A July 4 article incorrectly said that Pepco no longer owns transmission lines. The utility still owns such lines in the District and parts of Maryland. (Published 7/9/04)

Ever since the bucolic Washington & Old Dominion Trail was created along an abandoned Northern Virginia railroad track, nature has coexisted with another engine of commerce and growth: electric power.

The marriage of shady bike path below and high tension wires above was peaceful, it seemed, until contractors for Dominion Virginia Power, the state's largest utility with more than 2 million customers, began taking their chain saws last year to thousands of towering trees girding the path.

Dominion is shifting its systematic tree pruning program into high gear to shield its high-voltage transmission lines from falling tree limbs during severe weather.

The arboreal assault extends far beyond one trail in Northern Virginia. From Silver Spring to Bowie to Bethesda to the District, power companies are ramping up pruning operations along the transmission lines and smaller aboveground distribution wires of Washington's power grid.

A string of prolonged, embarrassing local outages and the blackout in August that left millions of people from Detroit to New York in the dark have created a climate of concern among federal and state power regulators about tree damage. Utilities that once stepped gingerly around tree cutting, fearing the wrath of nature lovers, now say the tree canopy must shrink to protect their customers.

"There's no question we are trying to get more aggressive to get additional clearance," said Bill Gausman, vice president of Pepco's asset management program.

Budgets for the work are growing by millions annually, and even backyard trees are targets. Of the tens of thousands of trees lost to Hurricane Isabel in September, an unprecedented number fell onto power lines from private property, according to the Maryland Public Service Commission.

Pepco, with 720,000 customers, is accelerating pruning in Silver Spring, Bethesda, Rockville, Aspen Hill and other dense, urbanized areas. The company has also identified dozens of distribution circuits in the District and Montgomery and Prince George's counties that are repeatedly knocked out during thunderstorms, ice storms and heat waves, when overloaded air conditioners cause power lines to sag. The principal cause: falling trees. Pepco plans to begin a pilot program in each jurisdiction this fall to target trees that need so much pruning that cutting them down altogether is best, Gausman said.

Critics of the utilities' new approach argue that foliage is more than just something nice to look at. It provides shade, filters pollutants and offers privacy from neighbors. They also note that human error was as much a cause of the Northeast blackout as trees.

"If a tree falls on a power line, it should not knock out the East Coast, and the solution should not be to knock down all the trees here," said Bob Morris, conservation chairman of the Sierra Club's D.C. chapter.

The face-off between nature enthusiasts and utilities has been most intense along the W&OD Trail, where cutting by Dominion contractors has left a landscape scarred by giant, leafless sticks and stumps.

To those who cycle, run, walk and even commute on the 45 miles of trail that zigzag between Shirlington and Purcellville, the utility is denuding a vista they have worked to preserve for 30 years -- a swath of 100-foot oaks, poplars, maples and sycamores amid the suburban sprawl.

"We're packed in so close together here," Penny Firth, who lives alongside the trail, told a Dominion executive at a meeting last week with Vienna residents alarmed by planned cutting. "This is a really nice opportunity for us to have this vista. Some of these trees are grand specimens. Isn't there a way not to cut them down?"

Trail users and suburban lawmakers are also incensed by Dominion's plan to construct 11 miles of high-voltage transmission lines along the last wooded stretch of the W&OD in Loudoun County to meet an increased demand for electricity from new subdivisions. The proposed collateral damage: 26,000 trees.

Trees and power lines are tangled in competing social needs: Just as people treasure the vanishing green space around them, they don't want to choose between their bikes and their air conditioners.

Governments find themselves besieged by constituents frustrated by prolonged outages yet furious at losing trees.

"If there's anything people want, it's a reliable system," said Scott Reilly, assistant chief administrative officer to Montgomery County Executive Douglas M. Duncan (D). "When they didn't have a reliable system, we heard about it."

The Aug. 14 blackout, which started in northeastern Ohio, did not hit the Washington area. Still, local utilities say they are taking their cue from investigators' conclusions about the causes. Among them was the failure of FirstEnergy Corp. of Akron, Ohio, to properly trim trees to keep transmission lines from hitting limbs and causing short circuits, which affected crucial power lines. Key computer systems also failed and grid operators had been poorly trained, a task force found.

