Niagara Falls Never Freezes Over

ENVIRONMENT

Despite sensational media reports, the falls aren’t going to freeze solid. (National Geographic)

Download and print your own coloring page of Niagara Falls.

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit, including today’s MapMaker Interactive map.

Although ice regularly forms on riverbanks and ice floes on inflowing Lake Erie are not uncommon, the Niagara River never really stops falling.
Photograph by DéRahier, courtesy Wikimedia. CC-BY-SA-3.0

Download and print your own coloring page of Niagara Falls here. In the winter, half of the “coloring” is done for you!
Illustration by Mary Crooks, National Geographic

Discussion Ideas

What is Niagara Falls? Take a look at today’s MapMaker Interactive map, as well as the “case study” in our resource on waterfalls for some help.
- Niagara Falls is the collective name for a series of waterfalls on the Niagara River, which straddles the Canadian province of Ontario and the U.S. state of New York. The three discrete waterfalls that make up Niagara Falls are Canadian Falls (also called Horseshoe Falls), American Falls, and Bridal Veil Falls. The two big waterfalls, Canadian and American Falls, are more than a kilometer (.62 miles) wide. Canadian Falls drops about 57 meters (188 feet) into the lower Niagara River.
- The north-flowing Niagara River drains Lake Erie into Lake Ontario. The dangerous drop of Niagara Falls prevents direct navigation between these two Great Lakes, but ships bypass the falls by way of the Welland Canal, part of the great St. Lawrence Seaway.
- Niagara Falls is a type of waterfall known as a block waterfall. Block waterfalls descend vertically from a wide stream (in this case, the Niagara River) over a blocky cliff. Other block waterfalls include Mosi-oa-Tunya (Victoria Falls), one of the “seven wonders of the natural world,” on the Zambezi River between Zimbabwe and Zambia; and Iguazu Falls, the largest waterfalls in the world, on the Iguazu River between Argentina and Brazil.
- Like almost all waterfalls, Niagara Falls is moving! The force of rushing water over the falls is eroding the rocks below. Niagara Falls has moved back more than 11 kilometers (7 miles) over 12,500 years! River management has reduced the falls’ current rate of erosion to less than a meter (1 foot) per year and could possibly reduce it to 1 foot per 10 years. Learn more about Niagara Falls geology here.

Why doesn’t Niagara Falls freeze?
- Physics. Freezing water requires colder temperatures as the volume and velocity of water increase. And there’s a lot of water at Niagara Falls, moving very quickly:
  - More than 168,000 cubic meters (6 million cubic feet) of water spill over the falls every minute during “peak daytime tourist hours.” The rapids above the falls reach a maximum speed of 40 kilometers per hour (25 miles per hour), with the fastest speeds occurring at the falls themselves—recorded at up to 109 kph (68 mph). Even with below-freezing weather, the temperature is never cold enough to freeze that amount of rapidly flowing water.

If the volume or velocity of the Niagara River was slowed or reduced, could the falls freeze?
- Yes! And it happened, once. In winter 1848, a huge ice jam on the upper Niagara River blocked all but a trickle of water from flowing to the falls. The tiny trickle froze, freezing the falls for several hours until the ice dam upstream was broken. We love this detail from the great Niagara Falls Marriott page: “Since the Falls always create a thundering sound while cascading over, the blockage resulted in silence around the falls.”
- Although the river below never stopped flowing, tourists and even shopkeepers used to enjoy a seasonal “ice bridge” connecting Canada and the U.S. After the sudden collapse of the ice bridge resulted in three deaths in 1912, most walking or climbing on the falls has been prohibited. (Exception: Two ice climbers became the first people to scale a frozen portion of Canadian Falls in 2015.)

Why won’t the flow of the Niagara River be slowed or reduced enough for the falls to freeze again?
- Booms and icebreakers—in other words, human activity. According to Quartz, “Each year, authorities deploy a long boom to restrain ice that would otherwise flow freely from Lake Erie into the river. That helps to keep hydroelectric intakes clear. Meanwhile ice-breaking ships work on breaking the backed-up ice into smaller pieces.”
  - Niagara Falls is kept flowing because the waters of the Niagara River are used by more than a million people.
    - Water from the Niagara River is used for drinking, hygiene, industry, fishing, and recreation.
    - Hydroelectric power plants on the upper Niagara River provide an important source of electricity for both Ontario and New York.