If approved by regulatory agencies, a 1,200-kilometre natural gas pipeline would be built through the Northwest Territories' Mackenzie Valley from the Beaufort Sea to a hub in northern Alberta. (CBC)

The Mackenzie Gas Project's backers and critics have one last chance to make their arguments to the National Energy Board, which began hearings Monday into the long-proposed Arctic gas pipeline.

Members of the energy board, an independent federal agency that must decide whether to approve the $16.2-billion proposed pipeline project, are in Yellowknife this week to hear final arguments from pipeline proponents and various interveners.

The NEB has been hearing evidence since 2006 on the proposal by a consortium of companies — led by Calgary-based Imperial Oil — to build a 1,200-kilometre natural gas pipeline from the Beaufort Sea, through Inuvik, N.W.T., and down the Northwest Territories' Mackenzie Valley to northwestern Alberta, where it would connect with existing networks.

"We believe it's a sound, potentially economic project that has the potential to provide meaningful, long-term positive benefits to a variety of stakeholders, including the companies involved, and governments, and the people of the North," Imperial spokesman Pius Rolheiser told CBC News on Friday.

The pipeline consortium also includes ExxonMobil Corp., ConocoPhillips, Royal Dutch Shell PLC and the Aboriginal Pipeline Group.

Last month, the consortium said natural gas could start flowing through the pipeline in 2018 at the earliest.

Conditional support

The consortium also told the energy board it will decide in 2013 whether to proceed with the project.

In December, the federally appointed Joint Review Panel gave its conditional support for the pipeline, as long as proponents follow the panel's 176 recommendations to address the project's environmental and socio-economic impacts.

The National Energy Board must now decide if the pipeline can go ahead. The board's decision will then be subject to final approval from the federal cabinet.

But leaders with the Dehcho First Nations, the only First Nation along the pipeline route that does not have a land claim signed with the federal government, say they want benefits to be put in place before a pipeline is built.

"We want to see our Dehcho process conclude, we want to see the implementation of our land-use plan as soon as possible, we want to have a happy resolution to our access and benefits [negotiations] with Imperial Oil," Dehcho Grand Chief Sam Gargan said.

"We also want to see a response from both [federal and territorial] governments on the Joint Review Panel hearings."

Officials with the federal Indian and Northern Affairs Department are expected to talk about some of the draft conditions that the NEB released last month. However, it's not clear if they will address all of the issues that may fall within the department's mandate.

The National Energy Board will also hold a round of hearings next week in Inuvik.