When a new island suddenly appeared and then disappeared on Williston Lake in B.C.’s northern interior this July, the mystery prompted immense public interest as officials began investigating the origins of the mirage-like island. Now, the mystery has been solved.
A local resident and boater named Rocky Avery was the first person to bring attention to the island when he posted a video that had been shared with him to Facebook on August 12. The video captures a bobbing mass of trees that has since been estimated to be roughly 70 metres wide and 140 metres long.
“I thought it was a hoax,” says Bob Gammer, a spokesperson for B.C. Hydro, which owns the man-made reservoir the island materialized on. “At first, we disregarded it as AI trickery, but as it got more and more attention on Facebook, we decided to look at satellite imagery and, sure enough, there was a little green blob in the middle of the water.”
The satellite images were able to track the island’s movements back to July 21, showing that it had detached from the shoreline. B.C. Hydro’s theory is that the island is made up of logs and woody debris that would have accumulated over a long period of time, given that many of the trees are mature. “As that material gradually decomposed, vegetation may have taken root and created a stable mass of interconnected debris and plant growth,” Gammer says. “We’ve had a full reservoir this year, and when that happens, shoreline debris, logs and whatnot, can lift up and float out into open water.”
In fact, B.C. Hydro was able to find satellite imagery from before the reservoir filled up that shows the island sitting on the shoreline apart from other vegetation, presumably ready to break free. Gammer says that while this isn’t the first time the reservoir has reached fullness—heavy thaw and summer rains caused a full reservoir in 2012 as well—there has never been a floating island spotted in the reservoir’s more than 50 year history.
For a short while, the floating island drew even more intrigue when it disappeared from the centre of the lake, but Gammer says they eventually located it along the shoreline where it was blending into the other vegetation after winds blew it 30 km north.
Because the floating island has remained intact, is very easy to spot, and has remained stationary along the shoreline for several weeks now, Gammer says it doesn’t pose a threat to boaters. B.C. Hydro’s W.A.C Bennett hydro electric dam should also remain unaffected, as the island sits around 100 km west of the dam.
For now, the island has found a new home base. If it remains there through the fall, Gammer says it will eventually become stagnant when the ice freezes. But who’s to say what could happen when the lake thaws. “If the reservoir doesn’t build to full next year, the island may not have enough water underneath it to float free and start moving again. So it may just be against the shoreline for quite some time.” says Gammer. “We’ll see what next year’s water levels bring.”
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