 500 kV extra-high-voltage transmission line from San Diego Gas & Electric (SDG&E), a regulated investor-owned utility whose service territory is San Diego and Orange counties — not Riverside County. Its parent company is Sempra Energy.
SDG&E says the line is needed to meet CAISO's 2022–2023 transmission planning requirements, moving power from southwestern generation areas to Southern California population centers, with a target commercial operation date of 2032 (CAISO's latest required in-service date is June 1, 2034). EHV lines like this typically carry 1,000–2,000 megawatts.
The core grievance: the corridor would route 500 kV towers through Temecula while delivering no direct benefit to the Riverside County residents who'd live beneath them.
The Temecula segment
The preliminary corridor runs from a proposed new substation north of SONGS eastward through Temecula, across the county line toward Palomar Mountain, and down to the existing Imperial Valley Substation. The contested portion in Temecula primarily follows the Temecula Creek corridor — land zoned Open Space Conservation — passing near Vail Ranch Middle School, the Santa Margarita River, and Pechanga tribal land.
Across its full length, the line is roughly 135–145 miles of 500 kV transmission, which CAISO estimated at about $2.3 billion in its Project Sponsor Selection Report (May 9, 2024). That figure is a CAISO planning estimate, not a final cost — SDG&E has not yet published its own, which is expected with its CPUC application. Only about 5 miles run through Temecula — the contested segment detailed below.
- Voltage
- 500 kV extra-high-voltage
- Within city limits
- ~5 miles, I-15 to Anza Rd
- Structures
- Steel lattice towers (~15–21, est.)
- Tower height
- ~125–200 ft (≈12–20 stories)
- Span between towers
- ~1,400–1,800 ft (4–6 football fields)
- Right-of-way
- ~200–250 ft (more on terrain)
- Study corridor
- 1,000 ft wide (not the final RoW)
- Land
- Temecula Creek — Open Space Conservation
Height, span, right-of-way, and the 1,000-ft corridor are figures put on the record at the May 26 Council meeting; the tower count is a community estimate (SDG&E gave none), and SDG&E says engineering is still preliminary — so several are ranges.
How it gets approved
Transmission lines above 50 kV are approved by the California Public Utilities Commission (CPUC) — five commissioners appointed by the Governor. SDG&E's own materials lay out a five-step process, and Temecula was only notified at step 4, after the project had already been planned and bid accepted by CAISO:
- 1California Energy Commission (CEC) — forecasts statewide energy demand.
- 2CPUC — sets generation/storage planning via the Integrated Resource Plan.
- 3CAISO — decides where lines go and picks the solution in its Transmission Plan.
- 4SDG&E — early engineering, environmental studies, community outreach. (← Temecula first notified here.)
- 5CPUC + state/federal agencies — review under CEQA/NEPA, approve, and grant rights-of-way.
What was said on the record
Much of what we know comes from one public, on-the-record accounting — the May 26, 2026 City Council meeting, where SDG&E, the California ISO, and City staff laid out the project and took questions. Each statement below links to the exact moment in the meeting video so you can hear it in context.
The line comes from the California ISO’s 2022–2023 Transmission Plan, approved May 18, 2023 as the “Imperial Valley–North of SONGS” project. It went out for competitive bid, was awarded to Horizon West in April 2024, and SDG&E assumed responsibility to build, own, and operate it in summer 2025.
Pressed on the 2023 bids, CAISO confirmed four were submitted — Horizon West, SDG&E, and California Grid. The Council said the selected Horizon West map was “the only primary map going through Temecula,” with the others routing through open space, and asked to see SDG&E’s original 153-mile route that avoided urban Temecula. CAISO said the full bids are confidential and only a selection report is public.
The 500 kV line would run from the existing Imperial Valley substation to a new “north of SONGS” substation — built by a separate developer — that ties into the 230 kV coastal system.
A 500 kV extra-high-voltage line is built to carry 1,000 to 2,000 megawatts — enough, staff said, to power roughly 1 million to 1.5 million homes.
About 5 miles of the proposed alignment runs through Temecula along Temecula Creek. The mapped 1,000-foot corridor is a study corridor, not the eventual right-of-way — and “no final decisions have been made.”
The cost is “borne by the ratepayers in California … all of the ratepayers of the investor-owned utilities — PG&E, Edison, SDG&E.” (SDG&E’s service territory is San Diego and Orange counties, not Riverside.)
“The largest driver of cost for a transmission line is the length of the line” — each added mile adds construction and material cost, a key factor in how the route gets chosen.
SDG&E is working to CAISO’s target in-service date of 2032: it plans to file its CPUC application before the end of 2026 and to begin construction in the fall of 2029.
See the full meeting — context, public testimony, and the Council's 5–0 vote to oppose the route — on the meeting page.
The bid: four routes, only one through a neighborhood
Before SDG&E ever took it over, the project went out for competitive bid through the California ISO in 2023. CAISO's own list of qualified applicants shows four companies submitted routes. CAISO picked Horizon West's — and according to CAISO's own Project Sponsor Selection Report (May 9, 2024), it was the only one of the four whose route ran through an urban area.
- Horizon West TransmissionSelectedThe only one of the four to route through an urban area.
- San Diego Gas & ElectricNon-urban route; crossed U.S. Forest Service land.
- Lotus Infrastructure / Southern California EdisonNon-urban route; crossed Forest Service and tribal land.
- California Grid Holdings (CalGrid)Non-urban route; crossed Forest Service and tribal land.
“Horizon West proposed a route that would traverse an urban area. The ISO understands that routing transmission facilities in urban areas poses a risk of public opposition, which can negatively impact budget and schedule risk.”— CAISO Project Sponsor Selection Report, May 9, 2024
CAISO acknowledged that risk in writing and selected the route anyway, judging that Horizon West had enough schedule “float” to absorb the delay. SDG&E — itself a losing bidder, with a non-urban route of its own — then took over the winning project's transmission line in summer 2025, so it is now building the Temecula route it did not originally propose. The full bids and the competing route maps remain confidential; only the selection report is public.
The May 26 Council exchange named only three bidders (Horizon West, SDG&E, California Grid); the fourth, named in CAISO's applicant list, was the Lotus Infrastructure / Southern California Edison team. CAISO's report says “an urban area,” not Temecula by name — the Temecula identification comes from the line's preliminary corridor.
It's been stopped here before
This is not the first time SDG&E has tried to push a 500 kV line through this region. In 2002, the CPUC denied the Valley-Rainbow Interconnect — a 500 kV line in this same southwest-Riverside corridor — because the company could not prove it was needed. In 2008, regulators rejected the Sunrise Powerlink's route through Anza-Borrego as “environmentally unacceptable and infeasible,” forcing it off the park. And from 2008 to 2012, this community and the Pechanga defeated the Liberty Quarry on the same county border.
See how this unfolded — and where it's headed.