PORTLAND, Ore. (May 1, 2026) — A major shift in how electricity is planned and delivered across the western United States began Friday as California Independent System Operator and PacifiCorp officially launched the Extended Day-Ahead Market, known as EDAM.
The new market expands coordination of electricity resources across a broad regional footprint, allowing utilities to plan energy use a day in advance rather than relying primarily on real-time adjustments. Officials say the change is expected to improve grid reliability, lower costs for consumers, and support the continued growth of renewable energy.
“Customers across the West are the big winners with today’s go-live,” said Ryan Flynn, president of Pacific Power, a division of PacifiCorp. “By coordinating across a broader footprint in the day-ahead, EDAM can more effectively deploy the most efficient resources, strengthening reliability, lowering costs, and enabling greater integration of diverse energy resources.”
Elliot Mainzer, president and CEO of CAISO, called the launch “the next chapter” in the evolution of a more interconnected Western electricity system.
“We are grateful for the partnership with PacifiCorp and a broad coalition of Western energy stakeholders who helped bring EDAM to fruition,” Mainzer said. “By working together, we are delivering greater reliability and affordability for energy consumers across the region.”
Building on a Proven Market
EDAM builds on the success of the Western Energy Imbalance Market, a real-time trading system launched in 2014 that balances electricity supply and demand every five minutes using the lowest-cost available resources.
That market has grown to include 22 participants across 11 states, representing roughly 80% of electricity demand in the West. Since its inception, it has generated more than $8.6 billion in benefits by reducing production costs and enabling energy sharing during times of grid stress, such as extreme weather or wildfires.
PacifiCorp alone reports more than $1.1 billion in customer benefits since joining the real-time market.
By extending coordination into the day-ahead timeframe—when most electricity scheduling decisions are made—EDAM allows grid operators to better optimize resource commitments and transmission use across major supply and demand centers.
Expansion Already Underway
The new market is expected to grow steadily. Portland General Electric has signed an implementation agreement and plans to join EDAM in October.
Several additional utilities are targeting participation in 2027, including the Los Angeles Department of Water and Power, Sacramento Municipal Utility District, Public Service Company of New Mexico, and Turlock Irrigation District. Once these entities are onboard, EDAM is projected to serve about 42% of the West’s electricity demand, based on data from the North American Electric Reliability Corporation.
Looking further ahead, the Imperial Irrigation District plans to join both EDAM and the real-time market in 2028, while other utilities—including NV Energy and Idaho Power—are evaluating participation.
Flexible Design and Governance Changes
EDAM is structured as a voluntary market that allows utilities to retain control over their own balancing authorities while participating in regional coordination. The system uses existing transmission infrastructure, avoids exit fees, and incorporates a daily resource sufficiency evaluation compatible with different state policies and programs.
The market’s design and tariffs have been approved by the Federal Energy Regulatory Commission.
Governance has also evolved alongside the market’s expansion. In July 2025, the Western Energy Markets Governing Body assumed primary authority over market rules, including independent filing rights with federal regulators.
Future governance could shift again under California legislation. California Assembly Bill 825 allows for the creation of a new independent entity, the Regional Organization for Western Energy, which could take over market oversight as early as 2028 if specific conditions are met.
Focus Turns to Performance
With EDAM now operational, market operators say the next phase will focus on monitoring performance and refining operations in collaboration with participating utilities.
Officials emphasize that continued coordination and stakeholder engagement will be critical as the Western grid faces growing demand, climate-related challenges, and an evolving mix of energy resources.
“Successful implementation of a market of this scale depends on disciplined execution and ongoing collaboration,” CAISO said in a statement.
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