Why Less Water Flows Over Niagara Falls Each Winter

Visitors to Niagara Falls are likely to notice that the famous waterfalls are not quite as full these days. The minimum flow over the falls has been intentionally cut. But why? Read on for the details.

Water Flow Over Niagara Falls Intentionally Reduced 

The minimum water flow over the iconic Niagara Falls has dropped from about 748,000 gallons per second to 374,000 gallons per second. The change was intentional, as officials divert water to generate hydroelectric power.

The change went into effect on November 1 and will remain in effect until April 1. The decision to reduce the minimum amount of water flowing over the falls by half is a part of an intentional strategy that balances the beauty of these falls with the need to generate clean energy.

The rules surrounding the flow of water over the falls go back to 1950. The U.S. and Canada signed a treaty designed to dictate how the two nations could use the power of these falls to generate electricity while preserving the popular tourist attraction.

The treaty allows more water to be diverted away from the falls and toward hydroelectric power plants located in both Ontario and New York. These plants use the power of the water to produce electricity.

The International Niagara Control Works is the structure that controls this process. Located about a half mile upstream from Horseshoe Falls, the structure encompasses 18 gates that are adjusted to control the river's flow and water levels. This water is then diverted toward the generating stations on both sides of the border.

The Niagara Power Project is distinguished as being the state of New York's largest electricity producer, with the ability to generate up to 2.6 million kilowatts of electricity. According to the New York Power Authority, "That clean energy is generated by two facilities, the Robert Moses Niagara Power Plant and the Lewiston Pump Generating Plant, with a combined 25 turbines spun by 748,000 gallons of water per second."

These rules shift with the changing seasons so that more water flows over the falls during the peak of the tourist season. At least 100,000 cubic feet per second must flow over these falls during the day from April 1 through October 31. This mandate drops to 50,000 cubic feet per second in the overnight hours. However, the lower minimum is in place around the clock from November 1 through March 31.

While those are the minimum flow rules, the actual amount of water is often higher depending on the weather at the time and the conditions on the Niagara River. This is why the falls sometimes look fuller at certain times.

How Cold Weather Impacts the Visitor Experience

In addition to the off-season water flow rules, the cold weather also changes the visitor experience at this popular tourist destination. For example, freezing mist has been known to create magical ice formations around the waterfalls during the winter.

On the flip side, several of the outdoor attractions shut down for the season. The Maid of the Mist boat tour on the U.S. side pauses operations during the winter.

Sadly, erosion chipping away at the underlying rock is slowly forcing the waterfalls upstream. According to the International Joint Commission, Niagara Falls moved upstream at an estimated rate of approximately 3.3 feet per year historically. However, that rate is now estimated to be closer to 4 inches annually, in large part due to the water that is being sent to the power station.

The natural shape of Horseshoe Falls has been changing over time as the curved edge of the falls gets longer. The erosion process is slowing down as the water spreads over a wider zone.

Humans have also been responsible for changes to the structure of Niagara Falls over the years. The American Falls ran dry in June of 1969 when engineers temporarily diverted water to determine how to best preserve the integrity of the natural wonder. This water diversion gave visitors the chance to see the exposed rock, absent of the roaring water. The barrier was removed a few months later, sending the water thundering again.

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