Suncrest 230kV Loop-in Project

The project is designed to enhance reliability to the region and enhance SDG&E’s capability to import more renewable energy from Imperial Valley. It will extend a double-circuit transmission line from the current transmission line between the Sycamore Canyon Substation, near Scripps Ranch, and the Miguel Substation, near Spring Valley, and extend it west to the Suncrest Substation east of Alpine. This region was identified as at risk of overloads and potential outages due to insufficient transmission capacity.

The existing transmission line between the Sycamore Canyon and Miguel substations runs north to south just east of the City of El Cajon. This line will be connected to the new double circuit transmission line, which will run east toward Alpine. Approximately three miles of the line will be underground along La Cresta Road in a more densely developed area. As the route moves east, it will transition to above ground. Near the Loveland Reservoir, the route roughly follows Japatul Road to the south. The last approximately three miles of the route turn northeast and follow an existing 500 kV transmission line to the Suncrest Substation east of Alpine.

This project was identified by the state grid operator, the California Independent System Operator (CAISO), in its 2022 – 2023 Transmission Plan as necessary to improve grid reliability and address operational constraints in the region. The proposed transmission line would span approximately 14 miles, connecting an existing transmission line near El Cajon to SDG&E’s Suncrest Substation, located south of I-8 and east of Alpine. Most of the transmission line will be overhead, with a potential underground segment along La Cresta Road. 

When siting a transmission line, there are a number of factors we consider including cost, environmental impacts, community impacts and engineering constraints. There is also a state policy, called the Garimendi Principles, that encourages siting new transmission facilities in the same corridors as existing rights-of-way, where feasible. In this case, we were able to consolidate transmission lines on the eastern portion of the project in an existing 500 kV corridor. From the existing corridor the route runs west in a manner that avoids adding excessive distance while avoiding scattered residential areas.

As the route gets closer to El Cajon, the area becomes more developed so the line will need to be placed underground to be cost-effective.

This project will require review and approval of the California Public Utilities Commission (CPUC) before it can be constructed. This review will begin with filing an application in late 2025. The CPUC review will include public hearings and opportunities for comment.

If approved by the CPUC, the project would begin construction around 2027 with a completion date expected in 2032.