CAISO declared its first transmission emergency of the summer July 2 as a fast-spreading Northern California wildfire forced Pacific Gas and Electric to de-energize transmission lines near one of the state’s key hydroelectric facilities.

By the morning of July 3, the Thompson Fire had burned more than 3,000 acres in Butte County, prompting the California Department of Forestry and Fire Protection (Cal Fire) to request PG&E de-energize circuits from the Wyandotte Substation that were in or near the fire, as well as several transmission lines, leaving about 4,200 residents without power.

Paul Moreno, a spokesperson for PG&E, told RTO Insider the utility was able to repair a few transmission lines, including one serving Lassen Municipal Utility District. The remaining three were expected to be restored July 4, but Moreno was unsure when staff will be able to re-energize the Wyandotte circuits.

“We’ve been closely tracking the weather forecasts and have geared up on staffing and are ready to respond to any heat-caused power outages,” Moreno said.

PG&E also announced a public safety power shutoff (PSPS) that went into effect the morning of July 2, leaving 2,200 Northern California residents across eight counties without power. While the utility hoped to restore power July 4, it was unsure of the timeline because of wildfire danger and dry winds.

The transmission emergency, which the ISO extended into July 3, comes at the start of an extended heat wave that will bring soaring temperatures to cities across much of the West, including Sacramento, Portland, Las Vegas and Phoenix.

While the ISO assured its power grid is stable and supply shortfalls weren’t forecast through July 3, high heat in the interior of the state could set temperature records.

“We are continuing to closely monitor long-duration extreme heat in California, with triple-digit temperatures forecast in the valley over the next several days,” an ISO spokesperson said. “We are also watching wildfire activity across the state. While fires are not currently affecting the bulk electricity system, wind direction can change quickly and impact generation and our transmission system.”

CAISO also issued a restricted maintenance operation (RMO) alert effective midnight July 3 through midnight July 10 to caution utilities and transmission operators to avoid taking equipment offline for routine maintenance. The RMO can help assure all generators and transmission lines are available to supply higher loads, according to the ISO spokesperson.

Hyatt Hydro Plant Taken Offline

The Thompson Fire started outside Oroville the morning of July 2. By late afternoon on July 3, the fire had grown to more than 3,500 acres and was 0% contained, according to Cal Fire. The agency has issued mandatory evacuation orders for many zones in Butte County and evacuation warnings were in place for others. The cause of the fire remains unknown, and there have been no reports of fatalities.

In a statement posted on X on July 2, the California Department of Water Resources (CDWR) said the fire ignited just north of its Oroville Field Division facilities and that “several” state water project facilities were under evacuation orders from the Butte County sheriff.

Among those was the Hyatt Powerplant, a 645-MW hydroelectric facility near Oroville Dam that CDWR temporarily shut down because of de-energized PG&E transmission lines. Plant staff were relocated to the nearby Thermalito Pumping-Generating Plant, the agency said.

The department was able to resume Hyatt’s operations on July 3, it said in a follow-up post. Staff found minor damage to nonessential infrastructure at the dam, but “there was no damage to the dam or spillway structure, and Oroville Dam remains safe,” it said.

No Alarms on West Coast, but EEA 2 Declared Inland

Despite the forecast for extended heat, utilities across the region have not expressed alarm about energy shortages, likely in part because of the lower demand seen during holiday weekends.

The Sacramento Municipal Utilities District, which is not part of CAISO but participates in the ISO’s Western Energy Imbalance Market, said this week it was prepared to meet electricity demand, “barring a grid or other emergency such as wildfire or unexpected significant power shortfall.”

Portland General Electric noted on its website that it too is prepared for “high temperatures and high electric use.” Portland-based Pacific Power urged its customers to take steps to conserve power during peak periods between 3 and 7 p.m. to reduce strain on the grid.

Nevada-based NV Energy hasn’t issued calls for conservation, but the utility did alert customers about its newly implemented PSPS policy in the event of high fire danger.

But in New Mexico, according to a source, the El Paso Electric balancing authority area in the SPP reliability coordinator footprint on July 2 was placed into an Energy Emergency Alert 2, in which the RTO requests emergency energy from available resources, activates emergency energy programs and calls for conservation from consumers.