Around the Falls
Most of the Niagara River never goes over Niagara Falls. Above the brink, New York and Ontario pull it underground and send it to the power plants at Lewiston and Queenston. This is where it goes, and how much, right now.
…of the river is going around the falls.
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The last seven days
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How the numbers work
The total is live: Environment Canada's gauge on the Niagara River at Fort Erie (02HA013), which measures everything leaving Lake Erie every five minutes.
The falls are measured too. The treaty's official falls flow comes from a rating curve at the Ashland Avenue gauge, in the gorge below the falls, and NOAA runs a live gauge there (9063007, every six minutes). That rating isn't published, so this page uses one fitted to 1,419 daily falls flows from the International Niagara Board of Control's reports for 2021 to 2023. It matches them to a median 3%; call it plus or minus 5%. Whatever leaves Fort Erie and doesn't go over the falls went to the power plants.
The 1950 Niagara Treaty sets the floor: at least 100,000 cfs on the falls in daytime tourist hours and 50,000 cfs the rest of the time, with the rest shared by the two countries. The dashed line on the chart is that minimum. In practice the falls sit right on it by day and well above it at night, because the plants can't take everything.
How the diversion divides between the countries is not published live, so it is shared in the ratio the Board reported for March to August 2023 (Robert Moses 56%, Sir Adam Beck 44%). The Fort Erie gauge posts about an hour and a half late, so the latest stretch holds the river at its last reading; water also takes a few hours to get from Fort Erie to the falls. If the NOAA gauge is down, the page falls back to the treaty minimums. The reservoirs' pumping follows power prices as well as the treaty. The reservoir cycle shown is the treaty's night-to-day swing: the extra water both sides may take at night is pumped up, then released evenly through the tourist day. The treaty's hours are written in Eastern Standard Time, so in summer they fall an hour later on the clock.
Channels: river from OpenStreetMap; the 2013 Niagara Tunnel is not in OSM, so its route is traced from a published map (it measures 10.3 km against the official 10.2). Capacities from NYPA, OPG and the Niagara Tunnel Project. The Grand Island and Goat Island splits (about 58/42 and 90/10) are rough. Imagery: Esri.