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

A floating forest island measuring approximately 70 by 140 metres was spotted on Canada’s largest reservoir — Williston Reservoir 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 manages the reservoir, initially suspected it was a fake generated by a neural network. A check of satellite images confirmed that the island was indeed in open water west of Finlay Arm on July 21. Its area was approximately 9,800 m² — about the size of two football fields.

The explanation turned out to be quite ordinary. For years, woody debris — timber carried by the water — had accumulated along the shore. It decomposed into a loose mass in which bushes and trees took root, while their interwoven roots bound the layer into a single whole. Heavy snowfall in the mountains the previous winter, followed by summer rains, raised the reservoir to its highest level in 14 years: in June and July, 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 the island sank: according to company representative Bob Gammer, it may have entered 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.