The Tweedsmuir Glacier in British Columbia, Canada, is surging into the Alsek River, threatening to block it. As the surge continues, outburst flooding from beneath the glacier could occur at any time.
If glacial ice blocks the river completely, a lake could form upstream, growing until the ice dam eventually fails. Such an event could cause an outburst flood that would threaten the safety of Alsek and Tatshenshini River rafters as well as commercial fishermen, visitors, concessioners and park staff in Dry Bay. In addition there is potential for park and private property damage.
Historically, the Tweedsmuir Glacier has blocked the river, most recently in 1975. When the river breaks through flooding has occurred downstream reaching as far as Dry Bay. The current surge was reported late in 2007 by Chris Larsen of the University of Alaska Fairbanksâ Geophysical Institute. At this time the face of the glacier is being eroded by the river current with ice breaking off into the river itself.
The National Park Service, in conjunction with federal and state agencies, officials in British Columbia, the Yukon and Parks Canada are monitoring the river daily and preparing response plans should a damming event occur. For pre-recorded updates on the status of the Alsek River you may contact the Tweedsmuir Hotline at 907-697-2695.
For a map showing the river and glacier, click on the link below.