Ground broke Sept. 3 outside Ely, Nevada, on a 500-kV line that has been on paper since the Reagan administration. Great Basin Transmission, an LS Power affiliate, is building the 285-mile Southwest Intertie Project-North, which closes the last gap in a high-voltage corridor running from Idaho’s Magic Valley to the Las Vegas area.
Federal authorization for the corridor dates to 1994. LS Power bought the development rights in 2005. Nevada Gov. Joe Lombardo stood at the groundbreaking 21 years later.
What the SWIP-North transmission line connects
Tied into two existing lines through Nevada, the finished 576-mile corridor moves roughly 2,000 MW in either direction. Bidirectional is the operative word here, and it explains how two buyers with opposite problems ended up paying for the same conductor.
California grid planners advanced SWIP-North through the CAISO process to pull Idaho wind generation south. Idaho Power went the other way, securing 500 MW moving north out of Desert Southwest markets to cover load growth at home. Same wires, opposite flows, different hours of the year. That is unusual, and it is the reason a line that sat dormant for three decades suddenly had two revenue streams instead of one.
What a $1.2 billion intertie costs to finance
CAISO put the capital cost at $1.23 billion in November 2024, not counting construction financing. The U.S. Energy Dept. had committed up to $331 million in capacity support back in 2024, a federal backstop that kept the project alive while Idaho Power worked out its participation. ENR reported at the time that construction was expected to start in 2025 and finish in 2027. Both dates slipped, which is roughly par for a 285-mile greenfield line crossing federal land.
Compare that to SunZia or Grain Belt Express Phase 1, both of which spent well over a decade in permitting before a single structure went up. Long-haul transmission in the West doesn’t fail on engineering. It fails on who signs the capacity contract.
Why the groundbreaking matters now
Load growth from data centers and electrification has changed the math on interregional transfer capacity. A line that once looked like a speculative wind export play now reads as a hedge: Idaho gets southwest surplus in winter, California gets northern wind in summer, and both avoid building generation they would rather not own.
The structures go up first, then the conductor. If LS Power holds schedule, the corridor energizes before the next round of Western resource adequacy filings comes due.