The California Independent System Operator declared a statewide Stage 2 emergency shortly before 6 p.m. Sunday, which means power outages are likely, because of excessive heat driving up electricity demand and use and putting strain on the regional power grid.
The nonprofit California ISO oversees the operation of California’s bulk electric power system and transmission lines. The California ISO called the emergency after a transmission line carrying power from Oregon to California, and another in-state power plant, went offline unexpectedly. The cause of these outages is unknown as of late Sunday afternoon.
The emergency declaration allows the ISO to use reserve power and to tap into emergency assistance from neighboring balancing authorities. During this Stage 2 emergency, if system conditions do not improve, the ISO may declare a Stage 3 emergency, which will lead to rotating power outages.
Consumer conservation was credited with helping to avoid power outages on Saturday. But extreme heat coupled with wildfires are contributing to increased energy demand and reduced supplies on Sunday, the ISO said.
Grid operators are predicting a shortfall of as much as 4,000 megawatts from the electric power supply late Sunday afternoon into the night.
Fires took out 1,600 MW of transmission resources on Saturday; about 500 MW of that loss was returned to service Sunday. But later Sunday, power plant outages due to the heat reduced supplies by another 625 MW.
Based on the current forecast and without significant conservation efforts, rotating power outages are likely throughout the state until at least 9 p.m. Sunday.
The ISO also has called a “flex alert,” a call to consumers to voluntarily conserve electricity, until 9 p.m. Sunday and from 3 to 9 p.m. Monday. Recommended conservation steps include setting air conditioner thermostats to 78 degrees or higher, turning off unnecessary lights and deferring use of major appliances.