Background 

What is WestTEC? 

WestTEC is an unprecedented partnership among diverse sectors of the energy industry, States and Tribes, environmental groups and project developers, that is focused on addressing urgent interregional transmission needs across the Western states. It is facilitated by the Western Power Pool and supported by independent industry consultants.   

Why is this planning process urgently needed? 

Electricity demand in the West is growing rapidly today, in sharp contrast to the last three decades. Electrification of many tasks—space heating and cooling, electric vehicles, manufacturing and industrial energy needs—together with the growth of data centers, is driving that growth. More extreme weather events can test electric utilities’ ability to serve peak loads. At the same time, new transmission links are taking longer to be sited and connected to the grid.  

WestTEC was launched as the necessary coordinated, data-driven analysis of Western transmission needs for the immediate and extended future. The scope includes planning analysis across the Western Interconnection to develop two major studies: this 10-Year Horizon Report focused on identifying near-term, actionable transmission upgrades needed by 2035, and a subsequent 20-Year Horizon Report that evaluates longer-term planning scenarios and transmission roadmaps through 2045. 

How does this work complement or differ from existing regional and interregional transmission planning processes? 

WestTEC was launched to address structural and analytical gaps in Western transmission planning. Current frameworks are widely recognized as insufficient for producing interregional transmission lines that connect the West’s regions and states. As the Western Interconnection experiences rapid load growth from electrification, the expansion of data-center and industrial demand, and accelerated resource additions to support resource adequacy and policy goals, the limitations of current processes have become more pronounced.

WestTEC proposes to bridge these gaps by enhancing interregional coordination, recognizing that while the Western grid is highly interconnected, its planning remains fragmented. Industry-led and guided by four commitments—different, inclusive, expedient and transparent—WestTEC provides a voluntary, credible platform for aligning methods, data and planning assumptions across the region. 

Why did WestTEC bring together a broad group of stakeholders? How many organizations were involved? How is WestTEC governed, and how are decisions made? 

Bringing together a broad group of stakeholders helped integrate diverse perspectives from the beginning, fostering widespread understanding and support. Over 70 individual organizations or agencies from all types of sectors across the energy industry participated, including states, Tribes, utilities, power marketing administrations, consumer advocates, independent power producers, independent transmission developers, public interest organizations, large loads/commercial loads, environmental organizations and more. 

WestTEC’s governance structure consists of three main committees: The Steering Committee, the WestTEC Assessment Technical Team (WATT), and the Regional Engagement Committee (REC). 

The Steering Committee is WestTEC’s primary decision-making body, working with and taking input from both the REC and WATT, and providing guidance to the WATT.   

The WATT is made up of representatives from organizations on the Steering Committee and selected additional technical and policy experts. The WATT includes an Independent Consultant selected by the Steering Committee who is responsible for supporting the WATT’s work and executing the technical and modeling analysis. 

The Regional Engagement Committee (REC) is the primary regional partner committee led by West-wide representatives of various industry sectors, including consumer-owned utilities, independent power producers, independent transmission companies, public interest organizations, consumer advocates, Tribes, and representatives of the WestTEC Steering Committee. The REC is responsible for reviewing scopes of work for technical studies, study proposals and other deliverables, bringing stakeholder input into the process, and providing feedback and recommendations to the WATT and Steering Committee. 

How does WestTEC ensure transparency and credibility in its work? 

Transparency is one of WestTEC’s foundational themes, carried out principally through the Regional Engagement Committee and a series of public webinars that provide frequent updates on the project. The unprecedented inclusivity, opportunities for input and feedback, reliance on sound data and use of well-respected independent consultants ensures a credible work product. 

What opportunities existed for stakeholder input during the study? 

The Regional Engagement Committee includes representatives from a broad range of industry sectors and stakeholders providing input, feedback and recommendations along the way, helping develop the study plan, informing the methodology and reference case, and helping build the scenarios that will be used in the 20-year study. REC meetings are open to the public and recordings are made available online. There have also been public webinars providing overall WestTEC updates about once a quarter. 

How is WestTEC engaged with States? 

WestTEC engages with states primarily through the CREPC Transmission Collaborative (CREPC-TC), which was formed alongside WestTEC as a specialized working group under the Committee on Regional Electric Power Cooperation (CREPC). The CREPC-TC provides a forum for utility commissioners and energy offices from Western states and provinces to share perspectives and coordinate on transmission planning, cost allocation and other regionally significant transmission issues. 

WestTEC leadership regularly meets with the CREPC-TC to review study plans, scenarios, and data assumptions, ensuring that state perspectives from across the West are incorporated into the design of the regional transmission study. In addition, state liaisons participate on the WestTEC Steering Committee and the WATT, supporting a consistent two-way flow of information between state policymakers and the WestTEC planning process. 

How has WestTEC engaged with Tribes? What future opportunities exist for Tribal input as projects move forward? 

WestTEC representatives have actively pursued opportunities to work with Tribal representatives and proposed several engagement pathways to ensure outreach with Tribes would be as robust as possible, remaining open to any additional suggestions. WestTEC determined the most effective early approach was to invite Tribal representatives to participate in existing committees and to meet Tribes where they are. This resulted in active engagement from several Tribal representatives, supplemented by outreach from WestTEC representatives at numerous Tribal conferences and organizational work groups. 

