Tree Canopy Grows Thinner

Heightened Pruning to Protect Power Lines Worries Residents

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.

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?"