The Niagara falls are a huge series of waterfalls on the Niagara River, stretching across the international border between New York State and Ontario, with twin cities sharing the name, on each side of the river.
The falls themselves are divided into three sections. On the Canadian side are the Horseshoe Falls, and on the American side, separated from the Horseshoe Falls by Goat Island are the American Falls and then the smaller Bridal Veil Falls separated from the American Falls by Luna Island. It is expected that Luna Island will one day break up, and so link the two falls on the American side.
Three hundred years ago the area was inhabited by the Iroquois Indian nation. The first European to see the falls was probably Etienne Brule in 1615. The Jesuit missionary Gabriele Lalemant recorded the Iroquois name for the river as Onguiaahra that same year, and the simplification of this, Niagara became the name the river was known by.
In 1812 James Madison declared war on Canada and the relics of this war can be seen all along the riverside. It was the rebuilding following this war that saw much of the development of the area, including Queenston and Chippewa. This led to the development of the area for tourists; the first staircase alongside the falls, the first ferry and the first paved road date from the 1820's.
Ever since this date the falls have remained a popular tourist attraction. The water in the river is used for many other purposes than the entertainment of tourists however. Over two hundred thousand cubic feet per second of water flow over the falls at peak flow, and this energy has been harnessed since 1759 in various guises to provide power to sawmills, factories and hydroelectric power facilities.
Hydroelectric power started flowing in the early twentieth century, and now between fifty and seventy-five percent of the water flow is diverted to provide power to the turbines. In order that the tourism industry is not damaged much of this diversion takes place at night. There is an agreement in place to keep the daytime water flow during the tourist season to 100,000 cubic feet per second, and 50,000 at all other times.
With such large volumes and forces of water involved the freezing of the falls seems an unlikely proposition. Ice frequently forms in the Niagara River and on Lake Eyrie, which feeds the river leading to ice on the falls, but this cold is not sufficient to freeze the falls.
Ice floes fuse and form ice bridges that the water still flows under, particularly downstream of the falls. It was at one time a common event that an ice bridge would form over the river, and the public would go out on the ice to sled, toboggan and enjoy themselves. Tragically in 1912 three people were killed when part of the ice bridge they were on collapsed and washed them downstream.
Only once has flow over the Horseshoe Falls been considered stopped by ice. This was on the 29th March 1848. It was reported in the Buffalo Express Newspaper that at eleven o'clock at night all was well, but by midnight all water powered machinery in local factories had ceased to work. The next day the riverbed above the falls was visible. The falls had not frozen but a massive ice floe had blocked the river, stopping virtually all water from traveling to the falls.
Local people are reported to have explored the riverbed, retrieving artifacts from the Iroquois Nation, the war with Canada and many other times. The water started flowing again when a sudden rise in temperature thawed the ice bridge, breaking it up. The noise of this was compared to thunder and everyone on the riverbed scrambled for shore, everyone escaping in time.
Water flow over the American falls has been recorded as "stopped" more frequently. A far lower volume of water goes over these falls than over the Horseshoe Falls, and the angle of approach means ice blocks the entrance to the falls from the river more easily. American engineers have taken advantage of this to try and clear rocks from below the falls. The flow was stopped deliberately in the 1960's to allow reinforcing of the lip of the falls to prevent it moving upstream.
It is unlikely that the falls will stop flowing again due to ice. Ice booms have been installed at the gateway from Lake Eyrie to preserve water flow for the power plants and ice does get through but in such large pieces as before. The ice that does reach the falls goes over and helps in the formation of ice bridges further down stream.