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Montana's LED street and yard lighting project


NorthWestern Energy started a four-year program to replace existing streetlights and yard lights in communities across our Montana service territory with energy-efficient LED (light-emitting diode) lights in 2018. About 43,000 NorthWestern-owned streetlights and 30,000 yard lights will be replaced by the end of 2022.

Missoula LED-41



Less energy
  • LEDs use 50% less electricity than traditional high pressure sodium (HPS) lights.
Reduced light pollution
  • With LEDs, NorthWestern is offering a full range of dark sky friendly options.
  • With LEDs, the light can be better directed to where it is needed – on the street and adjacent sidewalks.
  • Through smart technology additions, one day we could dim streetlights when no one is in the area, since the LEDs will have dimming capability.
Improved visibility
  • Old HPS lighting produces an orange-yellow light that does not render colors well. LEDs, on the other hand, output a fuller light spectrum that renders colors accurately.
  • NorthWestern chose “warm light” LEDs which are easier on the eyes than “cool white” LEDs.
Lower operation costs
  • Because LEDs are more efficient, they last longer and need to be replaced less often than HPS streetlights.
  • LEDs require less energy.
Improved safety and security
  • The new lights give increased safety at night through greater visibility and fewer streetlight outages.

About the project

Why now?
NorthWestern has been evaluating LED lighting technology for several years. Recent price decreases have made LED lights more cost effective. Also, manufacturers of current HPS products have indicated those products may not be readily available in the future with the increasing popularity of LEDs. NorthWestern has done its homework to select LED fixtures that will result in just and reasonable rates for customers while maintaining an appropriate amount of light for safety and minimizing light pollution.
Will all streetlights be replaced?
No. The NorthWestern Energy LED project will not affect customer-owned streetlights. For example, streetlights owned by cities or other local government entities and those owned by the Montana Department of Transportation will not be upgraded by NorthWestern.
What about yard lights?
About 30,000 yard lights and several thousand home owners association lights will be replaced in the coming years.
Are the new LED streetlights Dark-Sky compliant?
Wherever possible, we are using lights that are dark sky compliant, and the vast majority of the new LED lights are dark-sky compliant. They also meet any local lighting ordinances. The International Dark Sky Association’s guidance is to use LED products with a “warmer color,” 3000K (kelvin) or less because “3000K LED lighting saves energy and lowers costs, protects health and human safety, conserves nocturnal wildlife, and protects nightscapes.” All 70- and 100-watt cobra head fixtures will be 2700K going forward. Conversions of lights greater than 100 watts will continue to be replaced with 3000K lights. Most street lighting in the United States is 4000K. However, both the American Medical Association and the Dark Sky Association recommend a color temperature not to exceed 3000K, which is why NorthWestern is using 2700K and 3000K lights. For more information on dark sky standards, visit
Cost of project
The cost of the streetlight project is expected to be about $24 million, with the cost of the yard light project estimated to be about $9 million. Existing fixtures will be replaced on a one-to-one basis with equivalent LED products.
Project timeframe
We began converting streetlights in 2019 and yard lights in 2020. Both projects will continue through 2022.
Recycling old lights
NorthWestern is recycling the old high-pressure sodium lights through Four Corners Recycling in Bozeman. Four Corners recycles all parts of the old lights, including the metal heads, the glass lenses and the bulbs, some of which contain mercury. The recycling program was initiated by employees in a 2018 leadership program.

To learn more about specific light fixtures, see our Montana Lighting Services Guide.

For more information about the project, please contact:

Rick Edwards
Director of Community Connections


Jo Dee Black

Public relations specialist

Chris Risser in Billings recycling HPS lights

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