Arizona Wildfire Spreads, Threatens Power Systems

El Paso Electric Co. (EE) said the threat posed by an Arizona wildfire that spread overnight remains as winds gusts as high as 30 miles (48 kilometers) per hour fan the flames today.

The Wallow fire is burning in the White Mountains of eastern Arizona about 15 miles from a high-voltage transmission line that delivers 40 percent of the electricity used by the customers of El Paso Electric, Teresa Souza, a company spokeswoman said in an interview. The line delivers power from Palo Verde, the largest U.S. nuclear plant, to 371,000 homes and businesses in West Texas and southeastern New Mexico.

Firefighters had contained 5 percent of the blaze as of 11:55 a.m. local time today, according to a government incident report. The Arizona towns of Eagar, Springerville, Sunrise, Greer, Blue River, Alpine and Nutrioso were ordered evacuated as the fire expanded by 21,284 acres (8,613 hectares) to a total of 430,171 acres, according to the latest report. Located east of Phoenix, the blaze has destroyed 29 homes and threatens 2,700 more, as well as 473 commercial properties, the report showed.

“The winds are expected to increase later this afternoon, and that can cause spotting of other blazes because the fuel is so incredibly dry,” said Terri Wildermuth, a spokeswoman for the teams that are battling the fire, in a telephone interview.

Along with steady winds of 15 mph to 25 mph and stronger gusts, the relative humidity of the area will be low, said Ken Daniel, a meteorologist with the National Weather Service in Flagstaff, Arizona.

Smoke Danger

The eastern edge of the fire is about 8 miles away from transmission lines connecting Tucson, Arizona, to two power plants, and has not advanced in several days, UniSource Energy Corp. (UNS), owner of Tucson Electric Power, said in a statement today. “Firefighters have staged burnouts” in the area to establish a perimeter, the statement said.

TEP’s transmission towers are unlikely to burn, although “thick, billowing smoke” creates an alternate path for electric current and may “cause the lines to short circuit,” the utility said.

UniSource is bringing backup power supplies online, starting local natural gas-fueled plants that don’t always run because it costs more to produce power from those units than it does to get electricity over the threatened transmission lines, Joe Salkowski, a TEP spokesman, said yesterday. TEP also is coordinating with other utilities to provide additional sources of electricity if needed, he said.

Air quality in the area around the fire is considered “extremely hazardous,” according to the state of Arizona.

To contact the reporter on this story: Dan Hart in Washington at dahart@bloomberg.net

To contact the editor responsible for this story: Sylvia Wier at swier@bloomberg.net

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