The National Energy Board is giving Imperial Oil until the end of 2022 to start building the Mackenzie Gas Project.

In a decision released today, the board approved extending the project's "sunset clause" to Dec. 31, 2022. Previously, Imperial Oil and its partners had until the end of 2015 to begin building the 1,196-kilometre, $16.2-billion pipeline.

The N.W.T.'s Regulator of Oil and Gas Operations will also require Imperial Oil to file an annual report describing steps taken to advance the activities or decisions associated with making the final decision to construct the project.

Lisa Schmidt, a spokesperson for Imperial Oil, said in an email the company welcomes the decision to grant their request for an extension and the project participants "remain hopeful that they can assist in the development of Canada's significant northern gas resources."

"This extension will allow time to assess whether changes in the North American natural gas market, including the potential impact of numerous proposed LNG projects, will result in improved economics for development of Mackenzie Delta gas reserves."

Had the board not granted the extension, the long-delayed pipeline could have faced another environmental assessment, deterring Imperial Oil from moving forward.

If it's ever in fact built, the Mackenzie Gas Project, also known as the Mackenzie Valley pipeline, would transport gas about 1,200 kilometres from anchor fields in the Mackenzie Delta and along the Mackenzie River Valley to a hub in northern Alberta.

The board's decision still needs to be approved by the federal government.