Hurricane officials told centralized day‑ahead market will change how city buys power

UAMPS staff told Hurricane city officials and Power Board members that the California Independent System Operator’s extended day‑ahead market (EDAM) will replace many intra‑day bilateral wholesale trades and require day‑ahead demonstrations of resource sufficiency.

“Instead of bilaterally just, calling people up…all of that is, to be done on a day ahead basis,” Matt, a UAMPS market presenter, said during the briefing. He noted EDAM’s planned May 2026 startup and described how the centralized market will accept full resource submissions and economically dispatch them across the footprint.

Why it matters: EDAM changes when and how Hurricane must buy power. Under the new structure, each load‑serving entity must show by 9 a.m. day‑ahead that it has enough resources for forecasted hourly needs; Pacificorp will allocate the balancing‑area Resource Efficiency Evaluation (RSE/RFC) to its members based on historical shares. UAMPS will inherit the responsibility to demonstrate resources to the market and then allocate its RSE share among members, which can create over‑ or under‑procurement relative to prior bilateral practice.

Details: Under the centralized market, participants submit all available resources and the market operator lines them up by cost and transmission constraints. UAMPS staff explained two operational options for Hurricane’s internal generation: (1) keep local generation out of CAISO’s full network model and continue to self‑dispatch as today, preserving current transmission treatment; or (2) enter the generators into CAISO’s full network model, at which point the market may dispatch those units and they would be visible to CAISO for economic dispatch.

Staff cautioned that moving internal generation into the CAISO full network model can change transmission treatment and requires studies. Jackie (UAMPS counsel) said Pacificorp’s study to put member generation into CAISO’s model can take up to 18 months and requires an initial deposit (approximately $10,000). UAMPS staff said including generation in the full network model could remove favorable transmission treatment and add roughly $75,000 in charges in the example shown during the briefing.

Resource‑adequacy allocation: Pacificorp will translate its control‑area RFC into member obligations using recent historical shares (three‑year lookback). That means a member like Hurricane could be asked to demonstrate resources for a higher hourly obligation than it would select under the previous bilateral scheduling process; UAMPS would procure to meet that obligation day‑ahead and then settle imbalances through the market. Matt emphasized that UAMPS will still give members choices day‑ahead about which resources to offer or self‑schedule, but the timing and the demonstration requirement change.

Market risk and governance: Staff acknowledged early market operations may produce “bumps” as participants learn new roles; they said UAMPS plans January parallel runs and settlement testing before EDAM go‑live. UAMPS also described a one‑way decision: once member generation enters CAISO’s full network model, members cannot easily revert to the previous treatment without a long study process.

Quotes: “By 9AM, we have to demonstrate to the CAISO that we have sufficient resources,” Matt said. Jackie added that the study and metering changes needed to fully enroll generators are nontrivial and have cost and operational impacts.

Next steps: Staff recommended Hurricane keep its internal generation out of the full network model for now to preserve current transmission treatment and buy time to observe EDAM settlement results. UAMPS will run parallel comparisons starting in January, circulate settlement examples, and bring pooling‑agreement amendments for council action before EDAM’s go‑live.