Regional collaboration

In pursuit of the vision to operate the world’s most reliable, cost-effective, and environmentally sustainable power system, the California ISO aims to broaden interstate cooperation and collaboration.

Working with partners from across the West, our goal is to collectively shape regional solutions that will advance an affordable and reliable energy transition, maximize electricity consumer savings, grow environmental benefits, and respect state energy policies and objectives.  

Benefits of regional collaboration

There are multiple benefits to creating expanded regional solutions.

  • Wider energy trading markets keeps resource costs down, maximizing consumer electricity savings.
  • Regional coordination increases grid reliability through shared resources. When there’s a cloudy day in one part of the West, and wind output is high in another, power can be moved to where it’s needed most.
  • This resource sharing leads to improved use of clean energy sources, including wind, solar, and hydroelectric power.
  • Entities in a regional partnership can collectively plan for future transmission needs, making the most of existing and new assets.
  • Partners work together while respecting each others’ objectives and policies.

Collaborative energy markets

Regional collaboration, large resource diversity, and broad transmission connectivity across a wide geographical footprint will be key to achieving the greatest economic, reliability, and environmental benefits of a coordinated power grid.

An example of a regional solution already creating great benefits is the Western Energy Imbalance Market (WEIM). Since its launch in 2014, the WEIM has grown to 22 participating balancing areas representing 79% of the load in the Western Interconnection and is approaching $5.5 billion in benefits.

Because WEIM has been successful, the ISO is now working with stakeholders from across the West to expand the real-time WEIM into the day-ahead timeframe through the Extended Day-Ahead Market (EDAM). Read the EDAM fact sheet.

The future of regional collaboration

The EDAM initiative, which leverages and builds on existing features of the ISO’s day-ahead market and the WEIM, includes elements found in similar markets across the country, and used extensive stakeholder input to further improve the market design. The EDAM design was jointly approved by the ISO Board of Governors and WEM Governing Body in February 2023. In December 2023, the Federal Energy Regulatory Commission (FERC) accepted the EDAM tariff changes.

In addition to the EDAM initiative, the Western Interstate Energy Board, a larger group of energy entities, is working on the creation of a large and diverse West-wide electric market, currently dubbed the West Wide Governance Pathways Initiative. This initiative is focused on how to fairly govern such an organization that will enable every willing participant in the West to join in a broad array of market services with a large geographical footprint.

AB 825

Assembly Bill 825, passed by the California Legislature and signed by Gov. Gavin Newsom in 2025, was a landmark achievement for the future of energy collaboration and innovation across the Western United States. By establishing the framework for independent governance of Western electricity markets, the bill enables the California ISO and the state’s electric utilities to work with the new independent Regional Organization for Western Energy to help ensure that California and the rest of the West have a reliable and affordable bulk electric system that benefits consumers throughout the region.

ACR 188

Assembly Concurrent Resolution 188 (2022) requested that the CAISO, in consultation with other California Balancing Authorities produce a summary of recent relevant studies on the impacts of expanded regional cooperation on California.

Mar 8, 2023 Stakeholder meeting

SB 350 Study

California Senate Bill 350 (2015) directed the ISO to study the impacts of expanding the electricity grid over the western United States. Explore the regional energy market, find answers and explore the benefits of the SB 350 study in the fact sheets below.

Fact sheets

SB 350 final study results

View the CEC's Regional Grid Operator and Governance (Docket 16-RGO-1) page. Read the ISO Senate Bill 350 Study Transmittal Letter to Governor Brown from Sept. 15, 2016.

Technical reports and studies

Additional study results, consultant profiles and data

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