The Ontario Power Company hydro-electric generating plant opened in 1905, the same time as the Rankine Power Station. This American based company built its generating plant at the base of the Horseshoe Falls just above river level.
The generating station works as such, water enters from a bay located 1.6 kilometres upstream of the Falls near Dufferin Islands and is brought to the plant through buried conduit pipes and steel penstocks, all of which are tunnelled through the rock.
The conduits, two steel and one wooden, are bound with iron hoops and encased in cement run 1884 metres underground to the top of the generating station. There each conduit connects with six penstocks, each 1.83 metres in diameter. At the point where the conduits and the penstocks join, there is a section which turns upwards into a spillway called a surge tank.
The surge tanks purpose is to reduce fluctuations in head and pressure during both the increase and decrease of loads. The spillways are being opened or are provided with overflow pipes. They also send any excess water to the river when the load of the tank is suddenly reduced and in order to prevent any dangerous rise in pressure.
Unfortunately only one of these surge tanks exists today. Both are located south of the Queen Victoria Park Restaurant. The illumination battery is located on top of one of them.
The 15 generators produced 203,000 horsepower (132,500 kilowatts) of 25 cycle electric power. This plant has twice been flooded by ice and water in 1909 and 1938. Each time this happened the plant was put out of service for many months. The ice build up of the river in 1997, caused the plant to reduce power for several weeks.
In December 1999, the Ontario Power Generation Company (formerly Ontario Hydro) decommissioned the Ontario Power Station from service. This was done to accommodate the building of Casino Niagara, which is located on the former transformer building site. According to the Ontario Power Generation Company, this power station has been mothballed and its future status will be reviewed from time to time.