Mysterious floating island appears then vanishes in British Columbia's largest reservoir
A large, forested island was spotted drifting on the Williston Reservoir in northern B.C., but satellite images show it had disappeared within weeks.
In early July, a boater recorded a sizable, tree-covered island bobbing in the Williston Reservoir, British Columbia’s biggest man-made lake, and shared the footage online. B.C. Hydro’s spokesperson, Bob Gammer, initially doubted the claim but satellite imagery from July 21 verified a floating mass about 70 metres wide and 140 metres long, comparable to two NFL fields. By August 5, updated satellite snapshots showed the island had vanished, though officials said it might have drifted to a sheltered shoreline rather than sunk.
The utility believes the island formed over years from accumulated driftwood and vegetation that broke free as reservoir levels, at their highest in 14 years, rose. While no operational impacts are expected, B.C. Hydro will keep the lake under satellite surveillance and relies on public reports for future sightings. Similar floating islands have been documented in other dam reservoirs worldwide.
Why it matters
The event highlights how rising water levels can create unexpected hazards in large reservoirs, prompting monitoring and safety alerts for local communities.
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