Niagara Falls, frozen over. For six months in 1969, engineers completely turned off Niagara Falls!
How do you turn off a waterfall? Take a lesson from beavers and build a dam, of course! Even the great Niagara Falls can be stopped, as seen in 1969 when a team of engineers from the US Army Corps of Engineers did so for 6 months.
What kind of monster could stop such an expansive waterfall? The temporary dam was 600 feet across and was made up of nearly 30,000 tons of rock! The dam diverted the water from the American to the Canadian side from June to November.
Being such a huge tourist attraction, it would take a lot for the decision to close it to be made. Rockslides had caused a significant buildup of rock at the bottom of the American side of the falls. The engineers dammed the falls to clear these rocks and to repair faults to prevent future erosion on the American side.
Let’s take a look at what this dam had to deal with. During its peak in early summer, as much as 225,000 cubic feet of water flow down the waterfall ever second! It once eroded three feet of rock a year and currently erodes one foot every year. Even with humans controlling the flow, it is estimated that the falls will cease to exist in 50,000 years when it meets its source: Lake Erie.