RAPID CITY, S.D. (AP) — South Dakota electricity providers are considering measures to prevent trees from falling onto power lines five years after the third-largest wildfire in the Black Hills was started by a broken power line.

Flames from the 2013 Legion Lake Fire spread from Custer State Park into Wind Cave National Park and onto private property, ultimately scorching 84 miles (135 kilometers) of forest and grassland.

The fire's circumstances are directing electricity providers to seek out how to reduce the risk of trees falling onto their power lines, the Rapid City Journal reported .

There are an estimated 4 million trees that stand outside of the Black Hills Electric Cooperative's right-of-way, but are close enough to fall onto power lines, said Mike Chase, the cooperative's manager of marketing.

"It keeps our manager up at night during fire season, that's for sure," Chase said. "It keeps all of us worrying about something happening in a storm."

Robert Novembri, a utility vegetation management consultant, said it's impossible to remove every tree that could possibly strike a power line. He suggested trimming or removing some tall and healthy trees just beyond right-of-way corridors. But such a project would require cooperation from utility providers, electric cooperatives, landowners and land managers from federal and state agencies, he said.

"Obviously, if we want to have electricity and utilize electricity, we're going to have power lines, and some of those are going to go through the Black Hills," said Chris Nelson, a South Dakota public utilities commissioner. "It's always a balancing act between how much forest you want to cut for the right-of-way, versus the safety that you want to maintain with the power lines."

Obvious solutions, such as burying power lines or widening the right-of-way, are often cost-prohibitive or impractical, said Novembri.

"Ultimately, it would be best for everybody if there could be a dialogue amongst the different entities involved about how to best attack this," said Butte Electric Cooperative CEO John Lee.

"There's got to be some sort of a common-sense approach to this," he said. "Something has to change."

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Information from: Rapid City Journal, http://www.rapidcityjournal.com