Public Service Company of New Mexico has made it official: The utility signed an implementation agreement to begin participating in CAISO’s Extended Day-Ahead Market in fall 2027.
The move, which PNM announced July 1, also triggers Step 1 of the West-Wide Governance Pathways Initiative, an effort to create greater independence in the governance of CAISO’s regional markets.
Under that change, the Western Energy Markets (WEM) Governing Body now has primary decision-making authority over market rules for the Western Energy Imbalance Market (WEIM) and EDAM, rather than joint authority with CAISO’s Board of Governors.
PNM announced in November its intention to join EDAM rather than SPP’s competing day-ahead market, Markets+. One factor in the utility’s decision was its participation since 2021 in the WEIM, a real-time market that has provided PNM with nearly $170 million in benefits.
“The EDAM will integrate our state’s renewable energy potential while helping us continue to serve our customers with clean and reliable service at the lowest cost,” PNM CEO Don Tarry said in a statement.
PNM is the seventh entity to formally commit to joining EDAM. The others include PacifiCorp and Portland General Electric, which will begin participating in the market in 2026. The Los Angeles Department of Water and Power and the Balancing Authority of Northern California, which includes the Sacramento Municipal Utility District, signed agreements to join in 2027.
And in May, the Turlock Irrigation District and the Imperial Irrigation District (IID) signed implementation agreements formalizing their commitment to join EDAM. IID will also join the WEIM, in which Turlock already participates. (See Turlock Irrigation District to Join EDAM in 2027 and Imperial Irrigation District Inks Agreement to Join CAISO Markets.)
While PNM’s commitment to join EDAM is no surprise, it gives the CAISO market a solid foothold in a region rich with wind resources California seeks to tap to meet its ambitious clean energy goals.
“PNM’s participation strengthens the foundation of a more interconnected, reliable and cost-effective regional electricity market,” CAISO CEO Elliot Mainzer said in a statement.
BHE Montana, NV Energy, Idaho Power and Arizona G&T Cooperatives have indicated they’re leaning toward EDAM.
Step 1 Triggered
The CAISO Board of Governors and the WEM Governing Body last August approved a proposal in which Step 1 of the Pathways Initiative would be triggered when entities meeting certain size and geographic diversity criteria signed EDAM implementation agreements. (See CAISO, WEM Boards Approve Pathways ‘Step 1’ Plan.)
With PNM’s commitment to EDAM, utilities outside the CAISO balancing authority area that have signed EDAM implementation agreements represent a load equivalent to 75% of load in the CAISO balancing authority area — exceeding the 70% threshold to trigger Step 1.
And the EDAM commitments have enough geographic diversity because they include non-California entities from the Northwest and the Southwest, CAISO management said in a July 1 certification notice.
The Step 1 provisions also include a dispute resolution process. If the CAISO board and WEM Governing Body can’t agree on a particular proposal, they may file two proposals with FERC as “co-equal” options in a single document.
Another change enhances language in the WEIM and EDAM governance charter about considering the public interest.
“Independent governance of the Western Energy Markets is crucial for establishing a strong day-ahead energy market that will maximize consumer benefits,” Stacey Crowley, CAISO’s vice president of external affairs, wrote in a July 1 blog post.
Step 1 is seen as a temporary measure until Step 2 of the Pathways Initiative can be implemented.
Step 2 calls for transferring market governance to an independent “regional organization,” a move requiring changes to California law. Senate Bill 540, which would implement Step 2, was passed by the state Senate on June 4 and is now being considered in the Assembly. (See ‘Pathways’ Bill Passes California Senate on 36-0 Vote.)
‘Substantial Benefits’
PNM’s announcement of its intention to join EDAM followed the New Mexico Public Regulation Commission’s release of a set of “guiding principles” for utilities to use in selecting a day-ahead market. (See PNM Picks CAISO’s EDAM.)
“PNM continues to believe joining EDAM will offer substantial economic and operational benefits to New Mexico customers,” Kelsey Martinez, PNM’s director of regional market and transmission strategy, wrote in a June 30 filing with the PRC.
“This decision reflects a careful review of commission principles, including analysis of customer benefits, efficient resource dispatch and effective stakeholder engagement,” she added.
Martinez also noted in the filing that CAISO imposes no exit fees if an entity decides to leave EDAM. The entity may then return to WEIM-only participation or leave both the WEIM and EDAM.
Martinez said PNM would provide regular updates to the commission on its EDAM integration.


