The Giant Floating Island of Lake Chippewa Has to Be Pushed by Boats Almost Every Year

Lake Chippewa in Wisconsin, also known as the Chippewa Flowage, has a giant floating island that sometimes moves and blocks a crucial bridge. Local boat owners must work together to move it.

The lake was created in 1923 by flooding a large swamp. Soon after, peat bogs started to float to the surface and became perfect places for plant seeds to grow. Over time, grasses and trees grew on these floating bogs, causing them to expand. Today, they range from the size of a parking space to several acres. The largest, called the “Forty Acre Bog,” has mature trees and is located on the west side of the lake. Each year, local boat owners join forces to push it away from the bridge that connects the east and west sides of the lake.

“It happens almost every year. It takes a community effort and favorable winds to push them into place,” a local resident told Northern News Now.

According to the Chippewa Flowage website, the lake’s floating islands begin as mud flats that rise from the swamp below. Over time, vegetation grows on them, and the oldest islands even have trees. These trees can act like sails, moving the entire floating mass around the lake when the wind blows.

“It’s one of the first things you check for when you arrive in the morning: Where’s the bog?” said local resident Denny Reyes.

The floating island doesn’t always move, but when it does, it can block an important bridge that’s the only link between the East and West sides of the lake. When this happens, moving the island requires not just one large boat but dozens working together, with the wind helping them. Last year, 25 boats were needed to push the floating island away from the bridge.