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NWE Contact Bar, in Montana dial 1-888-467-2669, in South Dakota or Nebraska dial 1-800-245-6977
small brandTree Planting and Vegetation Management

Take a tour of Montana’s forests with our vegetation management team.

Our Vegetation Management Program (IVMP)

NorthWestern Energy develops and follows an annual Integrated Vegetation Management Plan (IVMP) for managing vegetation growth in our electric rights of way (ROWs). The primary objective of our plan is to reduce the likelihood of tree-caused outages on our electric system and to control noxious weeds. However, our IVMP also encourages the growth of native grasses and shrubs providing vegetation and habitat preferred by many species of wildlife.

The company has 7,200 miles of electric transmission ROW and about 15,000 miles of electric distribution ROW in Montana alone. These corridors vary from 10 to 75 feet on each side of the line depending on the voltage. Annually our group of skilled arborists and vegetation management technicians physically inspect our electric transmission lines and identify then address potential issues. We spend more than $8 million annually on transmission and distribution ROW maintenance. 

In addition to providing excellent habitat for wildlife like elk, deer, bears, small mammals and many songbirds, our ROWs play a strategic role in controlling wildland fires. Fire fighters often view our electric corridors as firebreaks as well as critical transportation routes for crews.

Developing a successful ROW management plan involves many groups. We work with representatives from the Forest Service, Bureau of Land Management, Montana Department of Natural Resources and Conservation along with individuals from city and county governments and tree or forestry agencies.

Planting and Maintaining Trees

Everyone likes trees. They give us shade, save energy, clean the air we breathe and look nice.

But when it comes to trees and power lines, proper planning and care are necessary for everyone’s safety and to have electric service you can count on.

For years, NorthWestern Energy has trimmed trees to keep power lines clear. This practice enables us to help maintain safe, reliable service for our customers.

Before You Plant, Get the Facts

Here are some quick facts you should know before planting a tree. For more help planning where you plant, download our tree planting guide here.
  • Pick a tree that’s appropriate for your climate and space.
  • Know where overhead power lines are and plant at least 15 to 20 feet away; trees that grow taller than 40 feet should be planted more than 35 feet away.
  • Call 811 to check for underground utility lines at least two working days before you dig.
  • Once you know where underground natural gas lines are, plant at least 25 feet away. And for more safety tips about planting along a gas pipeline, click here.

We Clear Our Lines to Protect You

Falling trees and tree limbs can cause high-voltage wires to break or sag to the ground, in some cases causing life-threatening situations for motorists and pedestrians.

Overgrown tree limbs near power lines can pose a danger to children. A child climbing an overgrown tree may touch a live power line.

We also want to protect our line crews, who often are exposed to dangerous situations when they are called out to repair a tree-related outage during stormy weather.

We Clear Our Lines to Protect Electrical Service

When tree branches touch power lines, they often cause outages. That happens most often in windy, stormy weather.

We estimate that a large number of our outages are caused by trees that fall onto power lines or limbs that touch power lines. Some outages last only a second, causing digital clocks to blink or computers to lose data; other outages can last much longer.

Many people are not aware there are laws against attaching material, including plants or signs, to utility poles without authorization from the utility. These materials make it hard for us to access poles and power lines if there’s a problem, and they can interfere with electrical service.

Pruning Trees

Directional pruning allows us to train the tree to grow away from power lines by removing only the branches that may come in contact with the wires. By selectively pruning the tree’s branches, much of the tree’s natural crown, or form, is retained. This is better for the health of the trees and is more cost efficient than topping because it doesn’t have to be done as frequently. The illustrations below depict proper pruning near power lines.

an example of proper pruning near power lines.
Image courtesy of

How Often Do We Clear Our Lines?

We clear the trees along our lines on a regular maintenance cycle. The shape, size and growth rate of trees affect how often they need pruning. Generally, our crews prune to create clearance to last for at least three years and to avoid problems with snow loading in winter.

Removing Trees

Sometimes it’s necessary to remove a tree that has become a hazard to the public or our electrical system.

If a tree or trees are classified as hazardous, NorthWestern Energy will correct this situation by removing the tree, leaving the wood and discussing a replacement option with the property owner. Wood larger than four inches from the tree belongs to the property owner and will be left behind. Small pieces of wood and branches are chipped at the job site and hauled away.

If you have a tree near one of our lines that you think needs to be pruned or removed, or if you notice a tree interfering with power lines contact us at 1-888-467-2669 in Montana or 1-800-245-6977 in South Dakota or Nebraska. To be safe, never attempt to prune a tree near our wires yourself.

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