The Turlock Irrigation District, a California public power utility, has signed an implementation agreement to join the Extended Day-Ahead Market, which the California Independent System Operator is launching next spring, CAISO said on May 19.
The publicly owned entity is the first irrigation district established in California. Founded in 1887, it now provides irrigation water and electricity to more than a quarter million customers in California’s Central Valley.
Its Board of Directors voted May 13 to authorize the district to join the Extended Day-Ahead Market in 2027 and the implementation agreement was signed over the weekend.
TID has experience participating in a fully integrated regional energy market as a member of the ISO-managed Western Energy Imbalance Market since 2021, realizing $28 million in cumulative cost savings, according to a staff report presented at its Board of Directors meeting.
“TID 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, said Brad Koehn, TID General Manager. “TID’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.”
Four other energy providers have already signed implementation agreements to join EDAM. PacifiCorp and Portland General Electric will begin participating in 2026. The Los Angeles Department of Water and Power and the Balancing Authority of Northern California, which includes the Sacramento Municipal Utility District, have signed agreements to join in 2027.
CAISO said other Western energy providers are also likely to join in the near future. BHE Montana, PNM and NV Energy have notified the ISO of their intentions to join EDAM. Idaho Power has indicated that it is leaning toward EDAM as its preferred day-ahead market and Arizona G&T Cooperatives, utilities representing 70% of WAPA Desert Southwest’s load, has also announced that they are studying the benefits of joining EDAM, as have several other utilities in the West.
"The ISO and its stakeholders have designed the day-ahead market to build on the proven track record of the WEIM," it said.
Just under $7 billion in cost-saving efficiencies have been delivered to the WEIM’s 22 participants across 11 Western states since the market began managing real-time, least-cost energy transactions in 2014.
The market continues to grow, with two additional participants expected to begin participating in 2026.
"The EDAM has been designed to unlock those benefits for WEIM participants in the day-ahead timeframe, where the bulk of energy transactions occur, and the reliability, economic and environmental benefits will be even greater," the grid operator said.
