Our emergency line is available 24 hours a day.
(888) 467-2669 (Montana)
(800) 245-6977 (South Dakota/Nebraska)
If you smell natural gas, call 911.
What to do if you smell natural gas
Pipeline markers

Pipeline markers
NorthWestern Energy & the Canada Montana Pipeline Company
Safety information
Call before you dig
How to Recognize a Gas Pipeline Leak
Call 911, if you notice any of these signs of a pipeline leak:
- An unusual blowing or hissing sound coming from the ground.
- Dirt or dust blowing from a hole in the ground.
- Bubbling ponds.
- Dead or discolored vegetation in an otherwise green area near a pipeline right of way.
- A fire close to a buried pipeline.
Pipeline Purpose and Reliability
Pipelines are the safest way to transport energy products, including natural gas, crude oil and other fuels. The U.S. Department of Transportation’s Pipeline & Hazardous Materials Safety Administration (PHMSA) regulates pipelines with the help of state partners. According to government and industry statistics, the most common cause of pipeline incidents is improper or unauthorized digging near a pipeline, which is why it’s important to call 811 before you dig. Pipeline operators carefully build, maintain and monitor the integrity and security of their lines.
Excess Gas Flow Valve Notice
If a gas service is installed to your home, you have the option to purchase an Excess Flow Valve (EFV) to be installed by NorthWestern Energy. An EFV is intended to stop the flow of gas if the service line is severed. The EFV Valve is placed in the service line where it leaves the gas main.
An EFV will stop the flow of gas only if the service line is severely damaged. It is important to note that an EFV will not protect you from a leak or broken line inside your home, or a small leak on the line in your yard. An example of when the valve provides protection is in the event the gas service is damaged from digging or extreme ground movement.
As required by the U.S. Department of Transportation (DOT), we are notifying you that an EFV that meets the minimum prescribed DOT performance standards, is available for installation on your natural gas service line.
The cost of installing the EFV will need to be evaluated by an engineer. If you are interested, please contact your local NorthWestern office to set up an appointment. Payment is required prior to installation of the EFV.
Excess Gas Flow Valve FAQs
How much does an Excess Flow Valve (EFV) cost?
The cost of installing the EFV will need to be evaluated by an engineer.
If you are interested, please contact your local NorthWestern Energy construction office to set up an appointment. This payment is required prior to installation of the EFV.
How do I know if I have an Excess Flow Valve (EFV)?
There is no way to visibly check. You most likely already have an EFV installed if:
- Your home/building was built since June 2008
- Your gas service line was replaced since June 2008