The short answer is no, the Niagara Falls are not turned off at night. The tremendous force of water going over the falls makes that impossible. However, the flow is reduced by about 50% overnight for power generation purposes.
Why Niagara Falls Cannot Be Turned Off
With over 3,160 tons of water going over the falls every second during the daytime, there is simply too much water and force involved to ever completely stop the flow. Even attempts to temporarily stop the falls for repair purposes have been unsuccessful. The raw power of the moving water cannot be easily controlled.
In 1969, the U.S. Army Corps of Engineers was granted permission to study the feasibility of temporarily stopping the American Falls for repair work. They concluded it could not be done without causing damage. The projected cost of trying to stop the falls for even a short time of a few months would be prohibitively expensive.
While it’s not possible to completely halt the immense force of the falls, the flow can be reduced somewhat at night when tourist demand drops off. Let’s look at how and why the Niagara Falls flow is modulated over 24 hours.
Overnight Reduction of Niagara Falls Water Flow
While the falls cannot be shut off entirely, the amount of water going over the cliffs is reduced by around 50% between 10 pm and 7 am each night. This is done to divert water to the intake channels for hydroelectric power generation further downstream.
During the daytime peak tourist hours, only enough water is diverted to the power plants to meet regional energy demands. More water is allowed to go over the falls to maximize their visual impact for sightseers. But at night, when fewer people are enjoying the views, more water can be diverted downstream.
How the Water Flow is Controlled
The rate of flow over Niagara Falls is controlled by adjusting how much water is diverted to three large intake channels located upstream of the waterfalls:
- The International Control Works, located on the Niagara River upstream of Horseshoe Falls, diverts water before it reaches the top of the falls.
- Also upstream of Horseshoe Falls, the Chippawa-Grass Island Pool intake can divert water around Goat Island, directing it away from American Falls and Bridal Veil Falls.
- Further upstream, the Dufferin Islands intake diverts water around Grand Island before it reaches the upper river rapids.
Opening and closing these intakes changes how much water continues downstream to cascade over the falls. More water is allowed to flow over the precipice during daytime hours when viewing demand peaks.
History of Manipulating Niagara Falls Water Flow
While large-scale diversion of Niagara River water began in the early 1800s for hydropower generation, it took until the mid-1900s before adjusting the flow over the falls became standard practice.
In the early 1950s, the International Niagara Board of Control was established to oversee and regulate diversion of water from the upper Niagara River. Nightly flow reductions were initiated in the 1960s to maximize power production when tourist demand was low.
The 1950 Niagara Treaty between the United States and Canada guarantees at least 100,000 cubic feet per second (cfs) of water goes over the falls during daylight hours. At night, this minimum is reduced to 50,000 cfs.
| Time Period | Minimum Niagara Falls Flow |
|---|---|
| Daytime (8 am to 10 pm) | 100,000 cubic feet per second |
| Overnight (10 pm to 8 am) | 50,000 cubic feet per second |
During the tourist season between April and September, overflow volumes are often 150,000 to 175,000 cfs during the day. In the overnight hours, flows diminish to around 75,000 cfs as more water gets channeled to hydro plants.
Environmental Concerns Regarding Reduced Water Flow
While modulating the volume of water going over Niagara Falls provides important hydropower production, it raises some environmental concerns.
Impacts on the Falls Viewscape
The reduced volume of water can diminish the visual impact of the falls at night. The cliffs are not covered as fully and appear less impressive in darkness with lower flow.
Effects on River Ecology
The larger overnight water diversions to intake channels leave less water cascading over the falls. This alters the downstream river environment and water flow patterns, which can impact fish and wildlife habitats.
Threats to Ice Formations
In winter, the reduced flow at night makes ice bridges along the river less stable. This endangers the beautiful ice formations along the brink of the falls and damages the winter scenery.
Visitor Experience During Reduced Overnight Flows
Since many tourists are sleeping at night, the lower overnight water flow over the falls is not noticed by most visitors. Daytime volumes are always highest to showcase maximum views during sightseeing hours.
However, some hardy travelers do make a point of seeing the falls illuminated at night when flows are diminished. While reduced from its daytime glory, the sheer massive size of Niagara Falls still impresses even with lower overnight flow.
Special Late Viewing Hours
To allow more visitors to experience the nighttime falls during high season, extended evening viewing hours are offered.
From May through October, Queen Victoria Park on the Canadian side stays open until 10:45 pm. This allows visitors to admire the falls for over an hour after the minimum guaranteed daytime flows end at 9:30 pm.
Illumination is used to maximize dramatic nighttime viewing. The American Falls and Horseshoe Falls have been specially lit since 1925. Different colored lights are often used to create dazzling nighttime displays.
Conclusion
In summary, the great Niagara Falls cannot be completely shut off at night. But water flow is reduced by about 50% overnight to divert more water to hydroelectric generation. This modulation does not affect daytime tourist experiences, as full flows are always maintained during daylight sightseeing hours. Only night owls touring after 10 pm will notice the diminished but still impressive flow.
The sheer vastness of the falls means they remain a marvel of nature even at reduced volume. While not as spectacular as its daytime counterpart, nighttime Niagara still thrills as a memorable sight bathed in illumination.