Unreported damage to a natural gas pipeline has been determined as the cause of an outage that affected 4,500 homes and businesses in the Melfort and St. Brieux areas.

SaskEnergy says that an investigation by an independent lab confirmed the cause, adding that the damage occurred sometime after the pipe was last inspected in 2015.

"It was damaged enough that the pipeline was dented, which weakened the steel and eventually led to the rupture," says Communications Officer Casey MacLeod.

The rupture occurred on January 10, and while the pipeline was repaired that same day, service wasn't fully restored until the following night.

The outage was considered critical by SaskEnergy due to it taking place in winter, and the temperatures at the time bringing extreme cold conditions.

MacLeod says that with the first phase of the investigation complete, they'll be searching for anyone who knows more information.

"We know what the cause of the rupture was now, so we are now going to be searching for anyone who was involved in causing the damage."

She adds that the incident shows how crucial it is to clearly mark buried infrastructure, and if you damage any lines, that it should be reported immediately so that the cost of repair is as low as possible.

SaskEnergy said at the time that it was the largest outage they ever had to deal with.