Canada's Last Lake Dammed by Ice Took Millennia to Form. It Drained in a Season.

For thousands of years, a layer of fresh water sat on top of the sea in Milne Fiord in Canada's far north, held in place by a dam of ice. In July 2020 the Milne Ice Shelf cracked apart. By autumn, the lake was mostly gone.

It was an epishelf lake, an arrangement in which an ice shelf traps fresh water above salt water that still connects to the open ocean. That made a layered habitat, with freshwater and marine life sharing one column of water, one floor above the other. It was the last such lake in Canada.

In late August 2026, researchers from four Canadian universities reconstructed the lake's end in Scientific Reports, drawing on 10 years of ocean data, satellite images and fieldwork. Jérémie Bonneau, who led the study, said the shelf and the lake spent decades wasting away, and the breakup finished the job.

Nobody was there to watch. The COVID pandemic canceled the 2020 field season, so the team's thermos-sized sensors, which logged depth, temperature and conductivity (a stand-in for saltiness), kept recording alone. Bernard Laval, another of the authors, said the team saw the breakup by satellite and reached the instruments two years later. Brackish water had pushed out the fresh layer by July 2022. Yearly checks since have found no sign of a return.

Fresh water entering the fiord runs straight out to sea. The lake could only return if the ice shelf did, and the researchers say the climate's trajectory rules that out.

In Inuktitut, the protected areas of northern Ellesmere Island are called Tuvaijuittuq, a name meaning a place of ice that never melts. The name has not changed. The water under it has.

Read the full story at Discover Wildlife, September 15, 2026

Hot Take: The instruments recorded the lake's end as it happened and reported it two years late, which on a geological clock still counts as live coverage.