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December 23, 2025

California Independent System Operator (CAISO)

Tucson Electric Power Signs up for Western EIM
The Western Energy Imbalance Market chalked up another future member after Tucson Electric Power signed an agreement saying it will join in April 2022.
FERC Denies PGE Rehearing over Contracts Dispute
FERC rejected PG&E’s request to rehear its ruling that it shares authority with a federal bankruptcy judge over any PPAs the utility might seek to modify.
Cold Forces NW to Dip More Deeply into EIM as Avista Joins
Pacific Northwest members reaped an unusually large chunk of the Western EIM's benefits in the first quarter, leaning on it to keep up with demand.
PG&E Departure Leaves EIM Vacancy
The CAISO Energy Imbalance Market's Governing Body will search for a candidate to replace Kristine Schmidt after she resigned earlier this month.
FERC Asks RTOs for more Details on Storage Rules
FERC issued deficiency letters to all six jurisdictional RTOs and ISOs over their proposed energy storage rules, pressing for definitions, tariff citations and other details.
SPP Solicits Interest in Western Real-time Market
SPP has made its long-held interest in the West official by “calling on interested utilities and other customers” to help build a real-time market “that will meet the electricity needs of the Western Interconnection.”
SMUD Goes Live in Western EIM
The Western Energy Imbalance Market continued expanding as the Sacramento Municipal Utility District became the first publicly-owned utility to begin participating in CAISO’s real-time electricity market for the West.
FERC Rejects CAISO RA Incentive Change
FERC rejected a CAISO plan to change incentive rules under its resource adequacy mechanism for wind and solar generation.
PNM’s Bid to Join Western EIM Gets Approved in Part
The New Mexico PRC granted two approvals PNM requested to join CAISO’s Western Energy Imbalance Market, but denied one concession the utility deemed key.
CAISO Board OKs Market Power Mitigation Remedy
CAISO’s Board unanimously approved a proposal to address concerns that the ISO’s market power mitigation rules disincentivize participation in the EIM.

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