Mysterious Floating Island Appears and Vanishes in B.C.’s Williston Reservoir
A massive floating island measuring roughly two NFL football fields in size mysteriously appeared and then vanished on the Williston Reservoir in northern British Columbia, baffling both local residents and power utility officials.
The forested land mass was first spotted bobbing in the massive man-made lake north of Mackenzie earlier this month, according to local resident Rocky Avery. Avery posted photos and video taken by a boater on social media, where the footage quickly circulated.
“It was a pretty amazing sight to see, never seen anything like that in my 40 years in this country,” Avery told CBC News, adding that he wanted to alert the public ahead of a major fishing derby and notify B.C. Hydro in case the debris drifted toward infrastructure.
When CBC News first contacted B.C. Hydro regarding the anomaly, spokesperson Bob Gammer expressed initial skepticism, noting that the rise of generative AI technology makes it difficult to trust unverified online videos at first glance.
“It’s certainly something we’ve not heard of before,” Gammer said, according to CBC News. “And with not very many people reporting it, it was difficult to locate.”
Satellite imagery dated July 21 subsequently confirmed the reality of the floating mass, locating it in the main body of the reservoir west of Finlay Bay, approximately 100 kilometres west of the W.A.C. Bennett Dam. Gammer stated that the island measured roughly 70 metres wide and 140 metres long, encompassing an area of approximately 9,800 square metres.
By Aug. 5, however, satellite data showed the object had vanished from the open water.
“We’ve been taking more updated snapshots and we can’t see the object anymore. So it’s disappeared now,” Gammer told CBC News. He noted that the disappearance does not mean the land mass sank to the bottom of the reservoir, suggesting instead that it may have drifted into a sheltered area along the shoreline.
B.C. Hydro confirmed that no operational impacts are expected from the incident, though the utility continues to monitor the reservoir for the island’s potential reappearance.
Impounded behind the W.A.C. Bennett Dam in 1968, the Williston Reservoir ranks as the seventh-largest reservoir globally and is visible from space. Heavy winter snowpacks and consistent summer rainfall filled the basin to capacity this year, forcing B.C. Hydro to open the dam’s spillways in June and July to manage water levels.
Gammer explained that the island likely formed over many years along the shoreline where driftwood accumulated, enabling trees and plants to take root in decomposing organic matter. As water levels rose to a point not seen in 14 years, the mass broke free from the bank, and winds carried it out into the open lake.
Avery noted that the high water levels have also washed out shoreline sand dunes and pulled more trees and debris out into the water than usual.
While rare on Williston Lake, floating islands are a documented phenomenon in large reservoir systems globally. Similar land masses have formed on Lake Chippewa in Wisconsin following dam construction, requiring annual towing by boat to keep them from striking local bridges, and researchers are studying floating islands impacting fisheries and navigation on Lake Victoria in Africa.
B.C. Hydro stated that it relies on ongoing public reports to monitor conditions across its vast reservoir network.