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Learn to recognize the distinctive early warning sign of a gas leak.

Natural gas is a safe and non-toxic energy source for heating your home, powering your gas range, water heater, fireplace, and more. But it’s also both colorless and naturally odorless – so how can you detect when you have a potentially dangerous leak inside your home?

We add a harmless ingredient called mercaptan to our natural gas to help you detect leaks. Mercaptan provides the distinctive “rotten egg” smell commonly associated with natural gas. If you smell this odor in or near your house, please Contact Us immediately.

Not sure what it smells like? We’ll be happy to send you a scratch-and-sniff postcard in the mail to help you recognize this awful, but important, smell:


SWL&P’s parent company, ALLETE, has entered an agreement to be acquired by a partnership led by Canada Pension Plan Investment Board and Global Infrastructure Partners and start the process to become a private company.

This transaction will not change our operations, strategy or shared purpose and values, and it is business as usual for all of us at SWL&P. Learn more at