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Project logoTransmission Rights-of-Way Vegetation Management

Protecting Power Operations and the Environment

Managing vegetation around transmission power lines is critical to the safe and reliable operation of the electric system we all enjoy. It's also good for the environment. Why?

  1. Because without proper management, trees would grow in rights-of-way, possibly becoming tall enough to cause a power outage and affect a very wide area, and
  2. Because, by keeping vegetation around transmission lines shrub-like, a fast-disappearing type of wildlife habitat is preserved.

This video (755kbps or 141kbps, approx. 10 mins.) explains the careful environmental stewardship involved in establishing and maintaining a shrubland habitat on transmission line rights-of-way.

Today, New England has more forest land than it did just 100 years ago. Unfortunately, our shrubland is disappearing, along with the wildlife that utilize this habitat. Shrublands provide animals with food, shelter and breeding areas. They offer a diverse ecosystem comprised of numerous plant and animal species. At the same time, trees cannot be allowed to grow within 15 feet of transmission structures and conductor wires without compromising the safe and reliable operation of the electric system.

For more information on types and locations of plantings compatible with transmission rights-of-way, use this Tree and Shrub Planting Guide  (4MB). (Click on selections in the table of contents for information on a particular tree or shrub, or use the bookmarks in the left-hand column to find other sections of the guide.)

Northeast Utilities addresses both issues with our vegetation management activities. Read more about NU's policies for using and maintaining rights-of-way. Our goal is to maintain stable, low-growing grass, shrub and wildflower communities in the power line rights-of-way we manage. This type of vegetation not only provides the ideal situation for the safe and reliable operation of our electric system, it offers the greatest potential for wildlife habitat.

The significance of vegetation and power lines
Forest, shrubland, and environmental stewardship
What construction can mean for the land
Construction protocol

The significance of vegetation and power lines

Unlike the distribution lines that bring power to homes and businesses, if a transmission line goes out of service a much broader geographical area will be affected by the interruption. A good example is the Blackout of 2003, when 50 million people in Canada, the Midwest and the Northeastern U.S. suddenly lost power. (Transmission lines contacting trees within rights-of-way were the underlying cause of that event.)

In the wake of the 2003 Blackout, Congress passed legislation that mandates more stringent standards and required clearances between transmission lines and vegetation. Utilities are now required to comply with these stricter standards or face violations and substantial fines.

Forest, shrubland, and environmental stewardship

The shrubland habitats that NU nurtures play a key role in the lives of threatened and endangered insects, migratory songbirds and plants. These habitats are increasingly rare in New England as the open landscape has reverted to forest.

Both the National Forest Service and the Audubon Society have recognized the role power line rights-of-way play in maintaining these important habitats. These open areas provide suitable conditions for the growth of non-forest plants. The flowering varieties serve as hosts to a wide range of pollinators, valuable species that have recently experienced a serious decline in the U.S. The low-growing shrubs and grassland areas also provide vital nesting, brood rearing, feeding and escape habitats for many species of migratory birds.

NU's strategies for maintaining rights-of-way have been recognized by the:

  • Connecticut Butterfly Association
  • University of Connecticut Center for Conservation and Biodiversity
  • New England Wildflower Association
  • Massachusetts Audubon Society
The Connecticut Audubon Society, in expressing support of the proposed New England East-West Solutions (NEEWS) transmission projects, noted that power line rights-of-way are currently providing almost the sole habitat for shrubland birds, the fastest declining bird group in the region.

NU has also received the U.S. Environmental Protection Agency's Champion Award for excellence in pesticide environmental stewardship by reducing the potential risks to the environment through the effective use of low-risk vegetation management strategies. NU was the first utility in the nation to receive this recognition.


Wetlands perform a range of functions, from preventing the degradation of water quality to serving as useful ground water and flood water conduits, from supplying aquifers to shoreline stabilization, and from wildlife habitats to recreation. Wetlands are generally protected on NU rights-of-way. During construction, however, wetlands must occasionally be disturbed. When this happens, the wetlands are restored.

What construction can mean for the land

Land disruption cannot be avoided during the construction of new transmission facilities; however, we take great care to minimize construction impact. We do this by locating new lines on existing rights-of-way, utilizing existing access roads and avoiding construction of structures and access roads in wetlands and watercourses wherever possible.

Still, clearing is necessary in construction. It not only facilitates the use of equipment and the safety of construction crews, it is important to the ultimate restoration of the right-of-way to shrubland by helping us manage the growth of desirable species.

The initial clearing produces striking visible changes in the land. But, in as little as a year from the end of construction, these rights-of-way spring back to life with the resurgence of native plants, humming with birds, insects and a host of other wildlife.

Construction protocol

Construction Protocol

Pre-construction Phase:

During this project phase, crews need to access the rights-of-way at different times to:

  • survey right-of-way boundaries and structure locations;
  • mark wetlands and environmentally sensitive areas;
  • take ground core samples; and
  • determine if there are any signs of historical or archeological artifacts in the area.
Vegetation may be minimally cleared, using light equipment and low ground pressure vehicles, and only in specific areas. The purpose of this clearing is to make crew access simple and safe, while disturbing as little ground as possible.

Construction Phases:

  1. The initial clearing produces the most significant results. It is limited to where construction access and operations are required and an environmentally sensitive clearing method is used. A professionally designed harvesting plan is used that involves removing all trees and a significant amount of lower-growing vegetation. This clearing not only helps with the construction process, it allows us to manage the growth of species desirable to a shrubland habitat, and to control unwanted species that would otherwise compete with the native plants and compromise the safe operation and maintenance of the electric system.

    We also:
    • Do not use herbicides during construction clearing.
    • Limit clearing only to those areas where new facilities will be installed. We don't clear the entire width of a right-of-way if construction will only take place on a portion of that corridor.
    • Do not remove stumps, unless a stump is where a structure or new access road is to be located. In this way we preserve the soil conditions and minimize ground disruption.
    • Install matting within previously marked wetland areas, to protect those areas and facilitate their restoration.
    • Improve access roads for safer working conditions and to contain the impact of construction traffic to limited areas within the right-of-way.
    • Identify areas where species of concern are located to prevent potential damage or harm to them.
  2. Throughout construction, vegetation will naturally reestablish, so there is an ongoing need for maintenance clearing to ensure that vegetation does not interfere with construction equipment and crews.
  3. Then, when construction is complete, we perform finishing work that includes removing or trimming any remaining hazardous trees.

Post-construction Phase:

During post-construction, we begin to restore the rights-of-way to a natural state.

  • We remove the wetland mats and any stone or other materials brought in during construction that are no longer needed or permitted.
  • Disturbed areas, such as access roads and construction areas, are seeded with grasses and wildflowers.
  • Native shrubs and groundcover are encouraged to grow.
  • Previously landscaped areas that were disturbed are restored.
Once power lines are built and energized, managing the vegetation within and adjacent to the transmission rights-of-way becomes an on-going activity critical to the safe and reliable operation of our electric system.

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