FERC approved a series of revisions related to the design of CAISO’s Extended Day-Ahead Market to support market implementation and avoid disruptions to existing contracts.
A primary issue in FERC’s April 8 order concerned intertie modeling and scheduling under EDAM (ER26-1294).
When EDAM launches on May 1 with PacifiCorp as the first participant, what were formerly two transfer points between the CAISO and PacifiCorp balancing authority areas will become internal EDAM interties, which would no longer function as scheduling points for the CAISO BAA.
This raised concerns among stakeholders, who argued that the elimination of the scheduling points could “disrupt forward contracts for resource adequacy supply or resources supporting renewable portfolio standard transactions, as well as commercial transactions to hedge the risk of congestion,” according to the order.
CAISO proposed a “transitional measure” to continue to allow import bidding limited to RA contracts and RPS transactions at those internal EDAM transfer locations.
“CAISO states that it intends to extend this transitional measure until at least the end of 2026, and that it plans to hold stakeholder discussions this year to further discuss intertie scheduling modeling to explore the mechanics of phasing out this transitional measure,” FERC wrote in approving the proposal.
CAISO also proposed, on a transitional basis, continuing to model non-resource-specific system resources under current practices.
Intertie resources in CAISO are modeled at specific scheduling points, but the ISO in 2025 proposed to model intertie resources under EDAM at generation aggregation points (GAPs). A GAP is the collection of supply resources in a BAA or group of BAAs.
The GAP approach would have improved power flow and market accuracy significantly, improved alignment with actual power flows by reducing phantom congestion and reduced operator conformance of transmission limits in real time.
In November 2025, stakeholders raised concerns about the GAP approach, saying it could lead to a market with multiple prices for the same intertie. Based on those concerns, CAISO proposed retaining pre-EDAM practices for CAISO intertie transactions for a time while it continues discussions with stakeholders. (See EDAM Intertie Scheduling Processes Raise Stakeholder Concerns.)
FERC approved the intertie proposals, saying, “We find that extending a limited option for bidding at CAISO interties that are EDAM transfer locations would give market participants time to gain familiarity with the EDAM design and adjust commercial arrangements that may rely on current scheduling approaches for intertie resources.”
“We also find that this proposal would help avoid adverse market or reliability outcomes that could result from disrupting existing contractual arrangements while CAISO continues its discussions with stakeholders about intertie scheduling modeling,” the order stated. “Accordingly, we find that the continued intertie bidding proposal is just and reasonable and not unduly discriminatory or preferential.”
FERC approved clarifications on how the 15-minute market and real-time dispatch would treat schedules cleared in the hour-ahead scheduling process at EDAM and WEIM transfer locations.
The commission also approved a slate of other revisions, including clarifications on congestion revenue rights, greenhouse gas accounting, the day-ahead contingency analysis tool, market information sharing, transmission charges and timing of price corrections.
