SAN DIEGO -- San Diego County officials said more than 150 wildfires in the county were sparked by downed power lines.

Some of the wildfires in 2003 and 2007 were started by power lines and high winds in the back country, officials said, and for that reason state regulators are in the process of making new rules.

One of those new rules could require more aggressive tree trimming near power lines.

"I am sounding the alarm now," said Diane Conklin of the Mussey Grade Alliance.

Conklin, a Ramona resident, said she is concerned about San Diego Gas & Electric's plan to follow the new rules by clearing a 50-foot perimeter around power poles and power lines.

Conklin said the plan would wipe out thousands of acres of trees across the county.

"SDG&E has asked for this massive tree-trimming program because they believe that is the best way to protect against fires," Conklin.

Right now SDG&E clears a minimum of 18 inches around powerlines and power poles. They want permission to increase that area with no maximum limit.

SDG&E spokeswoman Stephanie Donovan said, "We have to insure that our lines are in compliance in terms of having the tree branches away from the power lines 100 percent of the time all year long, maybe for a couple of years, so we have to trim back farther than the minimum to allow for growth."

Conklin said she thinks many trees could disappear if SDG&E's request is granted, and she is asking the state for maximums to insure that historic trees like those along Mussey Grade Road only get trimmed and not cut down.

"Those trees are beautiful, and we all want to see our community as beautiful as possible. But as I said before, the real tree removal hazard is the next wildfire," said

State regulators hope to have a decision by late summer.