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Pasadena Water & Power

  • CAISO Power Alerts & Rotating Outages Information

    PWP's power system is part of the statewide grid operated by the California Independent System Operator (CAISO). As part of our agreement with the CAISO, PWP's power resources are pooled with those from all other CAISO participants. This arrangement provides PWP with reliable backup power when our power sources have an outage. It also requires PWP to participate in rotating outages (AKA "rolling blackouts") when they are necessary to maintain the reliability of regional grid, even if all of PWP's generation resources are available and operating.

    While PWP strives to keep customers informed about the possibility of rolling blackouts, system conditions can change quickly and unpredictably. Furthermore, we do not publicly announce the specific location or boundaries of current or expected outages for your safety and security purposes.

    The following infomration is updated frequently by the CAISO, and you may subscribe to CAISO notifications if you wish.

    CAISO Alerts and Warnings

  • No active notices

  • CAISO "Flex Your Power" Conservation Alerts

  • No Flex notices issued in last 90 days

  • Links to CAISO Information 

    For energy conservation tips, visit PWP's "Save Energy" page

    Alerts, Warnings and Emergencies

    • Emergency notices are issued when operating reserves or transmission capacity limitations threaten the ability of the California ISO to safely and reliably operate the grid or energy markets through normal modes of operation.
    • Alert notices are issued one day before ISO may require extra resources to avoid electrical emergency.
    • Warning notices are issued hours in advance of when there may be a shortfall. Requests for conservation issued. Voluntary load reduction programs may be triggered at this point.
    • A Stage 1 Emergency is called when the minimum required Operating Reserve level falls below approximately seven percent. This amount can vary depending on the type of generation that’s running. Under a Stage 1 Emergency, the ISO continues to call for conservation, and will activate a Flex Alert.
    • A Stage 2 Emergency is called when the minimum Operating Reserve level falls below five percent. Under a Stage 2 Emergency, the ISO can call on “interruptible” programs operated by the utilities. Typically, participants in these programs are commercial and industrial customers who receive a lower electricity rate and in exchange, are required to reduce their energy usage by a predetermined amount when called upon during a Stage 2 Emergency.
    • One Hour Notification of Probable Load Interruption notices are issued to the utilities, public safety agencies, the media, regulatory agencies and market participants when a Stage 3 Emergency and rotating outages are deemed probable.
    • A Stage 3 Emergency is called when on-line Reserves fall below the minimum requirements (amount can vary- usually around 3 percent of the minimum Operating Reserve total). Under a stage 3 Emergency, the ISO may call on the utilities to reduce “firm load” by implementing rotating outages. This is a last resort, used only when a climbing demand for energy is close to surpassing the available supply. 

    Visit the CAISO web site for more informatiohn on CAISO Alerts, Warnings, and Emergencies.

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