Fast Facts & Frequently Asked Questions

What was the purpose of The Grazing Power Project?

Vegetation under transmission lines must be controlled in order to provide easier access to power lines for maintenance or power restoration during an emergency, help prevent outages, and provide safety for PSNH workers and contractors. The Grazing Power Project was designed to investigate whether sheep grazing is a cost-effective, environmentally friendly alternative for controlling this vegetation.

Who was responsible for the project?

It was a joint initiative between Public Service of New Hampshire (PSNH) and Bellwether Solutions, a local vegetation management company. Other project participants include the University of New Hampshire (UNH).

Why did the project end?

PSNH tested the use of sheep to maintain vegetation in our transmission rights-of-way for five years. The data collected during that time is presently being studied by scientists at the University of New Hampshire. A forthcoming report will provide an accurate assessment of just how well the sheep did. It is possible that PSNH will employ sheep again in the future, if it is shown that the sheep were effective.

How is vegetation in the rights-of-way typically maintained?

Most of the vegetation in PSNH rights-of-way is maintained through mechanical cutting. A 14-ton excavator with a hydraulic arm and a rotating drum is used to grind up trees and shrubs. Manual cutting with chain saws has also been used to a lesser degree, and herbicides were used a number of years ago but have not been used recently. Each right-of-way area is currently cleared about once every five years.

Why try sheep?

Sheep are natural lawnmowers, effective at clearing vegetation. Although they eat many different types of vegetation, sheep favor the leaves of young maple, oak, cherry and birch. These are problem species for electric utilities -- if left unmanaged; they will grow tall enough to interfere with the transmission lines.

Won’t the trees just grow back?

Like all green plants, trees use their leaves to store energy in their roots through the process of photosynthesis; if the trees are repeatedly stripped of their leaves, they are unable to produce the energy necessary to stay alive. By grazing a right-of-way multiple times within a 30-40 day period, suppression of tree growth occurs.

Do sheep eat more than just the targeted trees and shrubs?

While the sheep may eat some plants that we wish to keep on the right-of-way, the shepherds worked to herd the sheep toward target species (maple, cherry, oak and birch) to minimize the impact on other plants.

How many sheep were used in the project?

In its first year, the Grazing Power Project consisted of approximately 500 sheep. Following a successful first year, the flock doubled in size for year two. In years three, four and five the flock consisted of about 1200 sheep..

How were the sheep controlled?

The flock of sheep was controlled by shepherds 24 hours a day. The shepherds used herding dogs to assist in moving the sheep, and guard dogs to keep predators away. The flock always remained within protected electric fencing.

Have sheep been used this way before?

Yes. Before the invention of lawn mowers, sheep were widely used to control vegetation. In Canada, sheep are currently being used to control vegetation in forest plantations. In Denmark, Australia and other countries, sheep are often used to clear vegetation along roadsides.

What happened to the sheep that were used in the Grazing Power Project?

The PSNH project generated a lot of interest in the use of sheep to control vegetation. Bellwether Solutions now has some flocks working elsewhere, including the South - where the sheep are being used to control invasive plants like Kudzu.

What is the difference between a guard dog and a herding dog?

Guard dogs are large dogs trained to protect sheep from predators such as coyotes and bears. A guard dog will stay with the sheep, and will place itself between the predator and the flock. The smaller herding dogs help the shepherds move and herd the sheep by running around the flock on command.