As part of broad mandates issued this spring, the Federal Energy Regulatory Commission required the country's approximately 2,000 utilities to report their tree management strategies in detail last month. Meanwhile, the panel that monitors power grid operations has called for better reporting of tree-related outages. And Maryland regulators issued an order last month requiring, for the first time, that companies approach homeowners about trimming and in some cases removing trees on their property that could fall onto wires in a storm.

The new standards do not carry penalties -- for now. But as regulators push for mandatory enforcement, power companies say the new environment is what they needed to embark on more intrusive, though preventive, cutting plans.

"It's validated our approach," said Bill Rees, supervisor of forestry and right-of-way management for Baltimore Gas and Electric Co., whose service area includes Anne Arundel, Howard and parts of Montgomery, Prince George's and Calvert counties.

Like other utilities, BGE is spending more on its tree operations: $21 million this year, up from $17 million in 1999. Dominion has increased its maintenance budget by about 70 percent in three years. Pepco, which no longer owns transmission lines, will spend $30 million this year keeping trees away from its neighborhood distribution circuits. Virtually all the tree work is done by contractors who turn most of the tens of thousands of trees into mulch or firewood. The costs of tree trimming, like other operating expenses, are eventually passed on to customers, according to utility officials.

BGE is targeting several Bowie neighborhoods with frequent outages. Many homeowners who moved into the city's Levittown-modeled streets in the 1960s planted trees on their property lines to buffer them from neighbors. But power lines followed the property lines.

In some cases, the company has planted dogwoods and crab apples to replace tall maples and oaks. But BGE, like Pepco and Dominion, is not replacing the trees one for one.

"That would be a very expensive program, so we do it selectively," said Pepco's Gausman.

In the District, where the tree canopy has just begun to recover after decades of erosion, the forestry department is on its own mission to limit exposure to outages. The city is planting up to a dozen species of slow-growing trees that won't be taller than 30 feet, said Ainsley Caldwell, associate director of urban forestry. To compensate for lost height, the shorter trees are being planted closer together, he said.

Caldwell is working with Pepco to identify a test neighborhood of approximately 1,500 homes for aggressive cutting. "I'm not just looking at removing a tree because Pepco says it needs to be removed," he said.

In Virginia, outside the W&OD Trail, Dominion is targeting about 50 more miles of transmission line for energetic pruning, including Pimmit Run in McLean, Route 1 in Dumfries and Route 123 in Woodbridge to the Capital Beltway and east toward McLean.

On the trail itself, users mourn the loss of greenery.

"I'm worried they're going overboard," Tom Smith, a retired electronics executive, said last week as he strolled the path just outside Vienna on his daily, four-mile constitutional. In front of him, a contractor was cutting a maple tree in half.

A few nights later, at a meeting organized by Dels. Stephen C. Shannon (D-Fairfax) and James M. Scott (D-Fairfax), Dominion executives pledged to limit their work along two miles in the area. But they said they would be back to cut down all the trees if they appear to be in the way of power lines.

"It's just not acceptable to take the risk of having another Northeast blackout," said John Smatlak, the company's director of electric transmission.

The cutting, which started in Falls Church and Arlington County last year, is scheduled to move west to Leesburg to the last transmission tower by the end of the year, when Dominion is likely to have filed its application to the State Corporation Commission to extend the lines. Trail users already are pleading with the utility to find an alternative location. But Smatlak said the issue boils down to pure economics: Dominion owns an easement along the trail, and the cost of securing a new one would be prohibitive.

"You've got this leafy green canopy during the summer and it's 10 degrees cooler out there," W&OD trail manager Paul McCray said. "People like that. Does Dominion making a few more dollars override the destruction of the trail?"

Dominion Virginia Power plans to run a transmission line above the Washington & Old Dominion Trail in Leesburg.A flier along the Washington & Old Dominion Trail in Vienna, posted by a citizens group, details the plan to fell thousands of trees to protect power lines.