Ewe won't believe what New Hampshire is doing.

• Position: On First Reading

As Joyce Kilmer noted in his poem, trees are lovely. Except when they grow tall and hit power lines--resulting in outages to customers, safety hazards and costly repairs. In fact, trees are the second most common cause of power outages.

But New Hampshire has found an alternative to chemicals and manpower for controlling tree growth around power lines. It's sheep power.

And it's an environmentally friendly way to maintain the 25,000 acres (1,800 miles) of rights-of-way beneath power lines, keeping them free of saplings--for much less than the previous annual equipment and manpower costs of $2.5 million.

Sheep, Mother Nature's lawn mowers, are doing their part. "Cherry, oak, maple and birch are cake and ice cream to sheep," reports Dick Henry, a former shepherd and now president of Bellwether Solutions. A fully grown ewe can stand on her hind legs and remove more than 90 percent of the leaves on a 5-foot tree. A flock of sheep can chow down on young trees at a rate of up to three acres a day.

Henry approached Public Service of New Hampshire in 1998 with the idea of allowing 500 sheep, border collies and...