Report: Arcing power lines caused Utah wildfire

June 27- A helicopter carrying a bucket of water heads toward the Wood Hollow Fire in central Utah. (AP/Lynn DeBruin)

SALT LAKE CITY – A Utah wildfire that destroyed 52 homes and left one man dead was caused by arcing between power transmission lines that were built too closely together and sent a surge to the ground that ignited dry grass, a fire investigator said Wednesday.

The central Utah Wood Hollow Fire began June 23 and wasn't fully contained for 10 days, costing nearly $4 million to fight, according to state officials. Officials said 160 structures total were destroyed.

The 75-square-mile blaze began when winds caused two sets of high-voltage power lines to either touch or swing close enough to each other to create a surge than swept down the poles into dry brush, said Deputy Utah Fire Marshal Troy Mills.

Rocky Mountain Power, which owns the lines, said a thief stripped protective cooper wire from its poles that may have prevented the surge.

"The investigation into the Wood Hollow fire is a top priority for Rocky Mountain Power. We want to understand exactly what happened," the company said in a statement Wednesday. "We are in the process of doing our own detailed technical analysis in addition to cooperating with fire investigators. There are aspects of this investigation that have yet to be fully analyzed."

Mills, however, insisted that even with the copper wire in place, the surge would have easily overwhelmed the protections.

"That is the cause of the fire. There's some things where you've got to take a stand. It is what it is," Mills said.

Some residents of destroyed homes in the area say they're considering a lawsuit against the utility.

The fire marshal's report gave residents "a big jump on the case," said Sterling Hess, who lost a cabin to the fire.

"Rocky Mountain Power should have investigated their problem before it became a problem," Hess said.

Elsewhere in Utah, five major wildfires continued to burn Wednesday, but fire crews largely had them contained.

Meanwhile, fires burned across the West from California to Colorado, Oregon, Wyoming and Montana.

An eastern Oregon wildfire had grown to about 450 square miles on Wednesday, and authorities put some residents on notice that they might have to evacuate. Mike Stearly, spokesman for the fire management team, said triple-digit temperatures and low humidity could expand the blaze to nearly 621 square miles by late Wednesday.

A nearby fire had grown to about 70 square miles. Firefighters had little containment on both blazes.

A wildfire in the Boise National Forest east of Idaho's capital city was threatening about 100 homes Wednesday as lightning sparked several new fires across the state. The blaze on about 300 acres is a concern for a nearby subdivision about 25 miles from Boise, authorities said.

The state's largest wildfire had burned through about 340 square miles of dry grass and sage brush in south-central Idaho but was expected to be contained sometime Wednesday. It had burned no structures.

Federal fire officials in California said a blaze in the Mendocino National Forest, about 170 miles north of San Francisco, has burned about 25 square miles and continued to spread on Wednesday. It was about 35 percent contained and has led to campground closures and the evacuations of several nearby homes.

"It's still moving and growing in the southern line, but we're getting the resources we need to fight it," said fire information officer Deb Schweizer. More than 1,300 firefighters were battling the blaze.

Lightning sparked several new fires in southern Montana, including one that forced the evacuations of about 30 homes near Livingston 30 miles east of Bozeman. The fire was mostly contained Wednesday after burning more than 1,500 acres.

In southeastern Montana, officials reported the 389-square-mile Ash Creek was completely contained by Wednesday, but red-flag weather conditions persisted across the region.

The 29-square-mile Waldo Canyon outside Colorado Springs, Colo., was fully contained by Wednesday after killing two people and destroying nearly 350 homes, making it the most destructive in state history. Elsewhere in Colorado, firefighters worked to contain at least seven additional fires believed to have been sparked by lightning Tuesday evening.

Firefighters reported improved containment on two of Wyoming's largest wildfires and have begun attacking new fires elsewhere in the state.

The 153-square-mile Arapaho Fire in the Medicine Bow National Forest northwest of Wheatland was 85 percent contained, and in western Wyoming, the 100-square-mile Fontenelle Fire was about 75 contained, as crews worked to attack new blazes in eight other counties.

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Associated Press writers Jessie Bonner in Idaho, Terry Collins in California, Matt Volz in Wyoming, Tim Fought in Oregon and Steve Paulson in Colorado contributed to this report.