We recognize there is still much more work to do to strengthen Tribal engagement across the West. We understand ongoing, active engagement is essential, and we remain open to suggestions on how best to share information and seek feedback. 

What is the intended outcome for the 10-year report? 

WestTEC’s intent was to create an “actionable” study, meaning it contained practical recommendations and data designed to support the development and construction of actual transmission projects that improve the reliability and efficiency of the power grid. The results are a blueprint that developers, utilities and states can follow, guiding local and regional planning. The report itself provides a sound, credible evidence-based foundation that developers and regulators can rely on to advance projects.  

How long did it take to complete the report and how much did it cost? What is the timing for next steps? 

The WestTEC team scoped the work in late 2023 and officially began the project in 2024, leading to the release of the 10-year report on February 4, 2026. The 20-year report is expected to be completed before the end of 2026. The total cost of the WestTEC project is $6.1 million, including all technical work and stakeholder engagement, which has been extensive and spread over 2 1/2 years of work, as well as the development of new technology, models, and datasets. If WestTEC goes forward after the 20-year report and iterates to refresh the analysis in the future, we would anticipate some savings for future work because the models, technology and process that support the project are already built. There is an opportunity for stakeholders to continue WestTEC after its first run to refresh the analysis into the future. 

10-Year Horizon Report - Findings 

What are the needed transmission upgrades/additions identified in the 10-year report? 

The study results indicate the need for more than 12,600 miles of regionally significant transmission upgrades or additional transmission lines across the West by 2035. About two-thirds of those are projects that are already planned. The remaining third were identified as needs through the study’s various assessments. 

What are the report’s other key findings? 

The study outlined five key findings: 

1. The portfolio is necessary for the West to meet growing demand, integrate new resources, and strengthen reliability. 
2. Timely completion of planned projects is essential. If not, the gap of needed transmission projects will grow, and reliability challenges will worsen. 
3. The new “conceptual” projects identified in the study require sponsorship and support to develop. 
4. Transmission costs are manageable in context and look especially modest when compared to the overall generation and distribution investment in the region. Providing benefits over their decades of operations, these projects can also be seen as mitigating future electricity cost increases. 
5. Coordinated action among Western states, utilities, developers, and regional partners is necessary and can overcome development challenges. 

Did the 10-year analysis include a detailed benefits analysis? If there isn’t such an analysis, what are the benefits of the lines on the map? 

The 10-year study does not include a detailed benefits analysis. There will be a benefits analysis featured in the 20-year horizon study. This 10-year report does provide a blueprint for the future grid that supports increased reliability by ensuring resource adequacy and increasing resiliency. Benefits of completing the transmission solutions recommended in the study include: 

• Improving efficiency of grid operations, reducing congestion and lowering operating costs 
• Enhancing the ability to operate as an integrated network, sharing resources from one region to another especially in stressed conditions 
• Enabling the Western grid to support continued load growth and economic development across the region 

Does that outweigh the risks? 

We understand the risk inherent in developing transmission and the impact on communities. However, we believe the benefits far outweigh the risks, and that the greatest risk is to reliability if the transmission is not built. 

What happens if the transmission is not built? 

There is a real possibility that without this transmission infrastructure, the ability to reliably deliver electricity across all conditions is at risk. There could be higher costs and an inability to connect and share new generation resources across a wide footprint. In addition, states could struggle to meet policy objectives. 

Are the lines on the 10-year map the routes that will be used? 

In many cases, the lines on the map for the proposed projects are illustrations of conceptual potential transmission corridors and do not represent actual siting, alignments or final corridors for these projects. The exceptions are the planned projects that are far enough along in development such that their final routing has largely been determined. Final alignments are determined in a state-led siting process. 

Where will these new and upgraded power lines be located? Will they have to go through my community or through environmentally sensitive natural areas? 

There is always a tradeoff between bringing reliable power to communities and the visual and other impacts of the power lines. Engagement with communities and stakeholders is required to seek least impact routes. However, this plan isn’t intended to deal with the siting process, only to lay out what the emerging needs are and how to most cost-effectively meet them by adding capacity in critical corridors. 

What are the biggest uncertainties underlying the report’s conclusions? 

This study’s conclusions—like all studies evaluating future transmission needs—are subject to material uncertainties. Examples include the actual amount and location of realized load growth, the amount and type of resource deployment and the development feasibility of the identified transmission projects, among many other factors all with some degree of uncertainty. While WestTEC deployed state-of-the-art tools and updated data, many factors can influence transmission need and solutions. These uncertainties can be addressed through scenario analysis and continual revaluation of transmission needs and solutions, among other strategies. 

What will it cost to build all the necessary transmission projects? 

