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Idaho-Nevada transmission line starts construction after decades of planning

Idaho-Nevada transmission line starts construction after decades of planning

Built World

285-mile SWIP-North segment completes a 576-mile corridor linking Idaho wind to California demand

3 days ago: Construction officially underway

Overview

Updated 2 days ago

A 285-mile transmission line connecting Idaho to Nevada broke ground September 3 in Ely, Nevada. It completes a corridor first conceived in the 1980s: California wants Idaho wind moving south, and Idaho wants Desert Southwest power moving north.

The Southwest Intertie Project-North (SWIP-North) segment costs more than $1 billion and is expected online in 2028. A federal capacity-contract agreement worth up to $331 million was terminated in June, but construction is moving ahead.

Why it matters

If the line slips, Idaho faces grid shortfalls and California loses its one active route to Idaho wind power.

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Key Indicators

2,000 MW
Bidirectional capacity once corridor completes
Full Southwest Intertie Project moves 2 gigawatts either direction, with 500 MW northbound for Idaho Power.
285 miles
Length of SWIP-North segment
Runs from Midpoint Substation near Twin Falls, Idaho to Robinson Summit Substation near Ely, Nevada.
$1 billion+
Project investment
LS Power's total investment in the SWIP-North transmission line.
$331 million
DOE capacity agreement (terminated June 2026)
The Department of Energy committed up to $331 million in May 2024. The capacity-contract arrangement was terminated effective June 30, 2026; construction proceeds without it.

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People Involved

Organizations Involved

Timeline

1980s September 2026

11 events Latest: 3 days ago Showing 8 of 11
Tap a bar to jump to that date
  1. Construction officially underway

    Latest Milestone

    Engineering News-Record confirms the $1B-plus line is in construction, decades after first conceived.

  2. Groundbreaking in Ely, Nevada

    Milestone

    Nevada Governor Joe Lombardo joins LS Power officials to mark the start of construction.

  3. DOE capacity-contract agreement terminated

    Funding

    GBT Northbound LLC and other parties gave notice terminating the $331 million DOE capacity-contract facilitation agreement, effective June 30, 2026. DOE materials do not indicate withdrawal of a direct construction grant.

  4. Right-of-way nearly secured

    Milestone

    California ISO reports 99% of right-of-way acquired, project on track for June 2028 operation.

  5. Nevada regulators approve construction

    Regulatory

    Nevada gives the green light for the portion of the line crossing its state.

  6. Idaho regulators approve 500 MW deal

    Regulatory

    Commission approves Idaho Power's participation, citing projected shortfalls without the line.

  7. DOE commits up to $331 million

    Funding

    The US Department of Energy backs the roughly $1 billion project with federal capacity funding.

  8. California ISO selects Great Basin

    Decision

    CAISO picks LS Power's Great Basin Transmission to develop the SWIP-North segment.

  9. DesertLink segment begins delivery

    Construction

    The 60-mile DesertLink line connects the corridor to the California ISO grid.

  10. First corridor segment enters service

    Construction

    One Nevada Transmission Line, a 231-mile segment from Robinson Summit to near Las Vegas, goes live.

  11. Southwest Intertie corridor conceived

    Planning

    The idea of a high-voltage corridor linking Idaho and Nevada first takes shape.

Scenarios

1

SWIP-North energized on schedule in mid-2028

Likely Resolves by Q2 2028

Discussed by: California ISO, which in March 2026 reported the project at 99% right-of-way and on track for June 2028 operation

Construction proceeds without major delay. The line is energized by mid-2028, delivering 2,000 MW of bidirectional capacity. California gains access to Idaho wind generation, and Idaho Power's 500 MW northbound capacity comes online as regulators projected.

2

Right-of-way or supply chain delays push completion past 2028

Possible Resolves by Q3 2028

Discussed by: ENR, which noted the project spent decades in development; the outstanding 1% of right-of-way remains a risk

Final right-of-way parcels, equipment deliveries, or contractor schedules slip. The in-service date moves into 2029, extending the timeline for California wind access and Idaho Power's northbound capacity. Cost overruns could follow, raising questions about the federal contribution.

3

Idaho Power under-uses its northbound capacity

Uncertain Resolves by End of 2029

Discussed by: Idaho Power, which bought 500 MW northbound to cover projected shortfalls; regulators approved the deal in December 2025

The line comes online, but Idaho's northbound imports run below expectations if demand growth slows or cheaper generation emerges. Idaho Power reports low dispatch on SWIP-North, raising questions about the cost of its capacity agreement and whether the projection of shortfalls was accurate.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

Completed 1970

Pacific DC Intertie (1970)

The Bonneville Power Administration and Los Angeles Department of Water and Power completed an 846-mile, 3,100 megawatt direct-current line carrying Columbia River hydropower to Southern California.

Then

It eased California's summer peaking strain and gave the Pacific Northwest a market for surplus hydro.

Now

It set the template for trans-regional power exchange in the West, the backbone of the region's grid economics for five decades.

Why this matters now

SWIP-North is the modern version of the same trade: surplus power where it's generated (Idaho wind) moving to where demand is (California), with return capacity for Desert Southwest power.

Groundbreaking June 2023

TransWest Express (2023)

Groundbreaking on the TransWest Express, a 3,000 MW high-voltage line bringing Wyoming wind through Utah to southern Nevada. Construction continues with expected service in the late 2020s.

Then

The line will deliver Wyoming wind generation to California load centers once complete.

Now

It joined a wave of long-haul Western transmission projects showing how wind-rich states become export hubs.

Why this matters now

TransWest and SWIP-North move in parallel: both are Western corridors built on California-ISO access logic and both target 2028-era in-service dates, reflecting the region's coordinated push to move remote wind to population centers.

Sources

(8)