California’s power grid withstood the heat. So why did Healdsburg and three other cities have rolling blackouts?

Healdsburg and at least three other Northern California cities imposed rolling blackouts Tuesday night — even though the manager of the state’s power grid said it didn’t order them to conduct the rotating outages.

The rolling blackouts in Healdsburg and elsewhere resulted from a communication breakdown between the grid manager, the California Independent System Operator, and a Roseville-based joint powers authority called the Northern California Power Agency. All four cities belong to the Northern California group.

The group of municipal utilities, which also included Alameda, Lodi and Palo Alto, represented the only utilities that deliberately cut power to their residents.

The rest of the state’s grid withstood record heat and electricity consumption and narrowly averted what would have been the first rolling blackouts in California since 2020. The Independent System Operator declared a Stage 3 “emergency energy alert” just before 5:30 p.m. Tuesday — a signal that statewide rolling blackouts could happen at any moment — but was able to avoid outages. The alert ended at 8 p.m.

Even as the cities in the Northern California organization were cutting power, ISO spokeswoman Anne Gonzales said the grid manager hadn’t issued orders to start blackouts.

Lodi officials said they cut power to 1,372 households for about 45 minutes because of the error.

The Northern California agency “informed Lodi Electric that there was a communication error between them and Cal ISO that caused NCPA to issue the order to Lodi and other NCPA members,” Lodi officials said in a Facebook post.

Steve Schwabauer, the Lodi city manager, said Wednesday that the city has received some complaints from customers, but for the most part “people have been very gracious about it. ... We’ll do what we can to make it right.”

Exactly what went wrong wasn’t immediately clear. Randy Howard, general manager of the Northern California agency, couldn’t be reached for comment.

The group’s chairman, Healdsburg City Councilman David Hagele, said he hadn’t been briefed on the apparent snafu — even though he felt the effects of the error firsthand.

“Ours got cut off for 30 minutes or so,” he said.

In a Facebook post Wednesday, the City of Healdsburg confirmed a half-hour outage in one residential zone at NCPA’s direction.

“We fulfilled our obligation to promptly implement the order,“ the statement said. ”The City has since learned that there may have been miscommunications between CAISO and NCPA and that the directive may have been delivered prematurely. We are actively engaging with NCPA and CAISO to ensure that communication protocols are improved and clarified immediately. We share our community’s frustration with this situation. “

The Northern California group operates a handful of power plants and coordinates supplies for its member cities, as well as the Port of Oakland the Bay Area Rapid Transit district.

With record-breaking temperatures in the forecast again, Wednesday is likely to be another difficult day on the power grid. A Flex Alert was set to take effect at 4 p.m., a call for voluntary conservation.