FOLSOM, Calif. — The Western Energy Imbalance Market (WEIM), operated by the California Independent System Operator (ISO), delivered strong economic value, generating $1.62 Billion in economic benefits to participants during 2025. This brings the total cumulative savings to an impressive $8.24 billion since the market’s launch in 2014.
The WEIM enables balancing authorities across the West to buy and sell electricity in real time, improving grid reliability and reducing costs for customers.
With significant changes in market resources and operational dynamics across the West, maintaining an accurate picture of market performance is essential. Additional time was needed to post this report so that the ISO—working closely with its WEIM partners—could refine the benefits methodology to reflect these evolving market resources and system conditions. This helps to ensure its logic remains robust, transparent, and reflective of current conditions. For further information, please review the updated methodology document.
The 2025 fourth quarter economic benefit for each participant is shown below:
|Participants|(millions $)|
|Arizona Public Service|$ 9.46|
|AVANGRID Renewables|$ 19.85 |
|Avista|$ 5.79|
|Balancing Authority of Northern California|$ 37.15|
|Bonneville Power Administration|$ 3.83|
|California ISO|$ 8.21|
|El Paso Electric|$ 3.67|
|Idaho Power|$ 7.69|
|Los Angeles Department of Water & Power|$ 40.71|
|NV Energy|$ 83.10|
|NorthWestern Energy|$ 23.41|
|PacifiCorp|$ 66.45|
|Portland General Electric|$ 10.76|
|Public Service Company of New Mexico|$ 34.78|
|Puget Sound Energy|$ 16.58|
|Powerex|$ 0.93|
|Seattle City Light|$ 9.00|
|Salt River Project|$ 10.52|
|Tacoma Power|$ 3.05|
|Tucson Electric Power|$ 4.52|
|Turlock Irrigation District|$ 0.60|
|WAPA Desert Southwest|$ 15.59|
|Total|$415.65|