LS Power has begun construction on a 285-mile, 500-kV transmission line between Idaho and Nevada, advancing a more than $1 billion project that has spent decades in development as its financing structure and intended uses have evolved.
Great Basin marked the start of project construction on Sept. 3 with a groundbreaking in Ely, Nevada, for the Southwest Intertie Project-North, or SWIP-North, which will fill the missing link in a high-voltage corridor that stretches from Idaho’s Magic Valley to the Las Vegas area.
Nevada Governor Joe Lombardo joined project officials Sept. 3 in Ely, Nev., for SWIP-North’s formal groundbreaking on the 285-mile transmission line.
Photo courtesy of Nevada Governor Joe Lombardo via X
Combined with two existing transmission lines through Nevada, the completed 576-mile corridor will be able to move 2,000 MW in either direction. This two-way capability has become central to the value of the project, as California and Idaho pursue distinctly different uses.
California grid planners advanced SWIP-North primarily to access Idaho’s wind generation moving south. Idaho Power, by contrast, is securing 500 MW moving north from the Desert Southwest markets to help meet growing power demand.
The corridor was first envisioned in the 1980s, according to LS Power, which acquired development rights in 2005. Federal authorization dates to 1994, though the northern segment remained unbuilt.
Stake on the California line
ENR reported in May 2024 that the US Department of Energy had committed up to $331 million to help advance the roughly $1 billion project, with construction then expected to begin in 2025 and finish in 2027. The federal capacity agreement provided temporary support while Idaho Power pursued participation.
In November 2024, the California Independent System Operator (CAISO), California’s grid operator, put the project’s capital cost at $1.23 billion, excluding construction financing costs. About $950 million was associated with the share allocated to its taxpayers.
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California’s stake grew largely from state plans for about 1,000 MW of Idaho wind. Grid studies identified broader benefits, including reduced congestion at the California-Oregon intersection and a route for California’s excess solar power to move north. CAISO called SWIP-North the “only active transmission solution” that provides the state with direct access to Idaho wind. The Federal Energy Regulatory Commission accepted the CAISO-Great Basin development agreement in January 2025, finding its voluntary cost-sharing agreement fair and reasonable and roughly proportional to the expected benefits to California taxpayers.
Idaho takes the northern part
Idaho Power reached agreements with Great Basin the following month for 500 MW to move in the opposite direction, north of the Desert Southwest markets. The company will own an interest in 250 MW and will hold the rights to a further 250 MW for 40 years.
SWIP-North will connect Idaho’s Midpoint substation to Robinson Summit near Ely, Nevada, completing a transmission corridor through Nevada to the Las Vegas area and California’s ISO system.
Map courtesy of LS Power
“SWIP-North will help Idaho Power meet growing energy demands and reduce costs for our customers by connecting Idaho Power to the low-cost energy resources of the Desert Southwest,” Mitch Colburn, vice president of utilities planning, engineering and construction, said in a statement.
Idaho regulators approved the deal in December 2025. Without SWIP-North, commission staff projected that Idaho Power would face capacity shortfalls of 154 MW in 2028 and 384 MW in 2029 and characterized northbound capacity as a lower-cost, lower-risk option.
However, the Idaho Public Utilities Commission did not approve cost recovery for the project, reserving any determination of prudence for a future rate proceeding.
The procedure drew opposition from residents concerned about the integration of the California market and the development of renewable energy. Stop Lava Ridge argued that new Idaho wind projects are unlikely to materialize, while Idaho Power said SWIP-North is a transmission-only project separate from the Lava Ridge wind project, which the Trump administration canceled by the U.S. Department of the Interior last year even though it was scaled back to 1 GW and 241 turbines.
Nevada regulators also approved construction of the network in January 2026. In March, California’s ISO said the project had secured 99 percent of its right-of-way and remained on track to be operational by June 2028.
Construction is progressing
Great Basin had much of the project’s engineering and procurement underway before work began. POWER Engineers, now a unit of WSP Gobal, is the engineer of record and had completed at least 75% of the design by the end of 2024. The transmission line construction agreement uses a fixed global price for most of its scope and includes liquidated damages linked to scheduled milestones.
The work extends beyond the 285-mile line: expansions at the Midpoint and Robinson Summit substations and new series compensation equipment at SWIP-North and the existing One Nevada line, which operate within NV Energy’s system.
The Electrical Workers Union Local 1245 reported in January 2025 that Wilson Construction had been awarded work on the SWIP-North line. The union said in August that Summit had begun foundation work as Wilson prepared to begin construction on the line.
