Western Energy Imbalance Market (WEIM) Participants

These resources are intended for WEIM entities and participating generators that are directly involved in the Western Energy Imbalance Market. 


Business Practice Manuals

Business Practice Manuals contain implementation details through which the California ISO and market participants conduct business in accordance with the Tariff. The Business Practice Manual for Western Energy Imbalance Market contains information about all WEIM entity types.



The Western Energy Imbalance Market is governed by the California ISO (ISO) FERC-approved Tariff. Each section or appendix of the tariff is maintained and updated independently according to effective dates of the FERC accepted tariff amendment


Integrate with the ISO full network model

The network model defines system parameters, price node and market scheduling limit mappings and planned network model updates.


WEIM Resource Onboarding Procedure

This procedure helps WEIM entities submit the required onboarding documentation for new participating and non-participating resources. The procedure also applies when a non-participating resource would like to become a participating resource.


Transmission customers of WEIM entities

Our computer based training modules are for Transmission Customers of WEIM Entities to learn about participation in the WEIM, the real-time market, base schedules, system outages, metering and settlements. For WEIM updates, subscribe to news releases and notices.

Transmission customers should contact their WEIM entity for most questions. For all other questions, contact ISO customer service. Please refer to tips for asking questions for more guidance on how to identify the resource best suited to address inquires.

s. Section 29 of the ISO Tariff addresses the provisions related to the Western Energy Imbalance Market. Appendix B. 17 – 20 contains agreements related to WEIM participation.


Regulatory Filings

All publicly available California ISO-authored filings and FERC orders are posted on the ISO website.


ISO Department of Market Monitoring

The ISO Department of Market Monitoring (DMM) keeps a close watch on the efficiency and competitiveness of the Western Energy Imbalance Market. Links to tariff provisions discussing DMM’s role and responsibilities and various DMM reports, presentations and tariff filings are available on the ISO website.


Learning center courses

Western Energy Imbalance Market training

Explore topics pertaining to the real-time energy imbalance market that enables participants to buy and sell energy when needed.