The push to develop a resource adequacy program serving non-CAISO members of the ISO’s Extended Day-Ahead Market appears to be gathering momentum, with backers saying they aim to produce a draft design for the program in April.

That’s a key takeaway from a March 7 letter to the leaders of the CAISO Western Energy Markets (WEM) Body of State Regulators (BOSR), in which six utilities planning to join the EDAM spelled out the clearest vision yet for how the program could take shape: on the footing of the ISO’s Western Energy Imbalance Market.

“The WEIM’s proven ability to support reliable load service makes it a natural foundation for exploring an expanded framework through EDAM and an integrated RA solution,” the utilities said in the letter, which was signed by Mike Wilding, PacifiCorp vice president of energy supply management, on behalf of PacifiCorp, Balancing Authority of Northern California, NV Energy, Portland General Electric (PGE), Public Service Company of New Mexico (PNM) and Turlock Irrigation District.

The letter was addressed to BOSR Chair Gabriel Aguilera, chair of the New Mexico Public Regulation Commission, and Vice Chair John Hammond, a member of the Idaho Public Utilities Commission.

“A voluntary regional RA program aligned with an organized market footprint is expected to deliver value in several areas, including enhanced regional coordination, greater reliability and capacity savings for our customers,” Wilding wrote.

The letter comes nearly five months after a handful of utilities — including NV Energy, PacifiCorp, PGE and PNM — announced their intent to withdraw from the Western Power Pool’s Western Resource Adequacy Program (WRAP), choosing not to commit to the program’s first “binding” season in winter 2027. (See PacifiCorp Next to Leave WRAP After Raising Concerns.)

The WRAP, which was conceived and established before the competition between the EDAM and SPP’s Markets+, is operated by SPP but includes members intending to participate in either day-ahead market — although Markets+ members are required to join it.

Around the same time as the withdrawals, RTO Insider learned some of the withdrawing parties had already begun discussions to create an alternative RA program focused on EDAM participants. (See EDAM Participants Exploring Potential New Western RA Program.)

Wilding said the utilities envision the “offering to encompass the EDAM and WEIM footprint,” and noted they foresee it being governed by the Regional Organization for Western Energy (ROWE), the independent body established by the West-Wide Governance Pathways to oversee the WEIM and EDAM. (See Pathways’ ROWE Could Offer Western RA Program, PGE Says.)

“During the transition, the entities identified [in the letter], all of which are committed to EDAM or leaning toward EDAM, propose to guide the stakeholder process and encourage engagement from all interested parties. We recognize the importance of this initiative, but it is important to note that no official commitments or decisions have been made at this time,” he wrote.

The utilities welcome input from “state regulators, load-serving entities, suppliers and regional partners” as the initiative advances, Wilding wrote.

The effort’s backers intend to release “a draft design for a market-integrated solution” in April and “launch an open transitional stakeholder process to refine the program.” The first step will be to start dialogue during the WEM Regional Issues Forum meeting March 16, the letter said. The RA program is also on a March 19 meeting agenda of the ROWE’s newly established Formation Committee.

“The West faces a transformational moment. By building on the successes of WEIM and EDAM, we all have the opportunity to create a unified framework that advances reliability, affordability, regional transparency and regulatory goals,” Wilding wrote.