BHE Montana becomes eighth utility to commit to the Extended Day-Ahead Market
FOLSOM, Calif. – BHE Montana, an energy producer, operator and services provider that began participating in the Western Energy Imbalance Market (WEIM) in 2026, has formally committed to joining the California ISO-managed Extended Day-Ahead Market (EDAM) in 2028.
With the execution of its implementation agreement, BHE Montana becomes the eighth balancing authority to formally commit to participating in EDAM, further expanding the market’s regional footprint and benefits.
"The Extended Day-Ahead Market will allow BHE Montana to participate in a broader regional marketplace that helps power producers and transmission providers plan and schedule energy resources one day in advance,” the Montana energy provider said in a news release. “By coordinating with a larger network of participants across the West, BHE Montana will improve access to affordable energy supplies, make more efficient use of transmission infrastructure, and enhance overall system reliability.”
EDAM launched successfully on May 1, 2026, with PacifiCorp’s East and West balancing authority areas and the ISO. Portland General Electric is scheduled to begin trading energy in the day-ahead market in October.
Since going live, EDAM has delivered a range of positive outcomes, including efficient price formation, interregional trade, and strong resource sufficiency results across the participating balancing areas, which has been a boost to summer reliability.
Regional reliability has also been strengthened by the addition to the grid of about 36,000 megawatts (MW) of new resources in California since 2020, including more than 17,000 MW of battery storage capacity. This has enabled significant exports from the ISO footprint during what has been a record-setting summer for peak demand in the Western Interconnection.
“It’s exciting to see BHE Montana committed to both the real-time and day-ahead markets,” said Elliot Mainzer, the ISO’s president and CEO. “As EDAM continues to grow, more communities across the West will benefit from a proven platform that enhances reliability and supports affordability.”
The real-time and day-ahead electricity markets use proven, state-of-the-art technology to find and deliver the lowest-cost resources across a broad geographic region to meet power needs and manage congestion on transmission lines to maintain grid reliability.
In its first two months, EDAM delivered $11.38 million in cost savings, shared among PacifiCorp East, PacifiCorp West and the ISO balancing authority area. At the same time, the real-time Western Energy Imbalance Market, which launched in 2014, saw its cumulative cost savings top $9 billion last quarter. EDAM is projected to deliver even greater savings as new participants join the market and its geographic footprint expands.
When BHE Montana joined WEIM in May of this year, the company said participation in the real-time market enables the utility to coordinate and operate its assets and services for the benefit of its customers while supporting continued economic growth in Montana and throughout the greater Rocky Mountain region.
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About the California ISO
The California Independent System Operator (ISO) is a nonprofit public-benefit corporation responsible for the reliable operation of California’s bulk electric grid. The ISO provides transmission planning, open and nondiscriminatory access to one of the world's largest high-voltage transmission networks and operates competitive wholesale electricity markets for the benefit of consumers.
About the Western Energy Markets
The Western Energy Markets include the Western Energy Imbalance Market (WEIM) and the Extended Day-Ahead Market (EDAM), which provide regional market coordination across the West. The WEIM, launched in 2014, helps participants balance electricity supply and demand in real time and has delivered billions in benefits to market participants and their customers. EDAM began operation in 2026 and extends those benefits into the day-ahead timeframe through broader regional coordination. The Western Energy Markets Governing Body has primary decision-making authority over market rules specific to the WEIM and EDAM.