A 'Vanishing' Island Turned Up More Than 18 Miles Away on a British Columbia Reservoir
A tree-covered island that disappeared from a British Columbia reservoir has been found again, more than 18 miles from where it was first seen.
What looked like a disappearing act on a British Columbia reservoir turned out to be something stranger. A tree-covered island that showed up in satellite data, then seemed to vanish, has now been found again far from where it was first spotted.
The island was seen on Williston Reservoir, north of MacKenzie, and its existence was confirmed by B.C. Hydro using satellite data from July 20. Then it dropped out of satellite imagery by Aug. 5, leaving behind a small mystery.
In the clip below, the unusual floating landmass is part of a story that has now taken another turn. B.C. Hydro said on social media Monday that the island has been located again, this time along the shoreline and more than 18 miles from its original position.
How an island like this can exist at all
Despite how it looked, officials say it was not really a solid island in the usual sense. B.C. Hydro spokesman Bob Gammer had previously explained that something like this can form over several years, as driftwood builds up along the shore and plants and trees begin to grow in decomposing wood.
That process can create what appears to be a piece of land sitting on the water. Gammer said the island likely broke free from the shoreline because water levels in the reservoir rose.
Why visitors are being told to stay back
Even with trees growing on it, B.C. Hydro warned that the mass is unstable. The company said it is better understood as a loose collection of logs and decaying woody debris than a true island.
Because of that, visitors to the reservoir are being told not to get too close. According to the warning, the surface is unsafe to land on or climb across, so people should keep their distance.
Why an island can appear to move
Not every island is attached firmly to the bottom. Some are really floating mats made of peat, roots, grasses, shrubs, and sometimes even trees. Over time, shoreline plants can knit together into a buoyant mass. If that mass breaks free, it can drift like a raft.
This is more likely in places where water levels rise and fall a lot. When the water lifts a root mat, it can loosen from the shore. Wind, waves, changing currents, and ice can then push it across the water. A floating island may get stuck in a bay or against a bank for a while, then break loose and move again.
From a distance, these mats can look like normal land because they may support thick vegetation. Up close, they are often surprisingly unstable and can shift under weight.
Why reservoirs are especially changeable
A reservoir is a human made lake, usually held back by a dam. Unlike many natural lakes, reservoirs often change shape through the year as inflows, weather, and water management alter the level. Shorelines can be muddy, steep, or undercut, which helps chunks of vegetation detach.
Reservoirs can also have complex wind patterns and narrow channels that funnel floating debris. That means not just islands, but logs, weed mats, and root balls can travel long distances. After storms, rapid snowmelt, or strong seasonal water changes, these objects may show up in new places.
Floating vegetation is not always a bad thing. It can create shelter for fish, insects, and birds. But it can also block coves, tangle boat propellers, or carry invasive plants to new areas.
What to do if you spot one
Treat a floating island as a hazard, not a picnic spot. Do not assume it will hold your weight, even if it has grass or trees on it. The edges can be especially weak, and there may be deep, cold water immediately underneath.
If you are boating, give it space. A floating mat may hide submerged branches and roots that can damage a hull or foul a propeller. Its position can also change faster than expected if the wind picks up.
If you live near or visit a reservoir, check local waterway notices before launching a boat, especially after rough weather. If a large floating mass is blocking access, threatening a dock, or drifting near a water intake, report it to the local authority that manages the reservoir or boating access.
