A 70-by-140-metre forest island floated across a Canadian reservoir and disappeared from satellite images

A floating forest island measuring approximately 70 by 140 metres was spotted on Canada’s largest reservoir — Williston Lake in the province of British Columbia. Two weeks later, it disappeared from satellite images.

Local residents were the first to spot the mass. Rocky Avery, who lives in the area, posted photos on social media: “In 40 years, I’ve never seen anything like this.”

B.C. Hydro, the power company that operates the reservoir, initially suspected that the image was a fake generated by AI. A check of satellite images confirmed that the island was indeed in open water west of Finlay Arm on July 21. Its area was about 9,800 m² — roughly the size of two football fields.

The explanation turned out to be rather ordinary. For years, driftwood carried by the water had accumulated along the shoreline. It decomposed into a loose mass in which shrubs and trees took root, while their intertwined roots bound the layer into a single whole. Heavy snowfall in the mountains over the winter, followed by summer rains, raised the reservoir to its highest level in 14 years: in June and July, the spillways had to be opened. The layer broke away from the shore, and the trees’ crowns acted like sails.

By August 5, the island had disappeared from satellite images, but on August 12 it was filmed again — this time in the eastern part of the reservoir, in Peace Reach.

B.C. Hydro does not believe that the island sank: according to company representative Bob Gummer, it may have moved into a sheltered bay near the shore. Satellite monitoring is continuing, and the island is not affecting the operation of the hydroelectric facility. Local residents, however, complain that there is noticeably more floating debris this season and that it poses a danger to boats.