A huge floating island appeared on Williston Reservoir, then vanished. B.C. Hydro is watching the lake as experts explore how it formed.
A giant island appeared out of nowhere
A huge island suddenly showed up on Williston Reservoir in northern B.C.
Then, just as quickly, it vanished.
The strange sight was first spotted by a boater earlier this month. Photos and video soon spread online after local resident Rocky Avery shared them.
For Avery, the sight was hard to believe.
He said he had never seen anything like it during his 40 years in Canada.
The island was not small, either. It measured about 140 metres long and 70 metres wide.
That is close to the size of two football fields.
Satellite images confirmed it was real
At first, B.C. Hydro was not sure what to make of the photos.
That caution made sense. Fake images and AI-made videos are now common online.
However, satellite images later solved that mystery.
Images from July 21 showed the floating mass in the main part of Williston Reservoir, west of Finlay Bay.
The spot was about 100 kilometres west of the W.A.C. Bennett Dam.
B.C. Hydro estimated the island covered about 9,800 square metres.
So, yes, the strange island was real.
Then the island disappeared
There was another twist.
By Aug. 5, the island could no longer be seen in satellite images.
B.C. Hydro says it has not been found since.
Still, that does not mean the island sank.
Instead, it may have drifted back towards the shore. A sheltered area could have hidden it from view.
For now, B.C. Hydro is keeping watch.
The utility also says the island is not expected to affect its operations.
Why did the island start floating?
There is a likely explanation.
Williston Reservoir has seen very high water levels this year.
Heavy winter snow and steady summer rain helped fill the reservoir. In June and July, B.C. Hydro opened spillways at the W.A.C. Bennett Dam to release water.
The reservoir has not been full for about 14 years.
That may have helped set the island free.
Over many years, trees and other plant life can grow where driftwood and other organic material build up along the shore.
As water rises, that mass can break away.
Once it is free, wind and waves can push it across the water.
That appears to be one possible explanation for what happened at Williston Reservoir.
However, B.C. Hydro cannot say exactly where the island came from.
High water is moving more debris
Local residents have noticed other changes, too.
Avery says the high water has washed away some shoreline areas and moved more trees and debris into the reservoir.
That can create a serious boating risk.
Large logs may sit low in the water. On calm days, boaters may spot them. But waves can make them much harder to see.
A hidden tree can cause major damage if a boat hits it.
So, while the floating island may be gone for now, boaters still have good reason to stay alert.
Floating islands are not unheard of
The sight may sound like something from a movie.
Yet floating islands are a real natural phenomenon.
Similar events have happened in other large reservoirs.
In Wisconsin, for example, huge pieces of peat broke free after an area was flooded to create a reservoir.
Elsewhere, floating islands have also been studied for their effects on boating, fishing and water quality.
So, Williston Reservoir may have produced a rare sight in B.C., but nature has pulled off this trick before.
B.C. Hydro wants people to keep watch
Williston Reservoir is enormous.
Because of its size, checking every part of it by boat is not practical.
That is why B.C. Hydro also uses satellite images and reports from people in the area.
For now, the mystery remains.
The island appeared.
It drifted through one of B.C.’s largest reservoirs.
And then it disappeared.
But with water levels high and more debris moving through the lake, boaters are being urged to stay careful.
The next sighting could come from anyone on the water.
