Yukon considers 'ice boom' to help form Dawson ice bridge this winter

The Yukon government is looking at using an ice boom this winter to help construct the ice bridge from Dawson to West Dawson after two winters with no link between the communities, according to a report released last week by National Research Council Canada.

"An ice boom typically comprises a floating line of cable and pontoons at regular intervals that spans the river in order to accumulate the ice on the upstream side,"the report states.

It is used to make stable ice "by bringing together the drifting ice to allow it to freeze into an ice sheet."

The authors of the report said the Yukon government approached them to investigate why the Yukon River did not freeze at the George Black ferry crossing, where the ice bridge is usually built, for the last two winters.

• After government's failed attempt, Dawsonites build their own ice bridge

They were also asked to explore possible solutions if that continues to be the case.The 68-page document is a preliminary report.

'Preventative, pro-active measure'

The report outlines four different ways to deploy a boom, but says open water deployment "is the most commonly used approach in other rivers."

It's still unclear what type of ice boom will be used, according to the authors of the report. The Yukon government plans to issue a tender later this month for construction of the ice bridge, including supplying and installing the boom.

The researchers say ice booms are known to have little effect on river conditions and "do not impede fish migration."

"Note that open water boom deployment would be a preventative, pro-active measure, in the sense that it would be implemented even if the river ends up freezing entirely," reads the report.

Last year, spray ice was used to try and close the gap in the open water. The $125,000-gamble did not pay off, partly due to higher-than-usual temperatures.

Why can't the Yukon River freeze?

The Dawson ice bridge is 400 metres long and about 60 metres wide. Itis the only connection for about 150 people in West Dawson andSunnydale, to Dawson, over the winter.

The bridge'sopening dateranges from year to year, from early November to early February.The latest it closes is by the end of April.

The Yukon government has operated the ice bridge since the1960s.

As for why ice has not formed for the last two years, the researchers say more investigation is needed.

The report points to some areas like climate change, sandbars developing on the riverbed and effluent from the Dawson wastewater treatment plant.

There is a public meeting scheduled in Dawson on Tuesday afternoon at 4 p.m. at the Downtown Hotel to discuss the report.

"We want to keep communities connected in the Klondike," said Minister of Highways and Public Works RichardMostyn,in a news release.

"The report gives us tools and information to make informed long-term decisions about the ice bridge, find out where we're missing important empirical data, understand why the river isn't freezing and if there's anything we can do about it."