--- title: "What Time to Stand at Niagara Falls for the Full Treaty Flow" url: /the-falls-are-turned-down-at-night-and-a-treaty-says-so/ author: "Falls View" date_published: 2026-09-08T21:00:00+00:00 date_modified: 2026-09-08T21:00:00+00:00 categories: ["Niagara Falls"] image: https://www.bestwesternfallsview.com/wp-content/uploads/2026/09/traite-1950-une.jpg description: "A 1950 treaty cuts Niagara's guaranteed flow in half every night and all winter, so the hour a visitor arrives changes what they actually see." site: "Falls View" license: "Reproduction autorisée avec lien vers la source." --- # What Time to Stand at Niagara Falls for the Full Treaty Flow > A 1950 treaty cuts Niagara's guaranteed flow in half every night and all winter, so the hour a visitor arrives changes what they actually see. Niagara Falls looks the same in almost every photograph, but the amount of water going over the brink follows a fixed schedule, set out in a 1950 treaty between Canada and the United States. It is not the weather that turns the flow up and down. It is paperwork, and a gate upstream. The treaty guarantees a minimum combined flow over the Horseshoe and American Falls of 2,832 cubic metres per second, close to 100,000 cubic feet per second, during the day within a defined season. At night, and for the whole winter from November 1 to March 31, the guaranteed minimum falls to 1,416 cubic metres per second, exactly half. Horseshoe Falls, on the Canadian side, is roughly 57 metres high and somewhere between 670 and 790 metres wide depending on which agency measures it. American Falls is narrower, closer to 260 to 300 metres, so the same percentage cut reads differently on each side of the border. **Two numbers to remember** Daytime minimum in season: 2,832 cubic metres per second. Night and all winter: 1,416, half of that. ![Water pouring over the crest of Horseshoe Falls in daylight, full width](https://www.bestwesternfallsview.com/wp-content/uploads/2026/09/traite-1950-corps.jpg) *The daytime flow guaranteed by the 1950 treaty, seen from the Canadian bank.* The daytime window itself has two shapes. From April 1 to September 15, the full minimum runs from 8 a.m. to 10 p.m., Eastern time. From September 16 to October 31, it shortens to 8 a.m. to 8 p.m. Step outside either window, and the river drops to half strength before it reaches the edge, whatever the calendar says about sunrise or sunset. ## The hours that matter If the goal is to see the falls at their guaranteed daytime maximum, the safest hours are the middle of the day, well clear of the 8 a.m. start and the evening cutoff, from April through mid-October. Arrive at dawn in July hoping for the full flow and there is a chance the treaty clock has not switched over yet. Stay past 8 p.m. in late September and the same applies: the number quietly halves while the crowd on the railing is still taking photographs. The gap is not subtle once someone knows to look for it. A visitor who times a morning at the falls for eleven o'clock in July is looking at close to double the volume of a visitor standing in the same spot at eleven at night. The rock, the mist and the rainbow angle stay put. The water does not. **A rough rule** Between April and October, late morning to mid-afternoon sits comfortably inside every version of the daytime window the treaty allows. ## Winter is a different river From November through March, the treaty does not distinguish day from night. The half minimum applies around the clock. A traveller arriving at noon in January and one arriving at 2 a.m. are looking at the same guaranteed floor, ice conditions aside. Horseshoe Falls carries roughly ninety percent of whatever total is running at the time, American Falls the remaining tenth, so the split between the two does not change with the season. What changes is the total. None of this means the falls look thin in winter. Ice narrows the channel and slows the visible current in ways a flow figure does not capture, and even at half minimum the volume is still enormous by the standard of most rivers. The treaty number is a floor, not a description of what the eye takes in, and a frozen mist wall in February photographs just as dramatically as a July afternoon, for entirely different reasons. ## Where the surplus water goes Above the treaty minimums, whatever water is left is split equally between Canada and the United States for hydroelectric generation, drawn off upstream before it reaches the brink. Canada also receives an additional 141.6 cubic metres per second from the Long Lac and Ogoki diversions, water brought in from outside the Great Lakes basin, which does not count against its share of the Niagara flow itself. In practice, the falls a visitor watches are what is left over after two countries have already taken their agreed cut for power. **Not a fixed pipe** The surplus above the treaty minimum is divided equally between the two countries for power generation, on top of a separate allowance Canada gets from diversions outside the Niagara basin. ## A side effect: a slower retreat Regulating the flow has a second consequence that has nothing to do with sightseeing. Before the water was managed this closely, the falls were eating back into the riverbed at roughly one to one and a half metres a year, measured over more than five centuries. Since regulation began, that rate has slowed to about thirty centimetres a year, and continued management could push it down further, toward three centimetres a year. The same gate that decides how full the falls look at 9 p.m. is also the reason the edge is not moving as fast as it once did. ## Who turns the valve The flow is not set once and forgotten. A joint Canada-US committee operating under the International Joint Commission checks the numbers on a weekly basis and adjusts the intake at the power stations so the treaty minimums hold. The falls a visitor sees on any given day are the result of that week's calculation, not a natural discharge left alone since 1950. **Checked weekly** A binational committee under the International Joint Commission reviews the flow every week and adjusts intakes so the treaty floor is respected. None of this is visible from the railing. What is visible is the difference an hour or a season makes, and that difference has a paper trail running back to a signature from 1950, still checked every week, three quarters of a century later. --- ## À propos de l'auteur **Falls View** — Die Redaktion von Mein Südtirol: Pässe, Mautgebühren und Öffnungstermine, jede Angabe mit ihrem Datum.