FERC on Aug. 25 approved CAISO’s Western Energy Imbalance Market (WEIM) implementation agreement with Imperial Irrigation District (IID). 

The approved agreement specifies how CAISO will bring IID into the WEIM, including the costs and the scope of work involved. The commission’s order notes the ISO said the plan “adopts substantially similar provisions to WEIM implementation agreements previously approved by FERC” (ER25-2789). 

Under the agreement, IID will pay CAISO a fixed implementation fee of $120,000, and either party can terminate the agreement for any or no reason after first engaging in good faith discussions for 30 days to resolve any differences. The agreement also outlines limits of liability, notices and dispute resolution language, among other elements. 

CAISO and IID are also developing an implementation agreement for the ISO’s Extended Day-Ahead Market (EDAM). CAISO plans to admit IID into the WEIM and EDAM on the same day, no later than Oct. 1, 2028. 

Located in Southern California, IID provides power to about 165,000 customers and operates more than 1,800 miles of transmission and 5,000 miles of distribution lines. IID in May announced its intention to join the CAISO markets, a move the utility’s, general manager, Jamie Asbury, said “is a significant step toward modernizing how we purchase and manage power.” (See Imperial Irrigation District Inks Agreement to Join CAISO Markets.) 

In its order, FERC also granted CAISO a waiver request to allow IID’s WEIM implementation date to occur more than 24 months after the implementation agreement effective date of Sept. 2, 2025, which allows the utility to join the WEIM and EDAM concurrently in 2028. 

“CAISO and IID will require more than 24 months from the requested effective date of the WEIM Implementation Agreement to undertake the implementation steps needed to allow for IID’s concurrent participation in WEIM and EDAM,” CAISO said in its filing with FERC. 

The commission said it approved the waiver because CAISO “acted in good faith” by “promptly” filed the request shortly after the ISO and IID executed their agreement and “sufficiently in advance of the proposed effective date.”