California publicly owned utility Turlock Irrigation District has agreed to join CAISO’s Extended Day-Ahead Market in 2027, the ISO said May 19. 

Turlock’s board of directors voted May 13 to allow the district to join EDAM in 2027, with the implementation agreement signed the following weekend. Turlock is a member of CAISO’s Western Energy Imbalance Market (WEIM) and has saved $28 million since joining WEIM in 2021, CAISO stated. 

Turlock provides irrigation water and electricity to more than a quarter million customers in California’s Central Valley, according to the news release. 

“[Turlock] has had tremendous success in the Western Energy Imbalance Market, and we are excited to build on this partnership and leverage the increased economic, reliability and environmental benefits of the Extended Day-Ahead Market,” Brad Koehn, Turlock’s general manager, said in a statement. “[Turlock]’s continued alliance with the California Independent System Operator will enable the district to continue our stellar track record of providing reliable, affordable power to its customers.” 

The announcement comes as the race for participants between SPP and CAISO is both heating up and winding down as the two entities prepare to launch their respective Western day-ahead markets. 

SPP got a major win May 9 when the Bonneville Power Administration issued its long-awaited decision in favor of SPP’s Markets+. Puget Sound Energy followed suit shortly after. (See BPA Chooses Markets+ over EDAM and Puget Sound Energy Inks Agreement to Join Markets+.) 

Entities such as Xcel Energy subsidiary Public Service Company of Colorado, El Paso Electric and Tacoma Power also have committed to joining SPP’s day-ahead market. 

Meanwhile, PacifiCorp and Portland General Electric have agreed to begin participating in EDAM in 2026, with the Los Angeles Department of Water and Power and the Balancing Authority of Northern California set to join in 2027. (See LADWP Gets Board’s OK to Join CAISO’s EDAM.) 

BHE Montana, PNM, NV Energy, Idaho Power and Arizona G&T Cooperatives have indicated they’re leaning toward EDAM as their preferred day-ahead market choice.

In CAISO’s May 19 news release, the ISO said EDAM is built “on the proven track record of the WEIM.” 

“The Turlock Irrigation District has been a valued partner in the Western Energy Imbalance Market since 2021, and its decision to join the Extended Day-Ahead Market reflects the growing recognition of the markets’ significant economic, reliability and environmental benefits,” CAISO CEO Elliot Mainzer told RTO Insider in a statement. “As Turlock joins the community of EDAM entities, we are pleased with the continued expansion of the EDAM footprint and remain laser focused on achieving market go-live with PacifiCorp and Portland General in 2026.”