No, the 670 metre long structure built between 1953 and 1957 in the upper Niagara River above the falls is a water control structure. The structure consists of 18 movable gates that extend about half-way across the Niagara River to the international border between Canada and the United States. It does not hold back all the water of the Niagara River. Therefore it is incorrect to call it a dam as so many tour guides have done since it was built.
It is used to control the flow of water that flows over Niagara Falls. The international structure evenly distributes the flow of water over the Canadian Falls helping it keep its horseshoe shape. When the gates are up it also forces more water through four tunnels to the reservoirs at Queenston and Lewiston to be used to produce electricity during peak time.
Currently, the structure is undergoing major maintenance.