Let the debate begin: Here's the preliminary 145-mile route for a new SDG&E transmission line
San Diego Gas & Electric has released a preliminary route for a new electric transmission line running from Imperial Valley in the east to the border of San Diego and Orange counties in the west.
A desert conservation group has already come out in opposition to where SDG&E wants the proposed 145-mile corridor to go, while another critic says the line, dubbed the Golden Pacific Powerlink, may not be needed at all.
The debate will begin in earnest in a few weeks, when SDG&E hosts a pair of virtual open houses about the proposed energy pathway. That kicks off a years-long process that includes public hearings, environmental impact reviews and regulatory proceedings on the local, state and federal levels.
Ultimately, the California Public Utilities Commission, or CPUC, will have the final say on where the 500-kilovolt line will go, and whether it even gets built.
How this started
The power grid seeks additional resources to meet growing demand driven in large part by expected data center growth feeding the AI revolution and California’s efforts to switch from fossil fuels to renewable energy sources.
The California Independent System Operator, which manages the electric grid for about 80% of the state and a small portion of Nevada, drafted a 180-page transmission plan for 2022 and 2023.
It cited assumptions that the power system needs to add more than 40 gigawatts of new resources over the next 10 years to keep the electric system reliable and resilient - and meet California’s clean energy mandates.
The state aims to derive 100% of its power from carbon-free sources by 2045. Policymakers also intend to transition from buildings and homes using natural gas to electricity, not to mention converting California’s transportation sector from gasoline to electric vehicles.
“Significant amounts of new diverse generating capacity and the transmission upgrades are required to cost-effectively bring reliable decarbonized power to California consumers and industry across all seasons of the year,” the system operator, also known as the CAISO, said in its report.
The plan found the need for 45 transmission projects, with what was later named the Golden State Powerlink being one of them.
Details of the project
The proposal would connect SDG&E’s existing Imperial Valley substation to a still-to-be-constructed substation where San Diego and Orange counties meet. The exact location, just north of the San Onofre Nuclear Generating Station and Camp Pendleton, has not been released yet. Horizon West Transmission LLC will build the substation.
SDG&E obtained the rights to build the high-voltage transmission line.
The price tag has yet to be released, but it’s expected to come shortly before SDG&E formally files the project with the California Public Utilities Commission later this year. Costs will be spread proportionally among all ratepayers in the CAISO jurisdiction. Of that, SDG&E customers will shoulder 9% of the cost.
“As the state heads towards its 2045 goals, we know as a state that we’ll need significant additional generation,” Erica Martin, SDG&E’s director of project development, said. “And the generation doesn’t do us any good unless we have those energy freeways, the transmission lines, to carry them from the places where it’s generated to the places where people will use it.”
SDG&E recently released a map showing a preliminary route for the Golden Pacific Powerlink. The utility proposes a route that runs north from the Imperial Valley substation, moving laterally through a chunk of Anza-Borrego Desert State Park, heading up into Riverside County near Temecula and then terminating outside of Camp Pendleton.
“In this early phase, SDG&E is really trying to put the best proposal out there that we can, to set the project up for success at the CPUC,” Martin said. “But we will also need right-of-way from federal agencies as well as other state agencies along the route, and those will all have to coordinate and decide the best route for the project.”
The utility will host a pair of “virtual open houses” at noon and 5:30 p.m. on May 12 and 14 for the public to learn more. In-person open houses are planned for the summer and fall, before SDG&E’s filing with the CPUC, which will initiate the formal regulatory process.
A tentative timeline by SDG&E calls for potential construction of the transmission corridor in the fall of 2029, with the CAISO requesting the line going into service in 2032, or “2034 at the latest,” Martin said.
Opposition
Officials at the Anza-Borrego Foundation say the suggested route is a no-go.
“I think we need to take a scalpel to this process, rather than broad brush strokes just to achieve the most amount of money in the fastest amount of time,” said Bri Fordem, the organization’s executive director.
Judging by the map SDG&E released, Fordem estimated the transmission line would go through “anywhere between 25 and 30 miles” of Anza-Borrego Desert State Park.
The area is the “most biologically diverse park in the state system,” Fordem said. “It is home to the most endemic species, meaning these species live nowhere else than Anza-Borrego - the registered and listed endangered species of the Peninsular Bighorn Sheep, among several birds and reptiles, along with Kumeyaay sensitive burial sites that are in the path of this entire line.”
SDG&E calls for running transmission infrastructure alongside existing, but smaller, 69-kilovolt power lines within the park.
But since the Golden Pacific Powerlink is expected to use towers 150 to 200 feet tall to carry the power lines, Fordem expects the towers would meet Federal Aviation Administration requirements to have red lights atop them that would mar the desert’s night skies and increase light pollution.
“Nobody’s going to camp under the hum of a 500-KV line for a natural world experience,” she said.
The Anza-Borrego Foundation wants SDG&E to avoid the park altogether, by going above it from the north or below it from the south.
“If they’re committed to the resources of the county that they serve, they would be holding Anza-Borrego Desert State Park up high as an environmental commitment to their region and the rest of the state of California,” Fordem said.
Martin of SDG&E says the sheer size of Anza-Borrego, which is the largest of California’s state parks, makes it “not feasible” for the proposed transmission line to avoid crossing it. Plus, making the line longer increases costs, which are passed on to ratepayers.
The CPUC allows SDG&E to earn a “return on equity,” or profit, of 9.88% on infrastructure projects the commission approves.
Bill Powers, board member of the San Diego-based Protect Our Communities Foundation, sees parallels between the Golden Pacific Powerlink and SDG&E’s Sunrise Powerlink.
Described as one of the most scrutinized transmission projects in state history, the 117-mile Sunrise Powerlink went through an exhaustive environmental review that took five years, followed by about 18 months of construction, before it went into service in June 2012 at a price tag of $1.9 billion.
“A little-known historical fact is the (CPUC) administrative law judge’s draft decision in the Sunrise Powerlink case was to deny it,” Powers said.
Rather than building the Golden Pacific Powerlink, Powers suggests SDG&E upgrade existing transmission lines, using advanced composite conductors, and replace single-circuit towers with double-circuit towers. Doing those things, he says, could boost current capacity by twice as much.
More broadly, Powers thinks the CAISO, the CPUC and the state’s investor-owned utilities should ramp up rooftop solar installations to obviate the need to build more transmission lines.
“We have at least three times as much rooftop and parking lot solar potential in the urban and suburban areas of San Diego County, which is essentially the territory of San Diego Gas & Electric,” he said, which can help meet the state’s 2045 carbon-neutrality target.
SDG&E’s Martin deferred to the CAISO report that said the transmission project is needed.
“The state urgently needs the significant amount of generation, and there’s no clean energy transition without transmission,” she said. “We can’t afford to take 10 to 20 years to build a transmission line anymore.”
Because the Golden Pacific Powerlink involves electricity transmission and distribution, the project’s costs would also be shared by customers enrolled in the two community choice energy programs in the San Diego area - the Clean Energy Alliance and San Diego Community Power.
To register for the virtual open houses on May 12 and 14, go to the Golden Pacific Powerlink’s dedicated website, www.goldenpacificpowerlink.com.
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This story was originally published April 26, 2026 at 6:15 AM.