do they really turn the falls off in Niagara at night?

While OPG most definitely could shut the water in Niagara River directly off, using the control damns situated throughout the river, it would most certainly flood out Fort Erie, Navy Island and Chippawa, so they never will. Instead they use the control damns to divert more or less amounts of water into the Falls and into the Welland Canal, more famously known as the Chippawa Crick, which they can completely reverse the flow of if wanted. They do cut the amount of water flowing over the Falls at night, by diverting it into the turbines to produce more electricity, while less people will be viewing, as to not take away from the power of the Falls.

Although there are dams upstream which can affect the flow of water which goes over the Falls, turning them off to "a trickle" would be a violation of a US/Canada treaty. In 1950, a treaty which is commonly known as the "Diversion of Niagara Falls Treaty" was signed. According to the US Niagara Parks System website: "The treaty requires that during the daylight hours of the tourist season (0800 to 2200 hours local time, April 1st to September 15th and 0800 to 2000 hours local time September 16th to October 31st), the flow over Niagara Falls must not be less than 2832 cubic m/second (cubic m/s) [100,000 cubic ft per second (cfs)]. At all other times, the flow must not be less than 1416 cu m/s (50,000 cfs). The treaty also specifies that all water in excess of that required for domestic and sanitary purposes, navigation and the Falls flow may be diverted for power generation."

After dusk each night during the tourist season, the water flow rate going over the Falls is reduced to only 50,000 cubic feet per second. This allows the Hydro Authorities to draw more water for hydro generation.

During the night time, both Ontario Hydro and the New York State Power Authorities pump massive amounts of water into their gigantic water reservoirs in order to top them up. Ontario Hydro's reservoir is 212 acres and is smaller than the American Robert Moses Hydro reservoir. During the daytime when the water flow is increased over the Falls for the tourists, the hydro companies draw the water from their reservoirs for hydro generation to make up for any water deficit. I hoped this helped and yes i live near Niagara.

When they had to fix the waterfalls retreat they did devert more water do they could concrete the falls edge.

actually, there is some truth...see, they do turn them off, but not completely at night....since its dark, the hydro factory that uses the water from the falls to produce electricity takes in more water thus creating more electricity

well, at least in the canadian part of the falls...im from toronto

really, you think some guy has a tap, only mother nature could make something of such magnitude buddy, so no, they don't turn off niagra falls at night.

umm, no, its a water fall, its natural, its not controlled by humans

i think you were misinformed, or someone was joking with you, there are definately no dams before the falls to stop the water

it is not possible to turn a waterfall off.

Yes, to save water

7 Thumbs down, lol. Its a joke guys.