Fairfax County yesterday asked state regulators to order Dominion Virginia Power to suspend its aggressive tree cutting along the Washington & Old Dominion Trail.

County supervisors said they want the work to stop while a task force of arborists and park officials negotiates a plan with the utility to limit the cutting to those trees that could fall on the high-voltage transmission lines above the trail in severe weather. Emergency pruning would continue.

"We are hoping for less cutting, or at least more logical cutting," said Supervisor Linda Q. Smyth (D-Providence), whose district includes a stretch of the path through Vienna. "We are asking the state to slow the work down until we have a policy."

The letter to the Virginia State Corporation Commission also asks that Dominion be ordered to consult with area arborists before pruning and replace trees it cuts down with other species that won't grow tall enough to get tangled in power lines.

The 45-mile trail from Shirlington to Purcellville is where Dominion's ramped-up tree pruning program has left its most visible mark. The state's largest utility has been pruning and felling thousands of trees to protect power lines from falling limbs. Power companies in the District and Maryland also are stepping up tree work in response to prolonged outages caused by storms, including Hurricane Isabel last fall, and August's blackout from Detroit to New York. In some areas, crews are topping trees rather than pruning.

Cutting along the trail began in Falls Church and Arlington last year and is heading west toward Leesburg. It has prompted fierce opposition from bicyclists, hikers, neighbors and lawmakers, who say that the canopy of shade above them is being ruined. They do not want to jeopardize safety, they say, but they do want an agreed-upon plan with Dominion that would minimize the work.

"We want to formalize how they do it and when they do it," said Barbara Hildreth, head of the task force and a founder of the trail, whose 30th anniversary was last weekend. "We feel this is more cutting than they really need for the safety of the transmission lines. We're saying, pause the work along the whole trail until we agree to a plan."

But a Dominion official said yesterday that suspending the tree pruning could jeopardize the delivery of power to thousands of customers in a severe storm, especially during growing season.

"If we don't trim the trees along the right of way, the result could be devastating," Le-Ha Anderson, a company spokeswoman, said. "If there's no trimming, then those trees can come into contact with the lines and cause all kinds of problems."

Just as nature enthusiasts are monitoring the utility's tree cutting along the trail, federal and state regulators are watching the work "to make sure we maintain the right of way," Anderson said. But she said Dominion officials plan to "work diligently" with the community "to find a reasonable middle ground." Dominion officials have said they will replace some trees they cut down, but selectively.

What that will mean, in number of trees spared and those replaced, is unclear, although the State Corporation Commission may not be much help. Spokesman Ken Schrad said that a utility's tree-trimming practices may be beyond the scope of the commission, which is charged with "making sure people get reliable electric service."

The commission last issued tree maintenance guidelines in 2000, after an ice storm cut power to hundreds of thousands of customers. "The recommendation was for more aggressive trimming," Schrad said.