The head of Nalcor Energy expects damage will be done to Muskrat Falls structures this winter, due to a failure to install an ice boom in time — and delays he ultimately attributes to protests in October.

Nalcor simply ran out of time to install the boom this year, according to CEO Stan Marshall. Nalcor said Friday that installation had to be delayed one year as ice has already formed on the river.

Marshall attributes much of the missed deadline to anti-Muskrat Falls protesters, who disrupted work for about two weeks in October. But Nalcor Energy also suffered a setback with a leak in their cofferdam — they had to lower water levels, and the ice boom can only be installed with levels raised.

The ice boom structure would be placed upstream from the powerhouse, and is designed to catch debris and stabilize ice in the area. Marshall says its absence means he is expecting some amount of damage at the site.

"I am concerned, there's no question about that," he said on Friday, in an interview with CBC News. "It will depend on what the weather is like this winter, you'd have to assume at this point in time that there will be some damage to the structure."

Few options: Marshall

Marshall says there are really no other options to prevent damage to the Muskrat Falls structures, and the most the crown corporation can do now is to attempt to mitigate the costs.

The CEO said the company will create a second cofferdam-like structure downstream from the powerhouse, and said flooding of the Muskrat Falls reservoir is even more important now that the ice boom is missing.

Stan Marshall CEO Nalcor Muskrat Falls update

Stan Marshall says there few options to prevent damage to the Muskrat Falls structures, and the most the crown corporation can do now is to attempt to mitigate the costs. (CBC)

"You're trying to stabilize the ice sheet above the power plant. The higher the elevation, the more stable the sheet will be," he said.

But the water levels cannot be raised until the first cofferdam at the site is fixed, a process that is still ongoing.

In a news release Friday, Nalcor said it has identified problems with that cofferdam, which started leaking when water levels in the reservoir were raised last month.

Water levels were lowered to inspect the dam and work is underway now to fix it.

The Crown energy corporation said that work is in the final phase and should be finished in the "coming weeks."

Muskrat Falls cofferdam

The Muskrat Falls cofferdam is a temporary barrier, and Nalcor says seepage is common. (Nalcor Energy)

No cost estimate

Marshall says he has no cost estimate for how much the winter damage might cost Nalcor, and that the severity of the damage will depend on the weather conditions in Labrador this winter.

"This started with the demonstrations, and the several weeks of disruption we had, it used up all the time we had," Marshall claimed.

"It's the cumulative effect of all those things. As I said at the time, there's going to be substantial costs."

Major protests at the Muskrat Falls site ended in late October, but Indigenous groups in Labrador are still concerned about the methylmercury that will form when the land is flooded.

The province has agreed to lower the water levels next spring to provide a second chance to remove more vegetation or soil, depending on what is decided by an independent committee examining the issue.