The estimated cost of the projects identified in the study is about $60 billion (in today’s dollars). However, it’s important to look at this cost in the proper context. The annualized cost of the projects is about eight times less than the cost of the generation resources that must be added over the same time horizon. Additionally, the WestTEC 10-year portfolio’s total cost represents only about 2.5% of the average retail electric price in the West. In the long term, these transmission investments can be considered a cost-containment measure against future cost increases. This occurs by ensuring customers have access to lowest cost resources while avoiding economic inefficiencies on the grid. In this way, it will cost less to deliver reliable power in 2035 to electric customers across the Western grid by building this infrastructure than it would without it. 

10-Year Horizon Report - Methodology 

What was the methodology used in the study? 

The 2035 reference case was built using validated utility plans and best-available load, resource and transmission forecasts. This compilation of “bottoms up” forecasts sourced from utilities and other regional entities was critical to build a plausible reference case, which was needed for the consultants to perform transmission modeling and assessments. The transmission planning analysis followed a rigorous  developed with robust stakeholder input. 

What were the assessments used to determine transmission needs? 

The reference case provided the foundation for three assessments to determine transmission needs. 

1. The analysis uncovered areas with fundamental reliability needs. Upgrades to the transmission system would be needed to address these issues and ensure system reliability. This assessment is referred to as the System Reliability Analysis. 

2. The West’s transmission grid is increasingly operating as an integrated network, especially during stressed conditions where one region must rely on neighboring regions to help keep the lights on. The analysis identified projects needed to enhance connectivity between regions, which will help realize diversity benefits the future grid will rely on. This is the Interarea Deliverability Analysis. 

3. The analysis found economic inefficiencies or “bottlenecks” on the system. Projects are needed to relieve these highly congested constraints and increase access to more economic resources. This is the Congestion Analysis. 

What was not included in the report? 

The study scope was limited to recommendations for new or upgraded transmission lines. It did not consider siting or alignment, permitting, or cost allocation. However, WestTEC does enable and encourage coordination and employing all possible tools to overcome these and other development challenges.  

What assumptions were made about future load growth and resource additions? 

Load projections were sourced primarily from the WECC 2034 Anchor Data Set (ADS) and refined based on benchmarking with NREL’s Electrification Futures scenarios, review at WATT, and load data updates provided by utility participants. The resulting forecast shows peak demand growing at about 2.4% per year over the next 10 years. 

The resource trajectory is based on utility resource plan forecasts, so it is consistent with utility procurement plans and state policy objectives. WestTEC used existing and planned resources from the WECC 2034 ADS as a starting point, and added conceptual resources from the IRPs.  

Does the 10-year study assume there is any offshore wind?  How about nuclear? 

Resources in the 10-year timeframe are aligned largely with Western IRPs and other publicly available plans and documentation, including the CAISO 24-25 TPP. The 10-year study assumes that currently operating nuclear stations, including Palo Verde and Columbia Generating Station, remain operational through 2035. The study also assumes, consistent with PacifiCorp documentation, that approximately 345 MW of planned nuclear technology is operational in PacifiCorp East in Wyoming by 2035. 

The 10-year resource portfolio did not contain any offshore wind, but it is present in the 20-year resource portfolios consistent with CAISO TPP plans beyond a 10-year timeframe. 

Did the 10-year analysis make any assumptions about CAISO EDAM and SPP Markets+? If not, doesn’t that mean the 10-year results won’t really represent the way that energy will flow on the system? 

WestTEC performed the study assuming a future in which the West operates under a single day-ahead energy market. This allowed the study to focus less on near-term market seams (which could evolve over time) and more on long-term fundamentals that are likely to drive transmission infrastructure. 

WestTEC acknowledges that future iterations of WestTEC or other long-term planning efforts could include analysis of EDAM and Markets+ development. 

How does this report interact with FERC transmission planning and cost allocation rules? 

The WestTEC process is a complement to FERC-mandated transmission planning. It is non-jurisdictional, offers additional information and integrates insights across planning entities and regions. WestTEC does not consider cost allocation within its scope. 

What’s next? 

The study is intended to provide a blueprint for what transmission is needed; how does this blueprint get implemented? 

The report provides a blueprint for the future power grid, which developers, utilities, states and other organizations can use to guide coordinated implementation. While the report is intended to inform local and regional planning and catalyze development, it is up to others to bring these projects to life – WestTEC itself does not develop transmission projects. However, we recognize meaningful and sustained stakeholder engagement is essential to successful project development and that coordinated action can help overcome development challenges. 

What happens next for WestTEC? 

Following the release of the 10-year report, WestTEC will work to complete the 20-year horizon study, which is expected in 2026. Beyond that, the role of WestTEC is uncertain, though there is a need for ongoing interregional planning and analysis in the West, especially as conditions change. 

How does the 10-year analysis relate to the 20-year analysis? Do they build on each other? 

The 10-Year Horizon Study focuses on immediate transmission needs, while the 20-year Horizon Study will place greater emphasis on addressing planning uncertainties and quantifying the long-term value of a range of transmission portfolios. Specifically, the 20-year study includes an expanded reference case and examines scenarios that explore possible future states of the Western grid based on variations of technology development, load growth, policy changes and other factors. Importantly, the transmission portfolio included in the 10-year report may be adjusted based on what is learned in the 20-year analysis.