Niagara Falls Facts | Geology Facts & Figures

• More than 168,000 cubic metres (6 million cubic ft.) of water go over the crestline of the falls every minute during peak daytime tourist hours
• The Canadian Horseshoe Falls drops an average of 57 metres (188 ft.) into the Lower Niagara River
• The crest line of the Canadian Horseshoe Falls is approximately 670 metres (2,200 ft.) wide. The plunge pool beneath the falls is 35 metres (100 ft.) deep
• The height of the American Falls ranges between 21 to 34 metres (70-110 ft.). This measurement is taken from the top of the falls to the top of the rock pile at the base, called the talus slope. The height of the falls from the top of the falls to the river is 57 metres (188 ft.). The crest line of the American Falls is approximately 260 metres (850 ft.) wide
• The rapids above the falls reach a maximum speed of 40 km/hr or 25 mph, with the fastest speeds occur at the falls themselves (recorded up to 68 mph.) The water through the Whirlpool Rapids below the falls reaches 48 km/hr or 30 mph, and at Devil’s Hole Rapids 36km/hr.
• The Niagara River is a connecting channel between two Great Lakes, Erie and Ontario.
• Niagara Falls has moved back seven miles in 12,500 years and may be the fastest moving waterfalls in the world.

So, how much water actually flows over Niagara Falls? First, the term “tonnes” refers to a metric tonne, also known as a long ton. In this case, we are referring to water, which at standard temperature and pressure (STP) weighs one tonne per cubic metre. STP is the weight of water at zero degrees centigrade at seas level, which is one atmosphere (atm) of pressure. We can disregard temperature and pressure for this calculation, although you should be aware that the mass of water decreases as the temperature rises and/or the pressure decreases.

• During the high season, the “tourist flow” over the falls of 100,000 cubic feet per second (cfs) converts to 2,832 cubic metres per second (cms), meaning 2,832 tonnes of water per second is flowing over the falls.
• The “non-tourist flow” of 50,000 cfs converts to 1,416 cms, which means that 1,416 tonnes of water per second is flowing over the falls.

To convert from tonnes per second to tonnes per minute, multiply by 60. To convert from tonnes per second to tonnes per hour, multiply by 3,600.