If the Tweedsmuir Glacier is going to complete its surge across the Alsek River, it'll likely happen this winter, says a surface geologist with the Yukon Geological Survey.

Jeff Bond said last Thursday the winter months are the ideal time for glaciers to cross rivers. The water level is generally lower and the current less able to chew away at the surging wall of ice.

Galloping glaciers, Bond added, normally surge for one or two years at the most. So if the glacier is going to cross before the river gets the upper hand with the spring runoff and a more turbulent current, it'll have to happen soon, Bond expects.

"This is a critical time."

Bond said a time-lapse camera set up by the U.S. Geological Survey to track advances daily has shown there's not been a lot of movement since last summer, when the Star first reported the glacier's migration.

In the words of his colleague, surficial geologist Panya Lipovsky, who has been following the Tweedsmuir surge, "it seems to be quieting down."

The Tweedsmuir is inside the St. Elias Mountains, and is surging across the Alsek just above the famous Turnback Canyon, approximately 110 kilometres southwest of Haines Junction, inside the B.C. border

Bond said the glaciers in the St. Elias range are particularly active, and surge about every 30 years on average.

Records show the Tweedsmuir surged into the Alsek River back in 1974, but didn't make it across.

The Yukon Geological Survey group is talking about getting a time-lapse camera to watch over the Lowell Glacier, neighbour to the Tweedsmuir, Bond pointed out.

There are records of the Alsek being dammed by glacier activity before, but not as dramatically as it was in the 1850s.

As the St. Elias region was coming out of a mini-ice age back then, when glaciers where thicker, denser and generally more robust, the Lowell crossed the Alsek, and stayed put for what Bond suspects was somewhere between five and 10 years.

So large was the build-up of water behind the ice dam, it turned Haines Junction into beach front property, even though the community is some 400 metres higher in elevation than Turnback Canyon.

Research glaciologist Shad O'Neel of the U.S. Geological Survey agrees if the Tweedsmuir is going to cross the Alsek, it will probably be this winter.

Furthermore, O'Neel suggested, January is typically a month when surging glaciers that have slowed their pace will pick it back up again.

He explained glaciers begin to surge when their plumbing gets clogged up and so much water builds up inside, that it essentially creates a floating glacier.

With the arrival of winter, the surge can slow down as the interior plumbing freezes shut, more or less, he explained.

O'Neel said as the water pressure builds inside, however, the plumbing will let go again at some point, and the glacier will begin to move.

"January is a time they will start up again," he said. "But at least for the time being, it does not look like it is doing anything dramatic.

"But that does not mean we should not still pay attention."

Because of the potential for damming the Alsek and creating a potentially hazardous situation for anyone downriver once the dam lets go, the Tweedsmuir has caught the eye of many, O'Neel explained.

"There is definitely a lot of different people in touch with each other who are normally not in touch with each other."

Some of the worst floods are caused with the "catastrophic" release of water when a glacier dam lets go, he said, noting there is the community of Dry Bay where the Alsek empties it the sea.

O'Neel said for unknown reasons the onsite camera has stopped transmitting.

It could have become covered in snow, as it did in late November when two geologists - one from the Yukon and one from Alaska - flew in to repair it, he pointed out.

O'Neel said it may also have something to do with the short days and lack of sunlight for the solar-powered unit, which sends its images via satellite.

There is a desire to fly into the remote area to find out why it's not working, but at this point in the year, nobody's got any money left, he said.

O'Neel is hoping that with the return of longer daylight hours and more sunshine to power the unit, the camera may start sending again.

One way or the other, he expects somebody will get in to the site sometime in March.

He said from what he can tell, the Tweedsmuir Glacier has been surging for at least a year now, and has travelled 1.2 kilometres.

It has about 100 metres to go to reach the other side of the Alsek, which isn't all that much for a surging glacier to overcome, O'Neel said.

"It could do that in a week if it turns back on."