The water from the Niagara River falls over two waterfalls, divided by Goat Island. Only six percent of the water from the Niagara River falls over American Falls, while Horseshoe Falls (or Canadian Falls) carries the majority of the water. In 1969, a temporary dam was built to divert the water from American Falls to Horseshoe Falls for several months in order to study the erosion endemic to both waterfalls.