Former Natural Resources Minister Shawn Skinner expects the cost of Muskrat Falls could be as much as $8.5 billion.
"I certainly think the realm of 8 to 8.5 billion would a reasonable amount to expect," said Skinner, appearing on this week's episode of CBC Television's On Point, with guest host Jonathan Crowe.
"Some people have said 9, 10 billion, but I don't believe that personally speaking. I don't know if the government would move forward if it were to go to that kind of a number."
The government has pegged the project with a price-tag of $6.2 billion.
Skinner said there are going to be cost pressures on any project given the state of the economy and the availability of labour in the province.
"I don't think anybody is surprised to hear that Muskrat Falls might be costing more than we originally anticipated it to cost, a year or 18 months ago," he said.
Earlier in August, questions were raised about the cost of the project when Tom Adams, an Ontario-based energy analyst compared Muskrat Falls to an over-budget dam project in Manitoba.
Manitoba Hydro International (MHI) was one of the two partners in the over-budget Wuskwatim project. Its wholly-owned subsidiary is working on a cost-assessment of Muskrat Falls.
How high is too high?
"What we have to recognize is that mega-projects tend to be over budget," said former Liberal MP Siobhan Coady, who also appeared on this week's episide.
"What's the impossible number?"
"Cambridge University, Oxford University study this stuff because from a global perspective mega-projects tend to be 50 per cent or more overbudget, so we have to look for that impossible number," she added.
Skinner said there is more information to come in the fall when the house resumes, and it will be up to the government to sell the project to the people of Newfoundland and Labrador.