October 28, 2025
SWIP-N: Meeting California’s Renewable Goals
How California’s Renewable Energy Ambitions Threaten Idaho’s Energy Independence
By: Jeff Pierson
The Devil is in the Details
While reading through the 2022–2023 California Independent System Operator (CAISO) Transmission Plan, one phrase stood out: “regional, policy-driven project.” The term appears again in CAISO’s November 22, 2024 Transmittal Letter to FERC and within the 2022–2023 plan itself.
In its 2021–2023 Transmission Plans, CAISO had described the Southwest Intertie Project–North (SWIP-N) as a candidate for further study or “potential interregional coordination.” By 2023, CAISO’s Board considered SWIP-N “the most cost-effective, timely, and efficient solution to meet an identified public policy need.” In its 2024 filing to the Federal Energy Regulatory Commission under Section 205 of the Federal Power Act, CAISO confirmed the regional designation, explicitly stating that it was pursuing the project under its own tariff as a “voluntary agreement,” not as part of an interregional coordination process.
At first glance, the phrase “regional, policy-driven project” sounds like bureaucratic jargon. In reality, it defines how authority and responsibility are distributed. It means the project is not being pursued solely for market efficiency or grid reliability, but to advance specific state renewable energy policies, primarily California’s. In other words, this is not just about transmitting electricity. It is about who decides where that power goes, whose priorities shape the grid, and who ultimately bears the financial and operational risks.
Regional vs Interregional
Under the regional classification, California, acting through CAISO and its development partner Great Basin Transmission (a subsidiary of LS Power), gained full planning authority over a 500-kilovolt transmission corridor that runs through Idaho and Nevada. Idaho Power and the Idaho Public Utilities Commission (IPUC) remain involved only at the margins. They can regulate local costs, but they no longer share in the planning or decision-making process that determines how the project functions or whom it ultimately serves.
If SWIP-North had been classified as an interregional project, Idaho, Nevada, and California would have been legally required to coordinate planning, share costs, and jointly approve the project through their respective public utilities commissions. Each state would have retained authority over its portion of the costs and benefits, and Idaho would have had the right to evaluate the project’s economic and environmental justification.
By designating SWIP-North as regional, CAISO and LS Power avoided that process entirely. Idaho and Nevada have effectively become corridor states. Their land and transmission corridors are used, but their public representatives no longer have equal authority in deciding how the line operates or what share of capacity their ratepayers may access.
CAISO and LS Power now operate the project under California’s tariff, subject to FERC approval but not to joint state oversight. This structure allows California to decide how the line is built, how capacity is allocated, and how its market rules apply. The project is therefore shaped primarily to serve California’s policy goals rather than the shared reliability and affordability objectives that once defined regional interconnection.
California’s renewable-energy mandates and carbon-reduction targets now dictate the direction and justification of SWIP-North. It is not a partnership. It is a jurisdictional imbalance presented as “regional coordination.”
Market Effects: From Stability to Exposure
As SWIP-N comes under CAISO’s tariff, every megawatt transmitted through it can be priced according to CAISO’s locational marginal pricing (LMP) system. This algorithm determines energy prices based on supply, demand, and transmission congestion across CAISO’s network.
For Idaho Power, this means wholesale electricity traded through SWIP-N will no longer rely solely on bilateral contracts or cost-of-service pricing. Instead, prices will fluctuate with California’s real-time grid conditions. Even limited participation ties Idaho Power’s financial exposure to California’s market volatility.
The risk is most pronounced near the Harry Allen–Eldorado corridor in southern Nevada, one of the most congested points within CAISO’s footprint. Exports from Idaho could face rising congestion fees, while imports back into Idaho could become more expensive when California’s demand spikes.
Bonneville Power Administration (BPA) customers are also indirectly exposed. As CAISO expands its regional influence through projects like SWIP-N, market effects ripple northward through the Western Energy Imbalance Market and day-ahead market integration. Increased California-driven congestion and price volatility can elevate transmission costs for BPA’s balancing operations and influence wholesale rates for public utilities across the Northwest. As CAISO’s policy-driven pricing model extends its reach, traditionally stable hydro-based regions like those served by BPA may face new exposure to California’s market dynamics.
Idaho’s Limited Control
The Idaho Public Utilities Commission (IPUC) retains jurisdiction over Idaho Power’s cost recovery. Idaho Power cannot charge its customers for participation in SWIP-N unless it can demonstrate that the investment is prudent and provides a measurable benefit to Idaho ratepayers.
The IPUC can still:
- Approve or reject Idaho Power’s requests to recover costs through retail rates.
- Review the prudence of expenses related to CAISO market participation.
- Require transparency and accounting for any market settlements tied to SWIP-N.
In practical terms, Idaho still decides what its residents pay. However, because SWIP-N is not an interregional project, Idaho no longer has authority over the line’s planning, sizing, or operation. Those decisions now rest with CAISO, which determines:
- How transmission capacity is allocated among California, Nevada, and Idaho users.
- How congestion and tariffs are priced within its market system.
- How energy flows are prioritized under California’s renewable integration policies.
Bottom Line
SWIP-N changes Idaho’s role in the western power grid. Instead of remaining an independent actor within a shared regional system, Idaho becomes a secondary participant in California’s market.
This alignment introduces three long-term vulnerabilities:
- Price volatility: Idaho’s historically stable rates will begin to mirror California’s fluctuating grid conditions.
- Revenue risk: Idaho Power’s transmission investments could underperform during periods of renewable oversupply or curtailment.
- Policy dependence: California’s energy mandates, not Idaho’s, will determine the long-term value of Idaho’s transmission infrastructure.
The shift is subtle but significant. It transforms Idaho from a sovereign regulator into a dependent market participant.
SWIP-N, once promoted as a regional project intended to enhance shared reliability, now functions as a California-controlled conduit for renewable imports. Idaho retains authority over what its ratepayers are charged, but not over how those prices are formed. That distinction defines the new imbalance in the western grid.
References
California Independent System Operator (CAISO). (2024). 2023–2024 Transmission Planning Process Report.
Federal Energy Regulatory Commission (FERC). (2025, January 21). Order accepting development agreement between Great Basin Transmission LLC and CAISO regarding SWIP-N (Docket No. ER25-543). Washington, D.C.
Idaho Public Utilities Commission (IPUC). (2023). Integrated Resource Planning Guidelines. Boise, ID.
LS Power. (2024). Southwest Intertie Project Overview.
Disclaimer
This analysis represents opinion based on public filings from CAISO, FERC, and Idaho Power as of October 2025. It is for informational purposes only and does not constitute legal or regulatory advice.
