Rotating Power Outages

What is a Rotating Power Outage?

In the event of a state-wide power shortage, the California Independent System Operator (CAISO) will order Azusa Light & Water (ALW), and all other load serving entities under its authority, to shed a certain amount of load; usually up to 5%, depending on level of power shortage. To achieve this reduction, when cutting water facilities is not sufficient, ALW would temporarily interrupt a block of customers for about an hour, then interrupt a second block of customers of about the same size for the second hour of the event while restoring the first block at that time. This rotation of customer interruption would continue until the power shortage event has passed.

What is ALW’s protocol when a rotating power outage order is received?

To minimize inconvenience to its customers, ALW will always cut water system pumping facilities prior to implementing general customer rotating outages. The water pumping facilities require a significant amount of energy, and cutting them first may be sufficient to comply with CAISO load reduction orders.

What can I expect if my power is interrupted pursuant to a rotating power outage?

If your power is interrupted pursuant to a rotating outage you can expect it to last approximately one hour, and we will not interrupt service to any customer more than once per day. Power shortages will most likely occur during daylight hours, so lighting should not be a problem in most cases. We recommend that you keep your refrigerator closed, as much as possible, to preserve food temperatures during the hour-long power outage. Also, electric garage door openers will not work during power outages, so if manual garage door operation is difficult you may choose to park outside of the garage on a day of potential rotating power outages.

Will I be notified prior to a Rotating Power Outage?

When CAISO predicts a rotating power outage is imminent, ALW will advise its customers via the City website, email, and social media. Updates will also be provided as more information becomes available throughout the day of the power shortage event. We apologize we are not able to notify individual customers prior to interruptions due to dynamic system conditions.  Load reduction orders by the grid operator must be executed upon receiving the order and the list of customers interrupted will change throughout the event. 

Is conservation still needed?

Yes! Conservation is one of the primary methods used to avoid the need for rotating power outages during heatwaves, which significantly increase power demands due to air conditioning loads. ALW asks that you conserve energy from 3 PM to 10 PM to help avoid the need for rotating power outages.

Sign Up For Flex Alert

Flex Alerts are voluntary calls for consumers to save electricity issued by the California Independent System Operator (CAISO), the state’s grid operator, to prevent rotating power outages.

Sign up at to receive notification when consumers should reduce electricity use. When consumers receive a Flex Alert, it is important for them to shift their energy use to the morning and early afternoon hours.

What to do BEFORE a Flex Alert

    Pre-cool home by lowering thermostat
    Use major appliances
    Close window coverings

What to do DURING a Flex Alert

    Set thermostat to 78° or higher, if health permits
    Avoid using major appliances
    Turn off all unnecessary lights

For more tips on ways to save energy during a Flex Alert, go to