A group of Southwest electric cooperatives plans a study that could motivate the Western Area Power Administration’s (WAPA) Desert Southwest (DSW) Region to join CAISO’s Extended Day-Ahead Market (EDAM).
Arizona G&T Cooperatives (AzGT), a member-owned, nonprofit electric generation and transmission cooperative that accounts for 70% of WAPA’s DSW load, is looking for potential benefits if WAPA joined EDAM.
“Today marks an important milestone for the Arizona G&T Cooperatives as we announce our interest in exploring CAISO’s EDAM to determine potential benefits for our customers across Arizona,” AzGT CEO Patrick Ledger said in a press release. “We look forward to continued engagement with CAISO to build on the benefits we have seen through participation in WEIM, and to support WAPA as it explores expanding its participation.”
AzGT has not yet decided who will conduct the study.
The announcement follows WAPA’s March decision to pull the DSW region out of the second phase of SPP’s Markets+ development after determining it would see few benefits from both SPP’s and CAISO’s day-ahead markets. (See WAPA DSW Cites Lack of Benefits in Markets + Withdrawal.)
But WAPA expressed support for AzGT’s announcement.
“We applaud this first step by AzGT in considering the benefits of joining CAISO’s day-ahead market program,” WAPA administrator and CEO Tracey Lebeau said in a separate press release. “WAPA remains focused on providing value to our customers, and our leadership and Desert Southwest operations teams support this evaluation of EDAM. As a transmission provider, we know WAPA’s transmission system throughout the Southwest and its connectivity across the region will be a crucial factor in determining the value of any day-ahead market construct for our DSW customers.”
WAPA DSW has been a member of the Western Energy Imbalance Market since 2023. DSW operates the Western Area Lower Colorado balancing authority in Western Arizona and sells federal hydroelectric power and provides transmission service to nearly 70 cities, electric cooperatives, Native American tribes, government agencies and irrigation districts.
AzGT and more than 20 cooperative members, public power utilities and electrical districts took the first step in the process in September by engaging with CAISO to review the potential benefits of joining EDAM.
CAISO expressed enthusiasm for the announcement.
“We are honored to provide real-time energy market services for a diverse set of western utility partners, and excited to learn that AzGT intends to explore further benefits from the extended day-ahead market,” CAISO CEO Elliot Mainzer said. “WAPA and its customers bring critical resources and connectivity for many in the West, and we look forward to continuing the mutually beneficial partnership.”
Other entities engaged in EDAM are PacifiCorp and Portland General Electric, which executed implementation agreements and intend to join in 2026. Several other entities have indicated a leaning toward EDAM, including the Los Angeles Department of Water and Power, the Balancing Area of Northern California, Idaho Power, NV Energy and BHE Montana.
