LS Power, through its affiliate Great Basin Transmission, on Sept. 3 held a groundbreaking ceremony in Ely, Nevada, officially marking the start of construction on the Southwest Intertie Project-North (SWIP-North), a new 285–mile, 500 kilovolt transmission line connecting the Midpoint Substation near Twin Falls, Idaho, with the Robinson Summit Substation near Ely, Nevada.
“The project represents a $1 billion-plus investment in power infrastructure that will help strengthen grid reliability, reduce congestion and expand access to diverse power supply resources across the West,” LS Power said.
SWIP-North is the final segment of the Southwest Intertie Project -- a transmission corridor first conceived in the 1980s and advanced by LS Power since it acquired development rights in 2005.
Once complete, the corridor will span 576 miles, connecting Idaho’s Magic Valley near Twin Falls to Nevada’s Eldorado Valley south of Las Vegas.
More than 70% of SWIP-North will be built in Nevada. Once in service, it will complete a high-voltage transmission corridor stretching from southern Idaho to southern Nevada, building on two earlier phases developed by LS Power: the 231-mile One Nevada Transmission Line (ON Line), built in partnership with NV Energy and placed in service in 2014, and the 60-mile DesertLink line, placed in service in 2020.
"Together, these transmission paths create a critical link in the regional grid and enhance reliability through their connection to the California Independent System Operator (California ISO)," LS Power said.
Once SWIP-North is energized, the full transmission path will be capable of transmitting more than 2,000 megawatts of bidirectional electricity across the regional grid, including 500 MW of northbound capacity dedicated for Idaho Power customers.
The California ISO, NV Energy and Idaho Power will all share capacity rights on the line. This stems from an agreement between NV Energy and LS Power affiliates whereby NV Energy covers all costs for ON Line; LS Power covers all costs for SWIP-North; and both share capacity across the full path. LS Power has assigned its capacity rights to the California ISO and Idaho Power.
California ISO President and CEO Elliot Mainzer said, “Major transmission investments like SWIP-North are essential to building a more reliable, resilient and efficient Western grid. By creating a stronger connection across the West, this line will give grid operators greater flexibility to move power where it is needed most, improve access to diverse energy resources, and enhance our ability to respond to changing system conditions and extreme weather events.”
Construction on SWIP-North is expected to be completed in 2028.
Great Basin Transmission was selected by the California ISO in 2023 to develop, permit, finance, construct, own, operate and maintain the SWIP-North Project, with final cost recovery approval in 2024. Idaho Power obtained approval for participation in the project in 2025.
