Alsek River

Alsek River (Tlingit Aalseix̱') is a wilderness river flowing from Yukon into Northern British Columbia and into Alaska. It enters the Gulf of Alaska at Dry Bay. Most of the Alsek River's basin is within protected wilderness areas and National Parks. The Alsek and its main tributary, the Tatshenshini River, are part of the Canadian Heritage Rivers System and a UNESCO World Heritage Site. In the year 2016, the Alsek River captured the flow of the Slims River due to the retreat of Kaskawulsh Glacier. Researchers attributed the change in flow to human-caused climate change; this was the first time human-caused climate change was implicated in the reorganization of a river. Research indicates that in a few decades, Alsek River may further change its final course. The rapidly retreating Grand Plateau Glacier separates Alsek River and lake from nearby Grand Plateau Lake. Geologists predict that when the two lakes merge, Alsek River will abandon its current outlet in favour of the steeper way to the ocean through Grand Plateau Lake and a small embankment, moving its outlet some 17 miles (27 km) to the southeast, within the confines of Glacier Bay National Park.

Flows through: United States.

River data from Wikidata (CC0); lengths normalised to a common unit.