Mystery Island Breaks Loose in B.C. Reservoir, Then Vanishes

A giant floating island covered in trees broke away from the shore of a large lake in northern British Columbia, Canada. The island was about the size of two NFL football fields, covering nearly 9,800 square meters. Satellite photos confirmed the island was there on July 21, measuring about 70 meters wide and 140 meters long. When officials checked again later, though, it had vanished — possibly drifting into a quiet, sheltered bay.

The island was spotted on the Williston Reservoir, one of the largest man-made lakes in the world. The lake was created when the W.A.C. Bennett Dam was built in 1968. This past summer, the reservoir reached its highest water level in 14 years after a very snowy winter and a rainy summer. Because the water rose so high, the utility company B.C. Hydro had to open its spillways — special gates that release extra water — in June and July.

B.C. Hydro officials think the island formed slowly over many years. Pieces of driftwood piled up along the shoreline and began to rot, forming a thick, spongy platform. Over time, plants and even small trees took root on top of that platform. When the water surged this summer, the whole mass finally broke free and floated out into open water.

B.C. Hydro spokesperson Bob Gammer explained that wind and rising water can push a floating island far out into the lake — or tuck it away in a remote cove where satellites cannot easily spot it. "We've been taking more updated snapshots, and we can't see the object anymore," Gammer told CBC News. Officials say there are no major problems for the dam right now, but they are watching closely. The island's exact location remains unknown.

Floating islands are not as uncommon as you might expect, especially in lakes formed by dams. In Wisconsin, big chunks of peat bog have broken loose from Lake Chippewa before. One floating bog island there is so large that workers must push it with a boat each year to stop it from crashing into a nearby bridge. In Africa, researchers are studying how floating islands on Lake Victoria affect fishing and boat travel across three countries.

A drifting mass of trees, mud, and plants can cause real danger on the water. It can damage boats and could even clog or block important parts of a dam. Local resident Rocky Avery told CBC News that boating in the area has become much more risky this year. "Some are full-size trees and it'll do a lot of damage to your boat," Avery said. "You got to be super careful."

Scientists say events like this are becoming more common as climate change causes water levels to rise and storms to grow stronger. In the tiny Pacific island nation of Tuvalu, sea levels have risen nearly six inches over the last 30 years. Experts warn that by 2050, much of Tuvalu's land could sit below the high tide line. The nearby island nation of Palau could lose many of its 500 low-lying islands within 50 years. The mystery island in British Columbia may be a local story, but it is part of a much bigger pattern happening across the planet.