Western Energy Imbalance Market (WEIM)

Control center modernization is enhancing reliability

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WEIM Q2 Benefits Report
$420.44 million
Savings in Q2 2025
 
$7.4 billion
Total gross benefits since Nov 2014
 
9/19/2025

Gov. Newsom signs landmark legislation for independent governance of Western electricity markets

Governor Newsom’s signing of Assembly Bill 825 is a landmark achievement for the future of energy collaboration and innovation across the Western United States. He, along with the California Legislature and the broad coalition of supporters, have recognized the importance of making this crucial next step toward independent governance of Western electricity markets. Now that AB 825 is signed into law, the ISO will work closely with partners across California and the rest of the region to ensure a more reliable and affordable bulk electric system for the benefit of consumers throughout the West.

The western energy markets encompass the Western Energy Imbalance Market (WEIM) and the Extended Day-Ahead Market (EDAM). Developed in partnership with stakeholders from across the West, these markets have been designed to reflect and respect the region’s diversity.

A west-wide energy market is essential for the efficient and reliable distribution of electricity across the West. Coordinated management of diverse resources across a broad footprint has led to substantial cost savings to customers, improved reliability, and significant environmental benefits.

WEIM

 

The Western Energy Imbalance Market is a stand-alone market platform for balancing authorities in the West, enabling real-time balancing of supply and demand leveraging the diverse resources in the region. Since its launch in 2014, WEIM has expanded to include 21 balancing authorities outside of the ISO across 11 western states.

Learn more about WEIM

EDAM

 

Set to launch in 2026, the Extended Day-Ahead Market extends market operations into the day-ahead timeframe. Available to entities participating in WEIM, EDAM will assist balancing authorities in the West in pre-positioning supply to meet forecasted electric demand for the following day.

Learn more about EDAM

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