How Ice Bridges contribute to freezing
Ice bridges also form at the base of the Falls in the winter months.
The water flows very quickly through the Niagara River, but the ice chunks that go over the Falls collect and freeze to the rocks surrounding the base. Water continues to build on the ice that is there, resulting in an ice sheet or ice bridge that can accumulate anywhere from 40 to 80 feet thick. Air still manages to accumulate beneath the ice, which allows the water to continue to flow beneath the ice. That means the river does not completely freeze over.
In the early years of tourists visiting Niagara Falls, people were actually allowed to walk out onto the ice bridges that had formed at the base of the Falls. But in 1912, the ice bridge broke apart and 3 people who became stranded on chunks of the ice flow were swept down river, into the Whirlpool Rapids and drowned.
In 1938, a massive chunk of ice was swept down river from Lake Erie. It caused a chain raction of mouting ice and rising water levels which damaged the generators of the power station, and also crushed the docks of the Maid of the Mist and did so much damage to the Falls View Steel Arch Bridge that it collapsed a few days later.
In the 1960’s, an ice boom was placed at the mouth of the Niagara River to keep the ice from Lake Erie from flowing into the lower gorge of the river so an ice bridge will not form, yet it still allows water to continue flowing downstream.
Today, the New York Power Authority & Ontario Power Generation share the responsibility of tending to the 8,800-foot-long ice boom, which consists of steel pontoons that are linked together and anchored to the river’s bottom at Lake Erie's outlet to the Niagara River.