The International Control Dam, also known as the International Control Structure, operated by

Ontario Power Generation Ontario Power Generation Inc. (OPG) is a Crown corporation and "government business enterprise" that is responsible for approximately half of the electricity generation in the province of Ontario, Canada. It is wholly owned by the government ...

, is a

weir A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...

that controls the water diversions from the

Niagara River The Niagara River () is a river that flows north from Lake Erie to Lake Ontario. It forms part of the border between the province of Ontario in Canada (on the west) and the state of New York in the United States (on the east). There are diffe ...

and dispatches the water between the

New York Power Authority The New York Power Authority (NYPA), officially the Power Authority of the State of New York, is a New York State public-benefit corporation. It is the largest state public power utility in the United States. NYPA provides some of the lowest-co ...

and

in accordance with the terms of the 1950 Niagara Treaty. It was completed in 1954. To preserve

Niagara Falls Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the Canada–United States border, border between the Provinces and territories of Canada, province of Ontario in Canada and the U.S. state, state ...

' natural beauty and to ensure an "unbroken curtain of water" is flowing over the falls, the 1950 treaty was signed by the U.S. and Canada to limit water usage by power plants. The treaty allows higher summertime diversion at night when tourists are fewer and during the winter months when there are even fewer tourists. The treaty states that during daylight time during the tourist season (April 1 to October 31) there must be 100,000 cubic feet per second (2,800 m³/s) of water flowing over the falls, and during the night and off-tourist season there must be 50,000 cubic feet per second (1,400 m³/s) of water flowing over the falls. This treaty is monitored by the International Niagara Board of Control, part of the International Joint Commission, using a

NOAA The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

br>gauging station
above the falls. This weir allows water from the upper river to be diverted into the intakes for the American and Canadian power stations. Two tunnels on the American side take water under the city of

Niagara Falls, New York Niagara Falls is a city in Niagara County, New York, United States. As of the 2020 census, the city had a total population of 48,671. It is adjacent to the Niagara River, across from the city of Niagara Falls, Ontario, and named after the fame ...

and three tunnels on the Canadian side divert water under the city of

Niagara Falls, Ontario Niagara Falls is a city in Ontario, Canada. It is on the western bank of the Niagara River in the Golden Horseshoe region of Southern Ontario, with a population of 88,071 at the Canada 2016 Census, 2016 census. It is part of the List of census ...

. Once past these cities, the water flows into two canals and then into two large reservoirs. Behind the Canadian Sir Adam Beck Power Station is a reservoir covering 300 hectares (750 acres) and a similar reservoir on the US side behind the Robert Moses Power Plant. A trade off exists between the two main industries of Tourism and Hydroelectric Power. More water is diverted by the International Control Dam at night, between 10:00 pm and 7:00 am, filling the reservoirs over night, and allowing more water over Niagara Falls in the day-time hours for the tourists. As well, during the winter, from Nov. 1 to March 31, when it is not the tourism season, more water is diverted for electrical power during the whole 24 hour period. The pool of water located immediately upstream of the International Water Control Dam is named the "Chippawa - Grass Island pool".

References

External links

{{Commons category, International Control Dam
International Niagara Board of Control
Dams in Canada Niagara River Dams completed in 1954 Ontario Power Generation Canada–United States relations Weirs