Mysterious island appears on huge lake, then disappears: ‘I’ve never seen anything like it’

For a time, a floating island larger than a football field drifted across British Columbia’s Williston Reservoir. Then, just as suddenly, it disappeared from view.

People travelling by boat first spotted the landmass earlier in August. Local resident Rocky Avery shared photographs and videos on social media, where they quickly spread. Avery said he had lived in Canada for 40 years and had never seen anything similar. With a major fishing competition approaching, he wanted to alert participants and B.C. Hydro in case the island continued moving through the reservoir.

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I’ve never seen anything like it.

B.C. Hydro initially treated the images with caution. Spokesman Bob Gammer said the spread of generative artificial intelligence meant that online material could not always be trusted at first glance. Satellite images taken on July 21 later confirmed that the object existed. They placed it in the main part of the reservoir, west of Finlay Bay and about 100 kilometres west of the W.A.C. Bennett Dam.

B.C. Hydro estimated that the island measured about 140 metres in length and 70 metres in width, covering roughly 9,800 square metres. That is larger than a football field and nearly the size of two American football fields. By Aug. 5, however, the island no longer appeared in satellite imagery. “We took newer images and can no longer see the object. It has now disappeared,” Gammer said.

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We took newer images and can no longer see the object. It has now disappeared.

That does not necessarily mean the island sank. Gammer said it may have moved into a more sheltered area near the shore, and B.C. Hydro does not currently expect it to affect the hydroelectric system. He believes it may have formed over years where driftwood accumulated along the shoreline, allowing plants and trees to grow while organic material built up and decayed underneath. Rising water could then have broken the mass away, with wind pushing it into open water.

The reservoir reached full capacity this year after heavy winter snowfall and persistent summer rain. B.C. Hydro opened the dam’s spillways in June and July to release excess water. “We haven’t had a full reservoir in 14 years,” Gammer said, while acknowledging that the island’s exact origin cannot be established with certainty. Avery also reported that high water had erased parts of shoreline dunes used by quad-bike riders and left more trees and other debris in the lake than usual.

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We haven’t had a full reservoir in 14 years.